89 928 turbo

Greetings, it has been a while since I've been here, but need some ideas...

My 89 928 has developed some smoking issues at idle.

This engine was completely rebuilt and full head's done, valves too. Less than 4-5,000 since rebuild.

Compression check done (cold engine) - all appears to be good

vacume steady at <-18>

New plug wires, plugs, etc...

Took out the 42lb injectors and replaced stock 19's (and disconected the turbo).

Re-programmed to stock fuel map with Sharktuner

Car starts and idles normally, runs under load with no visible smoke, accelerates at WOT with no visible smoke and decelerates under load (2nd gear from about 35 to 40 mph with single backfire) but also, with no visible smoke.

It is not using excessive oil...

This does not typically happen when the engine is cold, just after it reaches operating temperatures. When the(warmed up) car sit's and idles it starts to kind of "loads up" and then excessive smoke comes out the tail pipe...it does not smell like fuel, and generally is grey...not black, not white....it doesn't smell a lot like oil either....There is a small but infrequent "miss" that also produces an additonal puff..it will do this at a stop light and then when I accelerate, it clears and then no more problem until the next red light (so it takes about 20-25 seconds of idle to happen).

So, I've basically taken it back to stock and we are going to do another compression check (hot) and a leak down test this upcoming weekend....

Any other ideas or if anyone experienced anything similiar...would be helpful

Thanks,

JT

SeanR

Sounds to me like a Temp II issue whereas when it gets hot it is adding more fuel than is necessary or a fouled/bad O2. Could also be MAF related but I'm leaning towards the first two options.

killav

John,

Is the fuel system stock? Have you pulled the vacume lines to the fuel dampners/regulator? Make sure those are not ruptured.

No changes in vacume system lately?? Or PCV system routing??



My Car is still running great BTW 2.5 years post RMT!!

Tom. M

How much is "not excessive". I can't remember how your breathers are configured under the intake?..did you block off all oil entering the intake?

Temp II is easy to check with a multi-meter.

Also..forgot..when my MAF was acting up it would load up the engine (way way rich) and if I let it idle and then take off...it would unleash the clouds of Hades and sunlight would disappear for those behind me... (ask Shane LOL..). If you have a spare MAF..might just want to toss that in there....

89 928 turbo

Tom,

I have a spare, but its stock and not the modified wide band from John Speaks, I have a different than stock O2 sensor, so I am not sure if it will function, but it is worth a try...

Mrmerlin

have you been losing any coolant?
When you remove the plugs,
do the plug removal after you have let it sit and idle till the misfires start happening,
then let it run for a few mins then shut it off and pull the plugs.

if you find any plugs that look extra clean or with rusty tips then you may have a coolant leak at the HG.

Also while its idling look under the car at the cats ,
if you have factory cats and they are glowing then you have extra fuel being fed into the engine ,
Warning dont let the engine run like this for more than 3 mins as it could cause a fire.

This could be a bad injector or a blown damper or FPR so pull the vacuum lines and smell for fuel
have you checked that all of the injector connectors are fastened?

Also pull the vacuum line off the 6 way splitter for the transmission see if there is any oil in the line