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Discussion Starter #1
So to recap on a long story/series of events that have lead me to here; here is a brief:

Car had issue starting. Took in and eventually had starter rebuilt. Working great now.
After starter replacement, battery wouldnt charge. Had alternator looked at. everything was fine. Went to replace fusible link. When i pulled that i noticed what the problem was with the charging. I had the line(Fusible link) from the starter to alternator on the jump post, not the 12v post of the starter solenoid. Fix, and car is charging and starting perfectly.

Since to first got the starter back in the car, a second problem arose. Car is now idling at just below 3000rpm.
*I did remove the air intake, TB, and Manifold to get to the starter. All is back properly(can really only hook up one way), no holes or tears in lines, everything looks and reads great.

On inspection, car is just having an issue with idle. when in gear and driving, it is perfectly fine. It just idles insanely high.
Tried relearning process. Nope
Tried 2 other possible ways i read about a relearn...Still Nope
Tried manually blocking some of the throttle body to limit air flow...car spins down and can get it to normal idle...or it dies because its difficult to hold that exact amount of closure.
**Suspicion? Throttle body is open to far at idle. Read somewhere where this can happen and it should be open at 6% on idle, and its stuck at 20% and idling at 3k. Confirmed...this is at least what it seems to be doing.

Next strange occurrence to this. If driving the car down the road, clutch out, and kick it out of gear, car will climb RPM till it hits between 4500-5500. then it will drop down to 1100-1200...then climb again and repeat.
If clutch is in, car will just idle at 3000. This is while going down the road. Many speed variations tested. Same across the board.

Last thing. After sitting for a day, the car will start and idle normally. 1100 or so. Then after driving it a minute, it will rise until it is idling at 3000 again.

Next. I replaced the TB. On the hope that the memory for it was located there and a new one would relearn. This did NOTHING. Everything is exactly the same.

Im at my end. Nothing is working. Any help, suggestions, trouble shooting would be more than appreciated. Im dying to get back on the road.

***Side note. Car did throw the P507 code, RPM idle too high. Which was sort of expected. It cleared and hasnt come back. But obviously is still idling too high.
 

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The PCV valve/connector could be leaking if it cracked, and you seem to have taken a lot of parts off that could leak - a boost leak test could be in order. Curious what it would do if the MAF was disconnected.

If you feel like those are probably all fine, or want to try something simpler; write down and clear any DTC codes (P507, etc) - assuming you have a scan tool or app on phone with bluetooth OBD2 reader. I believe the ECU will not relearn idle if there are DTC's present, so you may need to keep clearing codes while doing the next step:

"Now onto the best solution IMO. The best way I have found to bring the idle back down, is to force it. If you have a manual car, put the transmission in first with the e-brake up and slip the clutch until the idle is around the normal level. Do this multiple times and the idle will eventually stay there. Sometimes it will stay until you hit the throttle then it will jump back up again, don't worry mine did this too, just keep trying and eventually it will stay. It will take some time, mine took 3 days but now the idle is normal and the car runs great. If you have an automatic, my suggestion is to put the vehicle in drive with the a/c on. This might bring the idle low enough but chances are, a reflash may be your only solution."

More details and options (ECU reflash, driving the hell out of the car, etc)

- https://www.cobaltss.net/forums/problems-service-maintenance-69/high-idle-after-cleaning-throttle-body-fix-solution-answers-286328/
- https://www.cobaltss.net/forums/2-4l-le5-performance-tech-46/high-idle-after-cleaning-throttle-body-322529/
 

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Check for vacuum leaks or a faulty PCV.

It would be very useful to check the vehicle parameters to see what the ECM thinks the desired and actual throttle positions are.

I'm not saying it won't work, but I don't like the idea of slipping the clutch that much.
 

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Discussion Starter #4
Wow guys thanks!
Already great ideas. I honestly have a hard time believing its a leak...though im not going to swear it isnt.
A crack could be the issue. I had it apart twice with the exactly same result as far as idle, so i have to imagine i didnt do it wrong twice(as for a faulty connection leak).

As for a leak elsewhere...possible, but wouldnt that make it harder to get the throttle to spin down when covered? because it would be getting air elsewhere? or am i thinking about it wrong?
There just doesnt seem to be a(apparent) leak.

