86z28 stumbles under power almost perfect idle
#1
86z28 stumbles under power almost perfect idle
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 ....
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 ....
Last edited by 86z28slomaro; 10-08-2017 at 12:28 PM. Reason: Add info
#3
Re: 86z28 stumbles under power almost perfect idle
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 .
#4
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iTrader: (92)
Re: 86z28 stumbles under power almost perfect idle
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.
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.
#5
Re: 86z28 stumbles under power almost perfect idle
#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 .
#7
Re: 86z28 stumbles under power almost perfect idle
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
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#8
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iTrader: (92)
Re: 86z28 stumbles under power almost perfect idle
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
#9
Re: 86z28 stumbles under power almost perfect idle
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
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