Part throttle crap

[Nitrod86gt]

Ok this is a problem that has affected my car for about two years now. I installed heads, injectors, cam etc. at once and the car has never run right since. I'll tell you what I've tried and you guys suggest from there.
First my list of mods: (Items with a * by them were installed right before the problem)
This is an '86GT with 91 Shortblock.
Trickflow Track heat heads *
TFS stage 1 cam*
24lb injectors*
76mm C and L *
70MM edelbrock TB*
Cobra intake
K and N
Mac Long tubes
Mac H pipe
MSD 6AL*
Holley Laser Shot Coil*
Scorpion 1.72 rockers*
255LPH holley Fuel pump
Crane adjustable FPR (looks like a stock one. are these junk?)
and the rest are drivetrain mods that dont matter.

O.K. now, Here's the problem. Whenever I drive the car after I start and warm it part throttle operation is mush. It feels like it is missing or something is holding back the power. As you roll into the throttle its crappy until u hit a certain spot and then it clears up instantly and accelerates hard. WOT it runs well too but still doesnt feel 100%. Ok here's the weird part. I can be rolling down the road right after this happens and turn the key off (while im rolling) and then right back on and roll into the gas and it runs like a scalded dog. It runs like I feel like it should. Perfectly smooth, all kinds of part throttle power and WOT feels great. I drive it for a little bit more and then BAM part throttle sucks again unless I turn the key off and on again.
Here's what I've tried:
New O2's (twice)
New MAF electronics (twice)
New MAP off mass air car (or BAP)
New TPS (twice)
New Fuel Pump
New FP filter
New ground strap
New 5 speed computer from advanced auto and an A9P auto computer
That's all I can remember right now.
Ok it seems like an electrical problem by the nature of me turning it off and on and it running fine. Here's some things I had questions about
#1: I rebuilt my tranny and for some reason put a top plate on the T-5 that didn't have the sensor on top. (not the reverse switch) The connector for it is just hanging under the car not being used. Now I'm not sure of the function of this sensor but I heard that it can cause similar problems if not connected or if the voltage isn't right.
#2 I heard that the B.O.O. switch can cause similar problems. (again I know this sounds crazy but very experienced people have told me this)
#3 My speedo gear keeps getting shredded (wrong one in tranny) so do u think it's because the speedo drive isn't turning? (i beleive i tried this once by putting a new one in and it didnt work)
#4 Should i try and find an original 5 speed ecu? Im pretty sure that A9p should work.
#5 Should I try a Pro-M meter?
#6 could I have gotten a bum injector that sticks or something until its de-energized by turning the key off and it runs fine until it sticks again?
#7 The ground that looks like it comes out of the injector harness; is that the injector ground or what?I have aluminum heads and it is grounded to them. (big ring connector)

I'm sure I can think of more later but if you guys could offer suggestions so far i'd greatly apprecitate it. I am sorrythis is my first post and it's so long but as you can see I've tried almost everything and I am at my wits end. this problem has stumped some of the best in the business so far.. Any help PLEEAASSEEE!!!?

 

[sweet88gt]

Had a similar problem with part throttle drivablilty after thr H/C/I change. For whatever reason it ended up being my EGR. Try capping off the vac line and take it for a ride. If that helps its an easy fix.

 

[Nitrod86gt]

lol whoops already replaced the entire EGR valve and solonoied too...my bad

 

[Michael Yount]

Have you run the codes on it?

 

[Nitrod86gt]

well thats the funny thing...i can hook one of the cheaper LED based scanners up to it and it does absolutely nothing...like it can't even read it. I figured this had something to do with the '86 wiring harness and newer ecu... what about that sensor on the tranny guys? I need some in depth knowledge here..this isn't gonna be something easy...

 

[Michael Yount]

The sensor on the tranny is a neutral indicator switch. The computer checks to see that the car is in neutral as part of 1) the starting circuit, and 2) in order to let you run key on engine running codes. So unless you hook up the neutral safety switch, it won't let you pull the KOER codes -- but you should be able to pull the KOEO codes - assuming you've got it wired up correctly. Sounds to me like you need a schematic of the 86 model and whatever year harness you have in the car, and to get everything hooked up. The VSS (vehicle speed sensor) is also driven by the speedo gear and provides an input to the computer - so if your speedo gear is stripped, then you're also not getting a VSS signal, although that shouldn't cause the symptoms you've described.

 

[Nitrod86gt]

yeah i knew that was the neautral indicator switch but like i said some big dog 5.0 guru's have told me it CAN affect driveability in rare cases...also same thing for the B.O.O. switch...like i said im pretty sure i fixed the VSS problem once (before it stripped again) to try and fix this and it didnt work....anyone????

 

[2002BLGT]

I have had the same problem , put the stock injectors back in and added some timing helped alot , the spot where mine would clear up was when the timing would go to full advance ........so upping the timing will get it at full advance sooner in the rpm range ....but the stock injectors and going back to a 19lb sample tube in the C&L cleared up most of it

 

[Nitrod86gt]

well with the mods i have and the nitrous i run i cant afford to go back to stock injectors....i have seen plenty of people run 24's and a c and l with no problem so i doubt its that unless i just got some bad injectors....anyone seen an msd 6AL cause a problem like this?

 

[Michael Yount]

Does your C&L have the 24# sampling tube in it?

 

[2002BLGT]

well with the mods i have and the nitrous i run i cant afford to go back to stock injectors....i have seen plenty of people run 24's and a c and l with no problem so i doubt its that unless i just got some bad injectors....anyone seen an msd 6AL cause a problem like this?

Im spraying a 100 dry shot and have a wideband to check it , and its fine with the 19s , just jack the fuel pressure up to 43 psi when you spray it , I am running 38-39 when not spraying it ......17-19 degrees of timing when on motor , 12-13 degrees of timing when spraying , on the stock Hypercrappy pistons ....

 

[Nitrod86gt]

Does your C&L have the 24# sampling tube in it?

of course it does

 

[Nitrod86gt]

Im spraying a 100 dry shot and have a wideband to check it , and its fine with the 19s , just jack the fuel pressure up to 43 psi when you spray it , I am running 38-39 when not spraying it ......17-19 degrees of timing when on motor , 12-13 degrees of timing when spraying , on the stock Hypercrappy pistons ....

still though 24lbs injectors should not cause this...ive seen plenty of people with similar combos run em and they work like gangbusters...hell MMFF article i see with similar combos they run 24's...it STILL doesnt explain why it runs awesome when i turn the key off going down the road and then right back on and it runs awesome!!