I will definitely check the PCV first thing tomorrow, as well as fine tooth comb for cracks...
Barring that, looks like manual reset it is.
I didnt know this would do anything, thanks.

Will also be checking back for any further ideas.
 

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Discussion Starter #5
After typing out the last response something did cross my mind...
I do have the DDMworks CAI.
Just for further investigation. Am i mistaken, or would that probably rule out the PCV issue? Hose it new(ish) and not connected to plastic.
Or am i looking at the wrong thing?
 

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No the PCV could still be bad regardless of the CAI.

How modded is your car? Do you still have Your stock parts? A good place to start is put your car back stock and see if that clears it up.

Also have you checked your MAF? It usually would throw a code if faulty but it’s worth checking. Check wiring and Could Pull it to make sure it’s not broken, don’t touch the little diodes inside if you pull it out and check it. Those are what measure air flow and temps etc
 

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Discussion Starter #7
Only under the hood mod is the CAI. Everything else is stock. And this is the 2.4 not the redline.

Location of the PCV? and yes, theoretically i could reinstall the stock air intake and see what it does... but ive had the CAI installed for probably 7 months with no issues from second 1 of install.
Would that make a difference?
 

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Discussion Starter #8
New development.
I i tried to "Force to idle lower". It worked. after leaving gear or clutch back in car held idle wonderfully(though it was rough the entire time).
When i take off, seemed like when i was giving it gas, it would return to high idle.
So i let the car roll to a start after forcing low idle. Took off good, no gas, but then started to automatically open throttle. High RPM returned. Car was giving itself gas?(What?)

Im at a loss again. Not sure what else to look at.
 

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I think you need a diagnostic scanner to see what the throttle is being told to do. It is the first step in the diagnostic instructions.

When you had the throttle body and manifold off did you clean the seal surfaces? There are warnings about not using MEK or sharp objects to avoid damage.
 

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On the 2.4 there are only a few places you can have an issue.

If take off your air filter and, while the car is running, cover the end of the air intake where the filter normally would be, what happens?

Generally a high idle like you describe is caused by a leak somewhere after the MAF or a sticking throttle body.

The 2.4 only has 2 vac lines. One running from the intake manifold to the brake booster and the breather line from the valve cover to the intake is the other. Both, IIRC, are after the MAF and a leak in either could cause a problem.
 

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I assume there is an IAC valve on this application? If so, is it possible it's disconnected, damaged or stuck open with a piece of crud?
 

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This same (high idle) problem was discussed on the Solstice forum, and one of the guys found the actual throttle body relearn procedure in his service manual:

Start and idle the engine in park (or I presume, neutral) for 3 minutes.
Monitor the desired and actual RPMs with a scan tool.
RPM should begin to decrease.
Ignition off for 60 seconds.
Start and idle the engine in park (or I presume, neutral) for 3 minutes.
After 3 minutes the engine idle should be normal.
If the engine idle speed has not been learned, drive the vehicle above 44 MPH with several decelerations and extended idles.
If the engine idle speed still has not been learned, turn the ignition off for 60 seconds and repeat the process from the beginning.

IMPORTANT: If the check engine light comes on during the cycle with idle speed DTCs, clear the codes to allow the ECM to continue to learn.

So it appears that the ECM learns the correct idle speed on its own, but cannot do it if an idle-related DTC is set.
 

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Discussion Starter #13
This same (high idle) problem was discussed on the Solstice forum, and one of the guys found the actual throttle body relearn procedure in his service manual:

Start and idle the engine in park (or I presume, neutral) for 3 minutes.
Monitor the desired and actual RPMs with a scan tool.
RPM should begin to decrease.
Ignition off for 60 seconds.
Start and idle the engine in park (or I presume, neutral) for 3 minutes.
After 3 minutes the engine idle should be normal.
If the engine idle speed has not been learned, drive the vehicle above 44 MPH with several decelerations and extended idles.
If the engine idle speed still has not been learned, turn the ignition off for 60 seconds and repeat the process from the beginning.

IMPORTANT: If the check engine light comes on during the cycle with idle speed DTCs, clear the codes to allow the ECM to continue to learn.

So it appears that the ECM learns the correct idle speed on its own, but cannot do it if an idle-related DTC is set.
Ive tried this a few times now with the car not "Showing" a code.
I got a Fixd Bluetooth scanner and repeatedly cleared the P507 code that didn't seem to want to clear, even though it wasn't showing up on the dash.

