Eight_Ball

So I got this 5-speed boosted tC with a bunch of work done to it, slowly getting it more usable/ideal driving and am trying to sort out the one last running/driving "bug" the car has.

So as long as I've been driving it, when the car is very cold (as in, the first time driving it all day, or it's been sitting for like 8 hours at work), it will stutter a bit at low rpms under normal non-boosted acceleration. I'm running an AEM FIC, and it does this with/without the resistor mod. It always goes away after the car warms up a couple minutes, so I've never paid much attention to it.

What did get me thinking is this "new" issue (which MIGHT be related). Now that I've had my first full summer driving the car (last year I drove it in like October, so it was already cooling down a lot up here), if I'm driving the car for quite a while (say 45 mins on the highway or something) and if it's a really hot/humid day, the car has a small chance to stall when I clutch in to slow down. It only happens MAYBE once or twice a day (if even), when I'm doing lots of driving and when it's pretty hot outside, and the car always starts up fine again (or if I put it back in gear quickly it'll get going again, but I know that's not really the best idea) and drives fine after. I've tried keeping an eye on my AFR but that seems fine too.

My only thought has to do with a "previous" issue with the car. I'm running BC stage 2 cams, and having talked to paul dezod on this site, found that those cams were giving me problems with starting up (Cam Position Sensor couldn't get a good read on the cams when they were hot). That site now mentions to adjust the dowel pin so it doesn't happen to future cars, but what I was able to do was modify my CPS by trimming down the inside of the plastic housing such that the sensor sits farther into the engine. It fixed the startup problem (now always starts, never backfires when cranking), but I'm wondering if maybe that's somehow related to this now hot-stalling issue?

I've tried researching, but haven't found much of use. I've cleaned my MAF a couple months ago (haven't gotten around to throttle body), and I DO have a CEL, but don't have the tools/locations to get it checked (trying to find a place up here in Canada that'll let me scan my codes). I've heard that with more aggressive cams and injectors (880cc), issues like this might pop due to the ecu/fic combo not being able to adjust fast enough, but the only piece of advice I have found is potentially an O2 sensor problem, but it's noted to be unlikely the cause of stalling. I haven't been able to find anyone else with this problem, so hopefully someone has some thoughts on the matter?

paul_dezod

Cold start enrichment was modified indirectly by the AEM FIC calibration from your tuner. He pulled too much fuel and/or MAF clamp and/or O2 map is off which is causing this to occur.

That_Kid_Ju

I thought Cams + piggyback = not so great control?

paul_dezod

Well that is true too.

Eight_Ball

This is the most interesting part. Not sure if you remember helping me last time with that startup issue I had wherein:

Based on this we had done a few changes to my maps (at the time you didn't know about my cam thing), I'm wondering if maybe those changes then negatively affected this new issue, and maybe those old "bad" maps were actually fine (now that I got the startup issue sorted out with the sensor)? Maybe I'll try going back to those old maps (when I got my car tuned in spring) when I get a chance, worth a try at least.

paul_dezod

If anything, my changes where adding fuel in that cranking region so I am fairly doubtful that it was adversely effected your issue. You are more than welcome to try your old map(s) if you'd like, but my suspicions are that it will remain the same or get worse with the old maps (they where leaner). Unless whomever tuned you had the fuel trims out so far to the negative that me adding more fuel was like insult to injury.

Eight_Ball

Ah alright, worth a try due to the fact that it'll only take me a few minutes to do.

Any thoughts on the stalling issue? The only other thing I was going to mention with that is that sort of what I mentioned above, when the car revs down when clutching in during deceleration, it almost feels like it doesn't react fast/early enough then the revs drop down too low (say about 400) then it just gives up entirely and stalls. But it also feels as though the revs are dropping faster than they do when it's normally revving down.

paul_dezod

You should be remaining in gear and downshifting. Problem solved.

Eight_Ball

It doesn't seem affected by how low the rpms are before I clutch in, so I'm thinking there's still more to the problem.

burgandybomber

iTrader: (1)

LOL! Didnt you say this also helps the oil rings seal?

My car had idle hunting really bad before my Dezod tune Also, my car doesn't like to be under half a tank for some reason.

paul_dezod

Being in gear and engine braking/downshifting does in fact promote ENGINE piston ring sealing to the cylinder walls: true.

Fuel delivery and trajectory is very different on the second half of the tank than the first. This is why I always suggest never running below half a tank on a turbo tC.

Wish I got a $1 every time I was misquoted.

my06tc

iTrader: (2)

i usually dont go below a quarter of a tank...