PCM Options for Supercharged 454 / 4L80E

[dave w]

I'm open to ideas to upgrade from a $85 to something / anything that can operate a Supercharged 454 / 4L80E!

dave w

[93V8S10]

ELB running engine with piggybacked 7427 (or equivalent) running $0D modified for 4L80-E; or $0E/$31; or one of the trans only masks, controlling the transmission.

[dave w]

I did not know EBL would operate 2 Bar / 3 Bar MAP. That is good to know!

dave w

[Six_Shooter]

Or a 1227730/1227749 running $58/$59, with the aforementioned 16197427, or a stand alone tranny controller.

[dave w]

The vehicle is a 93 Chevy C3500 Dually, which has a 16147060 PCM ($85), so the current PCM can be reused.

dave w

[1project2many]

Dave,

Although it's typical to think "boost compatible calibration" when adding a turbo or supercharger, the requirements are different for the two forms of forced induction. While a turbo is a load dependent device needing a more complex tune, a supercharger's boost is a simpler function of rpm and throttle position. Knowing at what minimum RPM the S/C is able to provide boost allows very sufficient tuning using PE mode values. Once minimum RPM is exceeded, the minimum TPS at which boost occurs increases as RPM increases. This continues to maximum compressor flow or maximum engine rpm, whichever occurs first. PE mode enable rpm should be lower than or equal to minimum boost rpm, and tps values should not be higher than minimum boost tps. Spark can also be scaled by rpm although if using a 1 BAR cal with 1 BAR sensor you may feel lost without load based adjustment. In this case look for a TPS based PE spark table and use negative values if possible to decrease spark as throttle angle increases in PE mode. If the PE spark tables are limited to 8 bits, a simple change in code from ADD to SUB solves the problem. A C3500 dually is a heavy vehicle and you should expect it to spend large amounts of time under high load. Use a conservative spark table and make sure the knock retard is programmed to pull more spark out quickly and to add it back in very slowly just in case there's a problem. If you have a way to monitor an external 5V signal you can use a 2 BAR MAP and data logging to plot a graph of boost by RPM and TPS for use in future fine tuning this vehicle. Alternatively you can switch to a 2 BAR MAP and re-scale the MAP based calibration values appropriately using the voltage - pressure curve for your sensor. Since the ecm / pcm is not responsible for controlling boost, there is no advantage to using a calibration with extra functions built in to limit boost. Since MAP can be plotted as a function of RPM and TPS, you will provide acceptable performance mapping out boost fuel and spark tables using an alpha-N strategy. And since this is a heavy vehicle which will not subject to the same herky-jerky reactions as a lightweight car with a high power engine, you won't have to worry about the need for high resolution tables and overlapping functions to smooth any transitions in driver input. Bottom line for me would be to use the same mask unless I didn't have access to enough tuning data in which case I'd choose $0D.

[dave w]

Dave,

Although it's typical to think "boost compatible calibration" when adding a turbo or supercharger, the requirements are different for the two forms of forced induction. While a turbo is a load dependent device needing a more complex tune, a supercharger's boost is a simpler function of rpm and throttle position. Knowing at what minimum RPM the S/C is able to provide boost allows very sufficient tuning using PE mode values. Once minimum RPM is exceeded, the minimum TPS at which boost occurs increases as RPM increases. This continues to maximum compressor flow or maximum engine rpm, whichever occurs first. PE mode enable rpm should be lower than or equal to minimum boost rpm, and tps values should not be higher than minimum boost tps. Spark can also be scaled by rpm although if using a 1 BAR cal with 1 BAR sensor you may feel lost without load based adjustment. In this case look for a TPS based PE spark table and use negative values if possible to decrease spark as throttle angle increases in PE mode. If the PE spark tables are limited to 8 bits, a simple change in code from ADD to SUB solves the problem. A C3500 dually is a heavy vehicle and you should expect it to spend large amounts of time under high load. Use a conservative spark table and make sure the knock retard is programmed to pull more spark out quickly and to add it back in very slowly just in case there's a problem. If you have a way to monitor an external 5V signal you can use a 2 BAR MAP and data logging to plot a graph of boost by RPM and TPS for use in future fine tuning this vehicle. Alternatively you can switch to a 2 BAR MAP and re-scale the MAP based calibration values appropriately using the voltage - pressure curve for your sensor. Since the ecm / pcm is not responsible for controlling boost, there is no advantage to using a calibration with extra functions built in to limit boost. Since MAP can be plotted as a function of RPM and TPS, you will provide acceptable performance mapping out boost fuel and spark tables using an alpha-N strategy. And since this is a heavy vehicle which will not subject to the same herky-jerky reactions as a lightweight car with a high power engine, you won't have to worry about the need for high resolution tables and overlapping functions to smooth any transitions in driver input. Bottom line for me would be to use the same mask unless I didn't have access to enough tuning data in which case I'd choose $0D.

