Idle surge @ warmup.

[impalamike3800]

ok so I am at my wits end here on this one. seems as though when I start up the Impala after it sits (generally over night) the RPMs will surge. it start at my designated idle (say 1000RPMs) and after a few seconds it will drop to 500 and shoot up to around 1600 and do this for around 2 minutes. it will continue even after i have put it in drive and start to accelerate. but after 2 minutes it will be just fine. anyone run into this? I am going to attach my current BIN file to this so if someone wants to take a look and tell me where my issue lies.

mod list:

L36 block/bottom end
Ported lower intake
ported M90
3.3"pully
8 rib balancer w/5% OD for blower
P@P heads milled .030
130# springs
1.73 RR
S&S headers
48# injectors
meth injection
need any further info please dont hesitate to ask.

[3800 cavalier]

surging is usualy a lean condition at idle. with your mods you need to scale the maf transfer function. get a wide bad and have at her. load bearing dyno is best to do the maf transfer on but if not the street is ok to a point. so tune the maf.

[impalamike3800]

surging is usualy a lean condition at idle. with your mods you need to scale the maf transfer function. get a wide bad and have at her. load bearing dyno is best to do the maf transfer on but if not the street is ok to a point. so tune the maf.

I have a wideband on the car. so your saying just scan at 1st startup and when i see lean enrich. seems almost too easy to be it but ill give it a shot. oh yeah im using Tiny Tuner instead of HPT on this car. far more tables.

[3800 cavalier]

you should create a user defined pid then if you have a wide band. also lambda is much easier to deal with then afr. so make a comanded lambda pid and lambda error pid. then create a histogram fot maf lambda error and you simply use the values in the chart average that is. and multiply each corasponding cell by the histogram data in each position.

[impalamike3800]

I log the WB via EGR (EGR has been deleted). but yeah ill give that a shot.

[gtpthriller04]

I have the exact same issue once i installed my NIC cam. Only mine does this all the time, it never stops, well intill in stalls out finally. I kept thinking it was a vac leak, i checked and re-checked but nothing. None of my trims ever showed that there was a leak. I did find the 2 and 4 plugs to be ghost white while the rest were brownish, in turn points to the lean condition. Does the wideband have to be hooked up to the tuner so it can log the data?

Thanks

[oakleafresin]

You guys need to run open loop. Got rid of EVERY complaint I had about the car.

[impalamike3800]

You guys need to run open loop. Got rid of EVERY complaint I had about the car.

info?

[MMGT1]

Im curious how you are running open loop wthout going SD in a V6 as well?? Bangs the crap out of the trans, not good.

[oakleafresin]

There is no such thing as SD on the V6 PCMs. Open loop is simply NOT closed loop. For example, your car runs in OL while warming up and while WOT (the times when the O2 sensor is not being used by the vehicle).

First and foremost, don't consider OL unless you have a wideband (should be the second 'mod' you get after HPT anyway). OL is as simple as setting the closed loop enable temperature to 255* (or whatever the max is) and resetting your fuel trims (OL has no fuel trims so you don't want the ones the PCM already knows to interfere with your tuning.)

That's the way I'd do it if I only had HPT. There are still a few tables that you would be wise to edit that HPT doesn't give you access to.

The prefered way, and the way that will give you access to these tables is to have someone with DHP read a .bin from your car. Then, use TinyTuner to edit all the OL tables and write this file to the car with HPT (HPT will WRITE .bin files).

Tuning in OL is 200% easier than CL. No fuel trims, so just make a custom histogram logging MAF Hz VS the AFR error %. When you are done logging, simply copy, paste special onto your MAF table and bam, you're tuned perfectly. It's not quite as simple as I make it sound but a little experience and reading go a long way.

[BlackGS]

^^ x2. Open loop is just MAF fueling without trim adjustment. Makes it a whole lot easier to enter PE and not worry about locking to 0, which has always been a pain to tune around.

And it is just that easy to run open loop. I had a good closed loop tune, so I simply set closed loop enable temp to 255, reset the trims, and it ran perfect. I am running e85 with a wideband. My cruise AFR locks to lambda 1.0 (yeah, I know I should lean it a bit for better MPG), and my PE locked right where it was with closed loop.