Strange Boosting Issue - R32 Gt-R

[niZmO_Man]

Hey guys, I have a rather weird boosting issue with my car.

Car would run/boost fine, then all of a sudden it would run weird and won't boost past 6psi. I shut the engine off for about 5 seconds, fire it up, runs fine, then after a while (5-30 minutes, no certain interval i.e. random), same weird issue.

During this 'boosting problem' mode, as soon as the car goes above 0psi, it will surge and run rich. On overruns/shifting, it will dump fuel (exhaust makes cool popping noises).

Shut engine off for 5 seconds > fire it up > runs fine.

Sometimes it will run fine for over an hour. Sometimes it will happen after 5 minutes.

This issue occurs when the car is warm.

Perhaps AFM(s) is playing up, unable to afford a new pair of them unfortunately. Still doesn't explain why it won't boost past 6psi (or 350mmHg or 'halfway between 0 and 7' according to standard boost gauge).

Any ideas/experience?

[Hadouken]

sounds like a intermittent vac leak

[R34_Wong]

Mmmm, if its the AFM you'd be encountering stalling issue too...

When it won't boost, is it hesitating? If its a vac leak hopefully you'd be able to hear it...?

[niZmO_Man]

Yeah hesitates. Can't hear anything else though.

With the vac leak, why does the issue always disappear if I shut the engine down and fire it up after 5-10 seconds? That thing stumps me. Friken car, just more problems (HICAS flicker issue still there as well, definitely electrical).

I'll have to pull the crap off to fix exhaust leak anyway (not related as issue was present before the leak... I think).

[R34_Wong]

Does sound the the AFM's then unfortunately... there are some tuners who can patch them up... I know the guys at RE Customs down here did for me and haven't had an issue since...

Worth taking a look maybe?

[GTR_NUTZ]

I'd say it's your afm's. Try driving over pot holes and if it happens everytime you hit a pot hole then it's most likely dry solder joints on the pins in your afm's. Easy fix.

My car was doing it for a while. Took it to 3 different places and they couldn't find the fault.

[Hadouken]

ah yes.

Dry solder in afm

[iwanta34gtr]

Sounds electrical / AFM.

Start by cleaning them, grab some CRC mass air flow cleaner from super cheap. Check and clean your connections as well.

If no luck, then go down the repair / replace path.

Just thinking, depending where you are located, maybe there's someone nice on here that can lend you some AFM's to test before purchasing?

Edited September 5, 2012 by iwanta34gtr

[niZmO_Man]

fatz doesn't have any spares atm

I've done the AFM solder fix (which fixed up typical bad AFMs issue), but I think it's probably dying.

I'll pull it off again and check them out.

Cheers for the suggestions!

[SiR_RB]

Had the same issue with my previous GTR, changed both afms and problem solved

Chucked in some late model r33 gtr ones as they are slightly newer

Can be had for cheap, check the FS section

[niZmO_Man]

Cheers man. I did have a big suspicion that AFMs are at fault, just weird that after a few seconds of being off it runs fine again.

[R.3.2.G.T.R]

Cheers man. I did have a big suspicion that AFMs are at fault, just weird that after a few seconds of being off it runs fine again.

i have a couple of spare stock rb26 afms if u wanna test it out, in western syd

[niZmO_Man]

Ooops forgot to follow this topic. Thanks for the offer BWRGTR, I might have to take it up.

I got a pair of AFMs from Brisbane (apparently they were R33 but has R32 written on them lol). Chucked them in this time last week, car ran awesomely. The frequency of the slight miss on idle was reduced, car ran smoothly and boosted to 12psi without issues.

This morning, the problem reared its ugly head again! WTH!? Although the performance degredation wasn't as bad as before, it wasn't going past the 3/4 boost mark (~350mmHg) and hesitating/being lethargic. Shut the engine down at a set of traffic lights, fired it up and it ran good again.

At least on my R31, I just wiggle the AFM plug a bit and it runs good lol. This car brings much electrical headaches.

I'll have to look into doing a solder fix on possibly this or my old pair of AFMs and seeing how they go... Unless someone has a good pair of known fully working AFMs (BWRGTR?) hahaha.

Cheers guys.