The attached spreadsheet is from my 3rd chip in the tuning proces for the superchared 454 / 4L80E. It seems that at about 50% throttle position, the Kpa's are 100 or slightly more. The overall Lt Term average is 126.4 and the St Term average is 127.4 just a touch rich. I have a total of 34 knock counts, which I'm going to work on next. I like the idea of, "switching to a 2 BAR MAP and re-scale the MAP based calibration values appropriately using the voltage - pressure curve for your sensor." I've not used a 2 BAR MAP before, so I'm not sure what the voltage range is for a 2 BAR MAP (0v ~ 5v)? I'm thinking voltages about a certain value in the 2 BAR MAP would be positive pressure? Any input (link) on technical data for a 2 Bar MAP is greatly appreciated. I'm thinking I'm good on re-scaling the 2 BAR MAP data.

dave w

[EagleMark]

More than anyone ever needs to know about MAP sensors:
http://www.robietherobot.com/storm/mapsensor.htm

[dave w]

More than anyone ever needs to know about MAP sensors:
http://www.robietherobot.com/storm/mapsensor.htm

Thats what I needed! Now I need to redo the timing and fuel tables to the new values.

dave w

[1project2many]

Nice find, Mark. I've got similar data squirreled away here because I can never find it on the 'net when I need it.

Notice that the 2 BAR sensor pressure does not represent a simple scale of the 1 BAR value. It might be worthwhile to alter your definition file to accurately display MAP values for the 2 BAR sensor. Don't forget to check / adjust any trans tables and constants which are MAP based.

[dave w]

Here is what I'm thinking for a $85 2 BAR Conversion, see pic below. Currently the engine idles at about 40 Kpa. All feedback welcome!

dave w

[EagleMark]

Nice find, Mark. I've got similar data squirreled away here because I can never find it on the 'net when I need it.

Problem with the internet is when you go back the website and information is gone... when I find good stuff I save it all in a folder... but for now the chart he needed is here with a link...


Here is what I'm thinking for a $85 2 BAR Conversion, see pic below. Currently the engine idles at about 40 Kpa. All feedback welcome!

dave wYou and 1project2many seem to have your heads wrapped around this... other feedback is, did you ever get the adx I worked on, working? Gotta have data to do this. Don't think Datamaster does boost and I know it can't be custimized! Was it fianlly hooking up right and no glitch? Then some values are going to need to be changed to match 2 bar! In doing the TunerPro Look Up I found a few turbo and supercahrged adx files... Probably going to want to watch closely knock and if your lucky $85 adx may have retard. I changed the knock history table in my LT1 to spit out retard instead of knock counts and it gives me exact figure in cell to reduce.

:ttwwop:

[1project2many]

Dave, you've got the right idea with the chart for the two tables. The MAP voltage values in the table won't change, so the pressure they represent has to be adjusted. As long as you have a way to keep track of what your tuning you're good. I would probably get the definition file and ADX set up to show the correct values just to prevent a silly mistake but that may be because I've had more years to demonstrate to myself that I can actually make them. :) (I once accidentally set up a cal to enable lean cruise when in boost! I didn't hurt anything but it took a real effort to figure out why AFR was going leaner when the VE and PE tables were all set up for richer operation. )


Datamaster for $58 has checkboxes for OE 2 BAR cal or aftermarket 3 BAR cal. I wish it were more user configurable though. For $58 with DIS it doesn't display spark advance correctly. The displayed timing gets lower as spark advance increases! In order to get the correct values I have to subtract the reference angle from the displayed timing values. The result, without the sign, is the actual timing.

