My apologies, school and work have been hectic, but I was able to make an advancement.
First, in answer to your question about the O2 sensor, I just looked at online forums about removing catalytic converters, that was the advice given. Backing the sensor out of the pipe also lowers the temerature of the sensor which, from what I have been told, makes a difference.
Now on to the truck. The error code continually came up with an IACV message even after I replaced it twice so I busted out the multimeter and found a wire with spotty continuity. I cut it at both plugs and replaced the wire, some symptoms subsided. In an earlier post I said something about feeling the engine momentarily slowing down when I coasted, then speeding back up quickly. That has stopped, and the speed is less varyable now but still too high. I took it to a mechanic to have the IACV adjusted, he brought the engine speed as low as he could but it was still far from right.
When I turn on my truck cold, it runs barely above normal, about 1000 RPM. When I drive into town, if I stop at a stoplight or something my engine runs at normal speed, about 800, but uneven. If I shift into park, it only goes up to about 1100 and runs even. If I turn my truck off and turn it back on while it is still warm, whether its ten seconds or over an hour, the RPMs are at 14-1500. This makes no sense to me.
The diagnostics now show a fuel mixture problem, I believe it was lean but it has been a few weeks since I was able to get it in. I cleaned my O2 sensors with no change. I used my vacuum diagram and found the hose for engine speed control, I removed the hose from the manifold while running and the speed immediately went up, I put a finger over the manifold hole and the end of the hose, the speed came back down to where it was and both fingers had strong suction on them, could that rule out a vacuum leak? If not, is there another way I can? I followed the hose all the way to the end where the hose becomes a metal tube, no cracks anywhere.
I usually get about 13 MPG city, I am currently getting about 5.5 and three different local shops have had no luck. Thanks for any help you can offer.
Wednesday, April 14th, 2010 AT 3:11 PM