R34 Gtr Issue

[Johnny]

Hi there guys,

I have a little issue with my GTR, basically it loses power while driving then seems to come back in a few seconds.

The first time it happened i was driving completely normally, it was starting to build boost @3200rpm or so, the car lost all power and rpm dropped to just under 1000rpm. I immediately stopped the car and turned it off, when i restarted it one minute later it drove fine but happened again 2km later, just before i got home.

So far my troubleshooting yielded without success:

-Bad battery; as i hardly drive it the battery was dying so i changed it to a new high cca battery

-cleaned elec connection points for CAS

-cleaned AFM

Still to come/ideas

-Ordered new spark plugs and splitfire coils

-Bad CAS?

Ruled out:

-Loose cooler pipe as on WOT, boost holds strong.

-No backfires or running rich (no black puffs of smoke)

-No knocks (under 20)

Basically these intermittent faults are the worst cos the car seems fine, starts fine, drives fine and power feels the same so before i must take it to the professionals im hoping someone can maybe help; maybe had the same issue before?

I would be very appreciative of any help or advice given as i know this forum is one of the best when it comes to helping out fellow skyline/car enthusiasts.

-Johnny

[DVS JEZ]

Afm solder joints

[STATUS]

AFM or cas, watch your HC maf voltage when it loses power, unfortunately to trouble shoot the cas you can only swap it out with a known good one as the logs dont show the trigger faults.

[R31Nismoid]

AFM, common problem, totally intermittent.

[Johnny]

You guys are rockstars, it was some loose wires/connection of the AFM.

started the car just now, jiggled the airbox and the car stalled.

now ive just gotta figure out how to fix the plug. Can anyone shed some light on how to rewire the plugs or replace them all together? as i dont want this to happen again.

Can I buy new ones or does it require cutting them off and resoldering them back? I do wish to buy new plugs just for piece of mind or are they hardwired into the entire loom?

Again, thanks so much to you all.

-Johnny

[GTSBoy]

Just note - it may not be the connector/wiring at all. Just as all three guys above have said, the fault is common and it is inside the AFM. Dry solder joints that don't conduct properly all the time. Subject to vibration. The AFM can be opened up and repaired (which is fiddly) or you can just swaptronics it.

[R31Nismoid]

Yep it's not the plug, its the gizzards of the AFM.

Time for Nismo upgrade, dont waste time with 2nd hand AFMs. It'll just keep happening.

People have had some success with repairing them, but sometimes not (as in problem comes back later)

[GTSBoy]

In my case, I had one that did not respond to resoldering the internals, and one which has been on my car for maybe 8 years since I went in and touched up all the solder pads and joints and it has been solid. Each way bet for me. It's not a job for the hamfisted though.

[Johnny]

Yep it's not the plug, its the gizzards of the AFM.

Time for Nismo upgrade, dont waste time with 2nd hand AFMs. It'll just keep happening.

People have had some success with repairing them, but sometimes not (as in problem comes back later)

Im sure your right about the need to swap for some new AFM's and nismos would be the way to go but will need to be put on the dyno to map it.

Main thing id like to do is check which is the culprit, the plugs or the AFM's themselves

does this idea seem the way to go:

-get/borrow some standard AFMs to fit and see if that fixes the prob, if that works then i will buy the nismo units but if its just the plugs/wiring then simply fix them

I just checked the car again and it seems its either the lower AFM or plug/wire that is the one that need replacing.

what u think?

[R31Nismoid]

In my experience it is always the lower AFM. It would make sense as its closer to the heat etc.

I highly doubt it will be the plug, your car is not old enough. If it was a R32 GTR then i'd say possible.

The wires are nice and thick/simple compared to whats inside the AFM/circuitry being the reason (if you'd seen one apart, you'll know what i mean).

Just because you jiggle and it plays up, is the tell-tale sign the internals of the AFM are dead.

[Johnny]

In my experience it is always the lower AFM. It would make sense as its closer to the heat etc.

I highly doubt it will be the plug, your car is not old enough. If it was a R32 GTR then i'd say possible.

The wires are nice and thick/simple compared to whats inside the AFM/circuitry being the reason (if you'd seen one apart, you'll know what i mean).

Just because you jiggle and it plays up, is the tell-tale sign the internals of the AFM are dead.

Alright then, thanks ash. ill order some nismo's then. can i drive the car to the workshop or will the tune be completely off until i have it tuned on the dyno? maybe tow it down?

[R31Nismoid]

I doubt it will run well enough to be driven.

I accidentally flicked my Nismos over to stock a while ago & the car ran rather poorly

Just fit them there, doesnt take too long

[Johnny]

I doubt it will run well enough to be driven.

I accidentally flicked my Nismos over to stock a while ago & the car ran rather poorly

Just fit them there, doesnt take too long

I see your point ash. My plan is now to buy a set of second hand OEM AFM's so i can actually drive the car.

As per my previous thread of my stage 2 upgrade, i have new -9 turbz and cam gears sitting around so ill either buy nismo AFM's to pop in or simply swap my power fc to a d-jetro and eliminate them all together.

Ill search on the pros/cons of these ECU's and might even consider the VIPEC; then again, after all the hype surrounding them - has it died down yet lolz.

thanks again man.

[Johnny]

UPDATE: Ive decided to buy nismo AFM's for my car, having it towed to my tuner next week but until then im looking for stock of nismo AFM's

Do any traders or members on here have/sell them and have them in-stock to buy now?

[R31Nismoid]

grrenline.jp have always been the cheapest for Nismo AFMs unless someone else is having a sale etc.

Around $800 landed give/take

[Johnny]

I managed to find a member who has some nismos for sale which im buying and some standards from another member which im gonna buy too.

my plan now is to use the standards while i collect the last mods needed for my next mod stage and do it all at once.

Another question to anyone in the know:

I will have a set of stock AFMs where one dosent work and i know that sometimes for budget reasons, another member of the forum will need a replacment set who might be a bit tight on cash for z32s or nismos.

Can i have my current set repaired?

they currently work fine when cold but once at operating temp, they stop working; simply a wiring issue maybe? if its a cheap fix then i can fix them supply them to someone else in need.

Might be far fetched but just wanna be able to help another member as i have had plenty of advice and help myself and would like to do the same sometime.

-Johnny

[GTSBoy]

It's quite likely that there's one or more dry solder joints inside. They can be opened up and resoldered. May or may not work. The problem may not be a solder joint - there are other places (like the hot wire itself) that could have a break.