Jump to content
SAU Community

Does This Sound Like A Damaged Afm?

Everlong-S13

By Everlong-S13,
in Engines & Forced Induction

 Share

Recommended Posts

Everlong-S13 Community Regular

Everlong-S13

Posted
Posted

Hi guys,

I have a R34 GTT which was recently nistuned running 13psi on stock turbo with FMIC etc mods.

The car ran great a week after tune, then I took it for a long run up to Lancelin and noticed some pretty bad misfire in high revs.

While I was there I decided to clean the AFM gently with some rubbing alcohol. The misfire seems to have dissappeared however now the car has lost roughly half it's power on full boost past 3-4 rpm.

The turbo spools to 13psi as normal, and there is a loud intake noise however roughly half the power it should. I assume if it was a boost leak it would splutter and give out black smoke however this is not the case.

Curious to know if anyone knows if this is a typical symptom of a damaged AFM or something else like timing issue etc? Many thanks.

Link to comment
https://www.sau.com.au/forums/topic/418949-does-this-sound-like-a-damaged-afm/
Share on other sites
FeZ25 Rising Star

FeZ25

Posted
Posted

Would take it back to where you got it tuned and let them give it the once over to make sure everything they adjusted is in check.

Also check your coil-packs. My car wouldn't like high revs under boost. Put a set of yellowjackets in there and hey presto, no misfire.

Everlong-S13 Community Regular

Everlong-S13

Posted
  • Author
Posted

Booked into workshop next month, I'm going to check the coil packs and spark plugs while I wait.

It's getting worse now, holding down accelerator on full boost - the car literally lurches backwards from lack of power, and then splutters on idle briefly.

Odium Grand Master

Odium

Posted
Posted

Yeah within a week of me going to a highflow/injectors/powerfc/etc my coil packs let go... Misfiring under boost / higher rpm... I got some Splitfires and it's been perfect ever since

Also make sure that your spark plugs are fine, could be that the tune is slightly off and they have fouled after a while?

Everlong-S13 Community Regular

Everlong-S13

Posted
  • Author
Posted

I sprayed it with a pump spray cleaning alcohol, didn't actually touch the components.

Anyway I have replaced the spark plugs with no difference.

I took it for a drive and it's worse. It seems to really drop power at high revs/boost in a sort of shuddering kind of way, and repeats this shuddering in "waves" as you keep your foot down.

Th3 coilovers are spitfires so I didn't think they would damage easily??

Anyone know what his may be?

MrStabby Grand Master

MrStabby

Posted
Posted

Anyway I have replaced the spark plugs with no difference.

I took it for a drive and it's worse. It seems to really drop power at high revs/boost in a sort of shuddering kind of way, and repeats this shuddering in "waves" as you keep your foot down.

Th3 coilovers are spitfires so I didn't think they would damage easily??

Anyone know what his may be?

Did you use the same plug type at the same gap? If there's more gap then you've made it harder for the coils to make the spark, and it will make any ignition related missfire worse.

What gap are you running now?

Everlong-S13 Community Regular

Everlong-S13

Posted
  • Author
Posted

Hi guys thanks for the replies.

My previous plugs had 0.9mm gap so were the new plugs.

I took out the spit fires and put in a spare set of stock coils with no difference, either it's not the coils or plugs or both sets of coils were faulty.

I will find another AFM to test, no idea if a damaged AFM produces symptoms like this.

SKY338 Rookie

SKY338

Posted
Posted

Hi Mate,

I am experiencing the same symptoms and i was also wondering if it was the AFM. Mine however doesn’t hesitate it just has a flat spot between 4000-5500rpm and then lunches fine after 5500rpm. Almost like it has no energy and then decides to go. Can R&R be caused by a faulty AFM?

GTR_NUTZ Collaborator

GTR_NUTZ

Posted
Posted

If its braking down and misfiring under boost/load at higher rpm then I'd say coil packs. If you're hearing a loud induction noise then maybe one of your FMIC pipes/hoses has popped off and leaking boost BUT still seals up when off boost. Might pay to re check and re tighten.

And when you are cleaning your AFM I'd recommend a break cleaner or carbie cleaner in a spray (and one that comes with a straw nosil.) That shit dries to nothing and doesn't leave a oily residue like some 'parts washers'

Good luck!!

Everlong-S13 Community Regular

Everlong-S13

Posted
  • Author
Posted

Hi GTR_NUTZ thanks for your reply.

It seems everyone is saying coil packs so I guess I need to go in that direction and buy either a set of new spitfires or OEM coilpacks. I guess I was naive thinking that the spitfires would never fail on me.

Pretty sure it isnt a leaking hose/pipe as I have checked thoroughly.

SKY338 I am not sure but I may try to get my hands on a spare AFM in any case to test.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Nizzy_R34
      r34's love to squeal

      By Nizzy_R34 · Posted

      just an update to this, poor man pays twice  Tried sanding down the pulleys but it didnt do the trick. Chucked another second hand alternator in the na car which I got for free off my mate and its fixed the squelling. Must have been unlucky with the bearings.    As for my turbo car, I managed to pick up a cwc rb alternator conversion bracket + LS alternator for 250 off marketplace, looked to be in really good nick. Installed it , started the car and its not charging the battery.... ( Im not good with auto elec stuff so im not sure if this was all I needed to do but I verified such by using a multimeter on the battery when the engine was running and I was only getting 12.2v )   I had to modify the earth strap for the new LS alternator , factory earth strap was a 10mm bolt which did not fit the bolt on the LS alternator which was double the size so I cut it off , went to repco bought some ring terminals that fit, crimped it onto the old earth strap and bolted it up to the alternator , started the car and same issue. Ran like shit and was reading 12.2 at the battery.  For a "plug and play" advertised kit thats not very plug and play but alas.  My question is , am I missing something ? Ive been reading that some people recommend upgrading the stock 80 amp alternator fuse to a 140 amp but I dont see how that would stop the alternator charging especially at idle not under load.  Regardless ive pulled it out and am going to get it bench tested by an auto elec tomorrow but it would be handy to know if ive missed something silly or have done something wrong.   
    • Duncan
      Engine sputter

      By Duncan · Posted

      My wild guess is that you have popped off an intake pipe....check all of the hoses between the turbo and the throttle for splits or loose clamps.
    • Duncan
      S1 Autech 260RS Wiring Diagrams

      By Duncan · Posted

      Awesome, thanks for sharing!
    • Duncan
      Nissan fuga 450gt android screen

      By Duncan · Posted

      To provide more specific help, more information is needed. What Android screen? What is its wiring diagram? Does the car's wiring have power at any required BAT and ACC wires, and is the loom's earth good?
    • GTSBoy
      Nissan fuga 450gt android screen

      By GTSBoy · Posted

      So, now all you need to do is connect the 2 or 3x 12v feeds into the unit to permanent 12v, ACC 12V and IGN 12V that you can find in the spot behind the stereo, and the earth, and then it will switch on with the car.
×
×
  • Create New...