Major Problem With R32 Gtr

[PHATR32]

who the hell told map is more accuatre than afm??

[Duncan]

:werd: if a MAP sensor gives better driveability than AFMs why does pretty much every car run AFMs?

[markimak]

so im told. AFM's r inacurate they measure how much air goes thru the intake of the turbos. wher as the Map sensors r in throttle and measure the boosted air which is more consistant.

aint that right?

ok correct some of us mislead ppl. why r afms so much better than a Map read system?

Edited March 2, 2006 by markimak

[sav man]

AFM measures the volume of air going into the engine, a map sensor guesses the volume by comparing revs, pressure, and throttle position.

The volume of air is what realy counts, as it's the amount of air getting into the engine, not what pressure is behind it that gives you power. and say you hit full boost at ~ 4000rpm, the map sensor is going to read the same manifold pressure right till redline, and will have to guess the load axis for the ecu.

i have no idea if that makes any sence. But do a search, it has been covered heaps.

[GZillar]

sounds like it could be the knock sensor, nissan sesnors are crap! i had to replace my afm, o2 sensor and now my knock sensor in my 180.

also make sure you do not drive your car or leave it idling if the oil has no presure otherwise you will need new bearings whcih means a rebuild.

[Beer Baron]

the MAP sensor is direct manifold air pressure. not a vaccumed pressure like afm.

ok, firstly i have nfi what 'vacuumed pressure' is. pressure is a force pusing on something, vacuum is the pretty much the opposite. regardless, it's wrong. The mass air flow meters used in a GTR use a hotwire element that converts a change in temp to a voltage sigal which give an accurate measure of airflow. it has nothing to do with pressure as such. a Manifold Absolute Pressure sensor measure the pressure in the manifold (not in the throttle as you mentioned, after the throttle(s)). this is ok, but it's no where near as accurate as a hotwire type AFM. do a search in this forum as it's been covered many times before and you will learn a little about the differences.

[phatsky32r]

Hey dude i know how ya feel mine is doin the same only it fluctuates all over the place one minute it will drivin along fine then to pull up it doesnt want to idle. At first i thought afm's straight up but i pulled them off cleaned them out an it run a little better for awhile. So i had them tested an they checked out fine. I had a diagnostic check done on the car an in my fuel mapping area i was over fuelling pretty heavy in the high rev range so we pulled fuel out of that area but unforntunatel the problem still lingers

[markimak]

think this is a problem with alot of GTR's the amount of other GTR's that have done the same thing. hmm. mine hasnt acted up for over a week..

wat i did.

remove top AFM

clean afm with carby spray.

took off the connecting. cut old one off made up new connectors.

disassembled the afm cleaned connections. its only 4 screws.

connected all up.

Made heat shield for AFM plug with alfoil (looks dodgy, i did this to protect the heat shrink on the connector plug i made up.)

ran its so far so good.

noticed it aint as punchy as it was before. been meaning to reset ECU.

i was reluctant to snip up my harness. but had a spare plug off another GTR and used it as a reference.

[ali-turko]

ok i fink i have thi s problems aswell did u guys exprience while driving ur car would loss power wouldny go any where?? and sometimes had to pull over??

[markimak]

yep. try my fix if u want.

y not just wrap ur top AFM with alfoil to reflect the heat see how that goes.. 2 weeks and not a miss from here yet.

Edited March 23, 2007 by markimak