LS1 Idle Issues

[abrown]

I have a 99 TA M6 with a EPS 234/246 cam, 243 heads, FAST 102, 102mm Nick Williams TB, 85mm z06 MAF, and 42lb green top injectors.

I had the car tuned by a reputable shop a couple years ago for the heads and cam on stock injectors and LS6 intake and it ran and idled great. I added the FAST intake, NW TB, MAF, and 42lb injectors over the winter. I have since purchased EFI Live and am trying to get it dialed in as the shop is swamped and I am trying to get it down the beach tomorrow.

I am running into major idle issues, it will idle fine when it's cold and as it warms up but if I rev it up it dies as it idles down and will not idle on a hot start without throttle. I've tried playing with the idle set screw on the TB to get IACs down to the 40-80 range with little to no luck. I've also looked at the idle threads on this forum and have tried to apply the same thought process and knowledge into my tune. However, I have had no luck with the RAFIG process the "IAC - Long Term/Short Term Correction" PIDs are not supported.

I have an external wideband which is feeding data. I have attached my current tune file, my previous tune file, and a data log from last night. If some one with more knowledge then me could please give me some insight on where to start it would be greatly appreciated it!

Thanks.

[statesman]

Put your stock injectors back in and dial in your MAF and adjust your IAC effective area for the new throttle body. When you get that all squared up, then put in the new injectors.

If you can get all that done today, then you'll be able to take it to the beach tomorrow. :laugh:

[abrown]

I gave the stock injectors to a friend to use on one of his projects so I don't have that option. I have scaled the IFR tables to compensate for the additional fuel.

[joecar]

The RAFIG pids should be supported on 1999 F-car.

[joecar]

Looks like:
- Measure rail pressure (what FPR do you have...?).
- Minimum and Default pulse widths (B4003, B4004) don't look right, where'd these come from...?
- get MAF corrected (your MAF table is wrong, it cannot be bumpy).
- get VE tables corrected (correct Backup VE first, with immediate MAF DTC present, then paste/interpolate into Main VE).

Can't do idle tuning unless MAF and VE are correct.

If you have to, go back to the stock file (except for the injector tables) and start over.

[abrown]

When right clicking the "IAC - Long Term Correction" PID and choose "More information" it outputs the following:

"IAC - Long term correction, in gear, A/C Off {GM.IAC_LTD_DMA}

Units: g/s
Range: -32..32 g/s

Long term learned IAC airflow correction in drive with AC off.
This value is updated once per second based on the corresponding short term IAC airflow correction."

My Operating System is 09360361, I'm not sure if my OS just doesn't support those PIDs but I am unable to validate them.

[abrown]

Looks like:
- Measure rail pressure (what FPR do you have...?).
- Minimum and Default pulse widths (B4003, B4004) don't look right, where'd these come from...?
- get MAF corrected (your MAF table is wrong, it cannot be bumpy).
- get VE tables corrected (correct Back VE first, with immediate MAF DTC present, then paste/interpolate into Main VE).

Can't do idle tuning unless MAF and VE are correct.

If you have to, go back to the stock file (except for the injector tables) and start over.

- My Fuel Pressure Regulator is the factory one to my knowledge. Fuel Pressure should be 58 psi, I have not verified that though.
- I pulled all of my injector data from here: http://www.hptuners.com/forum/showthread.php?39160-42lb-Injector-data
- I'll spend some time cleaning up the MAF table
- Are you recommending in bullet 4, that I disable the MAF, log and input the data that results from that log? Just trying to understand.

[joecar]

...
- On the 4th bullet, are you recommending that I work the Backup VE Table with the MAF disabled, log that information, and apply to the Main VE Table?Yes correct, the Backup VE table (sorry I misspelled "Backup") with MAF disabled, then copy to Main VE table (may have to interpolate).

[abrown]

Okay I'll look into that. How do you recommend I disable the MAF? I cannot just unplug it as my MAF is being used to calculate IATs as well. Also, what is the difference between the Backup and Main VE tables?

[joecar]

Edit C2901,2,3 to make it fail, set them to 1.

Edit C6001 P0101 to to make it fail immediately, set it to 1-Trip .

[oreobadr]

Just a couple questions to joecar about this thread (sorry for hijacking but I have almost the exact same mods). I have attached my tune as well but my VE table is much higher across the entire board. Do you know the reason for this???

Also, why is his spark set so high for such early RPMs in spark high octane table (b5913)?

Why is the spark just set across the board for base spark in gear(b5932)? Is this because, base timing in gear is with the the throttle closed so it wont ever really get to highv alues of dyncylair?




My contributions to your tune.
Add some timing for very low so that the RPM will jump up when it attempts to die. This will help it idle and make it not stall.
Lastly, your IAC effective area should be .0122 instead of what it currently is. That is to adjust the ECU for the large throttle body.

[joecar]

I don't know why, I'm wondering what OEM tune it started out as.

[oreobadr]

Yeah, It seems very strange that is for sure.

[abrown]

Yeah, I've wondered the same thing honestly. I look at other peoples tunes and they seem way different then mine. I haven't messed with any of the spark tables but they do seem very high! I get no spark retard at WOT but I do get some at low rpm, high load. The car goes lean for a couple seconds, timing is retarded, comes rich and is okay. My buddy suggested my injector data may be off?

Oreobadr, what injectors are you running? Where did you pull your injector info from?

[oreobadr]

I am running 46 lb/hr fast injectors that are ls2 style injectors. I will look at your tune later tonight and tell you what your ifr table should look like

[abrown]

If you get a moment to provide some help that would be greatly appreciated!

[abrown]

The more I'm reading and working on this issue the more I'm thinking it is injector data. Looking at my injectors it appears I have "green giants" and not "green tops" as I initially thought. Bosch # 280-155-968

Looking at information on the web on these it appears these are more for multi valve engines due to the split spray pattern and are a pain to tune on the LS motors. Does anyone have any experience tuning these? Should I just sell these and buy another injector? What injector do y'all recommend I run?

[oreobadr]

I would switch to fast ls1 style injectors and call it a day.