Dunc Posted October 12, 2013 Share Posted October 12, 2013 My car is blowing 'smoke' at around 4k and it gets heavier/thicker as the revs increase. When I hit around 4.5-4.75k there's hesitation almost like hitting a limiter (Not as bad as when you blow an AFM and cant get over 2.5k though). Im still making positive boost, and I don't have a CEL. No weird noises. Initial thoughts were my AFM throwing bad readings, so I took some readings and it looked slightly suspicious - on idle 1.59v and when Im up around 4.5k RPM it maxes out to 4.64v. Ive since swapped in one of Scottys spares, and it has identical readings on the Informeter. Could it be a bad earth on the AFM circuit that's causing high readings, or are those numbers 'right' - can anyone compare? Im a bit stumped as to what else to look in to or play with. Suggestions welcome! Cheers, Dunc Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/ Share on other sites More sharing options...
PN-Mad Posted October 12, 2013 Share Posted October 12, 2013 Those numbers sound in the ball park from those I've tested. What colour is the smoke, white, black or grey? Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061271 Share on other sites More sharing options...
Dunc Posted October 12, 2013 Author Share Posted October 12, 2013 Those numbers sound in the ball park from those I've tested. What colour is the smoke, white, black or grey? I'd say black. Could be a bit grey-black I guess? Hard to tell when driving Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061273 Share on other sites More sharing options...
PN-Mad Posted October 12, 2013 Share Posted October 12, 2013 Yeah, it is hard to tell. Black is generally fuel smoke, so you need to look for leaks in I/C piping, hoses off the plenum, or any seals in the intake system. Spray joins with brake cleaner and see if the idle note changes. Pull a couple of plugs and inspect to see if excess fuel has been pumping through. Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061275 Share on other sites More sharing options...
PN-Mad Posted October 12, 2013 Share Posted October 12, 2013 The afm cut is around 5.12v, so your not hitting the flow cut. Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061277 Share on other sites More sharing options...
scotty nm35 Posted October 12, 2013 Share Posted October 12, 2013 Stock afm cut is much lower, around 4.7v the engine start backing out timing etc. Nismo ecu's will be different obviously. It definitely sounds like a boost leak somewhere... Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061375 Share on other sites More sharing options...
PN-Mad Posted October 12, 2013 Share Posted October 12, 2013 Stock afm cut is much lower, around 4.7v the engine start backing out timing etc. Nismo ecu's will be different obviously. It definitely sounds like a boost leak somewhere... Not from the cars I've logged. And it would be at least 1/2 a dozen running stock ecus. Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061427 Share on other sites More sharing options...
lstef11 Posted October 12, 2013 Share Posted October 12, 2013 im having the same problem i think mate does she smell like your running rich and are you idle rpm a bit higher than normal and a small put every now and then when shes warmed up on idle? Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061431 Share on other sites More sharing options...
Mr 20Valve Posted October 12, 2013 Share Posted October 12, 2013 Boost leak between the AFM & throttle body. Either that or its your muffler bearings... Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061455 Share on other sites More sharing options...
scotty nm35 Posted October 12, 2013 Share Posted October 12, 2013 Not from the cars I've logged. And it would be at least 1/2 a dozen running stock ecus. Argumentative kent. Why don't you help instead NA boy? Sounds like your logging software is faulty... There is a good reason the EMU needs a clamp at 4.7v for the 25det. Stick to logging the 3.5 with your Osirus crap. Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061486 Share on other sites More sharing options...
Dunc Posted October 12, 2013 Author Share Posted October 12, 2013 Stock afm cut is much lower, around 4.7v the engine start backing out timing etc. Nismo ecu's will be different obviously. It definitely sounds like a boost leak somewhere... I'm on an impul ecu, so I guess that makes sense that it might have similar afm cut. Will need to suss out for a boost leak then. Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061488 Share on other sites More sharing options...
