Rough Idle

[jrobinson81]

I just purchased a 1999 ford f350 with a 7.3l powerstroke. Upon purchasing the truck I had to have the transmission rebuilt. My mechanic also said he thought something was going on with cylinder 3. The truck has 80,000 miles. The truck has a constant white smoke coming from the exhaust, and idles a little rough. Is this normal? When I first brought the truck to him the computer showed numerous codes, but after fixing the transmission and reconnecting the battery the codes haven't shown back up. I have been driving it for a day, and still no engine light has come on. However it still idles a little rough, and the white smoke isn't overwhelming but constant. I would greatly appreciate any advice to my problem.

[pipelayerjdh]

White smoke usually is caused by cold conditions. It should stop after running for a few min. Have the injectors buzzed by a good mechanic. The scan tool should catch a problem.

[jrobinson81]

I had the injectors buzzed, and the injectors aren't the problem. We even checked the mapping sensor due to the amout of white smoke. The mapping sensor isn't the problem. The computer read something wrong with cylinder 3. My mechanic says he thinks it's one of two computers. Does this sound right? I need some help. Again the truck is missing and has a constant white smoke.

[mschn99]

did he run a cylender contribution test? An injector buzz test only tests the injectors electrically, while the contrubution test will help test the mechanical portion of the injectors

[jrobinson81]

I'm not sure if he did. I don't think so though. Would bad injectors cause the constant white smoke and rough idle? Like I said before we have narrowed it down to cylinder 3. I just don't know the extend of damage that could have taken place. When driving the vehicle normally you wouldn't know there was a problem. Its just when you are idling. How much would it cost to fix the injector?

[mschn99]

actuall you shouldnt get white smoke after the motor has warmed up.....does it always smoke white?? im wondering if you dont have coolant getting into that cylender if its always smoking white....

[jrobinson81]

Yes there is always white smoke. What does this mean?

That my friend is what that means.

[jrobinson81]

I don't know alot about engines. So if colant is getting into engine what needs to be fixed? Would it be a head gasket? The truck runs cool. I haven't driven it enough to see if it is using alot of coolant.

[jrobinson81]

I forgot to mention that the smoke has a very strong Diesel smell, so maybe it's more of a light blue smoke that a white.