1994 C4 Strange Engine Rumble
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Joined: Jul 2017
Posts: 93
Likes: 18
From: Texas
Somebody else will probably have other ideas, but here are a few things to look at, in no real order.
1. Unplug your injectors one at a time and see if the idle changes or stays the same.
2. Ensure all wires are securely connected to the distributor and plugs. If you haven't checked these before, it's tricky for the drivers side and involves getting under the car, but takes maybe 15 minutes including jacking the car up. Go under the front bumper and use your right hand, makes it easier to get the leverage needed to "snap" the wires onto the distributor.
3. Test the vacuum if the first two don't change anything. You can get a loaner from most parts stores. In the past, the EGR valve on my car failed resulting in similar symptoms (reduced power, rough idle in drive, stalling if I floored it from a stop, violent shaking when slowly accelerating in top gear with the TCC locked).
4. Test fuel pressure while the rough idle and shaking is occurring. I believe one of the above is more likely, but there is no reason not to test fuel pressure.
Good luck!
1. Unplug your injectors one at a time and see if the idle changes or stays the same.
2. Ensure all wires are securely connected to the distributor and plugs. If you haven't checked these before, it's tricky for the drivers side and involves getting under the car, but takes maybe 15 minutes including jacking the car up. Go under the front bumper and use your right hand, makes it easier to get the leverage needed to "snap" the wires onto the distributor.
3. Test the vacuum if the first two don't change anything. You can get a loaner from most parts stores. In the past, the EGR valve on my car failed resulting in similar symptoms (reduced power, rough idle in drive, stalling if I floored it from a stop, violent shaking when slowly accelerating in top gear with the TCC locked).
4. Test fuel pressure while the rough idle and shaking is occurring. I believe one of the above is more likely, but there is no reason not to test fuel pressure.
Good luck!
