..............

 

dont have a muffler

 

I kinda got to say the upsteam O2 as well . Try disconnecting it , the PCM will run the engine fine on preset setting stored in it's memory . This will cause a Check Engine light but cause no damage . If the problem stems from the sensor , your issue should go away with it unplugged . This is fine to try for a few days but not long term , the sensor will have to be replaced if the cause .

Be sure to tie back any wires from the exhaust for the test .

This will not always show up on a scan tool .

X2 on cleaning the AIC , it never hurts

 

My vote is for a clogged cat and/or bad (or on its way to going bad) sensor, especially if the plenum gasket is broken again. A sensor can occasionally generate voltage in the right range that the computer would deem "correct", but still be going bad. I'd personally look at the voltages on the TPS wires, the ones on the IAC sensor, and the pre-cat O2 sensor.

 

when he hooked the scanner up there the tps was reading just a hair higher than normal but everything else was normal. i will take the iac off and clean it and the cat is coming off next week and i believe the muffler shop can make me a new place for a new o2 sensor. maybe it will fix the problem

 

+1 ON THEM MUFFLER BEARINGS...If there not lubed properly they will go out and it'll run like shyte.


I keep telling people to lube them dang things. But, they dont..And you know what happens. There cars run like shyte..

 

My apologies, didn't know he had read the actual voltage. Even a hair higher than normal, I'd replace it. Did he test it at different throttle positions, or just at idle? If it tests just a hair over normal at idle, who knows if its working right when you give it a little gas (or more).

 

testing any sensor is a tricky thing. i work at a shop and i cant tell you how many times a sensor will test ok, but upon replacement the problem clears up completely. the problem is sensors send differing amounts of voltage based on their readings. so they could send the right amount sometimes, and the wrong amount other times. dont rely too heavily on the voltage meter telling you a sensor is ok. and i would assume if the upstream o2 sensor was in wrong you would have an exhaust leak that would cause it to pop and bang when you let off the throttle.

 

Anything in the range of .44 to .75v is normal with the throttle closed . It should be tested through the throttle range , not just idling , not with a scan tool , but with a multi-meter .
Theres accually an adjustment you can make on the TPS with a little modding to dial the TPS to the higher range , suppositly , it's to stop stumbling off the line and give quicker throttle response . I felt no gains , but no difference either , a little high won't hurt as long as it isn't above .75 from the start .

I'd still unplug the upstream 02 sensor .

Can you better describe your problem ? Does it last 30-40 secs then go normal again ? Hot or cold when doing this and/or is it shortly after starting ? The more details the better , I can't tell much online from here , .

 

he tested it at idle and while giving it some gas. readings were in the .6 range if I remember correctly. I had my cat looked at today and it's in perfect condition. didn't have the funds for him to check the o2 sensors but he said they looked fine. I still might try unplugging that first one just to see what it does and I'm gonna clean the Iac. it sounds like it's gonna shut off when the truck hasn't been drivin in a while like overnight. when it does this you can hear a loud sucking noise coming from the engine somewhere and i don't think it's the plenum because i just had that replaced and i looked into the intake yesterday and didn't see any oil. sometimes at a light when I accelerate it will be kinda sluggish but other times it'll fly off the line just great. I'm not sure about muffler bearings considering I don't have a muffler and have never heard of them. hope that helps a little