Hi all,

 

I bought a manual TT that had recently had an engine rebuild but still had some problems. I took a chance on it... this is generally my preferred approach, it's more fun... kind of.

 

When I picked up the car, I discovered that it smokes on overrun; decent plumes after engine braking at low speeds, then when the throttle is reapplied or if the engine settles at idle (typically when pulling up to a junction or slowing and accelerating between speed humps). No smoke when accelerating or at start up / idle. I have been doing a lot of googling and reading a lot of old forum threads about these symptoms, but none of them finished with a conclusive result. I will make sure that this thread has a conclusion even if it takes a while to figure out.

 

Advertised spec:

Engine rebuilt by Outlaw Customs

Wiseco forged pistons

Eagle rods

AEM series 1 ecu

615cc Nismo injectors

NA rear diff and hicas deleted

Rebuilt turbos

Stainless steel custom exhaust with H pipe and Greddy back boxes

HKS blow off valves

Currently running 380hp, mapped by DWR Performance

 

 

 

Culprit #1 - PCV

 

I noticed that the car had too much oil in it, and thought that maybe the PCV pipes are pulling oil up into the intake plenum during vacuum, which would then get burned off as the engine idled or accelerated. I looked into the balance tube holes and there is oil in the plenum.

 

I then did an oil change and deleted the PCVs for good measure (into a catch can), the pipes were full of oil! I also swapped the spark plugs from Iridium BKR7EIX (which sit too far in the head) to NGK PFR6B11C gapped to 0.035.

 

I have only driven the car around five miles since, at first it seemed much better but the smoke problem returned. Perhaps I need to drive it a bit more.

 

Should I also reroute the breathers at the front of the engine?

 

 

My next potential culprits are:

 

Culprit #2 - turbo seals

 

Culprit #3 - valve seals

 

Culprit #4 - piston rings

 

 

... anyone want to add to the list of possible culprits?

 

Cheers.

Edited February 19, 20196 yr by MattDaKav

Welcome to the club Matt and thank you for subscribing. If you PM me the details in the link below I can send you a Membership pack. Your membership number is 001834.

https://www.300zx.co.uk/forums/showthread.php?161407-F-A-O-NEW-Subscribed-Members-Info-needed

 

Can Mike at Outlaw Customs give some idea on why there are problems?

Thanks Gaz.

 

I've spoken to Mike via FB and he has been very helpful, although I don't think that he ever got to see the car again after finishing the build.

Time for a leak down test

Indeed. Compression and leak-down tests are on the to-do list.

As above re compression and leak down testing next to do. A ConZult test to see if the ECU has any error codes and

that everything is setup correctly and sensors working properly would be good practice.

 

At some point it would also be a good idea to change the HKS BOVs back to stock recircs:

 

http://www.twinturbo.net/nissan/300zx/forums/general/view/2421113/I-do-not-recommend-blow-off-valves-on-the-Z.html

It's running an AEM EMS 1 and the MAF is redundant now so BOVs should be ok?

 

I haven't got to plugging in a lap top to have a look around yet.

It's running an AEM EMS 1 and the MAF is redundant now so BOVs should be ok? .

 

With a MAP sensor yes.

 

Added - Although the AEM Series 1 is "plug and play" the ConZult s/w I referred to probably won't work with it.

Edited February 19, 20196 yr by AndrewG
ConZult info added

Hi Matt,

 

Welcome to the club, sorry about your engine woes.

 

 

 

Sounds like it could be piston rings if it smokes on over run.

Edited February 21, 20196 yr by RichardS

I'd have thought on a 'recent build' that the PCVs would be new.

Welcome to the club, good luck with you new toy.

Thanks all.

 

The PVCs were new but my theory was that they were picking up the over filled oil, like the sloshing of oil on track reportedly does.

 

I deleted them anyway as I hate the idea of PCV systems.

Think you will find the (edited) item in the advertised spec list is the problem !

 

I’d like to know how given, as per the OP, the PCV’s have been removed from the car.....

Edited February 21, 20196 yr by craig

Matt, how hard have you driven the car since going to a catch can setup? Have you got it hot enough to burn off any residual oil that may have lined the exhaust system? How much oil can you see in the Plenum (remove the balance bar and have a peak through the port)

I haven't driven it hard and only went for a 20 min drive. There was certainly oil in the plenum beforehand.

 

I will take her out for a longer drive on Thursday night.

It ll take a few miles to burn off oil in system after all my experience it’s not positive knowing who did engine sound like mine turned out to be rings same garage did mine three times before the garage got mine done good luck do research before you use garages .

I would advise an "Italian" tune up to clear out any residue.It will need 100 miles plus to clear it out successfully.If the smoke persists on overrun its 100% leak down time then i am afraid.

Johnyboy, Jimmer,

 

I like your optimism! Although if the cause of the smoke is now left over oil in the plenum or in the exhaust, I would've thought that it would be more constant (once warm), rather than coming on after the intake has been in vacuum as before when the suspect was oil being sucked up the PCV pipes... I would have expected a change.

 

I will certainly give her a spirited drive and will report back.

 

Thanks all.

not going to bother reading all the comments as i know what most of you will have to say so i will just give you the details of what happened, the engine was built by me yes and sadly was another one mapped by the garage next door to me. sadly it was another he got wrong hence why we no longer use him, it was found that the mapper again did not check the timing at 3000 rpm before mapping something which our new mapper found before even hitting the dyno. it was found that the timing should of been at 30 @ 3000 rpm but was actually rerading 65 degrees and this has caused some issues. we managed to get the car mapped elsewhere to a degree at low boost but gave no warranty with the engine due to the majour timing issue which was nothing to do with me. the customer at the time had all the evidance needed to take the mapper to court and get the engine fixed but he chose not to and just sold it on.

 

Thanks for the feedback Mike.

Hi Mike, thanks for the further details... although my understanding of the mapping process is limited, it may help me figure out what the current state of things is. Cheers.

 

Any thoughts on what damage having the timing off that much may have caused?

if the first mapper had found the issue like he should have it wouldn't of done any damage but due to the fact it spent a fair few hours on the dyno with the timing that far out i couldn't give warranty with the engine something the customer understood. i wish he had taken it further as he would of got his money back and another engine but he didnt want the hassle of courts so sold it. shame really

 

Yeah, but then I wouldn't have ended up with a Z32... so... silver lining (for me... kind of).

 

If it needs a rebuild, it is what it is. It's not my daily so no biggie... I'm just hoping it turns out to be something more easily resolved, even if that's a long shot.

honestly i think it is a long shot i believe it will need a refresh but i wish you luck with it i really do

 

Thank you. I have just bought myself a cheapo endoscope so I may discover something over the weekend.

Sorry, just so that I'm clear, do you mean that the timing would've damaged the pistons because they may have hit a valve? ... or some other reason?

Read up on Detonation.

Read up on Detonation.

 

Thanks

Sorry, just so that I'm clear, do you mean that the timing would've damaged the pistons because they may have hit a valve? ... or some other reason?

 

You can also damage the bearings through detonation and/or pre-ignition. I found this a useful read:

 

http://www.contactmagazine.com/Issue54/EngineBasics.html

Edited February 20, 20196 yr by AndrewG