My 85 ltd is doing the same thing, I checked the cylinder pressure and found it to be 40 lbs.The sprk plug was black from fuel and oil deposits, and still wet looking.I'm going to pull the valve cover and watch the roker action,maybe the intake isn't closing completely. I think that the answer is simply "lots of mileage" and probably needs a valve job. But don't rule out PVC valve,egr valve,vacuum leak or fuel pump. Ill let you know what the answer to mine is if you let me know what yours is. respectfully, TOM KLINE (GOOD LUCK)
I have a 1985 midsize LTD 5.0L HO Police/Taxi with Center Fuel Injection that has had this symptom from 1985 to 2007. An additional symptom was that it would ping a lot. A mechanic found that someone, possibly at the factory, had drilled a small hole in a plastic fitting for the EGR valve. After replacing the fitting and a vacuum operated valve it ran very good. While the engine doesn't die or ping now, sometimes the idle drops down and the engine gets a little shakey. My experienced guess is that it is an inherent intermittent, possibly temperature related, problem with this year model design for cars with the Center Fuel Injection. The problem can be effectively fixed by fixing all vacuum leaks and assuring all vacuum operated actuators are working; this greatly minimizes the frequency and amount of the intermittent slow idle and it eliminates the ping. The ping is probably caused by the vacuum system giving inaccurate input to the electronics that then advances the spark too much. Lee Jordan
bat motor mounts cause the shaking a knock sensor realizing its shaking is the light get new mounts
it could be your engine mounts are needing replaced
Earmites or grass seeds in the ears could cause this
Could be, A very high mileage/worn out engine, The PCV system not in working order,
EGR should turn on Service Engine light on 96 and later. The tube / pipe to the exhaust manifold can also become blocked. EGR could cause rough engine. Many other possibilities.
Could it be ball joints?
The problem could be many things. With the check engine light coming on, it could be an internal issue in the engine, or broken engine mounts causing the vibrations. The shaking could also be caused by a separate issue from the engine, including a loose tire, or an out of balance tire, or bad suspension.
No but could be associated with diseases that cause tremorsAdditional answer:Some of the medications that treat rheumatoid arthritis or other types of auto-immune disorders, may cause shaking hands or even cause neurological problems. If someone has arthritis and their hands are shaking, they should talk to their doctor.
There are several different diseases which can cause the body to start shaking. If the shaking is particularly violent, this could be epilepsy. A less violent shaking could be Parkinson's disease. But there are several other possibilities. Factors such as cold, nervousness, or fatigue can also result in shaking of various kinds.
If the problem disappears when the shifter in placed in neutral it could be a transmission or engine mounts
Tire out of balance is the most likely cause. Can also be a bent wheel.
No, but something that could cause uneven idle could cause the check engine light to turn on.No, but something that could cause uneven idle could cause the check engine light to turn on.