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1988 Mercedes 300ce, 1993 Mercedes 190e, 2003 Oldsmobile Alero, 2002 Chevy 2500 HD Duramax,
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95 Posts
Discussion Starter #1
It starts up and usually hold idle at around 1k rpm than after a few seconds it goes up to about 1.5k to 2.5k rpm.

It holds a high idle.

When I put on cruise control it doesn't stay in gear. If I set it at about 60 it will go down to 55 than downshift and get me back to 60. Now, this is more annoying than anything.

It seems once it gets warm 80c my idle gets terrible. It will not idle. It gets very low it goes from 1k rpm in D to 500 than it dies out. When it idles like this it sputters and seems to backfire, if I don't apply full throttle it just sputters and backfires. If I apply full throttle it seems to overcome it just fine and take off.

I'm also getting terrible gas mileage. 170 miles to 13.5 g.

If I pinch the breather line bewteen the idle control valve and manifold I can get the high idle to go away.

I also just replaced the headgasket so it could be a sensor n
Code:
ot hooked up.

I have takin it to two different mechanics and neither could find my problem.

Any answers would be greatly appreciated.

If you have any questions let me know.

I'm desperate at this point.

Thanks,
Ryan

(937)-570-3793
 

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Registered
1988 Mercedes 300ce, 1993 Mercedes 190e, 2003 Oldsmobile Alero, 2002 Chevy 2500 HD Duramax,
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95 Posts
Discussion Starter #2
Could this be an EGR problem?

Where does the vacuum line from the egr valve go to?

Thanks,
Ryan
 

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Registered
1993 190E 2.6, 1990 300SEL, 1992 300SE, 1992 400E, 1987 190E 2.6 murdered by my brother.
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1,291 Posts
Hey Newbie. If you want people to respond you should post what year. These cars vary a lot from year to year and sometimes within the same year. If your EGR was bad it would put a check engine light out. Check all your vacuum lines. When I ran my car without my airbox after my engine rebuild, it had high idle for 40 mins when I ran it for that long. After I put the air box and vacuum lines back on it went back to normal idle. So there is a leak somewhere. You have to fish around and find it.
 

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Registered
1988 Mercedes 300ce, 1993 Mercedes 190e, 2003 Oldsmobile Alero, 2002 Chevy 2500 HD Duramax,
Joined
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95 Posts
Discussion Starter #4
Idle Problems

hello,

Sorry, the year is 1993.

I have used about 4 cans of starting fluid looking for leaks.

I still have not been able to find any.

I almost completely took the intake out of the engine bay when I did the headgasket.

What are some commmon leak spots?

I replaced all the idle control valve hoses.

What controls the idle control valve?

Thanks,
Ryan
 

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Registered
1988 Mercedes 300ce, 1993 Mercedes 190e, 2003 Oldsmobile Alero, 2002 Chevy 2500 HD Duramax,
Joined
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95 Posts
Discussion Starter #5
idle problem

The backfire is coming from the engine bay, it seems like throttle bodie.
 

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Registered
1988 Mercedes 300ce, 1993 Mercedes 190e, 2003 Oldsmobile Alero, 2002 Chevy 2500 HD Duramax,
Joined
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95 Posts
Discussion Starter #7
I have read about 50 posts about similiar problems about half have no solution.
 

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Registered
'01 SLK230,'93 190E 2.3, 1971 LS5 Corvette Convertible
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2,216 Posts
hello,

Sorry, the year is 1993.

I have used about 4 cans of starting fluid looking for leaks.

I still have not been able to find any.

I almost completely took the intake out of the engine bay when I did the headgasket.

What are some commmon leak spots?

I replaced all the idle control valve hoses.

What controls the idle control valve?

Thanks,
Ryan
From the online manual:

"b) Engine speed too high at normal
operating temperature
Compress formed hose (arrow).
If there is a significant change in engine speed,
the idle air control valve is jamming or is not
electrically heated."

The Idle Control Valve is controlled by the CFI Module on pin 3 of the CFI connector.
After warm-up, you should feel the ICV pulsating. If you don't, then maybe the OVP relay isn't supplying the 12v battery supply to the ICV. Pull the connector off of the ICV and make sure you are getting 12v on pin 2 of the ICV connector with the ignition on, not running. If no voltage, then check the OVP relay.

*Note-on your car, the OVP relay socket has to be held to fully seat the OVP relay.

If you do have the OVP supply voltage at the ICV connector, then I would check the inside of the ICV to see if the valve is moving freely and not jammed.
 
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