went to the track last night and discovered a new problem, other than my rear end might be going out LOL

during my 1/4 mile runs, the car pulls hard and fine all the way thru 3rd gear untill just before the traps when my motor rpms is around 4100-4200rpms on factory tach.

the motor will be reving and the car accelerating but once i hit that spot about 4200rpms, the motor dies... rpms drop down to 4000rpms and wont climb much more. you can almost feel it but most certainly can see/hear the motor stop pulling. its quite obvious and i never had this problem occur before. its almost like i let off the gas abit. the motor is cuttin out

my question is this a sign of fuel pump goin bad and not feeding the motor at this speed/load? which doesnt make sense since the car pulls fine in first and second to 5 grand.

or is it the converter lockin up or something at that speed of around 93ish mph? this happens JUST before i cross the traps in the 1/4 mile. so i'm goin around 93ish mph.

or is it something else?? the car did it on all 5 runs the same way.

 

maybe you are running out of breath on the TPI?

 

not at 4200rpm.

Unplug your knock sensor (make sure when you run again the car is cool) and run some unleaded race gas in your tank mixed with premium. If you try this with the car too warm you could set of an SES light code 43, just shut it down and restart if this happens. My guess is your knock sensor is hearing something and pulling the timing way back. Also check for any intake restrictions, if you have a home-fabbed cold air make sure the hose isn't collapsing at high RPMs.

 

yeah its definately not the TPI wall

the motor is pulling, then the rpms drop down...not stop like TPI running out of breath. so something is stoppin the motor from running at that speed

and i'm running 89 octane if that helps. timing should be stock 6 degrees. car always ran fine before till last night

 

It just sound like the converter is entering force lock mode.
They are usually factory set to force lock at 77sh MPH.. some earlier, some later
Sound about right? It actually took me a while to figure that out on my car at track.. When I did it really picked up et by forcing lock later - though my car made peak TQ much higher then.
I actually had raced it years before I noticed. Then when I felt it though something was wrong as well, then looked into prom and figured it out. But really heard when I uncapped headers.
Car went from 11.3-11.0s But mine was dropping me way below pk TQ
killing acceleration.
Bring it around, well do a prom for it, and you fans - timing ect.
I can let you use my adapter and eprom if you wanna try.

 

thats what i was thinking, that the converter was lockin.. since it only was in 3rd gear. but seems odd to be locking up at that mph...

i just never noticed it before and been racing the car last year and this year...and have nearly 20 passes by now or so.

 

Maybe with the ET'S growing reducing gear might make it more noticable.
You can try disabling all together and/or putting a switch on..
Or like I said, we can make a new prom.

 

yeah i been wantin to get a scanner and see how the motor is workin on a run. i wanna see how the air fuel is and adjust fuel if need be to squeeze all the power i can outta it. lol

 

same thing happened on my 85 Z28, its the converter lockin.

 

Well the offer is here Quite wasting time..
Buy one of these:
GP1 Package: GM Adapter with 2 chips [GP1] - $55.00 : Moates.Net

Thats all you really need - And a quick drive here.

 

sweet man, thanks! i think i'm gonna take you up on that and order that stuff. hopefully middle next week, i'll have an idea on what i'm doing and get that order in

 

I got that problem likes its like a dead spot.

I was thinking it was the knock sensor, or converter locking.

I got it in 2nd alittle and 3rd, but both times I barely had aot of gas in the tank. so i dont know. i need to do some more data logging.

Its like rolling great and kinda stumbles and works it way back up enough to move alittle more.

I got to be lossing a tenth top end, might be a temperature thing as well. the first time it was 80 degree and 3rd gear did it, the next week i dropped 2 mph and did it in both gears. still ran 13.4's and 5's though.