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Idle problem Still having them.


jonlabree

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My problem seems to be only the idle. When coming to a stop or slowing down the idle stays at what ever rpms that the engine was running before I let up on the throttle.

Say I'm going 30 mph and reading 1500 RPM, I let up on the throttle to stop. The RPM stays at 1500 until I come to a complete stop. Then it come down to idle. I have checked and replaced all sensors on the throttle body, had Ryan, at SP adjust the chip. But I'm having the same problem. HELP!!

Anyone Please. It's hard on the brakes and transmission.

Jon..

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Guest Mc_Reatta

Did you clean the inside of the TB and butterfly, and the ports for the IAC?

What does looking at the readings for MAF, IAC, and TPS say in diagnostics?

(ED01, 21, 22)

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I have the same problem with my Olds trofeo, it seems when the temp air and water go up it stops. I have also noticed that after 5 or 6 complete stops it will stop. I have replaced intake gaskets cleaned everything related and makes no difference. I also have a related problem with the speedo some time it will say anywhere from 1 to 15 mph at a stand still, could the speed sensor cause both problems? Also there are no codes set.

Edited by zoltanb
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I've had the same problem for about a year on one of my Reattas. To clarify, the high RPM issue (for me) begins when starting the car from being completely cold and goes away when the car reaches normal operating temperature (190*). If the car had been sitting only 2-3 hours, all is OK. The car has to be completely cold for the high RPM issue to present itself.

I've had the following done (except for the plugs, all were done twice in case the item was faulty) and revs still remain high:

  • Oil pressure sensor
  • Replaced spark plugs
  • Replaced fuel filter
  • Replaced idle control valve
  • Replaced thermostat
  • Replaced PCV valve
  • Replaced O2 sensor
  • Replaced PCV Grommet
  • Serviced the fuel injectors

I've also tried two other ECMs and that didn't help. Not sure what else can be done.

On the positive, I have a car that idles nearly as quiet as my daily driver. And I probably have the cleanest engine in the country.

If time isn't an issue, I'll let the car idle until it reaches temperature and then be on my way. If I'm in a rush, I won't start driving until the temperature gauge hits the 3rd bar. After that, it takes about a mile before the car warms up and the issue goes away.

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Guest Corvanti

i'm really not sure i should post anymore "easy" solutions that have worked for me and others, but i had the same idle problem a couple of months ago.

after what Mc_Reatta stated about cleaning, if the MAF was not replaced, clean it with MAF cleaner. i did all that but it took a 30 minute drive to get the idle to gradually go all the way down. (ECM re-learning)? no problem the next day or after.

also, check your rubber vacuum lines for cracks, etc. another member had a rough idle problem - 2000 to around 500rpm. after replacing a MAF, he discovered a vac hose had slipped off. all is well now...

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Guest Mc_Reatta

Vacuum leak could be a culprit for sure.

That ceramic coating in the TB isn't keeping that butterfly from closing is it?

While you're in diagnostics check the temp sensors especially the MAT and coolant. (ED01, 23).

If none of that pans out, I suggest taking snapshots when problem is present and goes away and comparing all the parameters.

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If it was a vacuum leak would it correct when the car comes to a stop?

Ceramic coating is .0001 thick and is not stopping the butterfly from closing.

Any way I had this problem before I had it coated.

I will check sensor readings tomorrow. Thanks for some place to start looking.

It is very strange. The RPMs do not go down until the car come to a complete stop.

Jon..

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Guest Mc_Reatta

Looking back at zoltanb's comment about the speed sensor and your needing to stop to get idle down, I'm thinking you could disconnect the speed sensor and see if that makes any difference. Both ECM and BCM process that signal, but I have no idea why that would play into the idle speed.

Another strange idea would be to check none of the EGR valve pintles are sticking open.

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Tried everything that was offered. Disconnecting the outside temp sender only gets you hot air and a reading on the dash of -39 below on the dash readout.

Nothing seems to have changed, then yesterday it was fixed. I don't know how or why, but the idle went back to normal.

Coming down when I slow and when you put it in neutral at speed it drops like it should. As I am slowing it comes down equal to the speed.

Can't tell you what fixed it, but it's back to normal. But wait, that was yesterday. We will see what today brings.

Is there a speed sensor on the power steering?

Is there one in the transmission?

Jon..

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