[dave w]

I seem to be having trouble with my digital camera. I've resorted to my cell camera.

dave w

[dave w]

Problem with the internet is when you go back the website and information is gone... when I find good stuff I save it all in a folder... but for now the chart he needed is here with a link...

You and 1project2many seem to have your heads wrapped around this... other feedback is, did you ever get the adx I worked on, working? Gotta have data to do this. Don't think Datamaster does boost and I know it can't be custimized! Was it fianlly hooking up right and no glitch? Then some values are going to need to be changed to match 2 bar! In doing the TunerPro Look Up I found a few turbo and supercahrged adx files... Probably going to want to watch closely knock and if your lucky $85 adx may have retard. I changed the knock history table in my LT1 to spit out retard instead of knock counts and it gives me exact figure in cell to reduce.

:ttwwop:

I posted some pics. I am using a TunerPro .xdf, and data logging with DataMaster TTS. As many of you know, I tune for hire. This is a tune I am hired to do, so the final decision to convert to 2 BAR is not mine. At this point, I don't know if the owner will decide to go 2 BAR or not? If every "Truck Magazine" had 2 BAR conversions articles for superchargers, then I'm sure the owner would buy into the idea. I'm thinking the owner will not want to "Guinea Pig" what must seem like a wild idea to someone who does not even have an email address? The vehicle owner uses the Dually to tow "Toys" to some remote areas. I'm thinking the vehicle owner wants any available "Scan Tool Technician" to be able to help, should a problem occur. I'm always willing to share the information from a tune, unless otherwise requested not to.

dave w

[1project2many]

Dave, I can understand your situation. Many good technicians won't want to get involved with that engine as soon as they see the S/C installed, and rightly so. No one wants to be held responsible when a good fix is made bad by incomplete, improper, or badly implemented prior work. And when it comes to custom tuning, I'm sure you're well aware that everything down to faulty brake light bulbs and bad music on the radio will be blamed on the computer and the tune once you make a single change. I've been there myself plenty of times. If I were trying to sell the MAP conversion I would sell it by comparing it to adding a set of high quality aftermarket gauges to a truck with factory gauges. The factory gauges are still there, but they're just not as accurate as the ones you're putting in. If he goes for the swap I'd make a simple 3 column chart to include for anyone using a traditional scan tool: "If your scantool show this kPa, or this MAP voltage, the real MAP is this." All other scantool readings will look normal. I'd give the guy a few copies of my card and I'd probably tape one to the ecm and another to the hood so tech support is available in case he's broken down. And I'd probably point out that he's already been a guinea pig by installing an aftermarket part on a computer controlled engine which is not understood by the computer. Again, that's if I felt making the sale was worth the effort.

Good luck.

[EagleMark]

Plus it's an OEM part used on factory turbo and supercharger applications! It looks the same and will mount the same and plug in the same...

I'm curious what the manufacturer of the Supercharger says about tune after installation?

[dave w]

Dave, I can understand your situation. Many good technicians won't want to get involved with that engine as soon as they see the S/C installed, and rightly so. No one wants to be held responsible when a good fix is made bad by incomplete, improper, or badly implemented prior work. And when it comes to custom tuning, I'm sure you're well aware that everything down to faulty brake light bulbs and bad music on the radio will be blamed on the computer and the tune once you make a single change. I've been there myself plenty of times. If I were trying to sell the MAP conversion I would sell it by comparing it to adding a set of high quality aftermarket gauges to a truck with factory gauges. The factory gauges are still there, but they're just not as accurate as the ones you're putting in. If he goes for the swap I'd make a simple 3 column chart to include for anyone using a traditional scan tool: "If your scantool show this kPa, or this MAP voltage, the real MAP is this." All other scantool readings will look normal. I'd give the guy a few copies of my card and I'd probably tape one to the ecm and another to the hood so tech support is available in case he's broken down. And I'd probably point out that he's already been a guinea pig by installing an aftermarket part on a computer controlled engine which is not understood by the computer. Again, that's if I felt making the sale was worth the effort.

