2005 Grand Prix (Base) question

[terrancew3]

So my girlfriend has an '05 GP, and every time she starts it, the car revs up and then goes real low and then goes up to normal. It does it on electric start and with the key. Im not positive what it is, but to me it seems like a sensor is going bad (possibly a TPS or Idle sensor?). Has anyone with a GP ever had this issue? I think because of this, her electric start doesn't always stay running and just quits cause the idle gets real low for that instant. If I can figure this out, I wanna fix it for her. No codes are thrown either.

[nos4blood70]

How many miles? You can clean up all the sensors in the TB like the Idle Air control sensor.

[terrancew3]

How many miles? You can clean up all the sensors in the TB like the Idle Air control sensor.

I think somewhere around 106,000. What would I clean them with?

[nos4blood70]

Some MAF sensor cleaner. I wouldn't put something as harsh as TB cleaner on them.

[FasGP]

My 05 does this also for the last year, but I have not had time to troubleshoot. I am sure the IAC valve is a bit sticky, but my intention was to clean up all on the TB....

MAF cleaner only. This is a common issue on the drive by wire design...

[terrancew3]

My 05 does this also for the last year, but I have not had time to troubleshoot. I am sure the IAC valve is a bit sticky, but my intention was to clean up all on the TB....

MAF cleaner only. This is a common issue on the drive by wire design...

Someone on the GP forum told her its a good possibility that the IAC is stuck, but Idk where that even is on her car. Anyone got a detailed diagram of that?

[haro1225]

I think its part of that electronic box on the TB, and I'm not sure if that can even be cleaned, or if the whole unit would need to be replaced.

[terrancew3]

I think its part of that electronic box on the TB, and I'm not sure if that can even be cleaned, or if the whole unit would need to be replaced.

Yeah, I saw that when I was changing her plugs and wires last night. I couldn't quite figure out how that comes apart.

[FasGP]

I don't have a diagram, but it is a spring loaded unit. I sprayed a carb cleaner in a small metal cup and soaked it. I know there must be a way it comes apart, but I have always broken them. Most times, a soaking, wiping and cycling it numerous times in your hand will free it up and make it work again.

[terrancew3]

I don't have a diagram, but it is a spring loaded unit. I sprayed a carb cleaner in a small metal cup and soaked it. I know there must be a way it comes apart, but I have always broken them. Most times, a soaking, wiping and cycling it numerous times in your hand will free it up and make it work again.

Could I just spray a cleaner into the throttle body while its running, and hope that frees stuff up?

[FasGP]

I don't have a diagram, but it is a spring loaded unit. I sprayed a carb cleaner in a small metal cup and soaked it. I know there must be a way it comes apart, but I have always broken them. Most times, a soaking, wiping and cycling it numerous times in your hand will free it up and make it work again.

Could I just spray a cleaner into the throttle body while its running, and hope that frees stuff up?

No, the IAC control and spring parts sit behind a small top hat shaped head, inside a passage in the TB. There is two little screws...just remove them, and wiggle it very gently to take it out. Put a bit of grease on the seal when you put it back in and make sure it doesn't get damaged during removal or install.

[terrancew3]

No, the IAC control and spring parts sit behind a small top hat shaped head, inside a passage in the TB. There is two little screws...just remove them, and wiggle it very gently to take it out. Put a bit of grease on the seal when you put it back in and make sure it doesn't get damaged during removal or install.

Yeah, her TB doesn't look anything like that. That setup is how mine looks. When she comes over, I will take a picture and upload it on here.

[terrancew3]

For that IAT, is that what that extension wire is for? So when you install a aftermarket intake, you can extend the sensor closer to the filter?

[haro1225]

Is this what you have? (sorry for the crappy phone pic).

[FasGP]

Is this what you have? (sorry for the crappy phone pic).

Whoa...completely forgot about the drive by wire design...not sure where my brain is lately.

These do not have IAC...that function is electronically controlled via the PCM adjusting the plate in the TB. More than likely, the throttle body and/or MAF is very dirty. Something is not reading correct air flow due to sensor contamination, or restriction.

Sorry to send OP on a tangent...looking for parts that don't exist...

[terrancew3]

Yes it looks like that 2nd picture. I am are gonna order a new MAF today, so if that doesnt fix it there is something wrong somewhere else. All the plugs wires are replaced with AC/Delco iridium plugs and wireset. Maybe it could be a faulty coil pack? I guess we'll see when the MAF gets here.

[dmnowaksr]

You may want to try cleaning the MAF before spending good money on a new one. Also, check for a vacuum leak or possible loose intake tube or air cleaner housing. A vacuum leak would cause the exact issue that you described. The leak would cause the hi idle until the PCM could correct it to the pre set RPM.

[terrancew3]

Well, for 50 bucks its not a huge deal to pick up a new one. But I know I changed the air filter when she first got it, and it didnt do that back then. I told her she should get the CAI for it, to help with air flow and engine performance.

[terrancew3]

Turns out it was just a real dirty MAF. Sprayed some cleaner in the TB, and so far it's solved the issue. We'll see how it goes for the next few weeks.