95 LT-1 Idle Cell Comparison - Humidity?

[Terminal_Crazy]

Had a chance to do some tuning on the off-idle trims today. Unlike closed-throttle trims which seemed to be best when running very close to the fairly aggressive factory tune, it seems with this cam and the EGR it develops at low speeds a tamer set of trims is better.

closed	stock	open	stock
1-83	82	83	88
8-7e	7D	81	7B
4-86	80	81	83
3-80	80	80	83
6-88	84	81	7A
5-7f	80	7e	7D
7-75	74	7e	7E
2-86	83	84	86

I tried running the stock trims, but when I attempted to adjust for BLM split (lean on the right side again) a very noticeable surge / hard miss developed at low speeds and throttle openings. Even at 75mph in 6th with the cruise control on the engine was noticeably "unhappy" at lower loads.

The open trims above are much smoother tooling around town, and even improved overall smoothness when lugging the car up a hill in 6th gear at 1300 rpm. Something I've been unable to do since putting the stock cam in storage.

Startup fueling has been all over the place, but it's getting to be the time of year when this one will spend most of the next 4 months sitting in the garage so I should have plenty of time to work on that. I'm hoping this winter it will spend markedly less time sitting on stands with a major powertrain component absent.

Hiya
How did you calculate those Open throttle figues?
Closed throttle seems relatively straight forward.

Is there any easy way to display these in TunerPro in an easier to view format?
as in cylinder layout

1 2
3 4
5 6
7 8

I'm unable to tune currently. It's cold (icy) wet and dark.
My Speed Engineering Y pipe has arrived as my mate can't bend over 63mm pipe.
Winter project is Speed Engineering Long Tubes & dual cutouts.
All will be Thermal Barrier Ceramic coated once I just get my workspace set up.


Thanks
Mitch

[spfautsch]

How did you calculate those Open throttle figues?

That was merely a wild guess based on the trims I was running before reverting to something closer to stock. It's more or less 128 / 0x80 / 1.00 with a small bit more fuel on the right bank and then slightly less on the back cylinders (7 & 8) and slightly more to the front (1 & 2).

Is there any easy way to display these in TunerPro in an easier to view format?
as in cylinder layout

Not that I'm aware of. Honestly I had committed the small block chevy firing order and bank assignments to memory before I had fully developed facial hair, so representing them in firing order makes perfect sense to me. But having been forced at gunpoint to work on a modern ford v8 I can understand how it would be less than intuitive. When the ECM tells you there's a misfire on #7 I instinctively want to look at the left rear cylinder.

[spfautsch]

Anyone have an idea how the 12bf1 EOIT ramp out multiplier works? kur4o I thought you mentioned I should work on it when I'd tried decreasing EOIT with coolant temp.

In testing startup fueling I've been letting it come to temp at idle, and I believe I found something that could have been a factor with the really bad idle splits.

During warm-up when ECT hits 44c my O2s start to fluctuate - left moves around some but right goes dead lean. It stays this way until about 56c. This falls in line with the second EOIT transition - in the stock bin it's moving from 360* to 180*. Looking at some older logs, this lean condition didn't improve until around 65c. But the ecu had already switched to closed loop at 60c (which resulted in a massive split).

In looking at the disassembly I can't really tell what the ramp out multiplier does - I would presume it dampens the implementation of the EOIT value so as to not cause an abrupt shift in fueling, but I'm not sure what it's value represents. Whatever the case, it appears by what comments I'm seeing in the disassembly that the EOIT table data is interpolated only when transitioning to higher values (lower atdc degrees). It seems like the interpolation alone would offer adequate damping.

At any rate, I'm not sure there's any point to my questions - just looking for more information on how this all works.

I do however notice the possibility for a problem if the code transitions to closed loop at the "normal IAT" minimum closed loop temp (33c in base y-body tune). I'm moving that to 60c to match the "cold IAT" value in the 0x26e3 table,

[kur4o]

Anyone have an idea how the 12bf1 EOIT ramp out multiplier works? ,

From what I gather from experiments it is some kind of factor for graduate change of values. For example if you command a change from $20 to $40 it will slow down the change to by $01 each second. so the transition will takes place 40 seconds. That is only example. I haven`t test the actual rate with $10, nor I know in which direction the increase of it will take place, slowing or speeding the change.

