My car (94 318is) was running fine until one very cold night. The next morning, when I turned it on it was shaking pretty bad (throughout the rpm range), and it had very low power. I have tried to let it run for a while, but the problem seems unchanged. I changed the spark plugs also.
My Haynes manual lists these things to try if "Engine misfires throughout the driving speed range":
Fuel filter plugged
fuel pump faulty, or delivery pressure low
fuel tank vent blocked, or fuel pipes restricted
uneven or low cylinder compressions
worn, faulty, or incorrectly gapped spark plugs
faulty spark plug or spark plug wires
Does anyone have recommendations on which one of these might be the culprit? Or anything else I can do to check before I have it turned in to a mechanic. I wanted to at least get it running decently because I didn't want to have to pay a tow truck to get it to the mechanic. I was thinking to get one of those "spark plug wire tester" things to see if the spark plugs are actually firing, in case there is a problem with the wiring somewhere. Its just really peculiar that this problem appeared overnight.
Also, check to see that all the blades are on your motor fan. If a blade or two breaks off, you may never know it but this will cause the shaking and loss of power as well, due to the imbalance of the fan's rotation.
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Or, it could be condensation in the fuel. Go to auro parts store and buy a couple of bottles of dry gas, water out, gas line anti-freeze, etc (isopropyl alcohol) and dump them in the fuel tank, if it is condensation this will homogenize the water and allow it to pass and burn. I have had a couple of instances of this occurring and it will give you stalling, low power, no acceleration, backfiring, etc. Worth a shot, and it is inexpensive,.
I was going to post this problem as a new topic. But then I realized that jconline seems to be having the EXACT problem Im having. My 93 318IS was running beautifully until a week ago when it dropped to -39 F up here in lovely Canada! My car wouldn't start one morning... I tried boosting it several times, and it would come close to firing, but not QUITE... just wouldn't catch. I waited til it warmed up a bit, and tried again. No fire... Then I bought a little bottle of gas line antifreeze, and dumped it in the gas tank. She fired!!! But when I was letting it run for a while, I noticed the UP AND DOWN with RPM's when just sitting there in neutral. The exhaust Noise was equally as annoying... UP AND DOWN, UP AND DOWN.
Then my CHECK ENGINE light came on. When I took the car for a spin, this light turned off... BUT then came back when I was travelling at about the same speed, at about the same RPM. When I accelerated, or let off the gas, the light turned off again, only to come back again shortly. When I stop, and have the car in neutral, I still notice the UP AND DOWN RPMS. And occasionally when I step on the gas, it hesitates, and is kind of jumpy. Even travelling at a constant speed, sometimes, it just starts to decelerate, kinda jumpy...
JUST CUROIUS if you found anything out regarding this problem, or if anyone else has some insight as to what could be wrong here...Again I stress, it was FINE before the cold snap, now it's having thise problems listed above...
Maybe worth mentioning that I notice ALOT of exhaust fumes coming out. Stong smell... I don't know... Maybe it's just time to sell it! haha... Any help is greatly appreciated!
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i had that same problem. it wasnt funny in neutral. but when i hit the gas or brought it above 3500 rpms it shook. and like. there was just no power. if i try to give it some it wouldnt go. it would just shake. so. it was the coils. i think thats what they are called. they connect to the top of the spark plug and they are longish looking and stuff. pretty sure they are coils. those were bad. had to replace them. and now she is a beauty
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