whisler151

I had some new CS motor mounts installed last week. During the install the battery was unplugged. The next day I noticed that my idle was dropping to 650ish then back to 850. When at low speeds (usually in parking lots/garages) and the clutch is engaged the rpms drop to 450 or 500 and the car almost dies. It then bounces back up to compensate.

I also cannot pass inspection as the EVAP (and O2 sensor) are both "Not Ready". I have done several ODBii relearns to no avail. Could the EVAP be tied to the idle issue?

This is extremely embarrassing as my car nearly stalls every time I try to park or am in traffic. Here is a short video from my iPhone showing the clutch being engaged and the RPMs dropping.

Any advice?

http://www.youtube.com/watch?v=DlrPbHDy2Gw

STAGEUP

Check for exhaust leaks at the header collector. The o2 sensors might be sensing too much oxygen in the exhaust, thus pulling too much fuel. Make sure your intake tube is on tight, and the MAF sensor is tight as well.

Also, has it ever done this before?

TriGuy

iTrader: (1)

I bet it is your cam...I will send you my stock one and you can send me yours. That should fix the problem for you and i will just have to suffer with it myself....

In all seriousness, I think it most likely is having to do with your o2's...wonder if there is a leak somewhere?

whisler151

My O2 sensors are set to not report errors so it shouldn't be that. Right now it seems like the computer hasnt fully finished the diagnostic checks. Its been a week and almost 200 miles, I would have thought I would have completed enough drive cycles.

No, it's never done this before.

I dont have any check engine lights on and I did a full visual inspection. No leaks anywhere and everything is tight.

It's little problems like this that are the hardest to diagnose.

SilveradoSS500

Maybe tune related...who tuned the car?

whisler151

I thought that may be it too so I went back to SNL and had them re flash my tune. It didnt fix anything.

I guess I am at the mercy of the damn PCM doing enough drive cycles to OK the EVAP.

ColeGraham

iTrader: (8)

this is just weird, a real brain bender...i got nothing.

on the plus side, the video showed the in cabin sound with you exhaust, which was very help to me...

JJSimon904

iTrader: (8)

Almost gauranteed its in the tune. Mail order tunes dont always do the trick.

xxrillixx

iTrader: (118)

seems like an air issue to me. Almost like the system is getting unmetered air / vacuume leak. So i would look for leaks in any of the lines off the maf, or the back of the intake... any of the smaller black hoses that transfer air. Make sure your MAP, MAF, and O2's are plugged correctly.

Also, do you think your 02's could be bad? maybe they got wet during the install?

itsslow98

iTrader: (18)

I got something for ya lol.....cammed as well, if i turn the a/c on it will drop in RPMS the same way yours does until it finds its idle. Mine never stalls but for the first 5 minutes with the extra draw of the a/c on the charging system the rpms act the exact same way. Im willing to guess its a charging system problem with either the alternator or battery(most likely the alternator since the battery doesnt do anything while the car is running). I could be totally wrong but my rpms act identical.

greddy91

iTrader: (2)

It's not a mail order tune - they're local.

This is the first thing I thought of as well - you went with the 90mm TB and intake right? I'd pop the hood and start running your fingers around those areas and use your ears as well to feel and listen for any vacuum leaks.

He's got a great point - though he didn't say it... turn your a/c off see if it still does it... you have 4 idle points to set - over and under mph with a/c on and off. You might need to review and increase one of them.

STAGEUP

I am talking about your primary o2s, not secondary rear o2s. The rear o2s being turned off is a given with your mods.

If there are no exhaust leaks near the collector, and you checked your intake tube for leaks, then have your tuner increase your "Base Running Airflow" table.

zinner

iTrader: (1)

Having your tune reflashed will reset the ODBII test cycle and fuel trim tables.

It could be related to the battery being unplugged, that resets all the fuel trims which can really cause some erratic low idle situations. Especially on systems without a MAF. Is your tune a SD tune with a custom OS? I just got on to the V8 bandwagon, but I have had about 4 years experience with ecotec's and hptuners.

I had an Alero that when I would reset the fuel trims it would be an absolute nightmare to drive and would stall constantly, but after about 15 minutes the fuel trims would start to take and it would idle start to idle fine. Don't ask my why I was tuning an Alero If it's persisting I would start to discount my theory.

The unmetered air suggents are also viable. A good scanner can usually pick that up right away with short term fuel trims and eventually you will trigger a lean code and a CEL.

Brian Coles

My SS did the same thing when I had a plastic bag sucked up against filter. Check the intake. Ha ha.

whisler151

Thanks for all the advice guys.

I would never put in a mail order tune in my car. Its a dyno tune. I had him reflash the tune in case the battery being disconnected messed anything up.

I was starting to thin there is a vacuum leak as well. That would explain the random idle as well as the EVAP code. I just need to find it or rule it out.

I tried driving around with the AC off (sucks in a Texas summer) and it acted much better. It still was dropping unlike anything its ever done prior to this, but it was better. Short fix is to turn off AC when in traffic or parking.

Yep...had a few codes after the ported TB and intake so he adjusted that table. I looked at the headers for a leak (had to weld header after alternator wire incident) and all looked good.

That was the first thing I looked at, once my cone filter came off and the car was acting identical. Unfortunately that was not the case this time.

ColeGraham

iTrader: (8)

any updates whisler?

SilveradoSS500

+1 update?

STAGEUP

SO your fuel trims go lean when it the car does drops RPMs like that?

whisler151

Just got back from the lake and we drove the SRX. Im going to get up early tomorrow and see if I can figure anything else out. If I cant find anything then I'll schedule some time at the shop to troubleshoot it.

vmapper

iTrader: (8)

Spraying ether around intake and suspected areas is a good way to know if there are vacuum leaks as when the engine 'sniffs' it, your rpms revv...
feel or listening isn't going to cut it fining a 'leak'

i don't understand this either, the OP mentioned nothing about a CAM, Motormounts, unplugged battery and then the issue.
Did you get a cam installed ?
If you had some tuning, and it was off, and yes, your LTFT are zeroed, it would mean a) re-learning needed and then b) the aftermarket tune was off if that's the case. (meaning, not a good tune)

Vac Leak is a possibility. If you think its EVAP related, just plug up that specific hose to the manifold and see if that fixes the situation (removing the EVAP out of the equation)... usually would get a light from a bad EVAP solenoid though.

do you have scanning tools available? (ex. EFILive, HP) this would be a great asset in a situation like this.

Also, more specifics...
If your looking from an ECM standpoint.
There are warmup tables, based on ECT's...
is the car warmed up when this occurs?
There are also SPEED tables, clutch in driving (moving over a certain speed, ie. 4miles/hr) would be different than and a slow roll or stopped.

Does this occur in both situations?