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View Full Version : new turbo, 750cc injectors/tune with lean idle


600supersport
09-23-2012, 07:45 PM
'95 240sx se with redtop sr20det, z32 MAF, hks ssqv recirculated, greddy IC, koyo rad, dual electric fans, NGK bkr7e gapped .028, kinugawa td06 20g, hks WG, megan exhaust manifold, stock intake manifold/TB, stock internals With rocker arm stoppers, halman manual boost controller, walbro 255, nismo FPR 42psi, new five-0 750cc injectors, new 300zx fuel filter, ROM tune, AEM wideband and boost gauge, no A/C, with power steering, timing set to stock, new alternator/battery.

all vac lines are zip tied along with a smoke test showing NO leaks. recently changed both coolant temp sensors working fine. idk if the IACV can be tweaked, but i haven't touched it beyond some carb cleaner into the TB. i recently changed to this turbo, injectors and re-tune setup.

after swap on cold starts the car might take a couple seconds to turn over, but then idles between 14-15.5 for a few seconds, over 5-10 more seconds it climbs richer to 11 for a few seconds then another 5-10 seconds goes all the way to 17-18 and stays and kinda stutters every few seconds. the car cruises seemingly smooth between 13-16, WOT between 10.5-11.5 and pulls strong at 18psi. idle vacuum around 18-20 i believe, cruising off throttle vacuum up to 24. i can't hear the BOV at 1-2 psi like before, but it's definitely going off over 3-5psi now.

If i don't let the car warm up and drive too soon it might stall when i go into neutral. if i turn on the rear defroster it raises the idle a little from 800 to 900 and it idles a little smoother. this happened before the recently upgrades, but it previously idled between 14-16 AFRs. so idk if that's a related electrical gremlin i need to hunt down or part of my issue.

tell me the, "you're an idiot, check this, by doing this and i bet it's fine" advice, i dont care. im out of ideas. i thought it was a matter of the tuner just adding fuel at idle, but i dont really know how tuning works and im waiting to hear back if he has any resolutions.

Hardie
09-23-2012, 09:04 PM
So the tuner couldnt figure it out?

It could possibly be fuel filter? too restrictive-upgrade to 300ZX fuel filter

Are the injectors brand new? could be faulty-do you know what load they are under? possibly get them cleaned and flow tested.

Clean MAF

Did the problems only start happening once you had the tune?

Are your voltages stable?

fliprayzin240sx
09-23-2012, 09:09 PM
It doesnt really sound bad considering its leaning off throttle and on idle. Is the spark plugs gapped down to .030-.028? What exactly is the fpr set at? Did you ask Martin what fuel pressure he requires for the tune? How old is the o2 sensor?

600supersport
09-23-2012, 09:25 PM
thanks guys...newer 300zx fuel filter, plugs gapped at .028, injectors are brand new with flow charts with "very short lag times". checked the FPR last year when i bought the car, im 90% sure it was like 42-43 psi, where the tuner told me to keep it, bought the 02 sensor new last year with about 4-5k miles on it. the extra leanness came after the new injectors/tune. i did not clean the MAF. i'll DBL check the FPR tomorrow and clean the MAF, but they seem fine while cruising and at WOT.

Hardie
09-23-2012, 09:57 PM
I know it may sound stupid there is a small chance it could be your battery.

If all else fails check your compression.

600supersport
09-23-2012, 10:13 PM
this is slowly reminding me of the things ive re-done in the last year of owning this car lol, battery is new and bigger, i'll add compression test to the list tho. i've updated the original post with the points you guys made just to keep everything clear.

600supersport
09-23-2012, 11:40 PM
part of it was the previous owner putting on the wrong TB with wrong TPS (that may have even been faulty) that wouldn't give me the right setting either

Hardie
09-24-2012, 12:53 AM
The BOV could be your problem, to make sure swap it out with a mates on or either build/buy a boost leak tester.