smoke when going from WOT to no throttle

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silviasgp06
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smoke when going from WOT to no throttle

Postby silviasgp06 » Wed Sep 03, 2008 7:01 am

ok, if i go through the gears on a spirited drive in some situation i get smoke.

at WOT, if I go to say 6500rpms in first, then shift, go to 6500ish, shift 3rd, 6500 ish then pull off the throttle all the way after shifting to neutral, i get smoke until i get back on throttle again. BUT if i just let off in that gear im in no smoke.

im thinking its one of two things, -RiCHness smoke, wideband slightly confirms this

-or valve cover oil being sucked into the intake tube due to me not have a catch can yet. (I have a nismo oil pump, which is higher volume[right?] which may account for more oil up there than normal that isnt draining fast enough)

-or is this early signs of a turbo going bad?

not sure on the exact color of the smoke due to window tint, but it looks grey-ish and doesnt smell like burning oil.

any ideas?

-daryl

Modified by silviasgp06 at 11:54 AM 9/3/2008
Modified by silviasgp06 at 4:28 PM 9/3/2008


rb25drag
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Car: 1990 Nissan 240SX 5.3 Chevy + 60mm turbo + blow threw carb.

Re: smoke when going from WOT to no throttle (silviasgp06)

Postby rb25drag » Wed Sep 03, 2008 3:11 pm

I think it could be a couple of things, First Change the PVC and see if that helps, If not Take the coupler off the turbo and Check for oil ( should tell you if the turbo is going bad or not) And the final thing I think it could be is Possibly Valve seals.

silviasgp06
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Re: smoke when going from WOT to no throttle (rb25drag)

Postby silviasgp06 » Wed Sep 03, 2008 3:32 pm

i checked for oil in the turbo, there is but that could easily by the valve cover ventilation issue.

dont think its the valve seals cause it never show smoke on start up, even if its been sitting for a month. (came back from air force field training with no smoke on start up)

ill check the PCV though.
Modified by silviasgp06 at 5:50 PM 9/5/2008

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Joe
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Re: smoke when going from WOT to no throttle (silviasgp06)

Postby Joe » Wed Sep 03, 2008 3:41 pm

do you have a vented BOV?

silviasgp06
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Re: smoke when going from WOT to no throttle (Joe)

Postby silviasgp06 » Wed Sep 03, 2008 4:02 pm

nope still stock recirculated

pawpaw18_00
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Re: smoke when going from WOT to no throttle (silviasgp06)

Postby pawpaw18_00 » Thu Sep 04, 2008 6:59 pm

Best if you were to determine the color of the smoke...which would point you in the right direction...black smoke=too much fuel...blue=oil...and white=coolant...

silviasgp06
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Re: smoke when going from WOT to no throttle (dftsilvia)

Postby silviasgp06 » Fri Sep 12, 2008 9:54 pm

regardless of what the liquid being burned is..... it happening only after WOT is weird.

there is no smoke of any kind at WOT just if i was to go from WOT to zero throttle while still in gear. basically full boost to full vacuum.

rb25drag
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Re: smoke when going from WOT to no throttle (silviasgp06)

Postby rb25drag » Sat Sep 13, 2008 2:04 am

In a normal N/A engine that is valve seals, What all have you checked and done now?

Have you done a leak down test?

240z4u
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Re: smoke when going from WOT to no throttle (rb25drag)

Postby 240z4u » Sat Sep 13, 2008 4:13 am

I get a burp of richness when coasting down in certain areas of my map.

Evan

silviasgp06
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Car: 95 Nissan Zenki RB25 Powered

Re: smoke when going from WOT to no throttle (rb25drag)

Postby silviasgp06 » Sat Sep 13, 2008 11:08 am

so far ive checked for boost and vacuum leaks, im actually getting a leak down tester as soon as i can.

hoping its nothing serious...

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Kansei240sx
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Re: smoke when going from WOT to no throttle (silviasgp06)

Postby Kansei240sx » Sat Sep 13, 2008 7:35 pm

Getting the actual color of smoke would be alot help.

If its blue-ish, either oil blow by, or your valve stem seals on the intake, and possibly the exhaust are leaking when you let off the throttle due to the engines vacuum it creates when you snap the throttle body closed.

If its black, chances are you need to tune it out some and nothing major. Do a leak-down test on your cylinders and see what you get after the engines been close to operating temperature.

silviasgp06
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Re: smoke when going from WOT to no throttle (Kansei240sx)

Postby silviasgp06 » Thu Sep 25, 2008 4:43 am

update:

Had friend behind me the other day, says color was dark grey. richness? wideband doesnt seem to indicate this. and PFC injector duty cycle is 0% when you go to zero throttle during this event.

what color is synthetic oil when it burns. Im using amsoil 0w30

-thinking the turbo seals might be slowly getting bad. or valve cover PCV oil ventilation. -doing a leak down test as soon as I get time to do a little work.

just to restate the issue, this only happens after i run through the gears shifting at almost 7k and then lift off the throttle all the way and coast (in or out of that current gear) only happen right after that lift for a few seconds, and never any other time. It never smoke daily driving or on start up.

Also never happens if i do a quick acceleration to high RPM,( ie: getting on a freeway on ramp running through 1st 2nd and 3rd gear. but if i was to do that a few time the mysterious smoke shows up.)

please help, and if any of my descriptions is at all unclear please let me know.

ROULETTE77
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Re: smoke when going from WOT to no throttle

Postby ROULETTE77 » Fri Jul 29, 2022 1:21 pm

hay bro did you ever figure out what this was ? i have the exact same thing on my jdm s14 zenki...driving me nuts


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