Video...gee I wonder what it could be?

[SeanMc]

I guess the things happening could be attributed to the IAC going bad. But my god, how many am I going to go threw????

My idle

 

[Eric VerValin]

Wow.. that looks really familiar. I do believe it is the IAC if i remember. Mine used to do that a longggggg time ago. I think I just cleaned mine out with some carb cleaner, and made sure all the mechanical stuff wasnt binding up. And think that fixed it.. its been a long time tho so I can't say for sure.

Just curious.. if you start it, and when it dips low like that.. if you give it a touch of the gas pedal, does it even out right away? For some reason I remember doing that.

 

[SeanMc]

Nope, if I blip the gas, it'll go way up, and then almost stall. If I put it in park, everything evens out which is what happens in the video. But does that explain the loss of power while driving?

 

[Eric VerValin]

From what I've heard the IAC has almost no effect on driving / drivablitity. Its just at idle.. maybe someone else has an idea.. cause I'd like to know. Maybe you have some small kind of vaccum leak?

 

[SeanMc]

I got a CEL this morning. When the CEL came on, I felt a loss in power. I went to check the codes, but whenever I do the KOER test, when the RPMS start to raise in the beginning of the test, you'll hear what sounds like air come out of the intake, and the test won't continue. I did a KOEO, and in the stored codes I see 2 O2 codes (172, 173). HELP!

 

[hawkeye18]

ruh roh, sounds like a vacuum leak to me!

 

[nc89sho]

i second the vacuum leak problem. or possibly bad/mislearned idle programming.

 

[SeanMc]

I'll do the carb cleaner on the intake test again. BAH!

Thanks guys, I'll let you know what I find.

 

[Eric VerValin]

Well if you can hear it its probally pretty easy to notice.. something is either off, or rotted so bad you should easily notice it. Hope ya find it!

 

[Mr95Gl]

Carb cleaner will ruin the IAC. At least in my case it did. You more then likely have a vac leak.

 

[SASHO91]

Yeah, find that vacuum leak.... I have tried the carb cleaner on the intake manifold a few times, sometimes it works sometimes it doesnt.... either way there is a vacuum leak.

And why is you oil light coming on????? i thought that motor is built???? I mean, i know your trying to show us what the motor is doing, but still.....

 

[SeanMc]

That will happen when the RPMs go down. The oil light doesn't come on in normal driving or when the RPMs are up. Pressure is fine.

 

[Eric VerValin]

Carb cleaner will ruin the IAC. At least in my case it did. You more then likely have a vac leak.

How did it ruin it? Not that I dont belive ya, I just am curious. Is it bad on the rubber seals? Tell me I didnt ruin mine.. lol

 

[SASHO91]

Mine doesnt... I've had the RPM's sit at 500 for a minute or two, and no light.. (yes it works)

 

[SeanMc]

Josh, you don't have 3.3L w/cams either. Adam says he gets a slight light as well. Plus, my tach isn't totally accurate.

Here is what happens when I check codes. Noise Sorry about the quality, I did this in a hurry with my cell phone. But you can still hear the noise.

I used come STP throttle body and air intake cleaner to check for vacuum leaks, and I think I have them all over. After I sprayed down the intake, the idle went up and actually idled better. There was no spot where it would get worse.

 

[paulymick]

hey mine is doing this exact same thing ... just without the driveability problems...when shes warm...at a red light say...she;ll drop in rpms down to about 4-500 (every now and then) and the oil light will flicker just the exact same way...i am listening to where this goes...i believe mine is actually the IAC because the driveability is fine ... it just happens at idle

i have a high flow y with cats and new o2 sensors as well to go on tomorrow so i'll see what happens then

 

[hmthesing]

My old SHO did that as well. Cleaned the IAC and even got a new one. It'd go up and down and eventually even out. Also, when coming to a stop or just pushing the clutch in, it'd drop real low and sometimes ****. I never did figure it out before I sold it. Only damn thing wrong with that car.

Good luck!

 

[Axianator]

Nope, if I blip the gas, it'll go way up, and then almost stall. If I put it in park, everything evens out which is what happens in the video. But does that explain the loss of power while driving?

I would bet money that your EEC is attempting to learn around an overly-lean idle mixture, which is then manifesting itself in the form of learned adaptive corrections that are being applied to your part throttle and WOT fuel mixtures, thereby effecting your driveability. This condition could be caused by vacuum leaks and/or, given the 172 and 173 DTCs that you noted, the result of a dead rear HEGO sensor.

From what I've heard the IAC has almost no effect on driving / drivablitity. Its just at idle..

Actually, almost all EEC-IV strategies will make use of the IAC to control engine speed during deceleration conditions and other throttle input modes, such as off-idle-to-part-throttle transitions, etc.

Mine doesnt... I've had the RPM's sit at 500 for a minute or two, and no light.. (yes it works)

I have a hard time believing this would be the case with any V6 SHO engine.

 

[SeanMc]

I would bet money that your EEC is attempting to learn around an overly-lean idle mixture, which is then manifesting itself in the form of learned adaptive corrections that are being applied to your part throttle and WOT fuel mixtures, thereby effecting your driveability. This condition could be caused by vacuum leaks and/or, given the 172 and 173 DTCs that you noted, the result of a dead rear HEGO sensor.

Good morning Adam,

When I was home for lunch the yesterday, I broke out the tb and intake cleaner and sprayed down the intake. In numberous places, the idle would change for the better or worse. The couplers on there are all dry, cracking, and pieces are starting to come off. So, I have some couplers and intake gaskets on their way. Good time for me to install my BBBs, and ported & polished intake . Any news on your tuning service?