weird STFT with blow through MAF

[projectlnf]

allright i had this blow through working flawless before i rebuilt my motor and before i lost all my logs and tunes off of my other computer.. but now its got something crazy going on.. on my mechanical boost gauge i can get to about 0 vacuum and maybe 3 psi of boost and it goes bonkers.. it leans out to 18:1 and then richens up and does it again.. the car jerks like crazy and no matter how many MAF calibrations i do it doesnt help its a brand new maf. now i have noticed that sometimes when i do a maf calibration it wants me to reduce fuel??? thats what im confused about.. when i look at stft it zeros out during this process.. and ltft will read.. ill post up a log that i did when driving the other day its weird any input would be great

[cobaltssoverbooster]

have you explored software issues yet? said you lost your logs and stuff. maybe you need a write entire factory file conversion again or a re-install of hpt suite?

[projectlnf]

have you explored software issues yet? said you lost your logs and stuff. maybe you need a write entire factory file conversion again or a re-install of hpt suite?

well thats the thing i have the new hpt and i have done write entires.. it works perfect when i unhook the maf car runs flawless and thats how i have been running it but i want the maf back in the picture thats how the car is supposed to run. but once i hook it up all hell breaks loose.. and its only when you just barley break into boost like right at 0 inHg

[projectlnf]

oh and i lost my logs due to my other computer taking a shit lol i forgot to mention that

[projectlnf]

and this is a log of today a friend gave me a new maf and i stuck it in the intake instead of the charge pipe to see if that made a difference.. same deal??

[cobaltssoverbooster]

Did you re zero the base table when you re installed the maf.? Maf delete tunes have different Cal values by a wide spread

[projectlnf]

Did you re zero the base table when you re installed the maf.? Maf delete tunes have different Cal values by a wide spread

yeah i zeroed it but once i get to that certain point when it leans out fuel the stft read 0.0 so the maf correction table in the scanner isnt doing anything it just sits at the last calculated value.. but last night i put the maf infront of the turbo and redid all of the tables scalled the maf a crazy amount and now it seems to be better but i still want the blow through cuz of the BOV

[cobaltssoverbooster]

right i hear yea on location. weird it does that after a base reset. any visual damage to your maf extension harness? do you spray methanol before the maf? (its not on your mod list but it is known to cause these symptoms.)

[projectlnf]

right i hear yea on location. weird it does that after a base reset. any visual damage to your maf extension harness? do you spray methanol before the maf? (its not on your mod list but it is known to cause these symptoms.)

Well I quit spraying method after the rebuild so about 3 months ago.. And no I have two maf sensors and I swap between the two and it does the same thing

[cobaltssoverbooster]

I installed a maf backwards once lol yea it wasn't happy at all hahha. Is your waste gate or bov leaking at all? A small leak will cause fluctuations and lean trims.

[projectlnf]

I did a smoke test with the evap tester we have at my dealer I work at.. It doesn't leak. I mean when I'm talking the stft go zero they literally slam zero.and afrs go LEAN.. I talked to my shop fprmon today and he thinks its right around where the "cruise" areas are in the tune..also noticed maf reads 16 lb/min and be reads like 6 lb/min

[cobaltssoverbooster]

If you tested a new maf then we should call it good. Ve is low but maf is high. To calculate ve you need rpm, tps, map in the lnf. Sub factor sensor will be iat2. So Verify Sensor Data Reports By Testing manifold map, boost lo res for iat2 circuit, and throttle actuator circuits.
That's where I would go next. If they report back good I'm at a current lack of further ideas.

[projectlnf]

Tested all and they are all good on the tech 2.. I moved the maf back to the blow through position. It does it worse in the blow through.. I scaled the maf about 20 times in the intake position but it got a smidge better.. So I don't know.. BUT in limp mode I can still hit that load and cell.. It doesn't do it...

[projectlnf]

allright i scalled injectors really high to see if i could get it to stop going lean.. now it gets extremely rich lol but its better than lean.. but the stft problem is still there.. i get to a cruising area and it stops correcting and reads 0.0%

[cobaltssoverbooster]

Try plugging the emissions port off.

[projectlnf]

which port are you speaking of?

[cobaltssoverbooster]

Evaporative. Mine failed in the canister and caused all sorts of problems

[projectlnf]

how did you plug yours?

[cobaltssoverbooster]

Disconnect the evap line to the manifold and put a vacuum cap on the inlet of the solenoid that's bolted on the manifold. Disable all evap codes that arise.

I don't know how but I was pulling in extra fumes from the tank when the canister purge failed closed. I replaced the gas cap and it helped initially so I think in my case air was leaking past the cap and allowing the evap to draw fresh air into the tank as it sucked fumes from the tank into the intake at cruise. I threw a slew of codes driving me to different test before I got here.

Even if the canister vent fails open it will just consistently draw in extra fresh air. All un-metered as its after the maf.

[gregtharas]

check your plugs. may need to run a little hotter.