930 Smokes under Acceleration
 

Can anyone tell me why my 1988 Porsche 930 blows black smoke under acceleration but only when the turbo boost is indicating. I am guessing a turbo seal.....


Thanks


Steve Hall

Black smoke is probably just unburned fuel, indicating rich A/F mixture which can be regarded as good thing (better rich than lean, lean = adios pistons).

If your turbo-seal was shot you would get white/bluish smoke when on boost and tons of smoke on startup.

Mine also smoked black on accel....nothing to worry about.

Thankyou for your reply, I only bought this car 2 days ago and I am extremely happy with it. I am looking forward to the next few months of getting to know each other :)

This happened on a Grand National I use to have and it ended up being the turbo. When the seals start going bad it will smoke white when it accelerates. Eventually it will puff smoke idleing. Check into it.

I meant black smoke not white. Sorry

Check it out?
 

Have you any idea how I can check it out? I am in Riyadh and the local porsche dealer seems to think it is fine. I do not have a lot of confidence in them.

Steve

I have no idea where Riyadh is but I would find someone that has experience with turbos ie. desiel specialist, rx-7 guy. Maybe they can help. I don't believe there are external sign that a turbo is bad. Maybe there will be some play in the turbine but I doubt it.

Riyadh is in Saudi Arabia... so you may image my problem finding a decent garage.

It's probably just extra fuel unburned, the CIS system when adjusted a bit will go rich under initial boost and then lean out as the rev's get higher. The car will probably puff a little black smoke under initial boost and then be fine.

Does it have a IC? If so unhook it and see if there is oil in there. To much oil-bad seal. This does not mean that you have to go out and buy a new turbo unless it's very bad.

Have you checked your fuel pressures. I bet your WUR is bad causing a rich mixture under load

Naww...CIS barn-door usually overswings when you stomp on it and delivers heaps of fuel, hence black smoke...you can actually let somebody drive behind and smell the fumes. I bet it won't smell burned oil.

I wouldn't be too concerned with that until it starts belching blue smoke or starts smoking at idle.

You are right, the smoke does not smell of oil. Reading the above posts I am now pretty sure that it is unburnt fuel when I stomp on the accelerator.

I think I found most of the information I needed at this post
http://forums.pelicanparts.com/showthread.php?s=&threadid=114638&highlight=CIS+tu rbo

One more thing - if the car has any mods I would recommend you do at least one run on a dyno to check the a/f ratio. Any dyno operator will be ok - doesn't need any p car knowledge. This will confirm your rich condition and otherwise let you know that the car is well setup (and how much ho you have...)

Cheers - Ryan, fellow 930 owner

sorry - how much HP you have....

I have only owned the car for a couple of days :D , I am in Saudi Arabia until December and I will be shipping it home with me, then I will be able to get it set up properly.

If anyone is interested I fixed the problem(s) that was causing the black smoke as the car came onto boost. It was a number of large air leaks between the turbo and the engine. The PO had over-tightened the intercooler and cracked the core and stripped the mounting thread. So when the boost came on, the intercooler was lifting from its mount and most the air was escaping before the intercooler. I had the thread heli-coiled which fixed the major problem and I have a new intercooler on order. I can now develop .6 bar (due to the cracked intercooler core) and with the new intercooler I expect to have the problem solved.