Issues " Grand Prix GTP not starting correctly "

**Trump** · 02-19-2011

This is getting to be a pain. Last December my car, " 2004 Pontiac Grand Prix GTP " Started having a problem starting once it sat for about a half hour or less.

1) condition one was when I tried to start the car after it sat for about 15 min, I tried to start the car and it seemed like it wanted to keep turning over even after I let off the key.

2) A couple times I tried to start the car after it sat a while and kept trying to start the car and it surged like it was out of time or the cam sensor was not getting the right data, I turned the car off and let it set for over an hour, then it started right up no problem.

3) every time the car sets for an hour or more it will start perfect 100% of the time, but when the car set's for 10-15 minuets it normally acts up.

4) I have changed the whole ignition switch, cleaned the contacts also

5) I have changed the starter

6) No CODES COME UP

7) I had the car on the Snap On scanner
r and had it fully tested to see if something would come up, NOTHING showing on the Snap On Scanner.

Any Ideas ??

**Trump** · 02-20-2011

Well yesterday I ran the car again and it acted up the same. Again when the car is cold like setting overnight or for over an hour or so it starts properly 100% of the time. I let the car set for about 15 minutes after I drove it for about a half hour and tried to start the car and it acted up the same, it turned over ok, but when I let off on the key it seemed to want to keep turning over for a few seconds. After I finally got the car running it ran perfectly.

I changed the PCM last night so I will try it later today and see what it does. Luckily I have a spare PCM for the car.

I do not see any codes coming up or anything on the information panel for any issues.

Starter changed
The whole Ignition switch changed
Scanner verified no issues.

I do not feel a sensor is an issue, but it seems the issue is has something to do with HEAT, but if I run the motor for even ah hour and shut if off it will start right back up as I have tried it several times. I have thought of changing the cam sensor just for the heck of it, but added cost as I have already changed the starter and ignition switch.

**Trump** · 02-20-2011

Found out today that the PCM is NOT the cause of the starting issue. I have an idea now of what the issue may be, I will check it out tomorrow if I can. I see a lot of lookers, but nobody seems to have an idea on what the issue may be?

**BillBoost37** · 02-21-2011

I would have responded if I wasn't with the girl in NYC for the weekend.

That's an odd one. you changed the starter which tosses out the one idea that I had about it heating up and the bendix binding when it pushes out and getting stuck on the flywheel for a moment. Cables are obviously hooked up properly. Ign switch is replaced, you didn't leave us much to consider.

What's your idea?

**matt5112** · 02-21-2011

Originally Posted by Trump

I see a lot of lookers, but nobody seems to have an idea on what the issue may be?

I haven't seen too many threads with this type of issue in my short stint here. Sorry.

However I did see a thread suggesting the ICM overheats based on its close proximity to the coil bracket which is bolted directly to the front cylinder head.

You could try raising that up with a new bolt and some nuts.

The OP said he'd have issues with the car when it was hot out, his car would stall out and wouldnt restart for a short period of time.

Once he raised the coil bracket it was much better bceause the ICM didn't heat up as much.

OP went as far as placing a thermal probe on the ICM to monitor its temp.

Good luck with trying to solve this one.

**Trump** · 02-22-2011

Billboost37,

Ran more test, even changed the fuel filter. just kind of preventative maintenance along with removing that part from a potential problem. HEAT " temperature outside " itself is not the issue. If the heat was the issue the car would not start right back up after I shut it off.
I am glad to see a couple responses on the topic as I am sure that this has either happened to others or will happen at some time.
I just drove the car over 100 miles today parked the car and went in for a medical appointment and came back out in about an hour, the car was still warm, but it started up right away, no hesitation at all.

So here I am

1) Not the ignition switch or key or anything to do with ignition theft module as they have all been changed

2) Starter checked out to be ok, but changed it anyway, so the starter is not the issue

3) Changed Fuel Filter

4) changed PCM to my spare one, ha, more mileage, but still has the same starting problem.

I have another idea to try which I will attempt to try it soon. I will report back in after I try it out, it may take a few hours though.

