TPI-Formula350-

I'm tuning with TP5 and I just have an idle issue. It's always on start up open or closed loop. It surges from 1400 to 800 for a minute or so before settling to 800 rpms. I have the IDLE RPM vs. COOLANT TEMP set to around 800 for the car when its warm/closed loop. What's the best way to correct the surging? Should I pull a few degrees of timing from the MAIN SPARK TABLE in the 1400 to say 1000 rpm range in row 32 and 48(low load rows). Would lowering spark there lower surging in the rpms its rising at? Thanks

TPI-Formula350-

anyone??

ThEWhitebirD

iTrader: (1)

I've been battling the same problem or at least similar for a while now, but I have a different ecm.. warm start is fine but that first cold start... the car starts at 1500 rpms for a second then sinks like a rock and swings like you mentioned, once in a while stalls.. no matter what iac setting I try..

Ive read hacks and tried lots of settings from what I can tell it has something to do with choke or crank to run routines

JP86SS

iTrader: (1)

Allot of times I find surging is due to not setting the throttle blades correctly and resetting the IAC and TPS.
Getting the counts around 40 or lower keeps the IAC in control of the RPM.
Once the IAC loses control and SA is changing rapidly the surging can get swinging in a pattern.
Do the IAC unplugged (after A & B diagnostic jumpered) and adjust the throttle blades to get the RPM just below where it should be then shut down and reconnect it.
It will bring the RPM back up where it is commanded, Then reset the TPS so it reads idle correctly and see if that doesn't get you closer to low counts at idle.
That's always how I've done it IIRC.
If it is still acting up look at your logs to see if the SA is jumping around while small RPM errors occur at idle. Reduce the amount of compensation due to RPM error to help smooth it out.
Also check if you are crossing over VE cells that have large changes (this also applies to the SA tables)
Try to narrow down any large change that could occur in the areas.

In the end I never have the thottle blades closed enough that the engine could totally stall. Very close but not quite there.
HTH,
Jp

hellz_wings

iTrader: (2)

A few things:

1) What is your TPS voltage at? Should be around 0.54 volts.
2) You have removed the smog pump, have you tuned for it?
3) With that intake I think the EGR is non-existant? There are parameter in the PROM to adjust if the EGR is removed.
4) In the constants/scalers section, there are a bunch of things you can adjust in there to see how the car reacts (do you have live emulation? If so I would just play with the IAC steps in various places like "Idle RPM startup position" and lower them and see if that helps).

It could be a combination of things.. Maybe it's something un-related to tuning. Does it idle perfectly when it goes into closed loop? Is it only when you are in park/neutral and just starting the car? What if you put it in drive 5 seconds after you start the car, then does it correct itself or does it still surge even in drive?

scorp508

I just went through something similar with my MAF 32B BIN and it was a combination of things to smooth out the idle.

• Smoothing the SA cells in the idle area out so there is little to no change in timing due to small idle fluxuations.
• Doing the idle reset procedure to fix my TB blades and get my IAC counts up higher at idle. IAC count at idle was <10 previously.
• Confirming my TPS was still at 0.54v in the closed position.
• Making sure I wasn't bumping into my next BLM Cell # due to the idle RPM being at the cell boundary.
• Changing all EGR duty cycles to 0.0% since there is no EGR system attached.
• Removing the O2 mvdc adjustment when AIR divert is on since AIR system is not attached.
• Smoothing out the desired idle speed versus coolant temp table so it falls more gracefully and at a slower rate.

The last two probably didn't help much with the idle, but they couldn't have hurt.

Orr89RocZ

iTrader: (20)

whats the air fuel at cold start? It may want abit richer mixture to be more stable at first... i notice this on my 401 motor...its cold blooded in that cold start requires alot of fuel to keep it idling ok on first cold start and takes little while to lean out to stoich. As it heats up it doesnt need as much fuel because fuel will atomize better with warm chamber temps.

The other suggestions above are all great ideas to try. Lock spark advance in the idle cells to minimize changes and make sure the IAC/TPS is adjusted right. Should help idle.

I do believe there are some cold start AFR timeout tables that change how quickly fuel is pulled out at start up. First start requires alot of fuel to fire then it tapers off to commanded fuel levels which are usually abit less. The time delay that happens between first fire and normal operation may need lengthened to allow the motor to heat up abit longer before going off main fuel parameters. Just an idea.

hellz_wings

iTrader: (2)

Is he using 6E or 32b?

Orr89RocZ

iTrader: (20)

should be 6E last i recall