I have a lot of black smoke at idle. lots when cold, it gets a bit better when warms up.

I know I have a bad vacuum leak that I need to fix, I'm reading 6in/hg but I'm not sure it would cause the amount of black smoke I have out the exhaust.

Think is, my uego reads 14.7 shouldt it read really rich with lots of black smoke

I have LR maf, with a piggy back tuner, no cats.
LR adjustable frp set at 40, and it holds vacuum (I tested it).

I do have one leak. There is a hose that runs to the TB, that connection is broke. the hose is capped, but the pinhole on the TB is open. I'm looking for others.

should I turn down the fpr, or turn down maf piggie back? check for stuck injector? replace my o2 sensors? I'm starting to run out of options.

everything I can think of adjusts the amount of fuel, but why would my uego read fine? is that thing just throwing me a herring?
Thanks
Jeff

 

If its excessively rich you're gauge will read lean. It needs a good amount of burned fuel to read properly. If too rich the measurement becomes erratic

 

Get it to an Exhaust analizer (SMOG test station... or DYNO).. and have them confirm your WBO2 reading...

 

Could your O2/uego sensors be fouled by extremely running rich AND your prior turbo issues?

If you plug the Throttle Body hole temporarily -- does that improve things?
Half the vacuum lines on our 924 end in bolts/plugs :-)

mike

 

Plugging the TB bleed hole is a decent idea.. however the failure mode on MOST if not ALL WB O2 setups is to indicate full range lean (I.E. 21:1).. not stoiometric (14.7:1)...

Sensor could be fouled (disconnect sensor from exhaust pipe, and leave it hanging in free air to verify, it SHOULD indicate full lean (21:1 or whatever the upper reading limit is for the setup).. but I doubt this is the issue...

My first feeling is it is oil smoke... and the WB is indicating correctly.. but cant be real sure.. and oil smoke is usually NOT pure black... however it could be a combination if issues... I have seen cars idle at 10:1 without any appreciable black smoke... which is why I dont believe the OPs issue is mixture related... smoke improving as temperature comes up on the car could be mixture related, or a leaking seal closing up as temp comes up.

A full bore exhaust gas analyzer should be able to indicate WHAT the smoke is, and lead the OP to where it is coming from...

 

I have a feeling you are right. From what I have read, in order to have that much smoke, the car probably would not be running as well as it does. It actually runs really well, just is smoking really bad.

 

Bad turbo seal dumping oil straight in to the exhaust?

 

Just had my turbo rebuilt by majestic. The seals were shot (lots of movement in the shaft), but majestic pretty much replaced all the internals in the turbo.

 

Get the car onto an exhaust gas analyzer to be checked... Your Uego could very well be spot on... and at 14.7:1 there should be NO smoke, maybe even a little bit of water...

Easiest (safest) would be a dyno run... with O2 sensor... it will tell you if your WB is functioning correctly...

Smoke... now that is a bit more difficult to diagnose, but can be diagnosed..

What does the smoke smell like?

 

If your turbo was leaking oil, then it will take some time to burn out the remains from the exhaust...

 

figured out a couple things tonight that I have to fix, but no smoking gun yet (pun intended)
1) I dont have an 02 sensor. the spot is used for my wideband 02, and it does not output a signal for the dme like modern versions.

2) I have a huge hole in my intercooler causing major vacuum/boost issues.

My plan is to get a new/used intercooler. Not sure what to do about the o2. I could add a factory 02, or get a new wideband that outputs something the DME likes, or jsut run open loop. Its a racecar so no emissions.

 

You don't want to have your wideband o2 sensor before the turbo. You want it down around the flat section before the cat or test pipe or whatever you may have. Easiest solution IMO is to have an exhaust shop weld a bung in for your wideband o2 sensor and pick up a factory sensor to go back in.

 

I have a good stock intercooler if you need one....

And you can insert a loopback into the dme harness to put it into ROW mode... no more O2 sensor need!
http://www.motronic.ws/4in1.htm
1.8K ohm resistor into the coding plug (2 pin plug located on teh harness near the DME), No CAT, No Lambda..

 

Some wide bands will sit at 14.7 when the sensor is dead.
If the sensor always sits at 14.7, it's in need of replacement.

 

Thanks, Like I sadi I hadn't seen one sit at 14.7 when the sensor dies, but immagine one COULD...

Thanks fo rthe clarification!