**Gorecki** · 02-22-2011

Have you ever cleaned out the throttle body? I had close to this problem (started fine in the morning, stop at a store, won't start without gas pedal). Just a thought.

Also, would likely suspect a lot of those *lookers* are web crawlers and not people.

**Trump** · 02-23-2011

Originally Posted by Gorecki

Have you ever cleaned out the throttle body? I had close to this problem (started fine in the morning, stop at a store, won't start without gas pedal). Just a thought.

A.

Darn Goreck, you are right, I am in the process of doing it now. Yep that seems to be the issue even though it sure does not make any sense, but that is just part of life I guess. I wonder why more trends are not listed on here for this issue? I will take some pictures and post them if I can.

**Gorecki** · 02-23-2011

Originally Posted by Trump

Darn Goreck, you are right, I am in the process of doing it now. Yep that seems to be the issue even though it sure does not make any sense, but that is just part of life I guess. I wonder why more trends are not listed on here for this issue? I will take some pictures and post them if I can.

Cool!

Yeah, talk about probably the cheapest and most affective fix you'll ever have but it is a pretty common problem on far more vehicles than just these GPs.

BTW, I discovered this solution by searching these forums.

**Trump** · 02-23-2011

Well cleaning the Throttle Body was not a walk in the park, it took some time and really I wish I could have got it better. Well it does not look like I can add the pictures. Not really understanding all about this form yet so I apologize. Maybe there is another way to import Pictures to here? let me know if there is.

The inside of the Throttle Body had a lot of carbon built up on it, but not as bad as I have seen in the past. The intake of the Supercharger looked the worst. I cleaned the intake of the Supercharger with CRC Throttle Body Cleaner and a RAG.

I am thinking seriously of getting some Sea Foam, I use it on my Bass Boat motor all the time, they say it is good for the carbon so I may just try it. I just wanted to be sure it would not hurt the Supercharger !

Well I am heading out to give it a try, hope it will fix the starting issue FINALLY !

**Trump** · 02-23-2011

Well CRAP, The thought of having the car finally FIXED did NOT WORK. Cleaning the Throttle Body did not do the trick. Running Sea Foam did not cure the problem. I did find a wire bad on the fuel pump connection, not sure if that will fix the issue or not. I still have thoughts in my mind about the Cam Sensor, yeah I know it should through a code. Maybe the Cam sensor acts up is hot and after it has ran awhile??? Just not sure, but I am really getting tired of this. Seems the more I look, I do find issues along the way, maybe the are all adding to the problem whatever that is.

**Gorecki** · 02-23-2011

Man, that sucks...sorry dude. Completely understand getting frustrated and it sounds like you're trying really hard.

Might I suggest, promptly disconnecting the negative battery lead, followed by confidently thrusting the middle finger in the cars general direction and calling it a night with the hopes in the morning the car will have had an attitude change?

But seriously, you might want to take a step back because so often a simple answer is the correct one and on this car the computer controls SOOO MUCH that it's having a cause/effect you're just not seeing it yet.

Otherwise start tracking down from the point of air in and exhaust out. These things generally are simple, they need three things to basically work, air, fuel, spark. Somethings getting in the way of that process.

Good luck!

**Trump** · 02-24-2011

Originally Posted by Gorecki

Man, that sucks...sorry dude. Completely understand getting frustrated and it sounds like you're trying really hard.

Might I suggest, promptly disconnecting the negative battery lead, followed by confidently thrusting the middle finger in the cars general direction and calling it a night with the hopes in the morning the car will have had an attitude change?

But seriously, you might want to take a step back because so often a simple answer is the correct one and on this car the computer controls SOOO MUCH that it's having a cause/effect you're just not seeing it yet.

Otherwise start tracking down from the point of air in and exhaust out. These things generally are simple, they need three things to basically work, air, fuel, spark. Somethings getting in the way of that process.

Good luck!

Thanks Gorecki,

I have worked around cars all my life, but they are getting so complicated even the best computer scanners and such have a hard time detecting things. I have a degree in Automotive, but that was many moons ago for sure.

My car, the 2004 Grand Prix GTP which does not have a fuel pressure Regulator, it is all encompassed in the fuel pump. I am getting 60 psi so that should not be the issue.

