[ol][*]Tell if your O2 Sensor is bad?[*]Tell if you need a new TPS?[/ol]

I have NO CEL on and I know that is one way to tell.

What my problem is that after about 150 miles it starts dying when letting off the gas...sometimes...especially when driving slowly and letting off the gas. Also it will be hard to start after warmed up...by hard to start I mean I have to give it some gas to start it. After I reset the PCM it runs PERFECT for the next 150 or so miles.

Any help or ideas would help tremendously since it has been doing this for almost a year and I still have not figured it out.

Brad

 

have you cleaned your iac? that's what it sounds like. It's located behind the tb. Take it out and spray it good with carb cleaner. The almost dieing when you left off the gas, and the hard starting sounds like the iac to me. Anyways back to your original question. you can see if your o2 sensor is giong bad by a scan tool. and for the tps yu can see if it's going bad buy and osciliscope, you can also tell if your o2 sensor is going bad. I doubt you have an osciliscope, so there is really no true way to tell if each one is going bad. To tell you the truth, depending on how many miles your truck has, i'd just replace the tps and o2 sensor...your going to have to eventually, but i would definitally try the iac motor first[sm=signs003.gif]

 

I bought an IAC about 6 months ago and it helped but did not fix the problem. I have 200,000 miles on the truck so I think you are right about replacing them both.

So they can go bad without throwing the CEL?

Brad

 

my tps threw no codes but my rpms would go up and down when accelerating after a few months it threw a code of tps malfunciton(or similar) and i replaced and havent had any problems with it.

 

That could be it....I am not allowing my computer to throw a code since i am resetting the PCM as soon as it starts to happen.

Thanks...I hope that it fixes it.

Brad

 

obd II computers can sense sensors going bad, but as long as the senser is performing withing a set tolerance it won't throw the code. So your sensors could be at the very edge of the tolerances and your computer won't set the MIL becuase it's within the tolerances....