car died at higher speeds

[2kBlkGTP]

I have a 2000 grand prix coupe

I was testing out my new sparkplugs (NGK t6's or whatever) and i was accelerating on the highway (Late at night no1 was around at all) i started from like 70mph and when i got up to 116mph my car felt like it hit a brick wall. My temp was not high when i looked at it maybe around 190-200 degrees.

my mods are DHP 1.0, FWI, those spark plugs, zzp stage 1 TB, 3.4 pulley(w/ gatorback belt), 2.5in RT downpipe w/ hi-flow cat and u-bend removal and a dynomax cat back.

Also i think i have a "cracked exhaust manifold" thats what a guy in a shop told me he thinks i might have.

I was just wondering what could make my car stop like that? i've been at higher speeds b4 in it.

Any help would be great.
Chris

[2kBlkGTP]

does anyone have any idea what this might be? too much detonation so the pcm is pulling timing belt slippage, any ideas?

[2kBlkGTP]

Ttt

[guano]

thats pretty funny i had to say something about that because i just put some autolite 104s and msd 8.5mm wires, and i had the same f'in thing happen and its killin me. i took it out that night and it seemed better except when i got to about 104-109mph the same thing happend it was ridiculous. the rpms dropped and i heard and maybe felt some shutter? i dont know, like you said it hit a brick wall. kind of hard to hear whats really happening at those speeds. i really think it was KR. since then i put some 100 octane in and its lovin it. i can feel a difference but when i got up to about 112mph the same thing happened. the only mods i got are a 3.4 pulley, cold air intake, and those plugs and wires. do you think that stupid u-bend is really killin me? should i just say F the cat and the resonator cause my plates are registered to a no-emissions county. what the hell is wrong with this thing? 00 gtp 2dr

[2kBlkGTP]

IDK what it is, it only happened after i put my new plugs in..and idk if its your u-bend or cat because i have no u-bend and a high flow cat and it does the same thing to me(you should get rid of your u-bend though)...I an going to be scanning my car soon so I'll tell u what happens..its prolly the same thing stupid 2 door 00 gtp's

[guano]

hell yeah man keep me up on that. its killin me and you know its probably the same problem too. thanks man, since those new plugs it hasnt been right, i put em in 3 days ago along with the msd 8.5mm wires. i know its that shit.

[BNaylor]

Originally Posted by 2kBlkGTP

IDK what it is, it only happened after i put my new plugs in..and idk if its your u-bend or cat because i have no u-bend and a high flow cat and it does the same thing to me(you should get rid of your u-bend though)...I an going to be scanning my car soon so I'll tell u what happens..its prolly the same thing stupid 2 door 00 gtp's

Had a similar problem with our '97 GTP over a year ago. Have an ASE Perf. ECM chip so the speed limiter was out of the picture. We decided to try out Bosch Double Platinums and man did we lose top speed and the engine was acting weirdly. Even the tranny started shifting funny.
No DTC error codes generic or manufacturer specific or SES light.

Got rid of the Bosches and switched back to the AC Delco Rapidfire #14 and the problem disappeared. And later subsequently replaced the Rapidfires with AC Delco 14101 Iridiums and no problems either. Both AC Delco plugs seem to work fine with the MSD 8.5 wires.

I've heard some horror stories about running NGKs too. Good luck!

[2kBlkGTP]

it prolly is my plugs but thats ok for now, my car is deff. quicker at lower speeds..I'm scanning it soon so i'll let u know how that goes

[richtazz]

NGK and Bosch plugs are JUNK!!!! Switch back to AC Delco platinum or iridiums and your problem will go away.

[2kBlkGTP]

you are prolly right, I am prolly gunna b selling my car anyway soon. Have any ideas on what i could get with about $16k

[guano]

Originally Posted by richtazz

NGK and Bosch plugs are JUNK!!!! Switch back to AC Delco platinum or iridiums and your problem will go away.

what about autolite 104's? those are OK arent they? i mean maybe not since im having this problem, it seems that most run autolite plugs i thought thats what i was supposed to buy. now im not sure. 00 gtp 85k miles, 3.4 pulley, CAI, MSD 8.5's, no u-bend delete (yet). do you think those AL104s are phuckin up? its only at WOT at 105+mph. its not like im 105+ often but this thing needs to work right if at all. thanks.

ryan.....

