sputters/bogs under boost when maf plugged

[95gsxxx]

this just happened to me yesterday put of no where... drives runs in vacuum but once boost climbs the car runs terrible bogs and stutters doesnt build boost anymore. funny thing is when i unplug the maf it drives bad but builds and holds 10psi like normal.

changed the maf and the problem is still present
no boost leaks
plugs look rich

thanks for the help

upgrade list.
95 gsx
3in exhaust
cai
1g bov recric
front mount
16g @10psi

 

[chris00326]

Try a boost leak test and also check your fuel pressure regulator. when you changed out maf were you sure it was a good ood one?

 

[95gsxxx]

how would i check my fpr, and i have no boost leaks leaks. i dont know if this helps but my ltft used to be at +10 and now its at -10 . extremly lean?

 

[chris00326]

First to check the fpr pull off the vacuume line and se if you can smell fuel. if you do its a good indicator of a bad one. you can also start the car and pull the vacuume line and wait a little bit and if fuel starts coming out of it it is bad. have you changed fuel filter? have you replaced timing belt? If so are you sure its on time? You said it sputters under load abd youve replaced the maf so to me it sounds like a fuel or timing issue.

 

[95gsxxx]

im gonna check the fpr, and yeah i have a scan tool and its pulling timing like crazy under boost. and these stft and ltft are maxing out i dont understand because yesterday it was running perfect. i did my timing belt about a month ago and the cam and crank are lined up, have not done the fuel filter. but why would unplugging the maf make the car boost normal ?

i appreciating you helping me

 

[chris00326]

Its not a problem. As far as unplugging maf and it running better points to a bad maf. mine went out on my 1g a couple months ago and was causing it to dump massive fuel because the maf was reading to much air. i had no cel so the only way i was able to diagnose it was ti unplug it. it made it run better so i swapped it for a known good one and it fixed the problem instantly. Basically unplugging the maf sends the ecu into a kind of limp mode making it run on a set base value without the abilty to compensate or learn. With the computer pulling time you may have a bad cam angle sensor or a bad crank angle sensor. the cam angle has to do with spark timing and the crank angle sensor has to do with injector timing.

 

[SleepyTalon]

I'm having the same problem after switching to 2gn maf and injectors on my 90

 

[95gsxxx]

it was a loose ic piping coupler . i was to stubbern to actually do a blt and i did. car runs perfect

 

[ozrallyE9]

Check your ignition.

 

[95gsxxx]

blt's are always important, thaks guys