Good luck.

The technical information exchange about converting the Supercharger to a 2 BAR MAP is good stuff. I'm in hopes others find the exchange of information on a 2 BAR MAP conversion useful. I really appreciate the input 1project2many!

I'm not going to get rich by selling and servicing EFI Systems, but it helps support my "Toy" addiction. I sure can't quit my "day job" on the few sales I get each month. Ultimately, I'd like the vehicle owner to have a good tune. Seems the best option available for a good tune is a 2 BAR MAP conversion.

dave w

[JeepsAndGuns]

Not to hijack the thread, but as always, I want to learn a little here. I understand what a 2bar map sensor is.
From what I am reading, swapping to a 2bar map sensor is about the only real hard part that needs changed when going to forced industion? Since the 2 bar has the same output signal (if I am reading this thread correctly) then the only real mod to the code or tune would be whatever is needed for the fuel and spark parameters? I was thinking there was a lot more to it than that. I thought you had to use a forced induction specific ecm/pcm, and a forced induction specific cal/bin.
So again unless I am misunderstanding it, all thats really needed is to edit the XDF to display the correct map numbers in place of the old numbers?
I'm still a noob and still learning.
I have had a few dreams of installing two small turbos on my engine, one on each header. (where the little smiley that sets there and drools...lol)

[dave w]

Plus it's an OEM part used on factory turbo and supercharger applications! It looks the same and will mount the same and plug in the same...

I'm curious what the manufacturer of the Supercharger says about tune after installation?

NOTHING about tuning!

The Supercharger Manufacture recommends more fuel, recommending fuel pump upgrade and adding an adjustable fuel pressure regulator!

dave w

[dave w]

Not to hijack the thread, but as always, I want to learn a little here. I understand what a 2bar map sensor is.
From what I am reading, swapping to a 2bar map sensor is about the only real hard part that needs changed when going to forced industion? Since the 2 bar has the same output signal (if I am reading this thread correctly) then the only real mod to the code or tune would be whatever is needed for the fuel and spark parameters? I was thinking there was a lot more to it than that. I thought you had to use a forced induction specific ecm/pcm, and a forced induction specific cal/bin.
So again unless I am misunderstanding it, all thats really needed is to edit the XDF to display the correct map numbers in place of the old numbers?
I'm still a noob and still learning.
I have had a few dreams of installing two small turbos on my engine, one on each header. (where the little smiley that sets there and drools...lol)

The original thinking of this thread was to install forced induction specific ECM / PCM. Possibly the "Best Option" is to upgrade ECM / PCM. The idea / option of converting the current PCM to use 2 BAR was an excellent idea from 1project2many! Like mention earlier, all vacuum / Kpa parameters will need to be re-calibrated to a 2 BAR scale. Ultimately, converting the PCM to use a 2 BAR MAP has trade-offs in drive ability. I personally would like a VE / Timing table extension for the Boost and still use all the original VE / Timing table for natural aspiration!! Loosing about 1/3 of the VE / Timing table for boost will only hurt overall drive ability.:mad1:

dave w

[EagleMark]

As fast as that PCM is? I doubt it...

[dave w]

As fast as that PCM is? I doubt it...

Good point, but I'd like having the faster computer speed (compared to a 7747) through out current VE / Timing tables of the '7060 Natural Aspriation and expand VE / Timing tables for boost.

Typically a day at the "Dyno" in my area is about $500. I honestly don't know what a 2 BAR conversion is really worth? How can someone compare prices for such a conversion and be fair in pricing? Honestly, if it was my money I would not venture into a 2 BAR conversion without including a PCM / ECM upgrade. Currently I'd favor Dymanic EFI for the ECM upgrade, and use the original '7060 to control the 4L80E. The "Catch 22" is a PCM / ECM upgrade is not "Scan Tool Technician" friendly.

dave w

[EagleMark]

$OE would be?

