95 tahoe misfire when warm

[540cosmo]

i have a 95 tahoe 4x4 5.7 replaced o2 sensor,cap,rotor,plugs,ignition control module,temp sensor,wires 2 years ago they seem to be in good order,misfires only when warm runs great when cold,misfire under a load as well,the hotter the engine gets the worse the misfire,i am at a loss i cant afford to be just throwing parts at this,i have read and read for some solution but have found none can someone please give me some real advice

 

[SunlitComet]

first re inspect that cap/ rotor for moisture or residue build up and perhaps try cleaning fuel injector with a heavy dose of techron in the tank.

 

[gpracer1]

I am guessing this is a TBI engine since you said O2 sensor( ).....

In closed loop (cold engine) the ECM uses speed density and wont see the O2 sensor or use its input. If the truck runs good cold but bad hot, I would look at the things that are used in closed loop but not in open loop.

My guess would be the O2 sensor, and possibly the Engine Coolant Temp sensor (Im not sure if there is both a sensor (ECT) and sender (gauge) on that year.)

Also a warm engine uses less fuel than a cold one, so I doubt it is fuel starvation since it runs good cold.

 

[SunlitComet]

There is.

 

[540cosmo]

ran some seafoam in the vacuum line and some in the gas it may have gotten a little better but not much also if i run in third gear instead of od it seems not to misfire as bad but it is still there,also being yhis is a obd1 it does not have any codes or check engine light,any other thoughts?

 

[retorq]

ran some seafoam in the vacuum line and some in the gas it may have gotten a little better but not much also if i run in third gear instead of od it seems not to misfire as bad but it is still there,also being yhis is a obd1 it does not have any codes or check engine light,any other thoughts?

LOL There is check engine lights and scanners for them ... you need to do more research.

 

[Trippers99hoe]

ran some seafoam in the vacuum line and some in the gas it may have gotten a little better but not much also if i run in third gear instead of od it seems not to misfire as bad but it is still there,also being yhis is a obd1 it does not have any codes or check engine light,any other thoughts?

OBD1 has a check engine light(or service engine soon)if it is not operating it is burned out(just the bulb) or removed....turn the key to run(do not start the vehicle) ,if the check engine light doesn't come on it is not functioning.
Go to advanced auto they will read the codes for free.

 

[540cosmo]

LOL There is check engine lights and scanners for them ... you need to do more research.

yes i know there is a check engine light,and know the paper clip method of checking them iwas referring to that there was no check engine light on or have i found any codes with the self diagnostic check

 

[TTZ06]

ran some seafoam in the vacuum line and some in the gas it may have gotten a little better but not much also if i run in third gear instead of od it seems not to misfire as bad but it is still there,also being yhis is a obd1 it does not have any codes or check engine light,any other thoughts?

Where did you get those running boards from?

Nice truck

 

[540cosmo]

Where did you get those running boards from?

Nice truck

i made those myself. i am a welder fabricator by trade,these are 2x2 square tubing 1/8 inch thick welded solid and to the frame,here is another pic