1stcamaro89

i have a 94 z28 had it 4 less than a yr. no major engine work accept top end rebuild according 2 the dealer. spark plugs and cables all less than a yr old but it's idles rough. if u give it gas with low rpm's it sorta boggs down until rpm's reach around 1500 or so then it really picks up quick. i thot maybe it wuz timing issue but i don't have the tools 2 check it myself nor the money 2 get it tested. haven't checked the fuel filter yet and i kno there's no vaccuum leaks. no sensors r bad cuz i had them all tested and the only thing that came up wuz the tps wuz bad cuz the o2's showed it wuz running lean so i changed that aleady. dunno wut else it could b and i hope it's nuthin serious. i need help!

kennythethird3

i just had same problem did every test and nothin i unplugged an oxygen sensor and it straightened rate out,so best guess try checking the oxygen sensors

Guest47904

Please explain the connection between the TPS and O2's you refer to above.
did someone scan it? What was the code?

Did the TPS fix any of the problem?

Do you have a SES light on?

Have you tried disconnecting an O2 to see how it runs?

1stcamaro89

i took it 2 aamco and had them put it on a scanner. i don't remember the error code but they said it wuz showin the o2 on the driver side wuz giving lean readings due 2 a tps failure and they recommended a new tps which i already got and no it didn't fix the problem. dunno wut ses light iz and i have not tried disconnecting the o2 considering the last time they scanned it there were no error codes

1stcamaro89

which o2 sensor did u have the problem w/?

1stcamaro89

ok so i unplugged the 2 o2 sensore @ the headers and it didn't fix it so i'm @ a loss uv wut 2 do nxt

Injuneer

Sincere suggestion, based on observations as a Moderator here for more than 10 years.... this is a bulletin board, not IM. Typing in full words, rather than the "hooked on phonics" shorthand approach may get you more readers and more responses.

1stcamaro89

ok thanks for the suggestion. well as a moderator for 10 years do you have any suggestions on what could possibly be wrong with my car. ive been told there's more than just two o2's but i havent been able to find the others...maybe i'm just not lookin in the right places any help would be greatly appreciated

craby

pretty sure the 94 and most 95s have one sensor on each side. if i remember right when the computer switched to obd2 then the second 02 sensor was added to evaluate the cats. go to shbox and find tests for the tps and test it to see if its jumping around when u move the trottle up to full. should be at .5 to .7 at idle and 4.5 or in that area when wide open throttle. test the 02 sensors and see if they are working correctly. check air cleaner. check intake air temp sensor. check fuel pressure and fuel pressure regulator. check the intake hose/elbow for any leakage areas. check idle air contol vavle for fouling or crud buldup. are u smelling gas in the exhaust or the engine compartment? if the computer is getting a happy number from a sensor even if its wrong you will not get a code.

Injuneer

A OBD-I 93-95 F-Body LT1 has only two O2 sensors. There is a pre-cat O2 sensor at the base of the driver's side exhaust manifold, and another pre-cat O2 sensor on the passenger branch of the exhaust Y-pipe. Only the Y-Bodys (Corvettes) added a single after-cat sensor, when they adapted an interim "OBD-1.5" PCM - but this was never done on the F-body. Two after-cat O2 sensors were added to the F-Body in 96/97, with the advent of OBD-II.

I really don't understand the "Aamco" explanation of the TPS causing an O2 sensor lean code. How did they explain that one?

Do you have access to a scanner, or to PCM scanning software? If so, this may help you evaluate the way the engine is operating:

http://www.injuneer.com/ScanMast.html

How many miles on the engine? Have you ever had the injectors cleaned? When is the last time the plugs and plug wires were replaced? You're saying it runs strong after 1,500RPM? No sign of breaking up or misfires above 5,000rPM?

dnapowersports

Sounds similiar to my problem with my 94 which I'm still figuring out except when I unplugged the o2 it made a difference. I checked my fuel line pressure and its low - 25 psi. I'm thinking that may be why I'm having trouble and the o2 sensor is messing things up. Not sure but I would check your fuel pressure. May be why you're running lean if you have real low fuel pressure.

1stcamaro89

ok i don't have access to any scanners or equipment like that. as far as i can tell there's no vaccuum leaks. i have a brand new fuel pump so i doubt it's that but i haven't had the chance to check the filter yet. plugs and cables are less than a year old and the car has 209k+ but the dealer i got it from says it's had a top end overhaul. and i was wrong with the rpm readings. it runs fine afer 2k or 2100 but if i hit the gas hard before that it really boggs down. and the tps is brand new as well and i have already checked both o2 sensors. after i unplugged them it still ran the same as far as i can tell.