Hmm,

 

This isnt I guess to good

 

Had my Z bout a year now, had no probs with it what so ever, that was until recently!

 

Anyway, about a week ago I noticed when I first started the car in the cold and went to pull off it stuttered for a second or too then was fine. I was down to service it the following week so didnt really worry about it too much.

 

A week on, the hesitancy when pulling off seems to have gone, however it has been replaced by a new gift to me from my car, the gift of smoke and pure embarasement when flooring it.

 

When the car is standing still, I can rev and let off the accel and no smoke at all. I can even drive it normaly and everything is smooth with no smoke, I can even floor it and boost at 15psi all day with no smoke, however the problem is when I let off the accelerator after heavy accel, for the time the revs are dropping under engine breaking white-ish smokle starts flooding out of the back at the zorsts. The longer I drive the car, the less smoke comes out to a point where after a fair amount of driving it nearly completly stops on decel?

 

I really have no idea what it is? I guess water is getting in somewhere, perhaps a prob with the head gasket?? I'm really not sure? The car drives otherwise smooth and temperature stays low to normal, I have noticed a loss of some water recently but have no idea where to start looking.

 

I really need some help on diagnosing this prob. I am not worried about getting it fixed no matter what it is, I just want to know where to start instead of paying some cowboy of a mechanic 60.00 p/h to try and duagnose this.

 

Any help appreciated,

 

cheers

Maybe you should warm the engine to normal temp in the mornings before you drive off, and you sure the white smoke isnt condensation?

The weather has been cold and damp and thats when you get white smoke that dissapares quickly, if the smoke is lingering and you can smell it you may have a problem.

Also you may have a leaking water hose somewhere.

Its defo not condensation, its like I'm in a james bond movie and loads of whit smoke floods out of the back, sometimes the car goes a bit lumpy when it happens, a quick blip of the throttle again though and its back to normal????

 

Im still guessing head gasket probs, but not sure how to check. Some people have recomended me checking the tubbies as they could have worn seals letting oil in, but I cant see how that would produce white smoke??

Ok you havent put too much oil in have you?

garages can do tests on the smoke to see whats in it, oil or antifreeze etc

Nah not too much oil put recomended amount in about 3 months ago and been running fine up until a week ago?

 

When the white smoke come out I can notice a kind of burning smell?

 

It just seems weird that car boosts full and holds ok, drives smooth but its just under deceleration / engine braking, its doing me head in!!!!!

 

If anyone has any tips of where to start looking for oil / probs let me know, I'm going to get stripping tomorrow!!

sorry i cant help but you may have a major problem if the car was runing fine before then looks like you got to spend take it to se nisstec.

What oil do you use and has the level dropped at all.

 

The only thing I can think of is if some oil is leaking into one of the chambers and getting burnt up.

 

Have you still got Cat's ?.

 

It won;t be a head gasket as it would smoke all the time. Doubt turbo seals either as this would happen on acceleration rather than deceleration.

What oil do you use and has the level dropped at all.

 

The only thing I can think of is if some oil is leaking into one of the chambers and getting burnt up.

 

Have you still got Cat's ?.

 

It won;t be a head gasket as it would smoke all the time. Doubt turbo seals either as this would happen on acceleration rather than deceleration.

 

Going to check the oil level today,the coolant level had dropped but the last time I checked it was three months back when I serviced it (naughty naughty!) so not sure if that is a result of the prob.

 

I havn't got any cats on the car.

 

I was thinking about the same thing last night, if the gasket had gone it would be more regular than just on deceleration, and I thought the same if a problem with the turbos.

 

My most recent effort was going to be to replace the psv valves as they are only a tenner to see if it has any effect, even if its not the problem it will still be a good thing to replace them.

 

My biggest bug that I dont understand is why on deceleration from hard acceleration and at no other time?

 

The strange thing is it almost seems as if the car is over fueling, hence the spluttering and the smoke when letting off, appart from one thing, the colour is the wrong end of the spectrum!

Steddy there is a prob, no smoke at all when idle and reving, only when driving?? so I'm not sure those tests would work

You may have a vaccum leak. one of the small 4mm vaccum hoses may be perished or may have come loose. If you think the car is overfuelling then it may be worth resetting the ECU so it can relaern the settings. See if this fixes the problem.

My biggest bug that I dont understand is why on deceleration from hard acceleration and at no other time?

On overrun the greatest vacuum exists in the cylinders. This would make it more likely to suck in anything from the surrounding passageways if there is a small breach of the head gasket. This would obviously get pushed out of the back on the exhaust stroke.

 

If you're getting white smoke on overrun and your coolant level is dropping, I'm afraid I would be suspecting head gasket failure. However, I would definately expect it to be more pronounced out of one exhaust than the other as the steam would have to cross the exhaust balancing pipe to reach the other side. And I think you would be extraordinarily unlucky to have a head gasket failure in both banks at the same time!

sounds like valve stem oil seals - u sure its not oil burning. valve stem oil seal leak under overrun conditions as per mikes description.

 

head gasket would leak all the time if it was that severe as the cooling system is pressurised.

 

do you get a puff of smoke when you 1st start up?? i would check the plugs for oil deposits

head gasket would leak all the time if it was that severe as the cooling system is pressurised.

That's a very good point. The only time it wouldn't leak would be when the pressure in the cylinder was more than or equal to the pressure in the cooling system. So when the coolant is cold or when you are on a lot of boost it would leak less. However, if there was a very small breach, the flow would vary (I couldn't even guess how much!!!) with the pressure differential, even when the pressure in the coolant was greater than the pressure in the cylinder.

one other thing to check is your brake fluid level! if youre loosing brake fluid then it could be the rear seal in the master cyl, drawing into the engine through the servo.

 

this will also give white smoke

i have the same problem, apart from the smoke being blue, and i dont have the lumpy running whan it dose it!. looks like its coming from the drivers side on mine! and only on engine braking too!

 

Do you lot think its the valve seals? and not the turbo seals? as it only does it a few seconds after i come off boost.

Anyone?

Im not too sure mate still trying to diagnose my problem, but if its blue, more likely to be burnt oil than heated oil or water?

 

I had the plugs out on mine today, looked a bit coaked up, also wet oil in the passenger side turbo to intercooler hose, also coating of oil in the top of the inlet manifold? this time more so on the driver side?? cleaned all this out anyway. But no oil apparant in turbo hardpipe or intercooler hardpipe?? no trace of oil near the TB's?

 

Also checked the induction, the weather guard is not apparant and the blitz induction was dripping wet, needless to say i cleaned and dried it all then made a new plastic box that the filter sits in to keep it dry.

 

Replaced the plugs too, and cleaned up mas connectors and all other connectors i could find!!!!

 

Ran the car on tick over for 10 min, then ran the car at low boost for a couple of min, then high boost 6 times on the way home, no smoke, no lumpyness???

 

Weird! This is a phantom problem that is doing my head in!

 

I've topped up all fluid levels and oil level is still on high!

 

Im going to just run a few checks over the hoses in a weeks time to see if its collected any more, to see if it continues to smoke / gets worse, and what happens? thats all I can do for now.

 

Any other advice would be appreciated.

 

Oh and no smoke on start up, or when reving, or idle. No smoke under half throttle and now it appears no smoke sometimes on full throttle, seems to be under full load when backing off!

i have the same problem, apart from the smoke being blue, and i dont have the lumpy running whan it dose it!. looks like its coming from the drivers side on mine! and only on engine braking too!

 

Do you lot think its the valve seals? and not the turbo seals? as it only does it a few seconds after i come off boost.

 

yup, does sound more like VSOS's turbo seals generally leak more on boost.