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Hello! I just recently purchased a 2004 Grand Prix. It has a bit of an issue with starting. Sometimes the car starts and then has a slight shudder before returning to a stable idle. Sometimes however it will start and it will shudder and die. I did a little poking around on the internet and found that this is a very common problem for the 04 grand prix. Apart from the slight starting issue the car drives great and has no apparent issues at speed. I believe it could be a fuel issue but I would love to have anyone else’s input. I’m going to change the fuel filter and plugs tomorrow.
Thanks!
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[quote=”Black57″ post=37400]Hello! I just recently purchased a 2004 Grand Prix. It has a bit of an issue with starting. Sometimes the car starts and then has a slight shudder before returning to a stable idle. Sometimes however it will start and it will shudder and die. I did a little poking around on the internet and found that this is a very common problem for the 04 grand prix. Apart from the slight starting issue the car drives great and has no apparent issues at speed. I believe it could be a fuel issue but I would love to have anyone else’s input. I’m going to change the fuel filter and plugs tomorrow.
Thanks![/quote]I am not a car expert. This issue does sound like a Fuel Pump issue bases on the symtoms you specified. A common thing for the car does not surprise me any from knowing people with Pontiacs the Grand Prix in particular they are nothing but problems and will always require money to be dumped into them left and right. Have you tried revving the shit out of it once you start it? this should stable it out from my experience
Gm’s are known for intake gasket leaks. Try checking
for vacuum leaks. here are two ways to check for vac leaks.[quote=”LeoTheLion89″ post=37405]
I am not a car expert. This issue does sound like a Fuel Pump issue bases on the symtoms you specified. A common thing for the car does not surprise me any from knowing people with Pontiacs the Grand Prix in particular they are nothing but problems and will always require money to be dumped into them left and right. Have you tried revving the shit out of it once you start it? this should stable it out from my experience[/quote]
Yes, if you give the car gas while you start it then it will have no issue starting but this is not a solution and it is putting a bandaid on an underlying issue. I have cleaned the throttle body and the MAF. Perhaps the people you knew with Grand Prixs didn’t maintain their vehicles properly and did things like reving them up to start instead of fixing them. I will be checking the pump but only after I have eliminated things that are much cheaper i.e. filter, plugs, wires, etc.
[quote=”college man” post=37410]Gm’s are known for intake gasket leaks. Try checking
for vacuum leaks. here are two ways to check for vac leaks.I was thinking this could be a possible cause. Thanks! Ill check it out.
[quote=”Black57″ post=37411][quote=”LeoTheLion89″ post=37405]
I am not a car expert. This issue does sound like a Fuel Pump issue bases on the symtoms you specified. A common thing for the car does not surprise me any from knowing people with Pontiacs the Grand Prix in particular they are nothing but problems and will always require money to be dumped into them left and right. Have you tried revving the shit out of it once you start it? this should stable it out from my experience[/quote]
Yes, if you give the car gas while you start it then it will have no issue starting but this is not a solution and it is putting a bandaid on an underlying issue. I have cleaned the throttle body and the MAF. Perhaps the people you knew with Grand Prixs didn’t maintain their vehicles properly and did things like reving them up to start instead of fixing them. I will be checking the pump but only after I have eliminated things that are much cheaper i.e. filter, plugs, wires, etc.[/quote]
I just mean revv the shit outta it until the issue is fixed and no one i know has done that i have done it on my 01 Impala a couple time because it was sputtering i just gave it gas and it cleared up never happened since. of course that was before i changed to oil since the oil change it has not happened.
Checked for vacuum leaks. Unable to find any. Swapped plugs (didn’t expect this to have any effect on starting and it didnt. I just wanted to swap them.) Going to do the fuel filter today if I get the ambition.
Upon inspection of the fuel system I found that the gas tank has a big spot on it that looks clean ( like gas could possibly have leaked or is leaking) also when I remove the gas cap there is no sound of air release. Could this be a potential cause and is it necessary for the tank to hold pressure for adequate fuel pressure at the rail? Any info is appreciated!
[quote=”Black57″ post=37495]Upon inspection of the fuel system I found that the gas tank has a big spot on it that looks clean ( like gas could possibly have leaked or is leaking) also when I remove the gas cap there is no sound of air release. Could this be a potential cause and is it necessary for the tank to hold pressure for adequate fuel pressure at the rail? Any info is appreciated![/quote]
since metal gas tanks are no longer made its not that common for plastic tanks to leak unless they get cracked from some undercarriage damage. did you try spraying water on the plug wires and manifold gaskets when the engine is running?
If you are holding down the accelerator pedal during cranking to start the vehicle, you are starting in a clear flood mode.
I would also be looking to see if the FPR is leaking.
Do you have access to a scan tool that shows PID data?
I’m a current owner of a 2004 Pontiac Grand Prix GT. I’ve owned it for 8 years and 180k miles. The problem your describing is the sign a dirty MAF sensor and a dirty throttle body. I’m willing to bet the start up system is something like this.
Cold Start – Starts up pretty well
Warm Start – Will start then stall and then you need to give it some gas for it to run.The Grand Prix has a drive by wire system, meaning the throttle plate is electronically controlled. Essentially what happens is that the throttle plate get’s carbon build up on it from the EGR tube and is no longer able to return to absolute zero due to the carbon buildup. This provides a false reading to the ECU of where the throttle is. To correct it’s fairly straight forward.
1. Disconnect battery
2. Remove Intake Tube from Air Box and Throttle Body.. Disconnect MAF wires.
3. Remove MAF sensor and clean with MAF cleaner. Do not use throttle or carb cleaner
4. Remove wiring from TB.
5. Remove 4 bolts from TB holding to intake.
6. Carefully remove throttle body. It’s liquid cooled and there will be some coolant spilled. but not much.
7. Clean throttle body with carb cleaner and a soft toothbrush.
8. Re-assemble is basically the just reverse.Also if you have a 2004, be aware that the LIM Gaskets are prone to leaking, since GM used a plastic gasket and they had a tendency to fail. Replacement isn’t too bad of a job either. I did mine this summer.
If you want a great resource on everything regarding he GP. Take a look here.
Thanks! I stated before that I had cleaned the throttle body but I had actually only sprayed a little TB cleaner in it while it was running through the intake tube. I didn’t even look at the plate. So i took your advice and pulled the throttle body. It was filthy so i actually gave it a thorough cleaning with a toothbrush. The car seems to start perfectly as of right now. If it acts up I’ll update but I think this one might be case closed. Thanks all.
Great News. Hopefully this takes care of the issue. The 3800 Series is a great engine and pretty much bulletproof. It takes quite a bit to harm them. Yes, they may have some ancient technology, but it makes it up in reliability.
One thing to look for is the plastic coolant elbows that feed from the passenger side of the engine. They have a tendency to leak and eventually split.
The gas leak could be several things; could be the spout, it could be a return line leaking, I would definitely figure that out. If fuel is leaking out of somewhere it could possibly cause idle problems. I would just get the codes pulled before you spend too much money or time on it. There are a few places that will scan the computer for free. I think Pep Boys will do it for free
I don’t believe the OP mentioned it was posting any codes. One nice thing about the Gran Prix is if the fuel system is not being pressurized. It will display a “Check Gas Cap” message on the DIC indicating a massive failure in the system.
If the leak was caused by pin holes in the filler neck, EVAP canister or the Purge solenoid, it would register a minor leak, and post a code to the ECU.
I would think if the tank was leaking, it would have already registered a code already.
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