I have a stock 97 tahoe 5.7l 4x4 with 127000 miles.
I am experiencing two problem with my tahoe. i think they are separate but I'm not sure. There are 2 codes that are coming up p0305 (cylinder 5 misfire) and p0507 (idle control system RPM higher than expected). Also the O2 sensor (bank one 1 sensor 1) code came up. My thought was that the misfire caused this because when i cleared it, it did not come back but the misfire did.
I will start with the misfire. It is not that noticeable, it is just a little ruff when idling. I replaced the distributor, wires, and plugs but the code came back after a few days. When I first pulled the spark plug i thought that there was more to the problem then just a tune up. As you can see in the pics there is a lot of ash deposits. I did a compression test and it was fine, i dont remember the exact number but they were all pretty close. I then did a leak down test and it was also fine, 1/2 psi difference at 70 psi and less then 2 psi at 90 psi. So my next thought is injectors but would they do this to the spark plug? Any thoughts or ideals would be greatly appreciated.
My next problem I think has to do with the p0507 code. I replaced the idle air control valve and the TPS, it did not solve the problem. But it did help one of the problems, i noticed that my rpms were higher then normal at freeway speeds about 5 to 8 hundred rpms higher. But it did not solve the main problem and that is, when im driving and I take my foot off the gas the rpms drop but my speed does not. It gradually slows down but not any thing like it should. Its like I'm driving in cruse control but the cruse control cable is disconnected and my cruse control has not work for a while. I know that on the ford ranger when the separator plate gasket in the automatic transmission goes out it causes the same problem. I could not find any thing like this happening in a 4L60E transmission. Also when driving at idle the rpms and speed creep up. I can some times get it to go back down if I tap the gas fast. Could it just be the harness to the idle air control valve or tps? Any thoughts or ideas would be greatly appreciated?
Thank you,
I am experiencing two problem with my tahoe. i think they are separate but I'm not sure. There are 2 codes that are coming up p0305 (cylinder 5 misfire) and p0507 (idle control system RPM higher than expected). Also the O2 sensor (bank one 1 sensor 1) code came up. My thought was that the misfire caused this because when i cleared it, it did not come back but the misfire did.
I will start with the misfire. It is not that noticeable, it is just a little ruff when idling. I replaced the distributor, wires, and plugs but the code came back after a few days. When I first pulled the spark plug i thought that there was more to the problem then just a tune up. As you can see in the pics there is a lot of ash deposits. I did a compression test and it was fine, i dont remember the exact number but they were all pretty close. I then did a leak down test and it was also fine, 1/2 psi difference at 70 psi and less then 2 psi at 90 psi. So my next thought is injectors but would they do this to the spark plug? Any thoughts or ideals would be greatly appreciated.
My next problem I think has to do with the p0507 code. I replaced the idle air control valve and the TPS, it did not solve the problem. But it did help one of the problems, i noticed that my rpms were higher then normal at freeway speeds about 5 to 8 hundred rpms higher. But it did not solve the main problem and that is, when im driving and I take my foot off the gas the rpms drop but my speed does not. It gradually slows down but not any thing like it should. Its like I'm driving in cruse control but the cruse control cable is disconnected and my cruse control has not work for a while. I know that on the ford ranger when the separator plate gasket in the automatic transmission goes out it causes the same problem. I could not find any thing like this happening in a 4L60E transmission. Also when driving at idle the rpms and speed creep up. I can some times get it to go back down if I tap the gas fast. Could it just be the harness to the idle air control valve or tps? Any thoughts or ideas would be greatly appreciated?
Thank you,