I have a 1999 Grand Am SE 3.4L with automatic tranny and when I come to a stop at a red light or stop sign theres a vibration that you can see and feel. Its slowly getting worse. We looked at the motor and tranny mounts and they looked good, had the car in park shut off and rocked it back and forth and watched the engine for any lift to one side or the other and front or rear engine lift or movement and saw none. Wondering if it could be something else or if it still could possible be a motor and tranny mount? Car isnt running right now have to replace the front down pipe or flex pipe whichever its called, it cracked and made my car sound like an old V8 pick up, lol.
Vibration
- Thread starter tplat
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Roadrunner
New member
turn the car on open the hood and pull the throttle open by hand real fast and hard..if you get alot of movement then it could be the mounts
It idles fine its just when I`m stopped at like a red light or stop sign. Takes off fine, drives fine, it`s slowly gotten worse. As for the down pipe it had a crack in it and when my nephew was taking it off to weld the crack and the part that bolts to the exhaust manifold completely broke off at a spot where you cant get to it to weld, that gap between the two pieces isnt wide enough and the depth of where the crack would need to be welded is also a more then half inch in. He`s a welder by trade.
http://www.exhaustdistribution.net/servlet/the-565/CHEVROLET,-OLDSMOBILE,-PONTIAC-3.1L/Detail
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Will try that when I get it put back together. Figured why I got it apart I would go ahead and replace the plugs, manifold gaskets and valve cover gaskets.
Posted a reply earlier but it had a link in it and sofar it hasnt posted. It doesnt do it when sitting at idle. It only does in drive and when stopped at a red light or stop sign. As for the down pipe when my nephew went to pull it off it completely broke at a weld seam where 3 pieces of steel were welded together. The gap that you would have to get a welding tip into to weld it is to narrow without having to cut it apart and weld it back together in pieces starting with the inside piece. I found a new aftermarket replacement one online for $50.00 with free delivery. My nephew is a welder.
3.4 famous slight misfire on these engines. but not the plugs or wires or anything.it is amplified if it has bad or worn mounts. How to check: 2 people one has to power brake and other is looking for flex on mounts. or if you have a lift even better.
Thanks for the reply. Did find out that I need to replace some mounts. Ran into another problem. I had to install new struts and shortly after that my ABS, Traction Controll lights are coming on. Sometimes its just the loss of traction light comes on then goes off when taking off from a dead stop light at a red light or stop sign or when taking off for the first time in the day. Sometimes the ABS and Traction Controll lights come on and sometimes go off and sometimes stay on. When they do this I get what feels like a little bit of lag in the front end like a sticky brake caliper. Read that it could be a wheel speed sensor in the wheel bearings. Car has about 152k miles on it with not a lot of factory parts replaced other then the AC compressor, struts, down pipe, tie rods. Was wondering if anyone else thinks it might be a wheel speed sensor?
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Yeah the backside of the engine lifts up a decent amount so need to figure out which mount that is. Lower rear or left tranny mount?
OK, thanks for the reply. That's what I thought just wanted to make sure. Did some more reading up and there are 4 wheel sensors one in each wheel so I need to give a friend of mine a call and see if his scanner can scan for that. Pretty sure it does since his cost several grand although it will cost me a 12 pack of beer, not complaining though. But can that bad sensor cause a little bit of lug in the front wheels when I go to take off when it decides to act up?
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I guess if the ABS kicks in but I tend to doubt it, ABS would be disabled.
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When I go to take off from like a dead stop the loss of traction light comes on then a little bit of lug from the front end for a second then that's when the ABS & Traction control off light comes on. The ABS and Traction control off lights don't always come on but the loss of traction light almost always does now. So basicly the ABS & Traction Controll Off light come on after the loss of traction light and little bit of lug. Its an intermittent problem with the ABS and Traction Controlll Off light but the loss of traction light comes on and off more frequently.
Zimgxp
New member
The lug you are feeling is probably the traction control trying to control the wheel spin it thinks it is seeing.