Dunc Posted October 12, 2013 Author Share Posted October 12, 2013 Boost leak between the AFM & throttle body. Either that or its your muffler bearings... :squint: So any tips as to what specifically between the AFM and TB might leak? Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061489 Share on other sites More sharing options...
scotty nm35 Posted October 12, 2013 Share Posted October 12, 2013 Can you pressure test the intake? Just make up a bung for the rubber pipe and shove 20psi into the front of the turbo, it will quickly tell you if and where any leaks are. Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061490 Share on other sites More sharing options...
Jetwreck Posted October 12, 2013 Share Posted October 12, 2013 You say you have an impul....from memory they have no restraints. I blew my first motor on an impul. Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061583 Share on other sites More sharing options...
PN-Mad Posted October 12, 2013 Share Posted October 12, 2013 Argumentative kent. Why don't you help instead NA boy? Sounds like your logging software is faulty... There is a good reason the EMU needs a clamp at 4.7v for the 25det. Stick to logging the 3.5 with your Osirus crap. "its easy on my C34"? I did help... the AFM cut is above 5v. Seen it at 5.08-5.12v. Dont be jelly your China spec Consult can't handle the logging Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061593 Share on other sites More sharing options...
Commsman Posted October 13, 2013 Share Posted October 13, 2013 I'm with you Alex. My informeter shows above 5V & Uprev has logged above 5 as well. Can't remember exactly what voltage it is when my head bangs into the 'screen, but it's somewhere around 5.15V. Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061897 Share on other sites More sharing options...
Dunc Posted October 13, 2013 Author Share Posted October 13, 2013 Yeah, it is hard to tell. Black is generally fuel smoke, so you need to look for leaks in I/C piping, hoses off the plenum, or any seals in the intake system. Spray joins with brake cleaner and see if the idle note changes. Pull a couple of plugs and inspect to see if excess fuel has been pumping through. Ive checked all the IC piping and hoses off the plenum, it all feels sufficiently secure but now that Im really listening for it I can hear a bit of a hiss coming from around the centre of the plenum on idle. I went and grabbed some carby cleaner to throw around hoses to see if it changed at all but I couldnt get any difference out of it. Can you pressure test the intake? Just make up a bung for the rubber pipe and shove 20psi into the front of the turbo, it will quickly tell you if and where any leaks are. I think that test is outside of my skill set / available tools I threw a gopro on the back of the car to video the black smoke and 'limiter' hitting, Im not even sure that was hitting 4k on that drive though; so perhaps its getting worse? Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7061916 Share on other sites More sharing options...
PN-Mad Posted October 13, 2013 Share Posted October 13, 2013 Yep, looks like fuel. You may have fouled the plugs. Pull a couple out, and inspect. That little hiss might be the PCV. You'll have to check all lines for splits as well, maybe the boost gauge or controller lines. Might have blown a intake gasket. Just ideas. Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7062044 Share on other sites More sharing options...
Jetwreck Posted October 13, 2013 Share Posted October 13, 2013 Give me a call if you want..... Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7062067 Share on other sites More sharing options...
scotty nm35 Posted October 13, 2013 Share Posted October 13, 2013 I'm with you Alex. My informeter shows above 5V & Uprev has logged above 5 as well. Can't remember exactly what voltage it is when my head bangs into the 'screen, but it's somewhere around 5.15V. The afm drops out timing and dumps fuel at well below the 'head goes through the windscreen'. Lets just agree to disagree, you two are surely more proficient at this. Dunc, pressure testing the intake is easy, just grab an old tyre valve and a lid or plumbing cap that fits nicely into the rubber pipe, then use a pump/compressor to fill the intake. (you could even do it at the servo) Just checking if the fittings are loose won't tell you if there is a split in a hose somewhere you can't see. Link to comment https://www.sau.com.au/forums/topic/433250-m35-blowing-smoke-4k-rpm-hesitation-around-45-475k/#findComment-7062235 Share on other sites More sharing options...
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