20V Blacktop Idle And Black Smoke

[aurnob88]

Hey guys,

 

Today I checked out a clean AE92 with a Blacktop conversion / C160 6 speed conversion. The car overall drove well and revved out nice.

 

SOme issues were:

• When revved and hit VVTLI, black smoke comes out the exhaust. Not alot but quite a bit
  
• Idle is set at 2000rpm, when fan blower is turned on, tames down to 1500rpm.
  

Anyone know how to or how much to fix these issues? Or not worth fixing?

[altezzaclub]

Well, I figure black smoke is too rich, so a dyno run or mixture display will soon tell you.

 

If it wasn't really black smoke, then grey smoke would mean the rings are worn. If you could take it for a spin with a plug spanner in your pocket, just give it full throttle in 3rd then turn the ignition off at 4000-5000rpm.and push the clutch in. Coast to a stop and pop the spark plugs, checking the colour of the outside rim and the ceramic core.

 

The edge can be black with soot but no oil, and the core should be white or light tan coloured. A plug cut like that means you are seeing what is happening under power, rather then at idle when there is no load on the motor.

 

Idle shouldn't be set to 2000rpm, so either there is a fault they are trying to cover or something needs re-setting.

[aurnob88]

Well, I figure black smoke is too rich, so a dyno run or mixture display will soon tell you.

 

If it wasn't really black smoke, then grey smoke would mean the rings are worn. If you could take it for a spin with a plug spanner in your pocket, just give it full throttle in 3rd then turn the ignition off at 4000-5000rpm.and push the clutch in. Coast to a stop and pop the spark plugs, checking the colour of the outside rim and the ceramic core.

 

The edge can be black with soot but no oil, and the core should be white or light tan coloured. A plug cut like that means you are seeing what is happening under power, rather then at idle when there is no load on the motor.

 

Idle shouldn't be set to 2000rpm, so either there is a fault they are trying to cover or something needs re-setting.

 

Yeah the spark plugs are new and it was black smoke, so I'm assuming ECU is running to rich in higher revs, overfueling. By the way, car had a custom exhaust and cold air intake and I heard blacktop are realy sensitive to breathin changes.

 

The 2000RPM is a weird one, looking around now

[altezzaclub]

I heard blacktop are realy sensitive to breathin changes.

 

interesting- you can ruin your Altezza with a pod filter sometimes, it just depends on the air flow across the MAF. Some guys fit one with no problems, others can't get them to run right. We've quite a lot of posts about it.

[aurnob88]

Yeah the blacktop doesn't have an AFM though, only MAP sensor.

 

I was reading around and came across the fact that the ECU in these cars often has melted capacitors and what not, so thats something to chase up on.

[_FNQ_rolla_]

There could be a number of things that are going wrong I would firstly check all of the vacuum hoses and the ICV = Idle Control Valve (these can become clogged and need cleaning out. You are also are correct in saying that the ECU may/could be at fault, with leaking capacitors, (and if it has leaked over the ECU board then the whole board is stuffed) after all these ECU’s are between 14 to 16 years old now.

[aurnob88]

There could be a number of things that are going wrong I would firstly check all of the vacuum hoses and the ICV = Idle Control Valve (these can become clogged and need cleaning out. You are also are correct in saying that the ECU may/could be at fault, with leaking capacitors, (and if it has leaked over the ECU board then the whole board is stuffed) after all these ECU’s are between 14 to 16 years old now.

 

I'm assuming the ECU will most probably be done from what I'm reading as its that common. I was thinking, if I did get it, jsut take it to a PCB repair joint near my place and get them to fix up the ECU?