Idle problems, I have checked everything I know of.

[khartley]

I've had a bad idle for a long time now, and I've tried everything I can think of to get rid of it, and it won't go away.

I replaced the O ring on the BISS screw.

Tested for and fixed all boost leaks.

Tested TPS, has 4.95v

Replaced tb shaft seals, cleaned tb.


What it does is vary from 500 rpm up to 1500, sometimes it will even itself out for a while. When the idle is jumping around, so is the wideband, going from 13.5 all the way to 16. When the wideband goes lean, the idle goes down. Even while I'm driving I can feel it a little, and the wideband still won't stay still. Ever.

Today, I unplugged the TPS, the idle did not change at all. I also unplugged my GM 3" Maf, and the idle did not change (weird???) Then when I plugged the maf back in, the car died. I am attempting to tune with a Maft Pro.

Any thoughts, ideas? I have run out of things to check for.

 

[GT35RDSM]

Did you test your ISC? They tend to go out after a while. VFAQ has some info on setting the idle on a 1G, you basically have to ground out the ISC and then set your biss.

 

[khartley]

Actually forgot to mention I eliminated the ISC with the FIAV delete plate, I thought that may change my idle problems but nothing changed.

 

[GT35RDSM]

maybe a bad or leaking MAF, bad ECU?

 

[97gstnick]

Maybe you have a sticking throttle body. Check out this thread..
http://www.dsmtuners.com/forums/problem-diagnosis/345710-resolved-idle-surge-then-cel.html

 

[khartley]

I had my tb out and cleaned it, it is ok, not sticking. I also had my ECU out a couple months ago, no leaky caps and it looked fine.

I'm going to clean my maf today and see if that helps.

 

[khartley]

Cleaned the maf, nothing changed. Any other ideas?

 

[Fotowntalon]

I think i read somewhere that idle problems can be caused by having air in your coolant. so maybe try flushign the system... where did i read that from.. ahh here it is.

http://www.dsmtuners.com/forums/articles-engine-fuel/54439-idle-control-theory-operation.html

 

[outcastgsx]

Have you checked for vaccum leaks? I would check all my connections and all the wiring from the tps,maf,ect. Make sure you dont have an open circuit or a short to ground some where. Its always a good idea to just double check all your wireing.

 

[97gstnick]

If you push your throttle shut hard with your hand, does the idle go down?

 

[khartley]

97gstnick - no it doesn't. I will try and get air out of the coolant, its possible that I do.

 

[khartley]

Got all the bubbles out of the cooling system, no change. Threw on a different TPS for giggles, changed nothing as well.

I'm wondering if it is possible for me to have a bad translator or ECU causing problems.

 

[Aproductions]

are you venting to atmosphere (bov) or recirculating (bpv) ? I had a huge idle problem when i was venting to atmosphere, but then i recirculated and everything was fine.

 

[DarkSoulEclipse]

intake manofold gasket leak ?

 

[khartley]

are you venting to atmosphere (bov) or recirculating (bpv) ? I had a huge idle problem when i was venting to atmosphere, but then i recirculated and everything was fine.

I am venting, but I have a gm maf and translator, shouldn't affect anything.

I think I have found the culprit. After talking to full throttle about the translator, it can't handle the 750's on its own. I just ordered a chip from Jeff, we'll see what happens.

 

[97gstnick]

I am venting, but I have a gm maf and translator, shouldn't affect anything.

I think I have found the culprit. After talking to full throttle about the translator, it can't handle the 750's on its own. I just ordered a chip from Jeff, we'll see what happens.

yea, I think piggy backs are only good to 660cc. I use to have that same setup, translator with keydiver chip.

 

[khartley]

Thats pretty much what Bob at Full Throttle said. I guess I'll find out in a week or so when Steve gets done chipping the ECU for me!

 

[->PrOjEcTGS<-]

Is your IPS functioning properly? When the throttle plate is closed it will be open and when it's off idle it will be closed or vise versa (can't remember which way is correct). Anyway, it tells the ECU that it needs to be at idle and the best way to tell if it's functioning properly is if the injectors turn off on Deceleration from a high rpm. If they do, your wideband will read max lean. If not, it will still read that there is a fuel mixture (probably lean at about 17-18) and you'll hear popping coming from the exhaust or a very rough decel. As opposed to a very smooth sounding decel.

The only reason I ask about this is that there is a factory ground strap that goes from the top of the TB to one of the TB mounting bolts. Without this ground strap the IPS does not see any ground and will not communicate to the ECU that it's at idle.

It is normal for the rpm to fluctuate +/- 50-100rpm at idle when in closed loop and the O2 sensor is bouncing back and forth. Because with more fuel you get a higher rpm with less you go lower. But, it should not fluctuate from 500-1500, that's a little too much.

 

[khartley]

Where is this ground? I looked all over the tb and see nothing.

I have the chipped ECU in right now, and there is NO change. I unplugged my translator, and NOTHING CHANGED. I unplugged my maf, and NOTHING CHANGED... plugged it back in and still NOTHING CHANGED. I know this can't be right... but what the hell is wrong?

I've messed with the cam angle sensor, tps, and biss, and either it idles at 1200-1500 RPMS consistently, or it bounces from 500 to 1500. One or the other, absolutely NO in between.

Sorry for the capitals, but I'm trying to emphasize how incredibly FRUSTRATED I am.

 

[1997_GSX]

I am having a similar issue, did you ever figure it out?

 

[khartley]

Sorry for a very late reply, but I still haven't figured this out. I don't have much time to mess with it anymore, however I did buy a timing light with intentions to check base timing. The car idles nicely at 700 until it is fully warmed up, then it surges a while and eventually sits happily at 1500.

 

[concept4g63]

1500 is pretty high

 

[boosted0721]

Have you tried to take your tb apart,I had the same issues awhile ago and tried for a week to fig out.I had to take apart my tb into the two peices there is a top and bottom.It had four screws in it but almsot seam welded into place but i got em out with impact screwdriveer.But my gaskes in my tb was shot and expanded and i replaced that and that fixed it.there was some water getin into the tb becasue gasket was bad and would cause water to drip from exhaust and think was maken have bad readings.But replaceds that and it fixed the problem for me along with a new throtel cable.Each red light and stop sign i hit my rpms would get higher n higher.But that would b my 2cents to your problem.Idlle issues are never fun

 

[92AWDHX40]

did you do a boost leak test?

 

[red94gsx]

It could be your idle air control solenoid (also called idle speed control). My car has idle surge too, and I have yet to track down the exact cause.