I want to boost a Quad 4 engine with an Eaton M62 supercharger 10 psi of boost. What OBD I ECM/PCM would be compatible with MAF fuel control, 7X crank trigger and waste spark or coil on plug? Or should I do this some other way such as speed density?
I want to boost a Quad 4 engine with an Eaton M62 supercharger 10 psi of boost. What OBD I ECM/PCM would be compatible with MAF fuel control, 7X crank trigger and waste spark or coil on plug? Or should I do this some other way such as speed density?
Welcome to the forum!
Sounds like you're working on a fun project. The same 1227749 that was used in some Q4 cars was also used with different code in the turbo Sunbird and Syclone. There are three variables that need to be changed to allow the distributor based $58 code to work with the quad 4 DIS module. Depending on which ecm you have now you might have an unused 1X signal from the ignition module after the swap.
I was hoping to go mass flow but the 1227749 with speed density look like it would work. The 4 cylinder is $58A. I downloaded the AKDB bin file. What variables need to be changed to make it work with the Quad 4 DIS?
I guess to go mass flow I could use the PCM and ignition from a supercharged Ecotec.
There is a definition file out there for the 95 J car 2.3. IIRC that's a speed density calibration also.
You could switch to OBDII pcm and use MAF sensor. Technically you don't need the cam signal for the engine to run. But what definition file would you use? J-car definitions seem to be the domain of HPTuner.
OBDI Saturns used MAF but agan, where to find a definition file?
The $58 code (it's really the same code, I4 or V6) has a few cool things built in. For example, if knock doesn't stop when timing is retarded, the ecm is programmed to add fuel then to reduce boost. And the ecm will control the boost control valve. I don't know of a MAF ecm for four cylinder that will do that.
The values to change are max advance, max retard, and reference angle. It's simple but not... Many definition files out there have the wrong conversions. And you want to know whether or not you're using a crank with the notches 10 degrees advanced, which would change the reference angle from 60 deg to 70 deg. If you have the correct stock calibration for your car I could likely pull the limits out of the file.
There's a working $58 definition file posted here: http://www.gearhead-efi.com/Fuel-Inj...ll=1#post26402 There's also some good discussion about the values that need changing.
There are also the options of non stock codes, such as code 59, and sAUJP. Both should support dis and 4 cylinder and boost. Not sure of MAF. Hope that helps
No need to re-invent the wheel. But we can make it better
I have gone the less DIY route and use Tunercat. He does not list a definition file for Saturns but he may have one. I'll checkOriginally Posted by 1project2many
Tunercat has a $58 defintion file for 6 cylinders and a $58A definition file for 4 cylinder so there has to be a difference in where the data is located or how it is scaled
The $58A AKDB calibration for a Sunbird has the following:
-spark reference angle = 6
-max advance relative to reference = 54.14
-max retard relative to reference = -5.98
The $A8 AXRM for a 2.3L W41 Quad 4 has the following:
-spark reference angle = 74.9
-max advance relative to TDC = 60.1
-max retard relative to TDC = -9.8
Curious that different references points are used. I guess that the 6 degree spark reference angle on the Sunbird is the spec for setting base timing with the distributor. The ECM needs to know this to compare the total timing to limits. So the max total timing limit for the Sunbird is 6 + 54.14 = 60.14 degrees BTDC and the minimum total timing is 6 -5.98 = 0.02 BTDC as compared to 60.1 and -9.8 for the Quad 4. Now if the spark reference angle is changed to 74.9 degrees to account for the reluctor notch location then the max advance and retard need to be adjusted by 74.9 - 6 = 68.6 degrees and the value for the Quad 4 max advance become 60.1 - 68.6 = -8.5 and the max retard becomes -9.8 - 68.6 = -78.4. Have I got this right?
Next step is to look at wiring diagrams and see how the ignitions are wired to the ECM's for a distributor vs a DIS system
Yes, that's how the math works. If you were to change only the reference angle to 74.9 the max negative limit would always be applied and timing would be "locked" at the wrong amount.Curious that different references points are used. I guess that the 6 degree spark reference angle on the Sunbird is the spec for setting base timing with the distributor. The ECM needs to know this to compare the total timing to limits. So the max total timing limit for the Sunbird is 6 + 54.14 = 60.14 degrees BTDC and the minimum total timing is 6 -5.98 = 0.02 BTDC as compared to 60.1 and -9.8 for the Quad 4. Now if the spark reference angle is changed to 74.9 degrees to account for the reluctor notch location then the max advance and retard need to be adjusted by 74.9 - 6 = 68.6 degrees and the value for the Quad 4 max advance become 60.1 - 68.6 = -8.5 and the max retard becomes -9.8 - 68.6 = -78.4. Have I got this right?
The ecm cannot create spark advance. Instead it is programmed to count off microseconds from the time it receives a reference pulse to the time it sends a spark signal to the module. The time calculation uses rpm and a constant that represents the number of crank degrees between each reference pulse along with a value that represents reference angle minus the ecm's desired timing after combining the relative constants and tables. For a distributor based calibration the reference angle is inputted as the distributor base angle and the code generates positive "desired spark" values. But the reality is that the EST pulse to the ignition module is delayed then delivered to the cylinder immediately following the cylinder that generates the REF pulse. On a 1-3-4-2 engine cylinder 1 generates the pulse that starts the timer to create spark on cylinder 3. This works because the rotor and cap have the job of directing spark and the ecm only needs to count time.