The puzzling thing is that every so often it really acts like it is out of time when it starts or tries to start which throws my mind directly to the Cam Sensor. I had a neighbor over today and he watched the motor and fuel pressure as I had my fuel pressure gauge hooked up.

After the motor starts or when it starts, after it has sat for about 10 min after running for a period of then it is perfect, no issues with Tachometer or anything.

Some say or comment on the MAF, well again that would through a code and also I could unhook the MAF and try it. The MAF normally would give an idling issue or other noticeable issues if it was bad as I have had them go bad on other cars. The car only has about 36, 000 miles on it, just like new really.

**Gorecki** · 02-26-2011

Just a thought and I'm not going to bet my life on it but have you checked the PCV? That little guy could send enough bad flow to the MAP sensor telling the PCM things that aren't true and could cause some wacky behavior. I'd check it just because I can see something so simple stupid cause problems.

Next in line would be fuel injectors, could have a flow problem or bad/gummed o-ring that basically goes away after some flow for a period....? Dude, I dunno, if I were you, I would likely be pulling hair out by now.

**gtp239** · 02-27-2011

mine was doin the same thing on warm start would surge if i turned it off and back on.
it would surge and stall most of the time would not do it as bad if i threw it in gear i threw in a junk yard maf and cleaned the iac and its been running great for 2 months now.
Mine also had no codes on my ls1m1 scanner

**Trump** · 02-27-2011

PVC was really clean and I even ran some cleaner through the whole PVC system in the Supercharger as directed by others. I ran Sea Foam through the system and really cleaned it out good. The MAF has been checked as when the starting situation happened I unhooked the MAF as the car should and would run when the MAF is unhooked. I am going to try something today as I have another feeling of something going wrong. My car only has 37,000 on is to it is not like it is wore out or the parts are wore out. I think sometimes that having a car setting for so long that it may hurt it as much as being driven for some many miles. The symptoms of my situation may not be exactly the same as others, but the starting when it is hot seems to be of a common issue.

The IAC does not seem to be an issue, all the area of the Throttle Body were not bad as I had the Throttle Body off and did a through cleaning.

After I check the one item out I will post my findings.

**Trump** · 02-27-2011

Getting to the end of my road on this. I even took the fuel pump out today and checked it over and cleaned it. I had some injector cleaner as I have cleaned some injectors in the past. This particular fuel pump ( 2004 Supercharged Series III ) has only one line for pressure to the fuel rail. There is a RETURN fuel pressure unit in the fuel pump, I wonder how many months it took some Engineer to dream this one up. I cleaned the fuel pressure valve and check it out, seemed to be operating ok. I ran the fuel pump and it ran smooth and steady. Some have said that the fuel check valve has had signs of dirt in it to prevent fuel flow. This type of fuel pump does not have a check valve or any restriction on the output hose, it runs direct pressure to the fuel filter. The fuel filter has a bypass line for the return to the fuel pump pressure regulator which then goes back in the fuel tank. It appears that the fuel pressure regulator is set for about 60 PSI as that is the reading I get on the fuel rail Schroeder valve.

One thing I did notice after I installed the fuel pump back in the tank and then drove the car, the AVERAGE MILEAGE WENT WAY UP !!!. I have never seen this in the past, not sure, but it seems that whatever I did helped that part anyway. STILL A STARTING ISSUE THOUGH.

I have either changed or looked at about EVERYTHING I can think of at this time. Not giving up, I am just TIRED and broke right now !!

**Gorecki** · 02-28-2011

Document ID# 1558221
2004 Pontiac Grand Prix
Hesitation, Roughness, Light Chuggle or Check Engine Light, DTC P0300 (Reprogram PCM) #04-06-04-078 - (Oct 22, 2004)

Table 1:2005 Model Year VehiclesTable 2:2004 Model Year VehiclesHesitation, Roughness, Light Chuggle or Check Engine Light, DTC P0300 (Reprogram PCM)
2004-05 Pontiac Grand Prix
with 3.8L Engine (VIN 4 - RPO L32)
Condition

Some customers may comment on a hesitation or engine roughness with or without the Check Engine Light illuminating. Upon investigation, the technician may or may not find code P0300, Random Misfire Detected. In some rare cases, the customer may comment on a light surge or fishbite when crowding the throttle with the TCC applied.
Correction

If a DTC code P0300 is set, follow the diagnostics in the appropriate Service Manual. If the diagnostics do not lead to a solution or if no DTC code is set, then reprogram the PCM. A new calibration has been released to address this concern. The following tables show the calibration number for reference, program the PCM with the appropriate listed calibration, or later, for this condition.

