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Registered
1996 Sl320
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66 Posts
Discussion Starter #1
1994 sl500, 142,000 miles.
Hi,
I'm pulling hair out of my head now. After warm up, engine idles up/down for a few seconds and runs smooth for a few seconds. While I'm having this issue I can hear low poping sound from the muffler as if it's a misfire. Here's what I've done so far:
1) checked for vacuum leaks and I found one under air intake cover. After repairing it, no changes.
2) monitored fuel pressure at the rail while looking at a vacuum gauge hooked up to where the A/C vacuum normally hooks up to control Ac vents. Fuel pressure stays at 52psi while vacuum gauge fluctuates as engine idles up/down.
3) fixing the previously mentioned leakage cured my check engine light but still does not change the idling behavior.
4) changed engine harness, ETA, and cleaned the MAF sensor with no luck.
5) disconnected the MAF sensor and engine runs smooth but CEL came back. :surrender:
Now the only cel is 19 and means insufficient air to intake system.
Can regular instead of premium fuel cause this issue?
Is 52 psi normal running fuel pressure for that engine?
Any help I can get is greatly appreciated.
 

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Registered
1990 500SL
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86 Posts
idle control valve?

remove it and clean it. It's almost like regular maintenance.

Also, while in the area, clean your throttle body and spray intake cleaner while running the engine. I did this today while having a minute, and it really smoothened up my SL.
 

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Registered
1996 Sl320
Joined
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66 Posts
Discussion Starter #3
The throttle boby or as they call it ETA is a rebuilt unit only 4 months old from Reman. I will try to locate this idle control valve you mentioned and clean it once I leave work today. Thanks for the quick reply.
 

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Registered
1996 Sl320
Joined
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66 Posts
Discussion Starter #4
Finally, I got a check engine light today. I used the on board LED diagnostic indicator and I have a code 22 and still a code 19. Code 22 means Oxygen sensor heater,open or short circuit. Could it be that I need to replace o2 sensor since problem occurs only when engine is fully warmed up?
Anybody?
 

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Registered
1996 Sl320
Joined
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66 Posts
Discussion Starter #5
Great news. SOLD THE CAR TODAY FOR $6500. :thumbsup: more than I paid for it.
NO MORE HEADACHES. :thumbsup:
 
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