Engine Misses after warming up

[rdhack]

1995 Chevy 4x4 5.7L 5speed manuel trans

New plugs, wiring, distributor and rotary, air & fuel filters

cat converter was removed before I purchased

Runs great until warm then at slow speeds most noticably 3rd gear does not want to take fuel very well , misses. When gas pedal is pressed it hesitates. Am not getting any service engine soon flashes.

Im thinking maybe fuel pump or maybe clogged muffler.

Any one else have any ideas? Any helpful info would be greatly appreciated!

Richard

[leolkfrm]

welcome
put it on a good scan tool and check the sensor readings, sounds like one is acting up in closed loop

[rdhack]

Thanks for the input. I will do that.

I have another question. How many O2 sensors should this truck have? I found 1 off the left hand side of the exhaust manifold. I mentioned earlier that the cat had been removed before I purchased the truck, There is no O2 sensor on that side of the engine. The hole has been welded shut.

Im thinking of maybe reinstalling an replacement crossover-cat converter pipe with an O2 sensor . Do you think that would help?

Another question....I cant seem to find the wiring connector for that particuliar O2 sensor.Should it not be just hanging there?

Thanks!

[jimbo543]

unplug egr valve and drive

[Case 7230]

My `92 5.7 auto had exactly the same symptoms as you describe. There was no SES light and no codes. The vacuum to the EGR was already unplugged. After doing a lot of the things you have done I started running a can of Cyclo Fuel Injector Cleaner thru it. This seemed to make no difference. I then tested the only oxygen sensor as per Autozone and it tested faulty so replaced that. After driving it a couple of times it started to drive perfect. That was several months ago and still perfect.

[rdhack]

Thank you kindly Case 7230. I had already decided to replace the O2 sensor today. I previously owned a 4.3 L-1994 which had a 3 wire sensor on the other side of the engine so that why I was confused to how many there are supposed to be.

Again Thanks Guys

[Sneakysportsman]

There is only 1 O2 sens. and it is a 3 wire. Check the Fuel pressure spring in the Tbi Injector pod. I hade the same problem last week and my new engine was run running way too lean. I replaced the spring and the problem was cured. You could have a combo of an O2 and a fuel pressure. Have the pressure checked first because it is a lot easier to know if you have low pressure that to throw a pump at it. Dropping the tank is a terroble pain in the a$$.

[rdhack]

Oxygen Sensor fixed the problem. Truck now runs great. Sneaky, I guess the put different configurations of O2 sensors on these trucks since this was a 1 wire job.

Something interesting happened. I purchased a temperature sensor as well from NAPA and installed it. When I started the truck I had a service engine soon light. Drove it a bout 10 miles or so....tried to reset the computer....finally used my code scanner and said code 15 which was the temp. sensor. I put the old one back in and the light went off! What about that.

Thanks to whoever is responsible for this website, It is a dandy! And thanks to all those who responded to help.

[mudseeker]

sounds like you learned a valuable lesson. just because it's a new part doesn't mean it is a working part.

[rdhack]

O.K. Guys, Now I am confused. Truck ran great until yesterday and started missing again while on the way to a friends house. before I left I plugged the egr valve and it started and ran great until it warmed up to operating temperature and then started missing again. There are no service engine soon light flashing.

That's basically the way its been ....runs great until warming up then a miss most noticably in 3rd gear during acceleration.

New plugs, rotor, dist cap, dielectric grease on connections, O2 sensor, air & fuel filters. Wiring looks new & was installed before I traded for the truck with the plugs.

It cannot be much wrong but I am having trouble finding it..especially without a code reading to direct me.

Any help would be greatly appreciated!

Thanks