86 z28 305tpi 700r4

So I hate 2 even have 2 post this due to so many
similar issues ... but my car has hardly any power under light throttle IN GEAR .at idle it runs smooth as can be i can rev it up no problem... I still feel Loss of power at full throttle but no where near like In gear under light load .

I've done everything I can think of and im in desperate need of sum help .

Problem started about 2 weeks ago and slowly got worse . I've tested and adjusted my tps 3x. Tested and my iac . Checked voltage and wiring for both . Replaced my coil due to intermittent stumble ( fixed that issue ) . Replaced my dist. Cap/rotor wires plugs . Replaced vacuum lines ( all of em ) . Fuel filter . Intake gaskets . MAF. unrelated but torque converter and trans filter . Reset timing to 6* runs like dog **** . Set timing to 10* runs much better . I have 9mm moroso wire custom fit . MSD cap rotor n coil. Copper core plugs ( new maybe 200 miles ago ) . Slp stainless exhaust. No smoke out tailpipe no leaks that i can see from any where . Compression test is 175-180lbs . 42lbs pressure at the rail. Every sensor i can think of tests out fine . Replaced anything I seen didnt ohm out correctly . I'm lost fellas . Cant find any old posts to give me any other ideas or direction ....

 

Looks like your just down to injectors or a open in the tps. You can do a sweep on it. Blue wire to black and slowly open the throttle koeo.

 

yep i have correct fuel pressure but not sure about volume . At same time at WOT it will **** n get no problem so volume should be correct . Tested tps and set to. 55 like old threads showed swept to 5.v at WOT . ohm iac and it was good . Would injector or 2 cause the bog under light load, yet give me a decent response at WOT ? I've also replaced the FPR diaphragm .

 

http://www.gmtips.com/3rd-degree/dox/tips/ecm/prom.htm
If this applies I can update the programming. Worth looking into. I’m not sure if the injectors would cause the slight hesitation or not.

 

#2 chug at low speed . Mainly 2nd gear . It's got pretty decent speed pick up at full throttle but low rpm speeds it chugs jumps bucks w.e. u want to call it. But at idle i can rev it no problem. So you think its possibly ecm or my prom chip? I haven't looked at it yet . My injectors pulse correctly and they ohmed out correctly too . I wondered about my manifold pressure switch too .

 

You would have a map you have a maf. It might be the prom but if it’s the ecm you might be able to run it and tap on the ecm to see if it acts up at idle in park.

 

If the rain holds off today ill check edu after work . I did find some sketchy looking wires on the mad burn off relay and a corroded wire ill fix and update tonight

 

If the relay terminals are melted due to heat or a high amp draw you might want to use the 89 up relay.
https://www.thirdgen.org/forums/elec...ump-relay.html

 

Been few days got the bugs worked out....

Blocked coolant port passenger rear of head .

Busted injector that would not change idle of car not a shake or stumble when sprayed w. Carb cleaner .

So replaced all the intake gaskets , injectors w. 21 lb southbays , adjustable FPR from southbay as well , and coolant temp sensor infront of intake ( only due to cracked housing that happened during removal of intake ) ,

Fixed my problem and added estimated 70 hp after tuning everything .

As a side note fellas... if you buy southbay injectors for tpi rail ... be prepared ...The clips are a s.o.b. and the new injectors dont sit as far in as factory . theres 2 slots in the injector for the clip and it uses the slot closest to the injector nozzle . You dont have to use them as alot of people argue i just prefer to not fight them going in or out of rail and manifold. If you break a clip theyre 2$ at oreillys .

Also the fpr screw is right on the damn plenum ... i replaced w. A 50cent thumbscrew from local hardware store and much easier to adjust .

I hope this may be able to help someone else fix their car . i could have strangled the car if it only had a neck .... thanks for the replys
No bueno
Replacement retainer for the injectors