dies out after 93mph

[forcefed3.8's]

My GTX has a 3.25" pulley, SLP ram air, SLP loudmouth exhaust, 160 stat, NGK TR6 plugs, and a 2.5" pipe in place of the cat/u-bend, and I always run 94 octane. Sometimes I have a problem with it nose diving at 93+mph. It feels like it shuts down. Sometimes it doesn't happen. I even added 5 gallons of 112 octane, and no luck. It did it before and after the cat/u-bend delete, and yes, I do have an O2 simulator. I am thinking it is lean and I need an AFPR. Any ideas?

 

[Blown_GTP]

what gear are you in when it does this? mine does the same thing when im in 3rd and not drive. just an idea!

 

[mcad_c]

What size wheels and tires?

 

[TRYMY231S]

How old is your first O2 sensor? Could be time for a new one if you've been running 112. Still doesn't explain why it craps out at 93. Does it literally die or just not accelate as it use to? These cars have no top end (compared to V8's), so don't forgot (unless you have a cam & DHP).

 

[forcefed3.8's]

It dies out. Sometimes it only does 96 in the 1/4. When it doesn't die out, it does 100. I have stock 225/60 16's, and it is in 3rd gear. It did it before running 112. I doubt it is the O2.

 

[Blown_GTP]

well, i think thats the problem honestly because mine does that only sometimes in 3rd also.

 

[forcefed3.8's]

What are you saying is the problem?

 

[JasonGS]

I think he's saying, and I agree, that you're hitting the rev limiter in 3rd gear. Put it in OD.

 

[forcefed3.8's]

At 93mph? Why didn't it do this before, or all of the time for that matter?

 

[mcad_c]

I've noticed that too. It seems to me that the PCM knows you are at WOT and starts backing off the timing as you are accelerating toward the speed limiter. (108) See if backing off the pedal will allow zoom right up to 108.

 

[Blown_GTP]

yea, thats what im saying. if your back out of the throttle for a second you should be ok. or just pop it into drive. drive should make no difference in your 1/4 times. I have a question now, why is your speed limiter 108 mph and mine is 126 mph? i dont have a reprogrammed pcm either.

 

[TRYMY231S]

Isn't the GT's speed limiter 108?

 

[JasonGS]

Yes, the GT limiter is 108. The GS limiter is also 108. The GTP (with the identical BUICK engine) is 126! WTF!!!

 

[mcad_c]

Pontiac excitment!

I guess us "old folk" Buick owners do not have the quick reflexes of the young'ns.

 

[TRYMY231S]

HAHA! Sad but true. And everyone knows that GP's are faster.

 

[mcad_c]

It better be faster than 13.05 @ 105MPH...

 

[Blown_GTP]

LOL, that is wierd but the GTP will do 126. ive done it a couple times in mine and i have 3 friends with GTP's that can also hit 126mph. that is odd.

 

[forcefed3.8's]

126 here. There are 3 other GTP's my friends have, and they all go 126.

 

[TRYMY231S]

mcad_c: as you probably read in the other post I ran a 13.3 with a shot diff and 6 degrees of total timing. So after adding headers, an LSD, 3.29 gears, a cam, and some tuning I'll smoke you're 13.0.

 

[mcad_c]

hehe 13.0 is this years time. You better be able to run low 12's next year.

Com'on out to the GS Nats we can run a little gruge match.