There is 1 way to test it. Monitor the eside word_a9 while changing the EOIT target from end to end on the controller window with ignition on.
To do it open raw window in eehack, and loop in 50ms interval the command e4 ... 03 00 a9 00 aa , you will get a response with the word_a9.
Check how much it takes for the change. Than flash a bin with new 12b1f value, for example $20 and do the same test. Compare the results if it takes more or less time for the change to occur.

On ybody calibrations the timers for closed loop operations are set much lower. You can try increasing them if the engine doesn`t warm up fast enough.

At startup I found the it warms up best at pig rich condition o2 above 900mv, when running close to stoich at warm up, it run rough and you can feel some misses from time to time. I also played with idle spark and make a curve to change the spark during warm up.
I end up with that spark coolant temp corr table.

5.0    5.0    5.0    6.0    8.0    8.0    8.0    8.0    8.0    8.0    8.0    8.0    8.0    8.0    8.0
5.0    5.0    5.0    6.0    8.0    8.0    8.0    8.0    8.0    8.0    8.0    8.0    8.0    8.0    8.0
4.0    4.0    5.0    5.0    5.0    5.0    5.0    5.0    5.0    5.0    5.0    5.0    5.0    5.0    5.0
0.0    -11.0    -11.0    -11.0    -11.0    -11.0    -11.0    -2.0    3.0    3.0    3.0    3.0    3.0    3.0    3.0
0.0    -8.0    -8.0    -8.0    -8.0    -8.0    -8.0    -2.0    2.0    2.0    2.0    2.0    2.0    2.0    2.0
0.0    -6.0    -6.0    -6.0    -6.0    -6.0    -6.0    -2.0    2.0    2.0    2.0    2.0    2.0    2.0    2.0
0.0    -3.0    -3.0    -3.0    -3.0    -3.0    -3.0    -3.0    -3.0    0.0    0.0    0.0    0.0    0.0    0.0
0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0
0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0
0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0
0.0    0.0    0.0    0.0    -2.0    -2.0    -2.0    -6.0    -6.0    -6.0    -6.0    -6.0    -6.0    -6.0    -6.0
0.0    0.0    0.0    0.0    -8.0    -8.0    -12.0    -12.0    -12.0    -12.0    -12.0    -12.0    -12.0    -12.0    -12.0
0.0    0.0    0.0    0.0    -8.0    -8.0    -12.0    -12.0    -12.0    -12.0    -12.0    -12.0    -12.0    -12.0    -12.0

If you change that table beware that some xdfs can`t handle negative correction and zeroes the value when negative. I think I fixed it on the last xdf i posted here.

I plan to get the hotter thermostat also. Do you know a cross reference number for a Stant one.

[spfautsch]

There is also baro correction applied

...

The baro table runs from 53kp to 104.44kp and stock setting are -3 to 0* EOIT added to main EOIT table.

I've been thinking about this - is this adder before the 5.625 multiplier? If not it seems somewhat pointless.

The boiling point is reached when the vapor pressure of a liquid matches the atmospheric pressure. Raising the atmospheric pressure will raise the boiling point. Conversely, lowering the atmospheric pressure will lower the boiling point of the liquid.

This makes sense, except that at closed TPS evaporation will be taking place inside the port at well below atmospheric pressure. Makes me wonder if there's a closed throttle check happening before the adder.

On the subject of EOIT ramp out mulitplier:

There is 1 way to test it. Monitor the eside word_a9 while changing the EOIT target from end to end on the controller window with ignition on.
To do it open raw window in eehack, and loop in 50ms interval the command e4 ... 03 00 a9 00 aa , you will get a response with the word_a9.

Will this work with engine running or must it be off? I initially overlooked the words "with ignition on", tried with engine running and got the below error.

raw-command-dialog.png

Thinking about it, I assume this can't be done with engine in operation because it's on the e side?

[kur4o]

The boiling point lowers with lower atmospheric pressure. The only example I can think of is that you can`t boil eggs on a airplane`s high altitude since the water boils at much lower that 100*C temperature.
In high vacuum situation the fuel will boil and evaporate at lower temperature. I think that is also taken into account in transient fuel calculations and maybe that is the point of it. The evaporation rate of the fuel is not constant and that`s why the transient fuel routine only substract fuel, but never adds it. If that is somehow related with the camshaft events the lt4 transient calibration might be set different.

is this adder before the 5.625 multiplier?

It is added to the calculated EOIT table value. This multiplier is not used by the pcm, it is only to convert the hexvalues to human readable degrees.

