Thread: Used 04 GP 150K acceleration problems

tach bounces, shifts weird, hesitates as pedal is pressed, jerks twice every once in a while as I leave a green light and when 1/4 tank of gas when idling it makes a repetitive rumbling noise

I just bought this car last month and I really like it besides the problems. I have replaced the gas cap and when i checked the old air filter was WAAAAY dirty so i bought a new one. I got a gas cap code, then a large evap code and the symptoms mentioned above. The dealer had plugs replaced but not wires. Im told some of these things can be the crank position sensor, the evap vent solenoid, the fuel canister, map sensor or clogged catalytic converter. My dealers mechanic is a bozo so I could use you guys help right now! THANKS GUYS!

Just my 2 cents, but it sounds like the care was not well cared for and it lacking in maintenance. In addition to what Scottydoggs said, give it a complete tune up.

Filters: Air Filter, Fuel Filter, Cabin Filter, Oil Filter
Check/Replace plugs and wires
Clean Throttle Body
Clean/Replace PCV valve
Do a pan drop and replace the transmission filter and top off the fluid.
Flush the cooling system well. I'm hoping this was done by 150K or it's going to be bad in there.

No one mentioned to buy some Mass Air Flow (MAF) sensor cleaner and clean your MAF.

The guy flushed and changed tranny fluid, brakes, plugs, thermostat and I think it was because his mechanic was trying to pin point a problem. I bought some intake cleaner so ill give that a shot too. Im just waiting for a good day to drop it off at the dealerships mechanic since it will be free

Yea, flushing the transmission fluid was a bad idea unless you know the car's maintenance history. Also, why are you bringing your car back to the dealer if the mechanic is a bozo? Don't bring the car to someone you don't trust.

What plugs did they install? Should be irridiums, not platinums. Also, change the wires if they haven't been. Often just replacing plugs leads to a wire (or more) getting broken from being pulled off the plug. It may "look" ok, but leak voltage when reused. Simple test would be to start the car and pop the hood in a pitch black garage and spray a mist of water around all the plug wire boots at the coils and plug ends and look for tiny blue/white arching. If they are leaking it should be easy to spot.

Flushing a transmission is always a bad idea, I'm irritated by how many transmission shops still suggest doing so.

A power flush ruined my transmission on my '94 Bonneville. Never again.

Originally Posted by stocker

Yea, flushing the transmission fluid was a bad idea unless you know the car's maintenance history. Also, why are you bringing your car back to the dealer if the mechanic is a bozo? Don't bring the car to someone you don't trust.

He is replacing part by part for free. If I had the money I would say **** it and do it all myself.

I'd check idle air control valve


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Originally Posted by Gpmadness08

I'd check idle air control valve

The '04 + is a drive by wire system and doesn't use an idle air control valve. That all changed with the last gen.