hi, unplugged my maf today with the engine running, it kept running but very rough i assume this means that the MAF is fubard? the car is 94wrx with the green label MAF can i only use a green label for a replacemant? thanks.

 

Was the car hot, or cold?

 

hot!

 

AFAIK the engine stalling when removing the MAF sensor doesn't 100% indicate the MAF is knackered. Mine will keep running although very rough (rise and falls) and the monitor will throw up an error code 23 so it knows when its not there. Hot or cold.

This is on MY00 though.

 

cheers for that i will check the error codes later and also if i get chance measure the voltage of it to see what's going on.

 

Best bet is to run a voltmeter across it's signal pin-out (in it's connector) and ground, and see what the output voltages are through the rev range.

 

My MY99 was hunting when hot, and the maf was plugged in. When unpluging it, i found it would idle better when warm. I changed the maf, and it was fine.

My symptoms were exaggerated as i had a cold fault with the icv too.

 

when stationary or underload

 

Well, a true real world reading would be when driving, under load, so best to rig it up so that it can be read by you in the passenger seat, while an insured mate does the driving...

 

if results come back all clear then it would be worth checking your sparks plugs.......wouldnt it joz?u never know!

 

Indeed.

Sparks first; coilpack/s second.

99gw, what do you know about the Impreza's electrical system (I have a problem)?

 

thats what i do, what should the voltage read i have read somewhere it should be -1v@idle to 3v@full throttle?

 

What MY car do you have?

The MY93-96 green MAF cars, for example, are 1V at idle... and 5V (or it might be 4.5V?) at max load/revs.

 

got a my94wrx, is the signal output second from the bottom as you look at the maf from the engine bay?

 

Doh!


Not sure mate... What about letting car idle steady after warmed up and probing each pin. if you get a reading of about 1.0 - 1.2V then that will prob be it. If you then get someone to rev the car a bit and the reading rises and falls in concert with the revs then it's defo the output voltage pin-out...

 

tbh matey,i know very little!im sure theres alot of people with much more knowledge than me on here about the electrical system,electrics not really my thing,sorry i cant be of much help joz.worth getting a new thread up?

 

Would spark plugs cause hesitation?
Which are the ones to get or a modded scoob (the colder ones) is it NKG FPR7s or summut?

 

plugs would cause hesitation along with a number of things inc knock sensor! i used denso iridium (ik22) plugs gapped to 0.7mm

 

No worries mate - I think I've got to the bottom of my problem.

(Sorry for the mini hijack).

 

measured the voltage of the MAF sensor and they are as follows
0.3v ing on
1.0v @ idle
4.85v @ full throttle

so from the first 2 readings it is in spec what about the 4.85v at full throttle is this in spec?
cheers.

 

ANYONE! know the answer to this

 

Sorry for the late reply - yes, MAF is perfect!

You have no issues.

 

cheers buddy

 

How do you measure voltage on an MY99/00 MAF?

Ta

 

Same method.

Although the output range might be reversed i.e. 5V for idle; 0V for WOT(?) - can't remember tbh.

 

i attached a volt meter to the appropriate ecu pin and read the signal from the maf

 

How do you find out which ones are for the MAF signal?

 

With engine up to temp and idling, probe the wires until you get a Volt reading. It'll either be about 1V or 5V (can't remember if the later MAF's voltage is 'reversed'). Then run the voltmeter into the cabin and rev the car to near max revs. If the voltmeter rises and falls (or falls and rises) with the revs, then that's the signal wire.

Report back with your Volt readings at what revs, and we'll tell you if it's okay, etc...