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06 Grand Prix GXP issues- Help?

C

CODFATHER

New member
Took the car in today after dealing with an annoying problem for quite some time. I searched around online like crazy to see what the widest tire was that I could fit on a stock 18" gxp front wheel and ended up going with a set of 275/35/18 's. Almost as soon as I left the parking lot after having the new tires put on, i was having problems with my brakes.. Every time I would tap my breaks or go to stop, my anti lock brake system would kick in and almost nearly keeping from stopping completely. it scared the sh$# out of me! Once I would hit around 55-60 mph my abs, service brake soon, and traction control lights would all come on and the problem was solved. But ONLY if i get up to this speed will it fix my problem. So i took the car in today and found out that it is most likely the way the pc is tuned because when they took it for a drive, they said that my rear tires were showing about 4 mph faster than the front tires... He also said that my rear tires (nearly brand new) were wearing unevenly and that the insides of the were worn down to almost nothing! most likely an alignment issue which i can handle. But i have no idea how to tackle this issue with the wider front tires keeping me from being able to use my brakes the way their meant to used.
It is not the bearing or the sensors btw, had them all checked out and they are nice and tight.

Problem number 2
The car started over heating, long story short I need a new water pump. I wasn't seeing anything leaking and finally found that it was dripping a bit from the seal and that's why i never had a trace of it leaving the car. Filled up my reservoir and it fixed the problem (for now) but i was told that the pump required a manifold as well to replace and that it would be $800!! No way in hell am i paying that for something this simple. Anyone had any experience with this issue? Also when i brought my car in the shop told me that my throttle positioning sensor was going bad or was off or something and he said he cleaned it up.. that being said, my car now idles at 1100 rpms and is stupid annoying to sit in when its running. its been 6 hours and i already want to go back and wring this guy's neck because it now has an idle speed of about 17 mph!! I cannot stop very well any more at all, between the mix of the anti lock brakes kicking in when they arent supposed to and the car not wanting to stop because the motor is idling so high, i may run into a ton of problems in the future. its scary driving this thing now especially because of the high idle. Could he have messed with the position or something?
Any help would be much appreciated
 


Well for one, you cant just slap a huge size front tire on there without changing the rears aswell. 275 up front and 225 does not mix.

You need to find 2 more 18x8 front rims and run the same tire all the way around or go back to the front stock size, because then it matches the rears in rolling diameter.


As for the water pump, that should just be a pump iself I believe. I would do more research on the repair to double check, look on LS21-Tech they might have more info.
 
I read a thread on gmls4.com where someone replaced the water pump and the hardest part was working between fender and engine. Its only costs the cost of the water pump from local auto parts store plus the gasket. I'll search around and see if I can find that thread again for ya

Sent from my DROID RAZR using Tapatalk 2
 
if your running stock size in the back 225/50/18(683mm diameter) and the front 275/35/18(649mm diameter) I dont see how the backs are spinning quicker(more MPH) if they are bigger(taller).
That would no doubt mess up the whole equalibrium of the BCM system. Your tires have to be sized the same diameter wise for revolution matching with our ABS
I could see why at 60mph it would remedy itself..from g-force lightening the load on the front tires and centrifugal force changing the shape to become more flattened, the tires THEN become more evenly matched.
bill_zps6f2a93ed.png
 
Last edited:
marines542 said:
here is a video and that shop is trying to charge you way to da** much to replace the water pump
MasterPro® Water Pump 58-650 - Water Pump | O'Reilly Auto Parts
pump cost 80 bucks.

replacing water pump
and theres more threads...just google it its what i just did and took less than a couple minutes to find all the info

edit: for got the video link
Replacing water pump in Impala SS 2006 2007 2008 models - YouTube
Click to expand...

Thanks man really appreciate the help. I'll definitely be taking this route instead of having a shop tackle this. Any idea on the throttle issue?
 


spazzz said:
if your running stock size in the back 225/50/18(683mm diameter) and the front 275/35/18(649mm diameter) I dont see how the backs are spinning quicker(more MPH) if they are bigger(taller).
That would no doubt mess up the whole equalibrium of the BCM system. Your tires have to be sized the same diameter wise for revolution matching with our ABS
I could see why at 60mph it would remedy itself..from g-force lightening the load on the front tires and centrifugal force changing the shape to become more flattened, the tires THEN become more evenly matched.
bill_zps6f2a93ed.png
Click to expand...

So there's no way to have the new size tuned into the pcm to make this work? I was actually able to do this with my 96 Z28 without a problem and it fixed my abs issue. I had 285's in the back and stock size on the front and it was doing a very similar thing. As soon as I had a guy from LT1tuning.com tune my pcm he asked what tires i was running and once i told him he asked if i was having issues with my abs or traction control before i even said anything lol. After he was done tuning for the new size and the exhaust work that i had done to it, I never had that problem again.
 
Yep...thats the easy solution if you have access to Tuning software. I think JoshV has 275/?/18s on his car but on all four with same size rim. Once you do change it with the tune you'll have to stick with it unless of course you re-tune
 
Last edited:
spazzz said:
Yep...thats the easy solution if you have access to Tuning software. I think JoshV has 275/?/18s on his car but on all four with same size rim. Once you do change it with the tune you'll have to stick with it unless of course you re-tune
Click to expand...

this i do no issues ever 275/40/18
 
CODFATHER said:
Thanks man really appreciate the help. I'll definitely be taking this route instead of having a shop tackle this. Any idea on the throttle issue?
Click to expand...

