HELP! Really odd problems...

[TighTheChevyGuy]

I recently bought a 93 Tahoe w the 5.7L 350 L05. Its the last T.B.I. I do believe. I have put a new alternator, fuel pump, fuel pump relay, ecm, plugs, IAC motor, and i have done a lot of wrenching and cleaning on it, trying to restore it to its chevy pride.

I am having some really odd problems that i cannot seem to fix. I have a normal idle and rpms when my Hoe feels like it, then out of nowhere (in park, drive, neutral, driving down the road, whenever...) it will start to miss out. If i go to half throttle it seems to run quite a bit better until i have to let off the throttle. WOT sucks really bad and it seems to hate it so i stray away from that quite a bit. I thought it was caused by a shorted coil wire (the one straight to the bottom of the distributor) and upon replacing that wire it ran great for about 3 days. Then it randomly started acting up again. The IAC seems to have helped a slight bit. I have cleaned the terminals in the dist. cap and made sure all my connections are good as well. I'm thinking it may be that my TPS is wrong, or that it may be my coil itself (though this is uncommon), or maybe its my fuel pressure regulator.. im not sure. i have a ridiculous exhaust leak on the drivers side (common) from my manifold to the y-pipe which i intend to fix soon. im not sure if that could hurt a whole lot of stuff but my drivers side plugs have been burning extra hot (the ceramic is browning already after two weeks)...

i know this is a lot of info but i just figured it may help someone diagnose without a lot of questions and whatnot. please let me know if you think you are master mechanic enough to solve this humdinger. thanks yall. oh and it sat all winter without a hood hahah but thats not my fault, it was the guy i bought it from. gotta love an idiot.

 

[gpracer1]

How does it run in the first minute or two when cold?
You must fix the exhaust leak as your O2 sensor may see all that extra air. On top of that you may need a new O2 sensor also.

 

[TORONTO 95 GT]

I had the same issue with my 95 many years ago but it did throw a CEL when it was happening. Quick scan showed a TPS. Threw in a TPS and all was good.

 

[chevyboy831]

tps may b the issue, the exhaust issue is definately adding to your problem. fix the exhaust leak and recheck your live data if u can. allow the fuel trims to adjust and c what it does. how are the electrodes on the plugs?

 

[TighTheChevyGuy]

hey GP i am fixing the exhaust leak tonight hopefully. got new flange hardware n whatnot, just hoping nothing is broken off. kinda figured it might be an o2 but it jsut didnt seem to fit symptoms.

and to toronto and chevy, i read something about testing the resistance in my tps and adjusting it that way once upon a time, could i try that? and i dont have any codes, nor can i test it at work and w expired plates on it, i dont wanna risk runnin it to the shop since its obd 1.

 

[fire730]

It could be the O2 or the exhaust leak. Earlier systems relied heavily on the information received by the O2 sensors.

 

[TighTheChevyGuy]

alright i just got done w the coil and plug wires which were much needed regardless lol. also, i installed a dorman exhaust flange kit w the studs and springs which fixed the exhaust leak w a lil elbow grease added in hahah. however, my problems are not fixed. so how exactly do i spot a bad O2?? I have ran the heavy chevy on a modis scanner before and the O2 sends signals but could it be possible that its bad anyways? it runs really rich as i forgot to mention, not sure if the O2 says so or not, but when its idling i can smell the fuel.

chevyboy831, the electrodes look fine even though the ceramic was turning brown so damn fast.

 

[xanatost]

A bad O2 will make your truck run rich. It will run like crap too. Mine went out 2 weeks ago and I watched my gas gage drop. Fix it ASAP or run the risk of burning up your cats.

 

[SunlitComet]

I don't suppose you have the graph results of all four sensors do you?

 

[TighTheChevyGuy]

its a 93. only has one sensor on it from factory. also it has some ***** exhaust job done on it w.o cats. just has what seems to be a glass pack and it turns down just before the rear tires. and no, like i said i have expired plates on it so i keep driving to a minimum. and my mechanics shop is about ten mins away in a small town filled w dick cops. im not sure how to get any kinda reading offa it other than the modis scanner that they use up there. it just gives a live reading i do believe.