I ran the "relearn" again, and now its idling at 3500rpm...even worse now.
Havent taken it out to drive since the even higher idle, but why would it go up?

Also, a few days ago I took it to the dealer and had the PCM reflashed. Did absolutely nothing.
 

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Is this with the original throttle body or the new one?

What happened when you followed Robotech's advice from post #10 and blocked the air intake?
 

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So to recap on a long story/series of events that have lead me to here; here is a brief:

Car had issue starting. Took in and eventually had starter rebuilt. Working great now.
After starter replacement, battery wouldnt charge. Had alternator looked at. everything was fine. Went to replace fusible link. When i pulled that i noticed what the problem was with the charging. I had the line(Fusible link) from the starter to alternator on the jump post, not the 12v post of the starter solenoid. Fix, and car is charging and starting perfectly.

Since to first got the starter back in the car, a second problem arose. Car is now idling at just below 3000rpm.
*I did remove the air intake, TB, and Manifold to get to the starter. All is back properly(can really only hook up one way), no holes or tears in lines, everything looks and reads great.

On inspection, car is just having an issue with idle. when in gear and driving, it is perfectly fine. It just idles insanely high.
Tried relearning process. Nope
Tried 2 other possible ways i read about a relearn...Still Nope
Tried manually blocking some of the throttle body to limit air flow...car spins down and can get it to normal idle...or it dies because its difficult to hold that exact amount of closure.
**Suspicion? Throttle body is open to far at idle. Read somewhere where this can happen and it should be open at 6% on idle, and its stuck at 20% and idling at 3k. Confirmed...this is at least what it seems to be doing.

Next strange occurrence to this. If driving the car down the road, clutch out, and kick it out of gear, car will climb RPM till it hits between 4500-5500. then it will drop down to 1100-1200...then climb again and repeat.
If clutch is in, car will just idle at 3000. This is while going down the road. Many speed variations tested. Same across the board.

Last thing. After sitting for a day, the car will start and idle normally. 1100 or so. Then after driving it a minute, it will rise until it is idling at 3000 again.

Next. I replaced the TB. On the hope that the memory for it was located there and a new one would relearn. This did NOTHING. Everything is exactly the same.

Im at my end. Nothing is working. Any help, suggestions, trouble shooting would be more than appreciated. Im dying to get back on the road.

***Side note. Car did throw the P507 code, RPM idle too high. Which was sort of expected. It cleared and hasnt come back. But obviously is still idling too high.
My guess is that you have an air leak. Possibly the intake manifold gasket since you looked for leaks elsewhere.
 

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Discussion Starter #16
Is this with the original throttle body or the new one?

What happened when you followed Robotech's advice from post #10 and blocked the air intake?
Removing the filter and covering, or removing the entire CAI and covering the TB does the exact thing. Can limit the air flow until car dies down to idle lower.

This is with both the old and new TB, both did the same.
On checking car numbers from the OBDII reader, TB is open to about 25% at idle. On reading, shouldn't it be about 6%

When I force the lower idle(e-brake, and letting out clutch till it stays low on its own) it will set around 5-6%

Could a leak at the manifold be happening when covering TB is killing car?

My brother keeps saying he thinks it might have something to do with the MAF. Anyone else think so?

And as a note, only codes it has thrown this whole time is P507(High Idle...well duh) and P1400(cold start code? at least from what ive found)
 

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My 2.4 idles with the throttle at 25%. If I load the engine with the clutch the throttle opening goes up to maintain idle speed, but mine is idling normally, so that second item may be moot.
Reading a lower throttle opening when loading the engine doesn't make any sense to me. Did you do anything with wiring? It almost appears to be reading backwards.

If you expose the throttle body, where is the throttle plate? Have you done anything to move it or block its movement?

What does your MAF read? I am seeing 0.6 lb/min at idle.

You probably caused the P1400 by dragging the engine speed down. I would not recommend that you do that any more. It has no practical value and is only destroying the clutch.

What temperature is your O2 sensor indicating for catalyst temperature?
 

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Ok guys the old school way of checking for a leak is to spray Starter fluid and listen correct ?
I haven’t worked on a car in 10yrs so forgive me if I’m wrong
 
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