Code 45

[msb350]

Alright after wrestling with the engine all day I still can not get the engine to idle smooth warmed up. I inspected the IAC which was clean as well as the port on the TB. I checked the both the MAP and TPS sensor and both checked out. The evap canister was good an the engine runs great cold. I inspeced the O2 sensor since the engine was running rich and it was pretty fouled with carbon so I replaced it. Still the engine fluctuated from 500 to 650 RPM once it was at operating temp and does the same choppy idle while im sitting at a light. My only other guess is the temp sensor but I am not sure. Any ideas? Thanks for the help.

matt

 

[Thunder]

Temp sensor or TPS would be my best guess. Maby you should just buy a good scaner It will save you money in the long run.

 

[readymix]

I would check for an issue with the distro.
Pick-up coil
Wiring
Reluctor
Main shaft magnets..

 

[msb350]

Hmm I did not think of the distributor. Might be the source. I wont have the engine much longer since shes got 220K but I need it to last a little longer before I get a new engine in. I will have to check that temp sensor tomorrow. Also, I think the TB shaft is worn completely down. It feels like it is binding bad. Could this cause a bad idle? I did the paper clip test on the diagnostic port but I think I know of someone with a scanner to check out whats going on. If anyone else has any input feel free to add.

matt

 

[1985_K5_Silverado]

Sure, a worn and leaky TB shaft is just another vacuum leak. Spray a little carb cleaner where the shaft sticks out of the base plate and see if the engine speeds up momentarily.

 

[msb350]

Well after driving today I might have helped lessen the problem but I think readymix is right. I think the distributor might be the problem. I came off the highway today and on the feeder road I stopped at a light. The engine idled right at 600 but then it would start to drop 100 rpm and come instantly back to 600 rpm. It would do this every couple seconds. Everytime it does that it makes a very light thumping sound like it is missing or something. This makes me believe its related to the distributor but if theres any flaw in my logic please speak up. The wires, plugs, and rotor have been replaced but not the cap. It might be something internal. It is just wierd that it does this when the engine is warmed up so it still could be the coolant temp sensor aiding to the problem.
Thanks.

matt