Lvangundy

Ok, I'm wondering more and more about my engine issue. Is this a spark plug thing?

The latest discovery is that when in park, if I hold the RPM's and any number, let's say 1600, during a one minute period, the engine shakes pretty hard for a split second multiple times. It doesn't do it any any sort of pattern either, just randomly.

It does the same even if I rev the engine from the throttle body and you can also feel it if you put your hand anywhere in the engine bay. You can also detect this visually by watching the motor itself, you can see it shake.

Is there a way I can test the wires? I think this is part of my really bad gas mileage and performance issue. Somone give me some clues please!

additude

With problems like this you should take it in to the dealer and have them put it on the tester to locate the problem. Otherwise you could spend hours, days, weeks, months or more trying to find the problem.

However, it doesn't sound mechanical in nature, it sounds more electrical.

JBrady

I agree that proper diagnosis is a good thing BUT if your wires are old... replace them. I think I read where you replaced the spark plugs. Wires get old and just the stress of pulling them off the old plugs can and will cause damage. Same goes for changing just the caps and rotors. Even if the problem is something else I would still change the wires.

Another area that can cause problems is a dirty throttle body.

Another is the throttle position sensor.

Vacuum leaks are always suspect.

EGR.

PCV.

Contaminated MAF from air filter oil residue.

Dirty injector(s)

O2 sensor, this should through the "check engine" light.

Fuel pump.

Hope this "narrows" it down... :eek:

LOTC

I agree take it to the dealer for a check up.

BTW how hard is it to clean the throttle body, change the spark plugs and wires, and change the fuel injectors on a LS?

JBrady

Hard is a relative question. It is all basic r-and-r (remove and replace). Plug wires, caps and rotors are easiest. This is a good starter project and risks little more than skined knuckles and another set of parts if you mess up.

Plugs are a harder and should be done only if you understand how to measure the gap correctly, clean the thread and plug area, and are VERY careful not to strip or cross thread the holes.

Injectors should only be replaced by a well trained person as a gas leak is serious business. If in doubt, get help. If you want to learn... buy a manual, find someone trained that is willing to teach you AND/OR be willing to PAY the price of learning (if you have to ask... the price is too high)