Strong vibration above 4000 RPM - What to check?
03-29-2002, 01:13 AM
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Strong vibration above 4000 RPM - What to check?
Hi Folks,
I've been searching the archives and have read all about torque tubes, vacuum leaks, and various sensors, but none seem to cover what I'm experiencing. When accelerating the car is very "rough" above 4000 RPM. It does this in every gear, with quite a bit of noise and strong vibration in the shifter. Below this engine speed the car is very smooth, and it's performance is impressive even at lower revs. <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
The car is a 1988 S4 5-speed with 82000 miles on it, and overall it's in good condition. It doesn't appear to be the torque tube, but some posts suggest it might be a vacuum leak. I honestly don't know how to test for this, although it sounds like it would require special equipment. I'll keep searching to see if I can find out how to do this. I'm also going to do the "firefly" test.
Suggestions for things to try or check would be greatly appreciated!
Cheers,
Skip
I've been searching the archives and have read all about torque tubes, vacuum leaks, and various sensors, but none seem to cover what I'm experiencing. When accelerating the car is very "rough" above 4000 RPM. It does this in every gear, with quite a bit of noise and strong vibration in the shifter. Below this engine speed the car is very smooth, and it's performance is impressive even at lower revs. <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
The car is a 1988 S4 5-speed with 82000 miles on it, and overall it's in good condition. It doesn't appear to be the torque tube, but some posts suggest it might be a vacuum leak. I honestly don't know how to test for this, although it sounds like it would require special equipment. I'll keep searching to see if I can find out how to do this. I'm also going to do the "firefly" test.
Suggestions for things to try or check would be greatly appreciated!
Cheers,
Skip
03-29-2002, 03:50 AM
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If you think it might be the engine that's running rough, it could be the coils starting to fail - or a bad grounding connection between coils and engine. Bad coils could make the engine run rough at higher rpm.
Have you checked your ignition wires? If not, let the engine idle at night, and spray a very light mist of glass cleaner over them. Do you see any sparks?
What's the condition of your motor mounts? If they haven't been replaced, yet, they are most likely worn after all those years and miles.
Keep us updated!
Have you checked your ignition wires? If not, let the engine idle at night, and spray a very light mist of glass cleaner over them. Do you see any sparks?
What's the condition of your motor mounts? If they haven't been replaced, yet, they are most likely worn after all those years and miles.
Keep us updated!
03-29-2002, 12:43 PM
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Hi Nicole,
Thanks for the tips. I'll check for sparks in the ignition wires, but I'm not really sure how to check the coils or grouding connection. Time to search the archives to see if this is something I can do on my own!
The odd thing is that there are times when it is fairly smooth above 4000 RPM, and I'm going to see if there is any correlation to engine temp, etc.
Regarding the motor mounts, is the <a href="http://www.jageng.com/speedmount.htm" target="_blank">Shark Speed Mount</a> worth considering?
Thanks!
Skip
Thanks for the tips. I'll check for sparks in the ignition wires, but I'm not really sure how to check the coils or grouding connection. Time to search the archives to see if this is something I can do on my own!
The odd thing is that there are times when it is fairly smooth above 4000 RPM, and I'm going to see if there is any correlation to engine temp, etc.
Regarding the motor mounts, is the <a href="http://www.jageng.com/speedmount.htm" target="_blank">Shark Speed Mount</a> worth considering?
Thanks!
Skip
03-29-2002, 04:10 PM
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Hi Skip:
We have heard different opinions on those speed mounts - some totally love them, others say they are worried about the extra stress on the oil pan. Maybe it is just a temporary solution - I can't judge (my car has new original engine mounts, and it makes a big difference).
There are some people who replaced the original engine mounts with slightly modified Ford products, which are a lot less expensive. Maybe someone else on this boaard can give more detail on this option.
Good luck, and have fun!
We have heard different opinions on those speed mounts - some totally love them, others say they are worried about the extra stress on the oil pan. Maybe it is just a temporary solution - I can't judge (my car has new original engine mounts, and it makes a big difference).
There are some people who replaced the original engine mounts with slightly modified Ford products, which are a lot less expensive. Maybe someone else on this boaard can give more detail on this option.
Good luck, and have fun!