DIS is different. Reference angles are much greater with DIS, 60-70 degrees typically. The ecm math generates negative values for spark advance after subtracting the reference angle. What's interesting is that the ignition control hardware actually appears to change the time delay if the desired spark value is lower than -90 degrees.
Typically they are wired the same using the same four circuits and the same color wires. REF, EST, Bypass, and Return. Many Q4 engines used a 1X pulse signal in addition to the 4 common wires from the module. The 1X signal will not be used with the 7749.Next step is to look at wiring diagrams and see how the ignitions are wired to the ECM's for a distributor vs a DIS system
Well you learn something new every day. According to a Chilton I have, the ignition module is different for 92 and earlier vs 93 and later Quad 4. Both modules use a 7 notch reluctor integral to the crankshaft.
The earlier version ignition modules output 2 reference pulses (2X) for each crank shaft revolution. This would be the same as distributor crankshaft sensor with 4 teeth. This module also outputs a second (1X) pulse to the ECM which is driven by the "sync" notch on crankshaft reluctor. There are 5 wires that connect the DIS and PCM.
The 93 and later version outputs a 7X signal. I'm guessing it's just a pass through of the crankshaft position sensor pulses. There are four wires that connect the DIS and ECM
My Quad 4 has the first version. According to Chilton the 1X and 2X reference signals are both necessary to determine when to activate the fuel injectors. I think that this is because the Quad 4 is a hybrid of batch fire and sequential. The fuel injector are fired in pairs. Don't know why it was done this way - maybe emissions. Sounds like the 7749 is true batch fire and won't miss the 1X signal.
The early ignition module will work with the 7749. 7749 was used on the early Q4 cars. 1X signal is not required with 7749 and can be removed. The other 4 wires between module and ECM are mandatory.
Early system used a "start / run" module. The ignition module controlled spark during cranking and during certain ecm failure modes. The ecm would apply 5V to the bypass line when conditions were right for it to take over the job of creating spark and controlling advance. Later systems did away with the "start" portion of the module. ECM would deliver spark during both cranking and running.
The requirement to use 1X is because GM did some cool stuff and used both the 7749 and 8707 with the same calibration, AMDD. AMDD has code to detect which ecm it is installed in. The 8707 contains 1X detection circuitry and the 7749 does not. So omitting the 1X signal "back in the day" could mean the car won't start, or it could have no effect whatsoever. Better to say the signal is required.
The Q4 and the LT3 Turbo Sunbird both used "synchronous alternating batch fire" injection mode regardless of ecm. Injectors were triggered in pairs. There are other firing modes as well. Injectors can be triggered all at once through multiple fast pulses, or all at once one time per crank revolution, or all at once every other reference pulse.
There's a bunch of info that may or may not be interesting in this thread:
http://www.gearhead-efi.com/Fuel-Inj...RE-with-GM-ECM
This post explains a bunch of 4 cylinder DIS stuff.
http://www.gearhead-efi.com/Fuel-Inj...ll=1#post24934
I believe the $58A file displays a few different variables. The calibrations are the same. There used to be a Java application called Promgrammer that would let you change every single variable. It was the favorite tool for the SyTy guys. I have some pretty comprehensive definitions for Tunerpro and I can add variables if needed if you need to access something that isn't in Tunercat.Tunercat has a $58 defintion file for 6 cylinders and a $58A definition file for 4 cylinder so there has to be a difference in where the data is located or how it is scaled
1project2many,
Thanks for the reply and the links. Lots of good info.
Chilton say the 1X and 2x signals are necessary for fuel injector activation. I did elsewhere find info that says the Quad 4 fired one pair of injectors on the 1st notch and the other pair on the 4th notch. So it would need the 1X signal to know where the sync notch is. I don't see why that is necessary. It would be great if the 7749 could alternate pairs based on the 2X signal but all at once per crank revolution should work.
I emailed HPtuners inquired about using a P12 PCM from an Ecotec LSJ and got a cold shoulder big time - "We only work with OEM installations". So OBD II is starting to look pretty tough.
I downloaded an AKDB calibration for the Sunbird from this forum. I'm mystified how there is enough fuel delivery for boost. The peak VE is 89.1 at 4800 rpm which seems reasonable for this engine. The boost multiplier table has the following
kPa Multiplier
90 1.0
100 1.0
110 1.023
120 1.063
130 1.102
140 1.102
150 1.102
160 1.102
170 1.102
180 1.102
190 1.148
I also have a calibration for a 1990 turbo 3.1. In that calibration GM fudged the VE's up at high kPa's so they were increasing fuel with both artificial VE and boost multiplier.
New to boost and just realized that the 2 bar MAP signal will do the heavy lifting as far as fuel injector pulse width is concerned. So the boost multiplier is like an increase in VE while in boost maybe to compensate for better exhaust gas purging with forced induction.
I was using a turbo sunfire ecm with code 59 on a LO Quad-4 in a 1985 fiero and seemed to work well enough. Drove it for some years till i blew a head gasket and found cracks in the head and block.
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