2005 Model Year Vehicles

Axle Ratio
Transmission Control
Calibration Part Number
2.93:1 (RPO - FR2)
TAP Shift (RPO - KB7)
12595162
2.93:1 (RPO - FR2)
noTAP Shift (RPO - KB7 not shown
12595163
3.29:1 (RPO - FR9)
TAP Shift (RPO - KB7)
12595166

Important: Some 2004 vehicles may have a baffled style fuel tank per Corporate Bulletin Number 04-06-04-066. Check the Claim History in GM Vehicle Inquiry System to see if the fuel tank has been changed to a baffled style, P/N 15141578, since September 2004.

Additionally, the following nine vehicles were built with a baffled style fuel tank:

2G2WR524741345683
2G2WR524041348408
2G2WR524241348412
2G2WR524541348419
2G2WR524941348424
2G2WR524841348429
2G2WR524841348432
2G2WR524441348444
2G2WR524841348494

2004 Model Year Vehicles

Axle Ratio
Fuel Tank Type
Calibration Part Number
2.93:1 (RPO - FR2)
non Baffled
12596132
2.93:1 (RPO - FR2)
Baffled
12596137
3.29:1 (RPO - FR9)
non Baffled
12596134
3.29:1 (RPO - FR9)
Baffled
12596135

The new calibration will be released beginning with TIS satellite data update version 9.5 for 2004 available September 2004. As always, make sure your TECH2® is updated with the latest software version.
Warranty Information

For vehicles repaired under the applicable 8 year or 80,000 mile (130,000 kilometres) emission controller warranty, use:
Labor Operation
Description
Labor Time
J6353
Module, Engine Control - Reprogram
0.4 hr

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
Document ID# 1558221
2004 Pontiac Grand Prix

**Gorecki** · 02-28-2011

^^^ Just trying to find a cause. There seems to be enough findings about the PCM programming itself being an issue. I know you've swapped out the PCM but would not be shocked if the other had the same issues.

Yet another feeble attempt to get ya going.

**Trump** · 02-28-2011

Originally Posted by Gorecki

^^^ Just trying to find a cause. There seems to be enough findings about the PCM programming itself being an issue. I know you've swapped out the PCM but would not be shocked if the other had the same issues.

Yet another feeble attempt to get ya going.

Thanks Gorecki,

My VIN is 1G2WR524941372108, I see the ones listed on the chart you sent all started with a 2 and not a 1 ?

I drove the car about 200 miles today and it acted up the same when I started the car after letting it set for about 10 min. When it sat for 1/2 hour or more it started fine.

My thoughts are narrowing down to the fuel, I may pull the injection rail off later today when it cools down good and pull the injectors off and see if there is any issues on the flow through the rail.

Funny on how my gas mileage has improved sense I took the fuel pump out and cleaned it as well as the return pressure valve. Normally the car would set around 22.5 mpg running around 68 mph, today I hit 27mpg and may have gone up higher if I had more road to travel prior to stopping. The car has never done that in the past on the AVERAGE setting.

If it is a fuel delivery issue then WHY would it run so darn good once it has started? What else would cause the starting issue? PCM? if it was the PCM then why would it do it JUST for the first 10-15 min after it was shut off and not cause ANY other ISSUES AT ALL? I will need to look it up as I do not have a manual on my car, not sure if the injectors are a 50 lb injector or what as the fuel rail PSI is a 60 PSI or what is what I had on the Schroeder Valve with my gauge. I need to make another trip tomorrow so I am not sure if I will get to remove the fuel rail today or not?