Chevelle LS1 Swap Idle Issues

[LastCall]

Helping a buddy out with his ls1 swapped chevelle. I followed the idle tutorial and tips and tricks and it idles decent. Engine is a 99 ls1 with 4l60e and small cam.

The issue is this - when you first start the engine, it runs and idles fine. However, soon as you put it in gear. It either stalls or begins to stumble. If you give it a little gas when you go from park to drive, it is fine. And once in gear, it is fine. It is the initial park to drive/reverse, that either kills it or causes a stumble.

What should I be logging or what tables in the tune. I have attached a few logs and the tune that is in the car.

Any help would be greatly appreciated!!

[joecar]

Look at B4307 Desired Airflow -> In Gear


Also, you're logging too many pid channels, reduce the pid channel count to 24 or less (otherwise it misses some of the data frames, look at your TP signal for example).

[LastCall]

Look at B4307 Desired Airflow -> In Gear


Also, you're logging too many pid channels, reduce the pid channel count to 24 or less (otherwise it misses some of the data frames, look at your TP signal for example).

Thanks JoeCar!

I did RAFIG this afternoon, but the numbers seem off. Based on the numbers, it wanted me to remove air. I am a bit confused. So the idle is better, but still stumbles going from park to drive.

Logs and current tune below. Does anybody see anything?

[picnic_george]

Also, you're logging too many pid channels, reduce the pid channel count to 24 or less (otherwise it misses some of the data frames, look at your TP signal for example).You need to put this in your SIG lolol


Never near my laptop when I'm on here to look at a tune or log. But assuming your desired airflow is correct, what's your idle rpm and timing in gear?

[LastCall]

You need to put this in your SIG lolol


Never near my laptop when I'm on here to look at a tune or log. But assuming your desired airflow is correct, what's your idle rpm and timing in gear?

I didn't realized some data takes more than 1 channel of data. Duh!!

I have most of the timing tables right between 24-28 degrees low rpm/low air flow in base spark in gear, base spark in park, and low/hi octane tables. The stalling is the worst going from park to drive. It stumbles and/or dies.

[LastCall]

I added some more air into the desired air flow table. It is better but is stills stumbling and/or dying when going from park to reverse/drive. I have attached a copy of the latest tune.

Does anyone know where else I should look?

[statesman]

Set your O2 switch points {B4105} to 450.

Your VE table looks kinda high... did you tune that table with wideband or narrowband?

[LastCall]

Set your O2 switch points {B4105} to 450.

Your VE table looks kinda high... did you tune that table with wideband or narrowband?
I'll switch the 02 points as you suggested.

I took 10% out of the VE below 1200 as a starting point from stock tune. I think I need to spend some time redoing it, at least in the 4,8, and 1200 rpm cells.

I created a MAP to look at grams per second vs ECT, and the values seem very high.

At 176 degrees - 19.29
At 198 degrees - 21.52

Something seems wrong with those numbers, especially since the desired air flow is around 8-9 at those temperatures.

[statesman]

Those numbers look a bit wild. Is everything swapped over from the same donor or is this a frankenbuild?

[LastCall]

Those numbers look a bit wild. Is everything swapped over from the same donor or is this a frankenbuild?

It's a been of a frankenbuild. Lol

Has a new psi harness... Started with an 02 truck tune. Maf scaling is stock 02 5.3. I did change the injector flow rates since the car has an ls6 manifold with the 28.5 injectors and corvette fuel filters. Copied 02 corvette flow rates since the injectors are not referenced to vacuum.

[statesman]

The flow rate you're using is too low for those injectors. Grab a stock tune for an 02vette from tunefiledepot.com and use the numbers in that tune. Zero vacuum should be around 3.6 for those injectors.

[LastCall]

The flow rate you're using is too low for those injectors. Grab a stock tune for an 02vette from tunefiledepot.com and use the numbers in that tune. Zero vacuum should be around 3.6 for those injectors.

I am on my phone now so can't look at the flow rates, but I thought I copied them over from an 02 vette. 3.6 should be...?

Would that explain the high grams/sec on the maf?

[statesman]

3.6 should be...?

Should be the zero vacuum number... the first number on the list.

Here's the numbers I've got for an 02vette;

3.671875
3.695313
3.718750
3.742188
3.765625
3.781250
3.804688
3.828125
3.851563
3.875000
3.898438
3.914063
3.937500
3.960938
3.976563
4.000000
4.023438



Would that explain the high grams/sec on the maf?

No.... it's probably because you're using the stock MAF scaling. Try tuning the MAF first and then see what the numbers look like.

[joecar]

You need to put this in your SIG lolol

...Good idea, lol :cheers:

[joecar]

Also something else: is your FPR manifold referenced...?

[LastCall]

Should be the zero vacuum number... the first number on the list.

No.... it's probably because you're using the stock MAF scaling. Try tuning the MAF first and then see what the numbers look like.

I looked at the 02 vette IFR numbers, and converted the data units to pound per hour. They scaling would make them 31 pound injectors at zero vacuum. I am confused, since they are 28 pound injectors.

He doesn't have wideband, but I should be able to use the narrowbands and perform a CalcMAF using them? I know I cant do WOT tuning with the narrowbands, but just to try and get the lower frequencies of the MAF curve using them.


Also something else: is your FPR manifold referenced...?
It has the vette fuel filter with a return line, so I dont think it is vacuum referenced.

[statesman]

I looked at the 02 vette IFR numbers, and converted the data units to pound per hour. They scaling would make them 31 pound injectors at zero vacuum. I am confused, since they are 28 pound injectors.

That's GM factory tuning for ya... the camaro has the same injector as the vette but the camaro tune has a different set of numbers in the IFR table. :nixweiss:

The best way to get it right is to read the part number off the injector and then build your own IFR table from that... which is what I ended up doing for my own tune.


He doesn't have wideband, but I should be able to use the narrowbands and perform a CalcMAF using them? I know I cant do WOT tuning with the narrowbands, but just to try and get the lower frequencies of the MAF curve using them.

Narrowband is better than wideband for idle and part throttle tuning. Leave WOT tuning for last.

[Jetmech442]

Narrowband is better than wideband for idle and part throttle tuning. Leave WOT tuning for last.

could you explain a little why Nb's are better for idle and part throttle tuning?

[statesman]

could you explain a little why Nb's are better for idle and part throttle tuning?

Narrowbands are fairly precise around stoich but not so good when you move away from stoich. Stoich is what we're shooting for when doing idle and part throttle tuning... and that's exactly where the narrowband works best. What makes it better than a wideband is that the PCM knows the lag time between when the combustion gases are exhausted and when that exhaust gas will reach the narrowband sensor... so you get a more accurate interpretation of each fueling error.

[Jetmech442]

Narrowbands are fairly precise around stoich but not so good when you move away from stoich. Stoich is what we're shooting for when doing idle and part throttle tuning... and that's exactly where the narrowband works best. What makes it better than a wideband is that the PCM knows the lag time between when the combustion gases are exhausted and when that exhaust gas will reach the narrowband sensor... so you get a more accurate interpretation of each fueling error.

I don't want to hijack, so I'll just say thanks for the explanation.

[joecar]

+1 NBO2 is used for Closed Loop trimming to stoich.