I was wondering what to check for. It doesn't miss when the engine is cold, only once it warms up. And it doesn't miss at all at an idle, seems to miss mostly between about 35 and 55 MPH or when coasting down a hill , it just bumps and the check engine light isnt on. I changed the plugs last weekend, they all looked good and didn't really appear to need changing. I then changed the fuel filter on the frame, (is there only 1?). I have changed the cap and rotor in about the last year and a half. Plug wires "look" good, but i will probably do those next. I've also ran a bottle of heat in it, and a cheap dollar bottle of fuel injection cleaner. Is there any brand of fuel injection cleaner that will work if thats what it needs, or are they all pretty much the same? The air filter is good also. Any ideas?

 

Cap and rotor in the last year and a half. Some folks rack up 30K miles in that amount of time, some only 10K. Try doing a complete tune-up (cap, rotor, plugs, wires, air, breather, fuel, PCV, oil change), and O2 sensor every other, at one time. You say it's missing while coasting down a hill. Are you referring to a slight misfire out the exhaust? Could be a number of things. A overly rich mixture, EGR not working, incomplete burning, malfunctioning injectors, a non-functioning converter. When did you replace the oxygen sensors last? Have you done a fuel pressure check yet? Any codes thrown? Any changes to your exhaust system recently=new muffler, leaking system, duals?
There are a bunch of decent or better injector cleaners out there. The only two I have used are Justic's missing while coasting down a hill. Are you referring to a slight misfire out the exhaust? Could be a number of things. A overly rich mixture, EGR not working, incomplete burning, malfunctioning injectors, a non-functioning converter. When did you replace the oxygen sensors last? Have you done a fuel pressure check yet? Any codes thrown? Any changes to your exhaust system recently=new muffler, leaking system, duals?
There are a bunch of decent or better injector cleaners out there. The only two I have used are Justice Brothers Advanced formula, and BG 44K. They are both pricey , but a lot cheaper than a pro cleaning.

SL
I give up.

 

O2 sensors? Something I have never changed or knew existed. where is it(they?) located? This is the 1st computered truck I have owned.
Thanks

 

What does a typical diagnostic test cost to pull the codes? Do any auto parts stores do this ?

 

Does it idle pretty high when first started? Spray some carb cleaner around the base of the upper plenum where it bolts to the intake. The gaskets will break and cause a vacuum leak which results in your type of problem. I suggest going to the dealer and buy a 94 plenum gasket, because it is made from a type of plastic that won't break. Should be less than 15 bucks.

Robbie

 

Pulling the codes is free at AutoZone. The O2 sensors are located in the exhaust system. My 2000 has 2 on each side I believe.

Hunt4Fun