Shaking Engine at low RPMs
 

Hey everybody.

I have an '81 RX-7.

Bought it from a guy who attempted to rebuild the carb unsuccessfully, and could subsequently not get it running.

I got the carb working and put an exhaust on the car... but it's having some problems.

The most severe problem is that, when under load, the engine causes the car to shake back and forth as you accelerate or decelerate (and sometimes just as you cruise) in low RPMs.

This problem disappears at high RPMs.

The choke seems to even it out...


Anybody have any thoughts?

Thanks a lot,

Matt

Here are my thought what it is worth

Does it idle like crap ? Have you checked engine compression lately ?

what about engine mounts ? Are they any good ?

Hugues -

id guess a vacuum leak.. does it seem to smooth out aroudn 3-4K? more info..

check your engine mounts but, it sounds like low compression on the rear rotor. you can try ATF trick that sometimes restores some compression.

Well it can also be intake leaks. I just fixed my messed up idle after 2 years of pain and agony of not nowing what it was. First I took all the manifolds off and replaced all the gaskets and vacume hoses. After this the engine was much quieter but still shook a little. Next I turned the butterfly screw to close the butterflies a little because it was at 1000. Then I readjusted the TPS recet the ecu then took it for a spin and now my S-AFC reads only a 30 rpm difference up and down. Very smooth and nice tone as well. FINALLY.