engine is bucking

[Tommyg]

On a previous post I had a bucking problem when the car was cold. Now it is bucking all the time mostly under mild acceleration. What could this be?

 

[galoush]

Try the MAF .tap it with a screwdriver handle while eng is running if the eng acts up its most likely bad.

 

[TT/Ameasap]

Sometimes the tapping trick doesnt work but I think it is the Maf anyway.


Good to have a spare in the trunk.

 

[UNGN]

Bucking can be dirty injectors, too. Usually its the MAF, though. (or the TCC if its a trans related buck)

 

[Tommyg]

All of a sudden the engine runs fine. I put a bottle of STP gas treatment in and filled the tank with 93 octane Exxon. Let's see what happens. Tommy

 

[Fat Kid]

This happens to me very often and has for over a year and a half. I have tried replacing the MAF, the coil pack, the plug wires, the TPS, the crank angle sensor, and resetting the IAC, all to no avail. If you can fix it, let me know what helps you out.

 

[dyermullet]

Do you have a scan tool? Check out this post.
http://www.turbobuick.com/forums/showthread.php?s=&threadid=118674
Mine was only bucking under power. If I accelerated with just a light throtle it was alright.

I cleaned the engine grounds, which were are greasy and wet, so far the car seems good. I have since turned the boost up to 15psi and still no knock and the bucking problem hasn't came back.


Maby you can be more specific, is the car bucking only when under load? I described my problem as bucking, because the car would fall on it's face then pull real hard, it would do it real fast and the car would accually physically rock back and forth as going down the road.

My car dosn't run good untill it has warmed up. It stumbles with tip in throtle, but after it has warmed up to go into closed loop( i have a closed loop chip) it runs fine.

Be a little more specific and I am sure someone will be able to help you out.

Scott

 

[Tommyg]

The problem continues. It bucks under mild acceleration only--about 70% of the time--sometimes it runs fine. I find that it runs ok under mild boost. I am not going to floor it until I get a boost guage(which I've ordered) because I have no idea how much boost it has and I don't want to damage the motor. Where can I find a decent scanmaster--new or used? Please help--this thing is driving me crazy!!!!

 

[gofstbuick]

Usually a bucking problem is associated with a TPS problem. Check the voltage range on the TPS from idle to full throttle, key on engine off and look for voltage drop outs.

 

[Tommyg]

Hey Joe,got your email,thanks. What kind of tool/meter do I need to check this thing out. Jegs has a scan tool for $270 but I hate to spend that kind of money for something that I would rarely(I hope) use. Tommy

 

[GNSS]

If nothing else works, try unplugging the cam sensor and see if it goes away. I had a similar problem that turned out to be the sensor cap.

Jeff

 

[gofstbuick]

You could use a volt meter with 10 megaohm impedence. positive to signal wire and negative to sensor ground. Then measure from rest to full throttle and watch for voltage dropouts.

 

[Tommyg]

Jeff,where is the cam sensor?