Loss of power
 

I have a 2000 Bonneville SSEI and It starts great runs great. However going down highway when you give it gas like to go uphill or to pass whatever...It just seems to have no power whatsoever It also bucks and jumps when doing that. I test it seeral times and it seems to be fine when in park just does it when driving..even taking off and getting into the gas a little it does it. Any and all help on this matter will be great!

Hm sounds like a TC issue how is your trans fluid?

Transmission fluid looks really good I have checked it. I was wondering if it might be a TC issue but not sure what.

Any SES lights?

The check engine light also will come on while it is "bucking" the light flashes and then goes off. If that is any help.

If it flashes that usually means a misfire..Very plausable

Hmmm I guess I am confused as to why it doesnt do it in park. I can sit in the driveway in park and it runs fine. When the light flashes like that does it still leave a code on computer if I was to have it scanned?

It may be stored..I would start yes by having it scanned and if nothing is there we can go from there

ok. I have a buddy that has an OBDII scanner I will see if I can get him to scan it tomorrow sometime.

Alright Be sure to let us know what ya come up with!

coil pack.

That equals to a misfire but we dont want em to just start replacing parts if there is a potential code

I recently had the same problem had code come up as misfire on number 4,I was told by mech it was most probably the coil pack,I replaced all three myself with msd coil pack.the problem for me was the spark plug wire had broken near base due to dry rot.so my advise would be try a minor tune up of spark plugs and wires.in my case I did the msd wires also and they are very nice but pricey.now my car has no skipping issues at wot and an added benny of better mpg.hope this helps!

I agree, sounds like a coil pack/spark plug/spark plug wire issue. Pull the codes with a scanner and it should tell you which cylinder is misfiring. Then you can try swapping that coil pack with another and see if the problem follows to those cylinders. Otherwise you need to pull the plugs and see how they are looking, you can also test the wires and coils for resistance. We have write ups for testing the resistance on the coils.

Are you still running factory coils?

same problem on a 03 Alero 3.4L
 

Hey guys I am looking for what to do after you check: plugs, wires, coil packs, fuel filter, air filter, and injectors. I have also had a recent trans flush.

I have the same symptoms and I get a 306 code, multiple misfires on no. 6.

Any suggestions are welcome and appreciated. Thank you for your time and consideration.

Check and clean the contacts between the ICM and the ignition coil for cylinder #6.

Check up vacuum here

And as the gage of temperature of the engine - ECM, no gage dashboard. GP1

Still a photo to a post above. Here at me was vacuum loss

It was the cat. I found a mechanic in the area who was able to work with me to diagnose it, without charging me too much. His diagnostic hardware/software was avle to collect so much data that we were able to elimante everything but a clogged exhaust stream. CAT was immediately expected because of recent EGR issues.

Seems odd a bad cat would cause a misfire on one cylinder, but perhaps that happened to be what was affected when you scanned. Glad you found it.

I thought the same think and decided that the worker at advance auto parts who performed the the free scan wrote down 306 when he should have written 300- which would have indicated a random multiple misfire... you get what you pay for.