Very bad shaking problem when under power

jbizel · #1 04-07-2007, 06:32 PM

I have an 02 GT. A few days ago I was pulling out of a parking lot and I heard like a popping then a slight grinding sound coming from the engine bay. The popping was not like a backfire or anything. It was like something broke. At first, I heard the grinding noise everytime I would turn. Then the next day I did not hear any grinding or any other noises. But now when I step on the gas pedal my whole car shakes so bad. When I let off of the pedal there is NO shaking at all. Its only when I give the car some power. I checked all the engine mounts and they are all good. I stepped on the brake and gave the car some gas and the engine stayed down and didnt move at all. So thats why I think the mounts are good. Does anyone know what something like that could be? A buddy of mine mentioned that it could be a CV joint. Any help????????????

BNaylor · #2 04-07-2007, 07:27 PM

From a dead stop and flooring it like doing a burn out what does it do?

It could be transmission shudder. I would get it scanned and see if a P1811 DTC is stored. This DTC will not trigger a SES/CEL light. It would mean the line pressure is not being controlled properly possibly due to a flaky PCS solenoid or other valve body problems. A bad PCS will cause the shudder effect.

Other possibility would be the differential. CV joints or axle shafts very seldom, if ever, cause the shudder.

jbizel · #3 04-07-2007, 07:28 PM

From the dead stop I smash the gas and it doesnt really start shaking till about 3000 RPM. It seems to shake alot at higher rpms like right before it shifts.

BNaylor · #4 04-08-2007, 12:39 PM

How many miles are on your GP?

And do you still have the original CAT convertor?

jbizel · #5 04-09-2007, 12:17 AM

There is almost 109,000 miles on it. It is not the original CAT. It was replaced about a year ago with a high flow magnaflow.

BNaylor · #6 04-09-2007, 08:14 AM

I guess we can rule out the CAT for now. The Magnaflow hi-flow is good CAT convertor. Does this problem feel more like drivetrain or a misfire? Or are you getting any feeling or vibration through the steering?

wlkjr · #7 04-09-2007, 04:17 PM

Could it be the harmonic balancer?

Kraya · #8 04-10-2007, 08:12 PM

I seem to have a problem when im accelerating and the car seems like its shaking, but I know its not my tires. I do need my PCS changed because my tranny shifts rough sometimes. Also when I stop at a stoplight and i let my foot off the brake to let the car roll forward it seems like its chugging a bit... im not sure what that would be. I got the plugs and wires changed recently. Could this problem also have something to do with the tranny?

jbizel · #9 04-10-2007, 10:27 PM

Quote:

Originally Posted by bnaylor

Does this problem feel more like drivetrain or a misfire? Or are you getting any feeling or vibration through the steering?

The problem feels like the drivetrain. Yes I am getting shaking through the steering wheel. Its so bad that I have to make sure and use both hands just to hold it. It feels like I am driving on a washboarded road all the time.

jbizel · #10 05-04-2007, 03:16 PM

Just thought I would let anyone know that I fixed the shaking problem. I replaced both of the front axles and it drives super smooth. So it was the axles. Are the axles the same thing as the CV joints?

BNaylor · #11 05-04-2007, 03:44 PM

Thanks for the feedback. Technically yes. The inner and outer CV joints are part of the axle shaft aka half shaft.

Do you have any aftermarket lowering kit like an Eibach spring kit? I'm working with a local member with a GTP that installed one and he is eating up the passenger side axle shaft. He has been through 3 over the past year. And the CV boots keep on coming off due to the altered geometry and grease splatters out. We're working on modifying the engine mounts and drop the engine down to compensate.

jbizel · #12 05-04-2007, 04:17 PM

I have not had any suspension work done. It is all stock. I have an 02 40th Anniversary. I once read somewhere that the anniversarys are lowered about an inch from the factory. not sure if its true or not.

DJ JEFF · #13 05-05-2007, 02:25 PM

Hmmmm! Gee I wonder if this has been my problem? I have had this problem for 6 months on my 97 GTP. Now it would seem half shafts are is going to be my next purchase. I seriously have gone through my entire fuel and ignition system trying to figure this out. Bob knows I have bothered him about this for months. I also know it's hard to troubleshoot a car over the internet. My question now is what are some decent shafts to buy? GMPartDirect want $500. Thats crazy. AdvanceAutoparts want approx. $75 a piece for various brands. JB what ones did you put in?

jbizel · #14 05-05-2007, 08:56 PM

I have no idea wich ones I have in my car. I dont even know how much they were or anything like that. My mother has a good friend who owns an automotive shop who did all the work for me. he picked up the tab for me and she wouldnt tell me any info about the price and she didnt know what ones went in the car.

JJsAngel · #15 05-27-2009, 09:41 AM

My 04 GP is doing the same thing, but started after replacing the tires.The place where I had purchased the tires failed to tighten all but 1 lug on the front drivers side then sent me out on the highway to find this out the hard way! I had that problem taken care of but the car is still shaking and is steadily getting worse, could the lug nuts not being tightened have cause this problem with the axle? The car did not shake at all until the tires were replaced.

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