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jzx100 vvti 1jz runs rich as it warms up

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Old 05-11-14, 08:10 PM   #1
estomax
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Default jzx100 vvti 1jz runs rich as it warms up

Hey Guys,

i got my vvti 1jz running and i have been doing some searching but haven't found any conclusive answers to my dilemma.

my 1jz starts up super smooth and idles nicely when cold, but as it warms up it starts to run richer and richer and i am guessing as a result the idle starts to stumble and when it is warm it will barely idle, just put put put and if i give it gas and let it come back down to idle it just dies usually.

anyway i unplugged the MAF and it seemed to idle smoother, and died when i plugged it back in. i actually took video of that.. stupid nexus 5 and ****ty auto focus in video mode >_<

anyway after i ran it again with the maf unplugged it was back to its ****ty idling ways so i am not confident that was exactly the problem, but during my swap i did drop the MAF once so maybe i fubared it.

rather than just throw parts at it i'd like to hear from others who had their cars run richer and richer as it warmed up.

i checked the coolant temp sensor and its about 1.6K when cold and drops down when it warms up, half way warm was about .7K, which is in line.

also, no ECU codes, just deep codes 47 and 78 for sub-TPS and fuel pump ecu.

cheers for input
Marko
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1992 SC400 black, 1JZ VVTI with 350Z 6spd swap, running!
PM if u want the sc300/400 service manual, ill link you.
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Old 05-13-14, 09:19 PM   #2
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was able to hook up data logger and get this from engine off / cold start after 20 or so seconds. should the idle be 650 from the get go? i would think on a cold engine it would idle higher for a while... timing seems really low as well. does this give anyone a clue? also, the TPS varies from 0 degrees to max 74 degrees, hopefully someone can confirm thats what the ecu is supposed to see in a sweep. i still have to go out with a multimeter to check it.

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1992 SC400 black, 1JZ VVTI with 350Z 6spd swap, running!
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Last edited by estomax; 05-13-14 at 09:31 PM..
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Old 05-14-14, 05:09 PM   #3
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I've had similar problems with an intermittent ****ty idle/stumble, didn't seem to be related to a hot/cold condition though. But I was aftermarket turbo though, so two variables I didn't have that you could was the stock bov leaking and the stupid vsv for the stock bov which to me is retarded anyways. My issue ended up being the iacv. I ended up getting it in the closed position, then unplugged it and didn't have the problem for a month, so built a block off plate and ran it for another two years with zero issues. I had datalogging capability through my emanage when the issues started arising and noticed timing was completely ****ed, being around 0 when it would happen iirc. But also, my issue was intermittent, and not constant. Can you log iat with that program, and is it consistent with ambient temp or within a few degrees? You seem like a stand up guy so if things start making you pull your hair out I'd be willin to send you a maf to try if you pay for shipping and return it.
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Old 05-15-14, 09:09 AM   #4
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Hey. Try unplugging your tps. Friend of mine had the exact same issue as you. Also, if I were you and tps is the problem, I'd look for a non vvti 1j throttle body and tps, or at least the throttle body. The older version 4 wire sensor can be used just fine on the vvti ecu sans the 1 extra wire, and vvti 1j tps is non existent in the US. The vvti tps and non vvti tps can not be interchanged due to how the move, and I haven't been able to find one that works in the junkyard. Jzx90/z30 early tb bolts right up, also the option of a non trac tb, and option of easily sourced parts stateside.
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Old 05-16-14, 07:31 PM   #5
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it was the MAF. i took it off and cleaned it, and installed my air filter (had a sock on before) and now it reads 2 kPA at idle, so if anyone else has a problem with MAF then here is a good number for air flow / pressure field in the ecu logger - around 2 kpa at cold start and below 1 kpa at warmer idle.

ignition timing should be around 20 degrees at cold startup and as the rpms drop and ECU goes to closed loop it should settle around 18-19 at idle.

what do you guys' warm engines idle at? mine is creeping toward 500 rpm, seems a bit low, but i may have some boost leaks. got to drive it around the block and feel VVTI for the first time, boost definately comes in low, didn't go over 3000 but it pulls below that already.

thanks for the offer and help though!

cheers
Marko
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PM if u want the sc300/400 service manual, ill link you.

Last edited by estomax; 05-16-14 at 09:01 PM..
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Old 05-16-14, 07:31 PM
 
 
 
 
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