On the throttle problem it sounds to me like u should never ever ever go back to that shop. Cause u didn't have them do anything but replace tires when you took it in then you got it back and had that problem?A I reading what u originally posted correctly

Sent from my DROID RAZR using Tapatalk 2
 
And another thing...them doing something to ur car like cleaning the throttle position sensor and all with out u giving them permission to just sounds like they are the ones at taught for your problem. I would be ripping them a new a** hole. Just ask my dealership here who I about took to court once and now I'm about to again over something else they lied about and won't fix.

Sent from my DROID RAZR using Tapatalk 2
 


CODFATHER said:
Took the car in today after dealing with an annoying problem for quite some time. I searched around online like crazy to see what the widest tire was that I could fit on a stock 18" gxp front wheel and ended up going with a set of 275/35/18 's. Almost as soon as I left the parking lot after having the new tires put on, i was having problems with my brakes.. Every time I would tap my breaks or go to stop, my anti lock brake system would kick in and almost nearly keeping from stopping completely. it scared the sh$# out of me! Once I would hit around 55-60 mph my abs, service brake soon, and traction control lights would all come on and the problem was solved. But ONLY if i get up to this speed will it fix my problem. So i took the car in today and found out that it is most likely the way the pc is tuned because when they took it for a drive, they said that my rear tires were showing about 4 mph faster than the front tires... He also said that my rear tires (nearly brand new) were wearing unevenly and that the insides of the were worn down to almost nothing! most likely an alignment issue which i can handle. But i have no idea how to tackle this issue with the wider front tires keeping me from being able to use my brakes the way their meant to used.
It is not the bearing or the sensors btw, had them all checked out and they are nice and tight.

Problem number 2
The car started over heating, long story short I need a new water pump. I wasn't seeing anything leaking and finally found that it was dripping a bit from the seal and that's why i never had a trace of it leaving the car. Filled up my reservoir and it fixed the problem (for now) but i was told that the pump required a manifold as well to replace and that it would be $800!! No way in hell am i paying that for something this simple. Anyone had any experience with this issue? Also when i brought my car in the shop told me that my throttle positioning sensor was going bad or was off or something and he said he cleaned it up.. that being said, my car now idles at 1100 rpms and is stupid annoying to sit in when its running. its been 6 hours and i already want to go back and wring this guy's neck because it now has an idle speed of about 17 mph!! I cannot stop very well any more at all, between the mix of the anti lock brakes kicking in when they arent supposed to and the car not wanting to stop because the motor is idling so high, i may run into a ton of problems in the future. its scary driving this thing now especially because of the high idle. Could he have messed with the position or something?
Any help would be much appreciated
Click to expand...

As mentioned above either get your PCM Tuned or match the 35 series tires on the back as well. and yor issue will go away. however your speedo will more than likeley be off if you go under a 40 series. so choice is on you for the tires.

problem two there is no external throttle position sensor so that is a lie. you use a electronically actuated throttle body everything is internal. my first course of action would be to make sure the harness leading up to the plug is snug and secure and that no pins got bent while the dickweed was messing with your car. The plug that goes to your throttle body also needs to be snug and secure so check there as well. and remeber since the throttle body is commanded electronically by the PCM based off of the gas pedal position. make sure your floor mat isnt interfering with the pedal. other wise there is no other adjustments you or him could possibly make unless you use a tuner.

third: your water pump...hardest part is taking out the battery to get to it cleanly i have a thread on gmls4.com but will post instructions if you need them. there is no "manifold" to worry about. simply remove battery remove belt unbolt 4 screws to the pump and it will come out and then replace.the hardest part is probably battery removal. look on gpona.com under the gxp area for the battery removal sticky.
 
marines542 said:
And another thing...them doing something to ur car like cleaning the throttle position sensor and all with out u giving them permission to just sounds like they are the ones at taught for your problem. I would be ripping them a new a** hole. Just ask my dealership here who I about took to court once and now I'm about to again over something else they lied about and won't fix.

Sent from my DROID RAZR using Tapatalk 2
Click to expand...

I am definitely going to be having a talk with them. I didn't give them any consent to touch my car in that aspect I just told them to tell me what my problems were. If they are the cause of the sensor going bad then it's going to be on them because i never had a single problem with it before this crap
 
91parkave said:
As mentioned above either get your PCM Tuned or match the 35 series tires on the back as well. and yor issue will go away. however your speedo will more than likeley be off if you go under a 40 series. so choice is on you for the tires.

problem two there is no external throttle position sensor so that is a lie. you use a electronically actuated throttle body everything is internal. my first course of action would be to make sure the harness leading up to the plug is snug and secure and that no pins got bent while the dickweed was messing with your car. The plug that goes to your throttle body also needs to be snug and secure so check there as well. and remeber since the throttle body is commanded electronically by the PCM based off of the gas pedal position. make sure your floor mat isnt interfering with the pedal. other wise there is no other adjustments you or him could possibly make unless you use a tuner.

third: your water pump...hardest part is taking out the battery to get to it cleanly i have a thread on gmls4.com but will post instructions if you need them. there is no "manifold" to worry about. simply remove battery remove belt unbolt 4 screws to the pump and it will come out and then replace.the hardest part is probably battery removal. look on gpona.com under the gxp area for the battery removal sticky.
Click to expand...

Thank you so much! This helps tremendously! If i run into any snags i will throw my issues up on here or pm you for some write ups
Really appreciate the help
 
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