Blowing Smoke

[CATKICKER]

Hi Guys, my car started puffing smoke the other day and I might be looking at replacing the engine (has done over 220,000kms - RB20DET)

It happens when I absolutly gas it (around redline / fullboost) and when I back off or change gear, it puffs a pretty big cloud of dark smoke (don't think it is fuel)

I don't think it is my turbo as it is at high RPM not specifically high PSI that it happens. Plus I recently replaced it with a low km R34 turbo.

It is still driving perfectly fine, pulls hard but just puffs pretty hardcore when I back off. Started happening on a big highway drive a few weeks back and hasn't gone away. Pretty embarrasing when you drag someone off at the lights and then cover them in smoke!

Anyway, long story short, before I take it in to the mechanic for a diagnosis, what could it be?

Worn Rings? - I would have thought it would happen all the time not just when backing off

Worn / Damaged Valves? - Most likely in my mind...

Catch Can? - Maybe it is how I hooked it up? - Did a bit of research on here how others have done it...

Would be great to get some ideas.

Thanks in advance!!

Todd

[mad082]

if it is dark, then it is most likely just fuel. do you have an atmo bov? if you do then this may be the cause.

[CATKICKER]

if it is dark, then it is most likely just fuel. do you have an atmo bov? if you do then this may be the cause.

Yeah, but I still have the factory one... Might be the cheapie leaking? Might try putting in a couple of washers and removing the vaccume hose (and block that off of course)

Thanks very much for you help!

Todd

[CATKICKER]

Well... it wasn't the BOV!

I am going to have to check the ECU for error codes. Lets see if there is any insight in there... I am still thinking it is oil, it would have to be a SHITE load of fuel, and it seems to be running well!

Any other ideas?

Once I get the final verdict from the shop, I may look at replacing the engine with a low k jobbie (will only need the engine, no box, loom, puter or manifolds...) and building this one up over time with some more solid internals.

[CATKICKER]

I haven't had a chance to check the error codes... just wondering if it was fuel, could it be the AFM? and if that was the cause, could a faulty AFM cause my idle issue - Sits at 1500rpm when I stop at the lights and then after 5secs or so, it goes down... The problem goes away after an ECU reset but comes back after around 200k's. This leads me to think that the ECU is recieving an error (MAYBE THE AFM) and tries to adjust the A/F ratios to a safe level... Resetting the ECU didn't fix the cloud of smoke issue.

Just a thought.

BTW, I originally thought it could be the O2 sensor (idle issue) so I replaced that and rest the ECU. (obviously fixed it temporaraly) I also resoldered the AFM internals, cleaned it and cleaned out the ACC valve.

Seriously guys, I really do appreciate your help and will help others out when I can!

Thanks!

Todd

[Craved]

have you tried another ECU

with my std ECU - the car wouldnt idle AT ALL. like nothing, dont rev it manually it would stall

plugged in power FC . fixed

try anothers ecu

[SLYLNE]

my mates 33 gtst does this, after he boosts and changes gear after a few moments this huge puff of smoke comes out of his exhaust...

only thing came to mind was, either turbo smoke or bcoz he has no cat?

anyone confirm, having no cat would make smoke come out like that?

[RB30-POWER]

More then likely its just blowby that is getting sucked into the chamber through the PCV valve when you back off. The valve is held closed when there is no manifold vacuum (on boost) and when you back off it gets sucked through and out the exhaust. All sounds normal to me.

Edited September 10, 2006 by RB30-POWER

[SLYLNE]

cool, thanks..

u wouldnt happen to have a pic of where the pcv valve is located or be able to describe where that is?

thanks

[CATKICKER]

Removed my catch can and now is fine!

But now I am getting oil through my bov! must need to connect the catch can differently!! Will have to research!

Thanks for you suggestions!