I assume this can't be done with engine in operation because it's on the e side?

Only with IGN on, engine OFF the eside talks on the bus. With engine on the pcm is too busy to handle aldl requests.

[spfautsch]

This multiplier is not used by the pcm, it is only to convert the hexvalues to human readable degrees.

So the -3 would be a raw value, and would change eoit by ~17 degrees. That makes sense.

Either way, with a base at 0x50 or 270 ATDC that seems like a fairly small amount of evaporation time for aluminum heads based on our sweep tests.

It does give me another variable to go back and look at though - I didn't pay attention to baro when I generatd my sweep test data.

[Terminal_Crazy]

In testing startup fueling I've been letting it come to temp at idle, and I believe I found something that could have been a factor with the really bad idle splits.

During warm-up when ECT hits 44c my O2s start to fluctuate - left moves around some but right goes dead lean. It stays this way until about 56c. This falls in line with the second EOIT transition - in the stock bin it's moving from 360* to 180*. Looking at some older logs, this lean condition didn't improve until around 65c. But the ecu had already switched to closed loop at 60c (which resulted in a massive split).

Yes I've posted this previously a good while back.
Consistantly around 44C to 56C the RHS O2 flatlines.
The AFR gauge also leans out and car runs noticably rougher.
This is still in OL as I don't go CL until about 70C.

I've never found the cause. ( 3 sets of injectors have all done it).
at around 56C it seems to come back on line.

Another oddity I've mentioned before & nobody has answered...
Frequently noticed, I've had the car idling ( may not have been very hot, but certainly above 80C).
BLM's on one side would go up by say 5 points in several seconds.
The other side generally followed with 20-30 seconds

Mitch

[kur4o]

Consistantly around 44C to 56C the RHS O2 flatlines.

Mitch

It is the transition region of the EOIT target and could be related for sure. Maybe setting the transition to happen at higher temperatures can cure it some.

I have also experienced some flatlines of 02s and tried alot of stuff fixing it with no positive results. I suspected exhaust leak and tried adjusting the maf curve also. It could be of the cold 02s not reading right but wideband agrees too.
I will try to dig some logs and check the coolant temperatures.

[spfautsch]

kur4o your inbox is full. Thanks for the suggestions on monitoring the EOIT change - I'll try to give it a shot when I have a chance and report back.

On ybody calibrations the timers for closed loop operations are set much lower. You can try increasing them if the engine doesn`t warm up fast enough.

I just put my CL enable temp to 60c, and may go higher. I can't imagine why they would have even attempted to jump to closed loop at 33c, it seems absurd at that cold of an operating temp.

I also played with idle spark and make a curve to change the spark during warm up.
I end up with that spark coolant temp corr table.

I noticed this and will probably try to do the same once I have startup tables figured out. The reason behind this is that richer mixtures support faster flame front propagation (burn faster) so require less spark advance. The harshness you feel with lots of advance during warmup is cylinder pressure peaking sooner than is optimal (10-18 atdc depending on stroke and connecting rod lengths). This is another side-effect of the EGR developed by the cam overlap - at operating temps (and resultant leaner fueling) much more spark advance is needed because of the mostly inert (i.e. devoid of oxygen) exhaust gas diluting the charge.

I plan to get the hotter thermostat also. Do you know a cross reference number for a Stant one.

Sorry, I don't but will try searching for you. Unfortunately this is an alternate temp t-stat so Stant may not make one with this wax motor and in this size. If possible, try Amazon. Autozone sells this MotoRad piece rebranded as Duralast part # 15397. Or if nothing else works, if you PM me your address or that of a friend I'd gladly ship you one.

Another oddity I've mentioned before & nobody has answered...
Frequently noticed, I've had the car idling ( may not have been very hot, but certainly above 80C).
BLM's on one side would go up by say 5 points in several seconds.

I've never seen both sides jump like that, but have seen it on my right side. The only suggestion I can make is to keep in mind if you can hear any lope from your cam, what you're hearing is a misfire. And when the engine misses raw fuel gets into the exhaust which causes the O2s to read lean. And that causes the CL PID logic to add fuel when no additional fuel is needed. Perhaps the problem then "snowballs" due to the raw fuel.

I'm seeing this now with my EOIT at 0x68-0x69. I've found that when it's at 80c and higher the BLMs are adding 3-7% on both sides (134L, 137R is fairly common), and the raw fuel smell gets a bit worse. But as long as it continues to idle this smoothly at 800 RPM I honestly couldn't care less. As we all know, bigger cams like to run rich. I may just put my cats back on and call it good.