[1project2many]

NOTHING about tuning!

The Supercharger Manufacture recommends more fuel, recommending fuel pump upgrade and adding an adjustable fuel pressure regulator!

dave w

I've been through something similar. The customer did a no-no and improved the airflow of a stock 8.2 by changing cam and having head work done before adding the S/C. S/C maker refused to give any help... S/C system is designed for stock engine period. I asked for injector flow... "Proprietary." Silly... numbers were on outside of injector. I also asked about mfgr adjusting separate controller PW for fuel based on dyno readings. "Nope." I even threatened to pull the controller apart and make changes myself. "It's encoded and you can't read it." I didn't buy that story but it was ultimately the customer's decision and he didn't want to upset the S/C maker. About a month later he called to tell me he'd burnt a valve and was replacing the non-stock components with stockers. All because one company didn't want to play ball.


Loosing about 1/3 of the VE / Timing table for boost will only hurt overall drive ability.
For this application you would likely be ok. The weight of the vehicle and relatively slow changes in speed won't require high resolution tables to correct for transients. It is possible to rewrite the VE and fuel tables to make up for some lost resolution.

The 2 BAR calibration conversion without XDF and ADX file modification should be a 2 hr job. Changing the MAP sensor and modifying the connector probably won't require an hour's labor. Additional tuning cost depends on how much time is required.

[dave w]

Here are more pictures for Mark.

As for tuning, I have driven the vehicle 4 times now, for a total drive distance of about 80 miles. Time in Excel and time for the Test Drive for each tune is about 1 1/2 hour ~ 1 3/4 hour. About 8 hours total for now. The pictures show I'm just about done.

1project2many
I really appreciate the input that the old '7060 PCM is most likely good enough for the 2 BAR Conversion becase the vehicle is a C3500.

dave w

[EagleMark]

Here are more pictures for Mark.
dave wI know you can tune! Just wanted to see the cool rig! :thumbsup:

But now that I look at data to 100 KPA what does fuel do at 110 and up? Are you just making sure it does not go lean? I've never tuned boosted so with out 2 bar map data I wouldn't know what to do as your data is only showing no boost? So your VE at 100 kpa has to handle 100 kpa up to? that does not sound like a good idea compared to doing the 2 bar thing which would give VE/BLM 100 kpa up as well.

I think if your customer knew 2 bar MAP was factory part and bolted in, but gave tuning ability from 100kpa up it would be a no brainer. He may do it next time after he melts a motor towing toys up a 8 mile 4-6 % incline...

Do you know for sure there's no drop in fuel pressure high load? hope he's got exhaust temp gauges for right and left side.

[dave w]

I know you can tune! Just wanted to see the cool rig! :thumbsup:

But now that I look at data to 100 KPA what does fuel do at 110 and up? Are you just making sure it does not go lean? I've never tuned boosted so with out 2 bar map data I wouldn't know what to do as your data is only showing no boost? So your VE at 100 kpa has to handle 100 kpa up to? that does not sound like a good idea compared to doing the 2 bar thing which would give VE/BLM 100 kpa up as well.

I think if your customer knew 2 bar MAP was factory part and bolted in, but gave tuning ability from 100kpa up it would be a no brainer. He may do it next time after he melts a motor towing toys up a 8 mile 4-6 % incline...

Do you know for sure there's no drop in fuel pressure high load? hope he's got exhaust temp gauges for right and left side.

All the reasons above are why this engine needs either a different PCM / ECM capable of controlling boost , or a 2 BAR Conversion. For now I have spiked the VE tables for 90 Kpa and 100 Kpa into the mid 90's an attempt to avoid a melt down. The one bar map only goes up to 103 Kpa! It's just a guess spiking the VE tables will prevent an engine melt down. All the 100 Kpa timing tables all below 15 degrees. Knock counts are down from 34 to about 10 or so. The latest tune has even less 100 Kpa timing.

dave w

[EagleMark]

I agree! And if he refuses to do it properly you should remove your tune, leave it stock and walk away. Or? You need a signed waiver that you are not responsible for melted engine! Because he does not want to replace PCM and 2 bar to tune correctly. Right now it's just a guess and closer to not melting. This is a tow rig for toys and the location dicatates he may haul over Snoqualmie pass! That's a long uphill haul to be running a guess tune under boost hauling a load!!! Tuned properly he will find cooling system issue first.

