why is my motor shaking?

pomofro · Jan 25, 2004

ive got an 88 with full exhaust as far as i know. when my idle is set at around 900, the motor will stay still. when its set at 700 or so itll start jumpin around. randomly moving back and forth and i can feel it pretty good inside the car. it doesnt happen as soon as i stop but about a second or 2 once i stop. happens the worst when the cars pointed downhill for some reason. its been happening for a while. can someone help?

88stangmangt · Jan 25, 2004

well it is probally trying to cut off on you. are you messing wiht the idle?

90mustangGT · Jan 25, 2004

Inspect motor mounts.

89lxsport50 · Jan 26, 2004

That sounds similar to what mine is doing. When idleing at 750 it is rough and seems to randomly shake. You really feel it inside the car. When it is ideling at 900 or 1000 when warming up it is pretty smooth. I have not found the problem yet. Any suggestions would be appreciated.

89lxsport50 · Jan 26, 2004

I forgot to say that my motor mounts are brand new. They actually transfer more of the vibration now.

Schlodes · Jan 26, 2004

How is your harmonic balancer?

Unplug the coil wire, and have a buddy crank the engine over while you watch the balancer. If its wobbling and the robber is all cracked it could possibly be the balancer causing this too. Just a thought.

IndyBlk5.0 · Jan 26, 2004

me thinks your engine is getting to the point where it is wanting to stall. set it at 850 and be done with it....

PonyBoy90 · Jan 26, 2004

You fixed your motor mounts, did you do the tranny mounts too????

How's your drive shaft? If you fixed your mounts but have been driving with them broken for a long time, maybe your shaft is bent and causing the vibration.

90bluegt · Jan 26, 2004

Have you thought about the timing?? Because as you rev the motor the timing advances, maybe alittle more or less timing??

thanks

89lxsport50 · Jan 26, 2004

Tranny mount is new, I will check timing and balancer. The driveshaft is not spinning at idle. Thanks

PonyBoy90 · Jan 26, 2004

Whoops!

You're right, it doesn't spin. Doh!

IndyBlk5.0 · Jan 26, 2004

pomo, just a question, why are you setting your idle so low? 850 is the lowest i would even go..

88stangmangt · Jan 26, 2004

well i would hope your driveshaft wasnt spinning at idle. But it could just be the computer playing with the idle till she warms up then she will drop it back down to about 800.

pomofro · Jan 27, 2004

well thats the stock idle so i figured it cant be wrong. my timings at about 11 and i cant see the balancer moving. i can set the idle higher but i was just wondering y it would happen, is something wrong, and if im the only one with the problem.

PonyBoy90 · Jan 28, 2004

My foxbody engine has some shake too. It's stock and one of my engine mounts are cracked, but the engine seems to be holding ok for now as everything seems to be aligned.

You think maybe it's a cam issue? Does the engine run relatively quietly or is there some knocking?

I'd think it's acceptable. Maybe it's an engineering fault in that FORD didn't set up the engine bay right to eliminate all the shaking from the engine. I mean, a 302 is a big engine. The only engines I see that don't move are on Japanese import cars. Those run like sewing machines.

hllon4whls · Jan 28, 2004

The 302 was never a smooth as glass engine. A small miss can cause the engine to shake. Every engine will shake if the rpms get low enough. Unless your harmonic balancer is majorly damaged, you are not going to notice the harmonic vibrations that it is designed to eliminate.

While the car is idleing, go by the mufflers and listen for a puff comming out of the exhaust. This is a misfire. I have had some cars that no matter what I did, I couldnt get rid of an ever so slight miss at idle. The little exhaust puffing can also be caused by high timing, so like I said not a big deal.

My 302 in my F100 shook a little. It idled about 650-500 (carb) and ran great other than that. I have always run the timing high in motors to give them some guts.

jerry beach · Jan 28, 2004

Pull the codes from the puter. That is where you should start most of the time. Pull the plug wires off the dist. one at a time, each one should make the idle drop a little. After you pull each wire, put it right back on. You may get shocked a little doing this, so dont jerk your hand away and into the fan or belt. If one wire doesnt make a difference whether its on or off, then you have found your miss. How old are the cap, rotor, wires, plugs...? It may just be in need of a tune up.

pomofro · Feb 1, 2004

wouldnt the plugs look different if theres a miss cause i replaced them and they all looked fine

pomofro · Mar 6, 2004

i replaced the balancer and fuel filter and still cant get it to stop shaking. it happens randomly. sometimes at 850 rpms. im also having a big problem when i hit the gas below 1,700. if i press it to much, the shifter will shake like crazy and i wont go anywhere. sometimes theres a poppong sound from under the hood and as soon as that happens it takes off like a vtec. its wierd and its pissing me off, i dont know what to do

1991vert · Mar 6, 2004

pomofro said:
wouldnt the plugs look different if theres a miss cause i replaced them and they all looked fine

didnt happen with my stang, but when i did a tuneup on my beater 93 sundance, i was putting the little boot back on the dist. cap and wiggled loose a wire. it caused the engine to shake really bad. drove fora while not caring on the highway then got out at my g/f's and started looking around in the engine and saw the 1 wire was disconnected from both sides. also was taking me like 10 mins to get up to highway speeds. common signs of the spark plug problem is loss of power/acceleration and that crappy engine seizure. if you didn't lose any power/accel. i guess you can rule that out, but it was just a thought

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