trembling engine

[Fadi]

Hi all,

I had posted a message sometime in December about a locking/unlocking button installation in the center console since the doors will not automatically lock when the drivers door in locked from the inside. from the outside all is fine. I have an infrared door lock without key hole. Result is that this cannot be performed because the door lock communicates with the immobililzer installed on the car. Conclusion is that all vacuum and electro circuits are ok but driber door lock will not lock all other doors. Really strange.

Anyways to the thread topic. I had my car serviced, changing filters, engine oil and sparks. I collected the car and went for a long drive and everything seemed fine. At one point I got stuck in traffic and the cars were moving a couple of feet avary couple of minutes. The car started trembling. A slow burble of a trembel. The trembel was soft but annoying. It never did that before the service.

And a final question. Does the fuel filter have a fuel return valve? or should it have one?

Any coments? Thanks

[Mark Stetson]

Sometimes new plugs can be bad. What kind of plugs were installed? Were they the same as the old ones? There could have been an installation error. Could the idle speed have been reset? Was the car getting unusually hot in traffic? When the engine is hot, the timing is retarded to cut power. I don't know if this affects idle.

[-fad]

Hi Fadi-

possibly- the stage 2 fans kicked in when creaping and this is the source of the tremble..., also along this line- maybe the stage 3 (high speed) kicked in when you were crawling and this is the source of the tremble...

was a/c in use?

-fad

[Fadi]

Spark plugs were of the same type. The A/C was on supplying heat though.
This morning the trembel seems to have faded or reduced in intensity. If there is too much engine oil would that effect idle? If its just above the max level?

[Mark Stetson]

My engine would tremble at a specific idle speed - I think 600 rpm, where it wouldn't shake at 500. As -fad suggested, the a/c could affect the idle speed, perhaps nudging the idle into a range of harmonic imbalance. Guido suggested I change the motor mounts. When I did that, the idle shake was greatly reduced.

[-fad]

Fadi- you may wish to review the condition of your distributor caps and rotors, any trouble codes are stored, and/or put the car on the scope

fwiw- ...had the dist caps and rotors changed recently, and though the motor didn't appear to be 'trembling' or idling rough before the r/r- - was tons smoother after the r/r

-fad
'94 E500 (39.9k)