1989 5.0 GT smoke out tail pipe issue.

[trentg89]

Hi im new to the thread and recently purchased my first 5.0, the car sat in a garage since 2004 has a 120k miles one owner, and since then ive got it running. The issue im having is smoke out of the tail pipes but intermittently. It never smokes on a cold start the the times it does do it is when im driving at normal rpms for a long distance come to a stop, and once stopped the smoke will roll out for 10 to 15 seconds then disappear, some times its quite a bit. Since it started smoking, Ive done a compression test to all cylinders along with a leak down test and all cylinders were fine. I also went ahead and replaced valve seals thinking that was the issue along with pcv valve, but no change. I do pull a thermactor code but for the first valve off the smog pump. Not sure if that's the issue. Everything is basically stock besides, off road x pipe with cat delete, bbk headers, bbk air intake and Msd cap rotor and plug wires. The engine seems to run fine no hesitation or weird idling. The smoke is white in color and smells of fuel/oil. Any ideas would be appreciated Thanks.

 

[fredfifty]

injectors? maybe do a noid test. or of course run codes first and foremost.

 

[90sickfox]

Fuel ( generally ) makes black smoke. With compression test you can cross out headgasket... unless it's a very small leak.

Have you lost any coolant ? The throttle body spacer can leak putting coolant into the intake. It can cause mysterious white smoke. This has happened to me and a couple other guys. You can remove the bbk intake pipe and look in the throttle body. If its leaking you should see evidence of it....or you can pressure test the coolant system.

 

[trentg89]

Fuel ( generally ) makes black smoke. With compression test you can cross out headgasket... unless it's a very small leak.

Have you lost any coolant ? The throttle body spacer can leak putting coolant into the intake. It can cause mysterious white smoke. This has happened to me and a couple other guys. You can remove the bbk intake pipe and look in the throttle body. If its leaking you should see evidence of it....or you can pressure test the coolant system.

Hey sorry for the late response i looked inside the throttle bisy and no sign of coolant, i also went ahead and pressure tested the system wich hels 16 psi steady for 20 min. Still having the issue any help would be appreciated! Thanks.

 

[90sickfox]

With no cats these cars can stink to high hell. Fuel vapor in exhaust can curl your eyelids. The stock injectors should be an orange color. If they are any other color you need to make sure the MAF is an aftermarket one for the particular injectors....or there is a chip with correct tune.

If it has long tube headers it can affect the o2 sensor readings if the sensor is located too far down the header. O2 sensors need heat to work and being in a colder area away from the engine can change the reading causing a leaner fuel reading....which causes the computer to drop more fuel to compensate. ( I haven't seen this issue in a few years ).

Have you checked the pcv valve and the screen below it ? The pcv hose can put oil into the intake. Another thing that can cause oil to get into the cylinders is an intake gasket leak. Did any of the spark plugs have oil on them when you pulled them ?

A slipped intake gasket will usually cause a driveability issue and idle problems. Sometimes the vacuum reading will be low at idle.

 

[billison]

Pull your codes and see if you have any.

That said, a car sitting that long can do a lot. Make sure everything is clean and clear including the pcv filter