Why bother 2 bar on that PCM? OK it could be done, but wouldn't it be better with one of your 427 conversions with 2 bar added in $OE for the 4l80E, then you could do a proper tune developed for a well supported PCM... that could still be scan tooled anywhere, with notes on MAP readings and your card as suggested and he is covered anywhere.

Or do an internet search to find all the melted motors from that supercharger and no tune, print and show him what's not reported in magizines... the famous first twin turbo LS1 corvette in magizines is here in my town with a melted motor, that never made it back in the magizine. Motor is new but no one will touch it to tune, it's still sitting... looking pretty. 1000 hp does not last long without proper fuel... I calculated what he has for fuel and it's only half what's needed...

[dave w]

Here is what I'm thinking for a $85 2 BAR Conversion, see pic below. Currently the engine idles at about 40 Kpa. All feedback welcome!

dave w

I have revised my thinking on the chart posted in the above tread. The supercharger is rated for 6 psi boost, so I'm thinking the 2 BAR MAP will not show 5 VDC at 6 psi boost. I'm thinking the 6 PSI boost will have a maximum voltage of about 3.4 ~ 3.6 VDC from a 2 BAR MAP sensor. That's not really a good range of voltage for tuning from 20 Kpa to about 140 Kpa.

dave w

[EagleMark]

:thumbsup: So if you tweak the adx for datalogging... you could tune it correctly! No changes needed in xdf or 2 bar conversion. Then the vehicle could be scan tooled anywhere as stock! Scan tool would not notice VE or spark tables were changed. Unless they drove and recorded/compared data to compare spark curve may be differant. But the owner should have told them by then it is differant. But he is safe on road to get repairs at any shop if a code light comes on or sensor goes bad etc...

So in adx 100kpa (usually 4.5 to 4.8 volts) get's changed to 140 and then work down however you choose. Like 70 becomes the old 100. Only you and your adx would know what goes in cells on bin by useing the adx table. Bin and xdf look stock but are tuned correctly to 140kpa

No that won't work because everthing from 100kpa to 140kpa would still be in last column, 5 volt..., but it could still work with 2 bar becaue it works with vacuum and positive pressure and changing adx ! Last couple rows of that chart you take out of equation because my suburban MAP is 4.45 volt at 94.14 key on engine off, may be because I'm at 2000 feet elevation. But slipping in a 2 bar and a reworked adx would give you data you need at boost. Split the other cells down to 20 map or where your bin goes down to. So that takes out first few rows of chart. Now if you look at chart with out first 2 rows and last 2 rows it's pretty close to same amount of cells to tune in bin. If the ADX is like many in increments kpa by 5 at lower load then by 10 at higher load and your only loosing a couple readings as far as how many cells Only you would know what cell to tune in bin from adx chart!

[gregs78cam]

I actually thought about trying this out a year or so ago. And aside from losing a little bit of resolution in the timing, and VE tables I think it should work.

[dave w]

Mark,
I think your getting the idea of how a .bin could be re-calibrated for 2 BAR MAP with a range of 20 Kpa ~ 140 Kpa.:thumbsup: The 2 BAR MAP will more than likely produce voltages from about 0.02 ~ 3.50 Volts. Positive PSI (Boost) voltages will start at about 2.50 Volts. The Timing and VE Tables are going to be divided by Voltage vs. RPM. The data logs I have now, will be used to construct a baseline / comparision for the 2 BAR MAP Voltages vs. RPM.

What I really dislike about this PCM is with a Supercharger, the Vacuum Tune will be based on voltages from 0.02 ~ 2.5 volts which is half the voltage range (0 ~ 5 volts) that is currently used for 0 ~ 100 Kpa. The Boost Tune will be voltages from 2.50 ~ 3.50 volts starting at 100 Kpa ending at 140 Kpa.

