Had this problem for years now and wanna get to the bottom of it! My Zed runs perfectly during normal driving and anything other than Foot in the carpet full boost which is 1.1 bar...

 

During full throttle it pulls really well, no hesitation and no det.. Just a plume of Black smoke out the back! If driving at 3 quarters throttle around 11psi boost, there is no smoke...

 

I know i have a dead passenger O2 sensor but apparently this won't effect full throttle driving as they go into closed loop. Also fuel ecconomy is good during normal driving!!

 

The Fuel pressure regulator is ok, obviously on full boost it would not need to regulate anything i guess!

 

I have no boost leaks and also the temp sensor, are fine

 

Could it be the MAF is reading too high on full boost and giving the ECU the wrong info or something else??? Please help somebody!!!

Could be the air flow meter as you mention, but also could be caused buy a restricted intake, you don`t have a fleebay induction kit on by anychance? try running with out it as a test.

 

Jeff TT

Could be the air flow meter as you mention, but also could be caused buy a restricted intake, you don`t have a fleebay induction kit on by anychance? try running with out it as a test.

 

Jeff TT

 

Hi Jeff! Was hoping you would post a reply! I'm running a blitz sus air filter which again i've had for years. As well as giving the filter a regular clean i've also cleaned the Air Flow Meter recently with electrical contact cleaner. Just weird how it only does it on full boost and everything else during normal driving is fine... Spark plugs are ok too!

 

Only other thing with the air flow meter is the rear mesh has been removed but the front mesh where the filter goes on too is still intact..

The mesh removal will not be the cause of the problem, sometimes the easiest way to track these oddball issues down is to borrow or beg suspect parts for known good ones and do a few swaps.

 

Have seen air flow meters do some really odd things in certain rev range, doing a road test with ConZult conected would help track down if the afm is suddenly going rich,, try disconnecting both 02 sensors incase one of those is suddenly changing state. (ie corrupted data input)

 

You could also try a test run with the induction kit removed as part of a general process of elimination.

 

Also not unknown for engine ecu to go bad and cause many odd symptoms, not seen one do the exact same rich running you have but again possible.The black smoke is clearly overfulling or restricted air intake, boost leaks do the same as not all of the air is drawn though the afm, how have you done your boost leaks test and at what pressure.

 

Another random fault we have come across is incorrect egr valve operation so disable this by oulling the vacuum pipe off and blocking.

 

 

Any more info you can think about will help to give some more suggestions.

 

 

Jeff

Edited January 31, 201114 yr by JeffTT

The mesh removal will not be the cause of the problem, sometimes the easiest way to track these oddball issues down is to borrow or beg suspect parts for known good ones and do a few swaps.

 

Have seen air flow meters do some really odd things in certain rev range, doing a road test with ConZult conected would help track down if the afm is suddenly going rich,, try disconnecting both 02 sensors incase one of those is suddenly changing state. (ie corrupted data input)

 

You could also try a test run with the induction kit removed as part of a general process of elimination.

 

Also not unknown for engine ecu to go bad and cause many odd symptoms, not seen one do the exact same rich running you have but again possible.The black smoke is clearly overfulling or restricted air intake, boost leaks do the same as not all of the air is drawn though the afm, how have you done your boost leaks test and at what pressure.

Any more info you can think about will help to give some more suggestions.

 

 

Jeff

 

I've done the boost leak test using a compressor, boost leak tester to fit in bung and set it around 9psi to fill the system. The hose that goes from the balance bar to the brake master cylinder had a split causing a psssssssss but replaced that now and no more pssssss!

 

DannZX has conZult on his laptop so if I ask him nicely if we could go for a drive with it plugged in and report back the results... Will try with the O2 sensors disconnected and see if that makes a difference.

 

Running an AndyP stage 2 chip which again had for a few years now!

Only other things I can think of are, The AndyP chip is an AUTO and my car is a UK Manual Zed.

 

I know my gearbox netural switch doesn't work anymore...

 

I've got baily blow off valves in place of the recircs but there is no leak from them as far as i know from the boost leak test!

 

Thanks again Jeff!

Running an AndyP stage 2 chip which again had for a few years now!

Only other things I can think of are, The AndyP chip is an AUTO and my car is a UK Manual Zed.

 

hi, just a question... have you asked AndyP if his chip is set up to over-fuel?

 

I don't know if his do but the last chip I had was ... a re-map fixed it.

hi, just a question... have you asked AndyP if his chip is set up to over-fuel?

 

I don't know if his do but the last chip I had was ... a re-map fixed it.

 

Hello! The chip never used to do it when I first installed it, I know it's designed to run an absolute max of 1.2 bar and i'm running at 1.1 bar..

 

Only reason i'm suspecting it's a MAF problem is when I first had the chip I was running a differnt MAF then that got wet and failed... Got a 2nd hand one, genuine Nissan one off SWZ again years ago now and eventually got round to noticing a plumb of black smoke when putting my foot hard to the floor.

 

Cured all the boost leaks thinking it was them causing the drama but still getting the same results on full throttle... It's a good MAF apart from the full throttle bit! Z is very responsive!

When you say you cleaned your filter, you didn't put that filter oil stuff on it did you?

 

I've heard of the the oil being sucked into the maf and coating the wire, therefore giving inaccurate readings.

 

Just a thought.

When you say you cleaned your filter, you didn't put that filter oil stuff on it did you?

 

I've heard of the the oil being sucked into the maf and coating the wire, therefore giving inaccurate readings.

 

Just a thought.

 

No mate, it's a blitzsus metal filter so always clean it in hot soapy water once every few months to get rid of the crap, then dry it with a hair dryer till bone dry.The MAF itself is as clean as clean, especially with the electrical contact cleaner sprayed on it! That's part of the routine now!

 

Jon

Ok update on this one as well, after doing yet another boost leak test it turned out and only after running the compressor at a higher pressure, the passenger side intake clamp wasn't tight enough causing a tiny ammount air to leak out just before the throttle body. Obcvously under boost during driving this was made worse causing the black smoke at higher boost levels..

 

The air flow meter was telling the ecu how much fuel to chuck into the engine but not all the air was getting there hence the overfuelling problem! Also had a small pin prick hole in the rubber pipe that goes to the Second intake pipe to the Idle unit... Amazing how such small leaks can cause such drama!!!