[2kBlkGTP]

I changed my mind im not selling my car. I guess i need to change the plugs on it soon because I think the NGK's r messing up at higher speeds. well i hope its just the plugs..but it makes sence that it would be.

[BIG-L]

3.4 pulley, CAI, MSD 8.5's, no u-bend delete (yet). do you think those AL104s are phuckin up?

What kind of gap are you guy's running on those plug's ??

I think that the 104's are to cold for the mods you have.You would be better off with going 1 colder with the 605's.

Here is a general guideline for which spark plug heat range is right for your modified supercharged vehicle using Auotlite, are as followed:

- Use AutoLite 605's (one heat range colder) if your car is similarily modded like this: has a 3.40” supercharger pulley, CAI (cold air induction) setup, and a lower-temp thermostat.

- Use AutoLite 104's (two heat ranges colder) if your car is similarily modded like this: has a 3.25” supercharger pulley, 1.80:1 or 1.90:1 rocker arms or very mild cam, CAI setup, lower-temp thermostat, exhaust headers, cat-back exhaust system, and reprogrammed PCM.

- Use AutoLite 103's (three heat ranges colder) if your car is similarily modded like this: has a 3.0” supercharger pulley, 1.90:1 rocker arms or aggressive cam, CAI setup, lower-temp thermostat, exhaust headers, cat-back exhaust system, port and polished supercharger housing and/or throttle body, and reprogrammed PCM.

It is recommended that you set the gap on these to .055”-.058”.

my mods are DHP 1.0, FWI, those spark plugs, zzp stage 1 TB, 3.4 pulley(w/ gatorback belt), 2.5in RT downpipe w/ hi-flow cat and u-bend removal and a dynomax cat back.

Again,I feel that they are to cold.

A general guideline for which spark plug heat range is right for your modified supercharged vehicle using NGK's, are as followed:

- Use NGK TR55's (one heat range colder) if your car is similarily modded like this: has a 3.40” supercharger pulley, CAI (cold air induction) setup, and a lower-temp thermostat.

- Use NGK TR6's (two heat ranges colder) if your car is similarily modded like this: has a 3.25” supercharger pulley, 1.80:1 or 1.90:1 rocker arms or very mild cam, CAI setup, lower-temp thermostat, exhaust headers, cat-back exhaust system, and reprogrammed PCM.

It is recommended that you set the gap on these to .055”-.058”.

[adblink182]

ya keep in mind you cant always just go out and buy spark plugs and throw them in. The gap needs to be checked and adjusted if needed

[BNaylor]

Originally Posted by adblink182

ya keep in mind you cant always just go out and buy spark plugs and throw them in. The gap needs to be checked and adjusted if needed

If you review the responses, the issue is not just going out arbitrarily and putting in new plugs or not checking something as simple as the gap. These GTPs or GTs are modded out and you have to be careful on which plug you buy depending on those mods. I totally agree with Big-L. For example the guy running the Autolite Racing plugs is probably running too cold plugs not only based on his mods but his overall driving conditions.....climate and geographical location has a lot to do with it. It is important to take a read on the plugs and see if the ceramic is white/light tan in color and that there are no side effects from switching to the new plugs.

For my given situation I found out that the AC Delco Iridiums (41101)work the best for me overall. I'm running a '97 GTP on city streets which includes stoplight to stoplight and long idle times. I am not running at constant high rpms or racing all the time, etc.

Here are the mods: Thrasher 3.4 SC pulley, Thrasher CAI, Granatelli MAF,
MSD 8.5mm wires, throttle body spacer, u-bend delete, hi-flow CAT,
ASE Perf. ECM Chip

ET: 14.3 @ 96mph - 79 degrees, over 4,000 feet alt., 26% humidity