Rough Idle Help

[xlr857]

My buddy's 95 5.0 is running really rough. We did a compression test 140 on all 8 cylinders. Changed wires, plugs show engine is running real lean, no check engine light. At high rpms it shakes real bad. Any ideas. We were thinking injectors maybe.

 

[jerry beach]

Does it shake in nuetral at highway speeds? Does it shake in high gear at 55mph? Does it do it when you sit still and rev the engine? We can help if you provide that info.

 

[xlr857]

It shakes in neutral pretty bad just idling, If you jump on it it and accelerate it smooths out between 3,000 and 4000 rpm. Any higher and it starts to shake real bad almost like a dropped cylinder.

 

[jerry beach]

did it do this before the compression test? I am guessing yes. Pull the codes from the puter first, and do the goose test at the end. This will tell you if all the injectors are functioning equally. After the last engine running code, floor it and let it go real quick. Just make the rpms rise to 2500 or so. The puter will cut one injector at a time and give you the numbers of any weak ones it detects.

If your car has a check engine light, you only need the jumper wire. Otherwise you can use a cheap test light in place of the volt meter. Make sure the firing order is correct and that you are using the correct one for the engine.