Problem when letting of the throttle, RPM going upp and down. 500E-92

[-Mackan-]

Hello!


I have a some what small problem with my car, when I drive it and have to let the throttle up, the RPM falls like it's supposed to, but when it reach about 1000-1200rpm its starts to go up and down.

But when my car is completely stopped it runs just fine, and on every other RPM as well. The problem occurs only when decelerating and around (1-1,2K rpm)

I changed the upper harness last year.
Rotor and caps are okey.
Replaced the LH module last year to, but the problem remains the same.

Any ideas? I'm thinking ETA?

/Markus

 

[emerydc8]

Hi Markus. It's funny that you should mention that because I just replaced my ETA on my E420 and there is an intermittent problem with idle when the car is in drive or reverse. It idles at about 500 RPM but bounces up and down about 200 RPM once or twice per second. When I put it into neutral the problem stops. I just pulled the codes and got a new DTC 14 on pin 7 (EA/CC/ISC) which is the code for "closed throttle position switch."

Have you tried to put the car into neutral as you are coasting to see if the problem still exists? I don't know why going to neutral would affect my idle, but it does. The strange thing is that the problem cropped up right before I installed the ETA yesterday, so I'm not convinced it's a problem with the ETA. I ordered a neutral safety switch because I suspect that's what may be causing the problem. Have you pulled the codes on yours?

 

[500AMM]

Maybe a shot in the dark - but isn't a vacuum line activated when the car is put in drive?
If so it could be a vacuum leak only.

 

[emerydc8]

Wow, that would make a lot of sense because I had just replaced the valve cover gaskets and was climbing all over the engine compartment trying to get to those rear valve cover bolts. Now, if I can just figure out what vacuum line it is, I'm in business. Thanks, Arnt!

ADDENDUM: Come to think of it, I did break a vacuum line connector and I tried using JB Weld as a temporary fix until the part comes this week. It was the "Y" connector in the picture that the EPC calls a Connector: Fuel Distributor. Do you think this could affect the idle?

 

[500AMM]

I guess I was thinking on that upshift delay switch described here:
http://www.500eboard.com/forums/sho...itchover-Valve-Open-Short-Circuit-(DM-Code-26)