For VE the '7060 has 12 cells, so the 2 BAR MAP would split the 3.50 volts by 12 cells. For Timing the ' 7060 has 15 cells, so the 2 BAR MAP would split the 3.50 volts by 15 cells.

If anyone is interested, the Excel spreadsheet I posted earlier has the data sorted by KPA / RPM with 0 ~ 5 volt readings; so it would be possible to make a 2 BAR MAP baseline of their own.

dave w

[dave w]

So I was thinking about GM vehicles with superchargers and maybe some of the supercharged vehicles used a MAP? What I'm wondering is if the MAP sensor for OEM superchargers are calibrated 0 ~ 5 volts / 0 ~ 150 Kpa instead of 0 ~ 208 Kpa? I can't find any tech info on GM part # 12580698, 12580698, or 12615136. It would be nice to get some better resolution for a 2 BAR MAP Conversion.

dave w

[Six_Shooter]

ALL GM MAP sensors that I have seen work on a 0-5V range.

1 BAR - 0 to 100 KPA
2 BAR - 0 to 200 KPA
3 BAR - 0 to 300 KPA
(high figures are rounded)

You would have to use a non GM MAP sensor to get other ranges, like 1.5 BAR or 2.5 BAR MAP sensors to get more resolution, but being able to see that little bit of positive intake pressure. You would have to investigate the transfer function of each to make sure they will read correctly.

My concern with using a 2 BAR MAP in place of a 1 BAR MAP is the key on BARO settings, this is where I wish I knew more about the actual programming language to account for that, I have a few codes that I'd like to add 2 BAR support to.

[1project2many]

Today's constant technology improvements make it seem like you need more/faster/better to get any job done. It's very easy to lose perspective. A 10,000 lb+ truck using an engine with a fairly mild configuration is not demanding high resolution tables, extremely fast processor speeds, or a large amount of concern over the ecm's inability to be a new, modern controller. Here are some considerations:

1) All GM vehicles using a Delco 2 BAR sensor at least until the introduction of the Ecotec 2.0 S/C engine used a 5V signal. This signal is sent to an 8 bit A/D converter and even some of the the newer, faster processors used an 8 bit a/d converter. It is the converter, not the sensor voltage range, which ultimately determines the resolution available from the sensor.

2) The turbo Sunbird, GMC Syclone, and Turbo Grand Prix all used less than the full range of the MAP sensor from the OEM. All can all be tuned extremely well using this sensor given enough time. One individual I know rewrote the code in his TGP to accurately calculate air usage and fuel requirements within 1% using the OEM MAP.

3) The 6.5 turbo diesel engine commonly used in trucks in the 90's and up to 2002 in vans typically runs less than 8 psi with the 2 BAR MAP. This 68HC11 equipped pcm controls transmission, boost, injection pump timing, and fuel volume in GM's first big "drive by wire" application.

4) My 2.2 powered Cavalier turbo was the worst combination of parts, just to prove a point. Too small turbo, non-intercooled, over 9:1 compression, 87 octane fueled, manual transmission, massive injectors. My wife (who drives like a granny) used that car daily for several years without troubles. From the driver's seat it seemed 100% like an OEM vehicle except that it had a bunch of extra power. It even got better than stock mileage as long as you stayed out of boost.

5) My Sunbird is running 17 psi using a 3 BAR sensor, same 8 bit resolution A/D, same OE spark and fuel tables (re-scaled of course) and a manual transmission. That car is so driveable that no one I've loaned it to wants to give it back. This despite the naysayers who claim switching from 2 BAR to 3 BAR will cause driveabliity due to lost resolution.

6) My friend's Sunbird is over 24 psi now using the same 3 BAR sensor. I was able to tune it to be mild in town and extremely driveable even though the entire combination started as an untamed ride that would break tires free at the smallest throttle increases. It's so driveable in fact that the owner has asked me if I can but some of the agressiveness back so it's like the cars he had in the '70s. What a challenge... build a tune to mimic "Snotrod."

