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

[alal30319 at gmail.com]

Jay

Thanks, the plugs are good and on tight. I would not expect it to be the
plugs because if it was a bad one, you would usually see a constant miss. In
this case, it can be smooth on startup, but then act out after a drive which
is why i'm thinking that it may be o2 sensor or computer related.


On Mon, Jun 6, 2011 at 6:18 PM, Jay Hirsch <j.hirsch at mac.com> wrote:


> 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.

> >

> > The MB Coupes Website!

> > W126 SEC Mailing List

> > Postings remain property of MB Coupes, L.L.C.

>

> The MB Coupes Website!

> W126 SEC Mailing List

> Postings remain property of MB Coupes, L.L.C.

>

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