running EXTREMELY LEAN at idle

[RWD_GTR]

like title says my car runs hella lean at idle and pops. <like a misfire pop

now ive got all new spark plugs gapped to 0.8mm
ordered a new fuel pump. but im starting to doubt thats the issue since its ok at throttle.(still lean tho) like 18+:1 a/f at idle. and at throttle its 15-17:1 a/f

any ideas? see my build in gtr projects Project Mexi Skyrine

[M13]

vacuum leak.

[RWD_GTR]

everyone keeps saying this but i have no idea where a vaccum leak could be. ive looked over everything.

what should it be for vaccum at idle? my aem gauge says 22. and stays a consistant 22.

[Bugsly17]

too much air, or not enough fuel.

vacuum leak will cause it to run richer i believe.

[RhdHybrid]

I would try the fuel filter first..... Then abit of propane from a "Unlit" torch. Stick it in around the intake manifold, if it idles up... you found your leak.... A vacuum leak will cause a high idle, as well as surging in some cases as the ECU tries to correct it...

Just my 2 cents

Edit* my AEM truboost gives a -19 at idle, as does my good friends GTR

[RWD_GTR]

I would try the fuel filter first..... Then abit of propane from a "Unlit" torch. Stick it in around the intake manifold, if it idles up... you found your leak.... A vacuum leak will cause a high idle, as well as surging in some cases as the ECU tries to correct it...

Just my 2 cents

Edit* my AEM truboost gives a -19 at idle, as does my good friends GTR

haha too much vaccum? i wonder how that is possible.

i tried turning down my idle screw therefore reducing air but it starts to run like poop.

and btw i got a new fuel filter already.

[RhdHybrid]

Vac at -22... could be guage calibration off or we are taking our vac/boost source from different locations. Maybe you have a bad fuel pressure reg.... or maybe you have a ground broke and your injectors are having a voltage loss, this would be the same as large injectors with a long latency. But check to make sure you are grounding good.

[Black BNR32]

pressure test yo system son

and check your maf voltage output

[RWD_GTR]

ok. it cannot be a vaccum leak. i started it up and -22 vaccum and 13.5:1 afr. and it idled like a champ. then slowly as it warmed up it got worse and worse til it hit 18 then i shut it down.

if it was a vaccum leak it would be bad the entire time.

hopefully when i get my walbro that fixes the issue but i highly doubt it.

i remember hearing once that a car runs like crap with a bad temp sensor. but that shouldnt make it lean

[kengeroo]

had the exact scenario after a clutch master booster replacement.... running lean A/F's were off the scale....
A/F's were fine when on throttle
forgot the O-ring between the booster and master causing vacuum leak

everything fine and dandy once o-ring was installed...

[RWD_GTR]

i just dont understand how a vaccum leak would make it run lean. i got quite a few things to try. im thinkin pull off all vaccum lines and see if its better.

[LuckyGTR]

18-19 way too lean !!! 14-15 at idle is around perfect then bettween 10.7 till 11.9 on trottel !!

thats a perfect af

[RWD_GTR]

^thanks for that..............

it does not have vaccum leaks.

only things it can be now is wiring,fuel pump,sensor/sensors.

[leeaspin]

maybe your guage is screwed

[nismo-152]

maybe your guage is screwed

You could be pulling air in after the maf somewhere. Have you checked the gaskets on the turbos suction side?