thunderstruck507

iTrader: (18)

Been tuning my roommates car some and it's coming together pretty well. Runs and drives great even with the A/C on. But it has an intermittent lean spike stumble off idle which seems to be more prominent when the engine is cool.

Car has been tuned with Calc.vet function of EFI live and has an installed lc1. I also bumped up the timing at idle a little. Wondering if the transition in timing could be it.

If not what is the best place to look for what could be the cause? Any useful PIDs I should log to help pin point it?

I'm still learning and this is a free tune so pardon if it's a novice question.

sweet-94z28

iTrader: (30)

Sounds to me like it needs a little fuel added via the VE table in the high map areas or a little timing removed under a slight amount of load. What year car? Is it any time you come off of idle?

thunderstruck507

iTrader: (18)

It is an 01 or 02.

Not anytime off idle, its on a cold start and doesn't always happen. IIRC he said he catches a glimpse of the wideband gauge hitting high teen to low 20s for a split second when it occurs.

I'll see if I can catch it on a log. We just loaded a more refined version of the tune so it might already be cured, just want a good place to look if it continues.

BLK02WS6

iTrader: (2)

Post the tune and log...

thunderstruck507

iTrader: (18)

I'll try to grab a log, he just found a leaking valve cover gasket so I'm wondering if it was causing a cold vacuum leak until the heat swelled everything up.

DMM

Are you absolutely sure it's fuel and not timing? I'd try adding a degree or two in the high octane tables and see if that helps it.

Black99TransAm

iTrader: (16)

I was about to start a new topic until I saw this. im having the exact same issue but mine is worse. it does it all the time hot or cold.

basically if I ease into the throttle when revving or accelerating then its fine. but any quick throttle transition from idle it goes completely lean on the wideband (22.4) im at a loss cause on the maf table and on the ve table I have added a ton of fuel in the lower rpm areas and it hasn't helped... if anyone can give us some insight since he seems to have the same issue as me. I have talked to 3 tuners about it and I get mixed answers and none have helped... anyways here is my tune and log on hp tuners. maybe helping on of us will fix both our issues

Bowtie316

iTrader: (1)

What plugs are you guys using? Running too cold of a plug could foul up or plugs could be fouled from running too rich initially. If a cylinder misfires it will dump a bunch of oxygen into the exhaust and cause it to read lean, even if the mixture is perfect.

Does the injector pw dip during the lean condition? If not I would suspect a misfire rather than a lean condition.

DMM

You should start your own thread on the matter....but you need a LOT of work there with the MAF and VE tables. They're both WAY off. Your timing is what you are feeling...the 1000 RPM to 1200 RPM tables are 10* or more apart from another which you will definitely feel as a stumble. Your PE needs work to.

Start a thread with your mods and state what wideband you're using.