6) The _only_ times that I've had a need for more than OE ability was in vehicles with rapid engine response and cams having large overlap. And this is when trying to make them extremely mild and driveable around town then behave like monsters if asked. OE calibrations don't do well with rapid decel / rapid accel transitions, especially in the AE area. Time and again that's become a hurdle I've had to work around, generally de-tuning the car slightly to make up for lack of capability to get AE right. If there were anywhere I'd ask for a bunch of resolution, it's AE.

[gregs78cam]

I agree, the loss of resolution should not make much of a difference because the RPM will change faster than the Kpa, in the lower gears and the PCMs ability to interpolate between cells chould make up for a lot. Also AE and PE should be able to cover up a lot of the left over inaccuracy.

[1project2many]

BARO readings are taken at key on, engine off. Many cals will update BARO when in WOT for a period of time when temp and other conditions are right. Skipping BARO update at WOT is generally a fairly easy matter.

FWIW $58 / $59 turbo code has poor support for BARO. GM decided there is no appropriate time to read BARO from the MAP when the engine is running so they used a calculated BARO update based on the stock engine / vehicle configuration and the KOEO BARO reading. If the base vehicle configuration is altered in any way the BARO updates are no longer correct. Additionally, the BARO readings at KOEO are not updated if crank voltage is not within a specific window leading to a default BARO reading being used. One method I've thought of to provide BARO updates with a turbo calibration is to use TPS, boost, rpm and rate of change, and the filtered vs current MAP values. For a given turbo engine, turbo contribution will be minimum below a specific rpm. If WOT exists for a certain time, engine rpm is below the threshold, rpm is increasing less than a specific amount, and filtered MAP matches current MAP, then use the current MAP to update BARO. Correctly implemented this limits BARO to occuring when turbo contribution is zero. Of course the easier way from a code standpoint is to simply poll a dedicated BARO sensor if you have a spare 5V input.

Hmm.... maybe a binary output used to briefly switch the MAP signal line to a BARO sensor is a practical solution. Instead of waiting until WOT simply watch for TPS below max value and TPS change to be near zero for a set time. Switch signal to BARO, get reading, switch back. If any TPS is detected immediately switch signal to MAP and exit routine.

[gregs78cam]

I was going to add the part about wiring in a second MAP for Baro, and then write the code to check that sensor when in DFCO, because there would be real need for the MAP reading at that time.

[dave w]

The vehicle owner has accepted delivery of his vehicle after a very comprehensive test drive. The vehicle owner is very satisfied with the tune. The vehicle owner declined all upgrade options that were exchanged in this tread.

I'd like to thank everyone for the input provided on the options to better tune this vehicle.:wtg: I hope that the knowledge shared within this tread is a benefit to all.

dave w

[EagleMark]

Glad he's happy!

I thought this was a very interesting topic and learned a lot! :thumbsup:

[1project2many]

To turn a phrase,

If it drives good, it is good.

Maybe the next guy will spring for the whole shebang.

[TravisMartin]

I'm always willing to share the information from a tune, unless otherwise requested not to.

dave w

How did this turn out? I'm brand new here, and to EFI mods, and have a project underway that would benefit from your experience. I'm putting a '95 TBI 454/4L80E into my '78 C10 shorty. I'm confident I can handle the hardware and wiring end, but not so much on tuning. I'll start with the stock '95 tune to sort out the conversion, but I have a Whipple kit waiting in the wings that I'd like to add to the mix, so I could sure use some pointers. How did the customer's dually turn out?

Thanks!

Travis

[dave w]

How did this turn out? I'm brand new here, and to EFI mods, and have a project underway that would benefit from your experience. I'm putting a '95 TBI 454/4L80E into my '78 C10 shorty. I'm confident I can handle the hardware and wiring end, but not so much on tuning. I'll start with the stock '95 tune to sort out the conversion, but I have a Whipple kit waiting in the wings that I'd like to add to the mix, so I could sure use some pointers. How did the customer's dually turn out?

Thanks!

Travis

The Dually owner only contacted me once after accepting delivery, he was selling the Dually without the supercharger and wanted a stock chip.

Hindsight being 20/20, I would recommend using a Dynamic EFI system for boost: http://www.dynamicefi.com/EBL_Choice.php

dave w