I've also noticed that the CL PID loop seems to be biased towards rich. In other words it is more eager to add fuel to compensate for a perceived lean condition, than it removes fuel due to a similar rich condition.

Edit: kur4o - I've also noticed what I think you've mentioned with tuning startup fueling. I've found if I shut the engine down when not at full operating temperature, and especially when not also in closed loop - the amount of fuel left in the ports dramatically changes how the next startup goes. I'm trying to develop a methodology for tackling this, but it seems like it's going to involve letting the engine sit idle (not running) for 2-3 days between tests, and bringing it up to full operating temp each time before shutting it down.

[spfautsch]

I've found a Stant 45967 and Gates 33747S that are close, and are shown on another vehicle application that uses the Motorad part (2004 Nissan 2.4L).

The only problem I see with them is they appear to have smaller primary disk openings and the bypass disk stem (on the bottom) is about 2.5mm shorter than the one called for. The Motorad is only about 1mm shorter. This means the bypass may not close completely when the thermostat is open. Probably wouldn't cause any trouble, but I'd prefer the Motorad piece.

[LeMarky Dissod]

I've found a Stant 45967 and Gates 33747S that are close, and are shown on another vehicle application that uses the Motorad part (2004 Nissan 2.4L).
The only problem I see with them is they appear to have smaller primary disk openings and the bypass disk stem (on the bottom) is about 2.5mm shorter than the one called for. The Motorad is only about 1mm shorter.
This means the bypass may not close completely when the thermostat is open. Probably wouldn't cause any trouble, but I'd prefer the Motorad piece.

https://www.z28.com/threads/thermost.../#post-1590316

… The [LT1] thermostat does two things.
The first is to control the coolant coming from the radiator to the pump. The second (the lower disk) cuts off the bypass route that the coolant takes when the thermostat is closed.
When the thermostat is cold/closed, the coolant flows continually through the engine without going to the radiator. That way the thermostat gets an accurate reading.
When the thermostat opens, that path is closed off and all coolant goes through the radiator. Without a thermostat installed, some of the coolant will go back to the engine without going through the radiator.

Besides MotoRad & Stant, I can't think of any other brand names whose thermostats I'd trust.LT1 H2Opumps need LT1 thermostats.

[kur4o]

I've found a Stant 45967 and Gates 33747S that are close, and are shown on another vehicle application that uses the Motorad part (2004 Nissan 2.4L).

The only problem I see with them is they appear to have smaller primary disk openings and the bypass disk stem (on the bottom) is about 2.5mm shorter than the one called for. The Motorad is only about 1mm shorter. This means the bypass may not close completely when the thermostat is open. Probably wouldn't cause any trouble, but I'd prefer the Motorad piece.

Thanks for the part numbers. Does the stock gasket works fine with the 2028?
I also investigate the matter through rockauto and made a list of 2028 interchange part numbers with different open temp and applications. From what I gathered as info, The lT1 thremostat is the same overall dimension as the sbc 94-00 but flows more due to enlarged opening. Too bad delco doesn`t make 170* one.

The main question is, will the 2028 flows enough or should I keep the 160* one and do the cardboard thermostat mod. While searching I also found that the nascar guys target 200-210*F as the best temperature for the combustion process. Completely in par with the most fan settings 100*C-on 95*C-off pre obd2 emission standarts.
Somehow I nailed the temp down with 93*C low and 96*C high.

The reverse flow cooling system might change the Nascar equation and the optimal for lt1 could be 90-93 *C. STill needs experiments to confirm.

For startup test you can always clean the left over fuel with some starter time and injectors fuses off. Nailing down the pedal above 80% tps also stops fuel from being sprayed.

I make some test with hot restarts. First hot restart is always good. Second is almost good and on the third I have long cranking. The test was made with 4-5 seconds run time.

It could be subjective feel but when I adjust the fuel flow constant and return back to stock maf curve, the engine run much much better even though the wideband and spark didn`t show any deviations. I also witness some real low map values.

I dig up 2 logs where 02s flat drop from 50 to 53 *C, than recover with no apparent reason. I know for sure I have other logs too but can`t find them. In par with the EOIT target change from 44 to 56 degrees or 270* to 180* which interpolated is 225*-247.5* at 50-53*C. Really wierd.