[W126 Coupe] 87 560SEC (euro) running problems

[Jay Hirsch]

Just a suggestion

Pull the plugs  and put them back in making sure each one is in fact screwed all the way in

Jay H
On Jun 6, 2011, at 5:59 PM, alal30319 at gmail.com wrote:


> All

> 

> I posted this on a couple of forums but i've not been able to get any tangible answers so I thought I would cross post here:

> 

> Here is my scenario:

> 

> When I bought this car, I got it to run like a scalded ape. It was fast and smooth. I replaced the plugs (NGK non resistor), plug wires, coil, rotor and crank position sensor.

> 

> Recently, I had a bad miss which I've been trying to chase down. I initially thought it was a bad fuel distributor or injectors caused by bad gas, so I pulled the injectors and checked them. Some of them were a little weak so I replaced all 8 and got the car to run very well at idle. But after running the engine for a while, it would develop a miss on and off and you'd see the oil pressure gauge drop when it does. 

> 

> After a long drive, the miss would get worse and become more constant.

> 

> I've been able to disconnect the electrical connection to the EHA and get the car to idle better.

> 

> I've checked for vacuum leaks but could not find any. The vacuum gauge on the dash is pinned to the left until the car develops a miss and then it will move towards the center (about 1/2 way between far left and center).

> 

> I swapped out the EHA with another that I had on shelf but this did not change the symptoms.

> 

> I suspect that it could be the O2 sensors, or the computer trying to lean out the mixture but I am not sure how to test these.

> 

> I'd be grateful for your thoughts.

> 

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