AFM Problem / Repair

[Guest smithy2167]

On an R32 GT-R, I think I have an Air Flow Meter problem. Every so often the engine dies, stumbles, won't rev, the idle goes haywire and sometimes it stalls. After a short time, it recovers and drives normally again. It feels like there's a fuel blockage but I've replaced the fuel filter - no change.

Putting the ECU in diagnostic mode showed an AFM error. Cleaning the AFM connector contacts made no difference. I remember way back reading about people having problems with the AFM internal wiring to the connector. Can't find anything in the archives though.

Before I lash out on a new AFM (gulp!), I want to have a go at fixing the old one. Does anyone have any details of this problem and how to fix it without wrecking the AFM?

Dave.

[KamikazeR33]

one bit of advice... if ur not a prob at fixing these, dont bother trying in my opinion

i broke one of the fins inside the afm tube.. tried to solder it back together... no use

just had to buy a 2nd hand one

[sewid]

Did you clean the AFM filament itself with some CRC Eletrical Contact Cleaner? There are a few (thousand) threads about that on here. Try that before you buy a new one.

[Guest smithy2167]

The repair seems to be possible as others seem to have done it - I just want to learn from their mistakes before I tackle it ;-).

I saw the LONG AFM cleaning thread and I'll certainly be doing that. However, this problem is much more severe than simply an idle stumble.

[Cubes]

How does it drive when cold? Any difference to when it is warm? I.e worse?

[Guest smithy2167]

Normally it drives fine either hot or cold - perhaps a little fluffy when cold but it's always done that - the ECU seems to have a warm-up mode where things are backed off a little.

This fault has the engine falling flat on its face, stumbling and almost stalling, but usually rights itself after 10-20 secs. I'm worried it's going to become permanent shortly though.

[DAMQIK GTS-T]

Ok I am one of the lucky that have managed to fix my Afm, I will point out that I only have one afm due to the fact I have a gts do you know which one of yours is playing up?

anyway the problem I had sounded the same as yours the car would start running funny and would often stall ecu diags said Afm. so with nothing to lose I cut out the black rubber seal to the square lid of the afm under neath is a copper plate which I un soldered under that is a circuit board the problem is that the plug is directly soldered to this board and the solder joints have broken (prob due to vibration) I simply re soldered the joints of the circuit board to the plug re soldered the copper plate back and sealed the cover back in with silicon (the sensor safe type) and all is now good. (you must re seal the cover as there is some kind of air temp sensor on the mainboard in the AFM

Good luck with yours

Regards

Damqik

[DAMQIK GTS-T]

Also here is a link that may help

http://www.mr2.com/TEXT/AFM_Notes.html

[Guest smithy2167]

Thanks for that Damqik.

Unfortunately, the ECU doesn't say which AFM is faulty. Other info I have says that if one AFM fails, the ECU uses the signal from the other AFM. It only goes into limp-home mode (limiting revs to 2400) if it loses BOTH signals. So maybe I have one dead and one dying! Or a fault in some common wiring. Time to get out the multimeter I think.

[Cubes]

Disconnect one and see how you go.. If you go in to limp mode then you know which one is dead, the one connected.

[DAMQIK GTS-T]

A quick check would be to peel back the rubber boot to the afm plugs and ground the black wire of your multimeter and with the engine running grab the red probe and check the output of the afm (useually the white wire) signal should be between 0.1 - 5.0 volts depending on revs and load.

Regards

Damqik