Jump to content
SAU Community

Recommended Posts

Hey guys - got a problem to report - wondering if anyone can help out.

Last night me thinks - it's cold, 0.9 bar is going to be waaay safe so I dial it in and plant it in fourth. At this point a few things happened - which have happened before:

first boost comes up - ok, all good

then suddenly everything cuts completely for about half a sec - felt like I'd turned the key off!

then it cuts back in...

then it misfires around 5000rpm - which I'm guessing is the plugs and I'm hopefully going to fix that problem today...

the first problem of the engine/revs cut I'm thinking is the AFM going past it's voltage limit and shutting down.. does this sound right? what can I do to fix it? I've sprayed/cleaned it with heaps and heaps of electrical cleaner which didn't seem to make much difference..

Any ideas?

Link to comment
https://www.sau.com.au/forums/topic/17194-afm-problems-i-think/
Share on other sites

Caminperth,

I had the same thing happen to me when I had my car at about 13psi while mucking around. It was fine on the dyno but as soon as it was on the road it would start to have the problem you described.

The guy told me that it would be even worse on a colder day due to the fact that there was too much air getting into the engine and the air/fuel ratios where not adjusting correctly on my stock ecu.

A SAFC would probably fix your problem, I have a simple Pivot air/fuel meter (1 universal setting) and adjusted it to make it a little bit leaner and it has fixed the problem for me.

I am no mechanic/tuner so it is just a suggestion ;)

Daniel

aidwin - as you said man - it's not the speed cut..

b005t - yea - i know what the speed cut is like and this ain't it. :rolleyes: and yea - am still running stock cooler...

adrian - could be - but it's fully intermitent..

bam - i wish i could afford the gtr!

daniel - i've got an afc and itc (old skool apexi fuel and ignition controllers) and that should sort out the fuel issuses at higher boost...

i fixed up the plug issue today - tho can't really try it out in this weather.. :)

still at a loss as to what it could be.. still got an inkling it's the airflow meter maxing out... will do it more when there's cold weather due to more air due to the density change... sound right?

Cam,

It's the boost cut/fuel cut. The boost controller has nothing to do with it, it's the AFM that tells the computer when it senses too much air flowing, which means too much boost, and it will hit boost cut, resulting in a nasty sudden halt to the car:D

You'll need to replace your ECU or get a fuel cut defender to stop this happening. It is worsened by the fact you have a stock cooler, and cold air is denser, thereby the AFM senses more air flowing:D

Hope that made sense (and is true)

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


  • Similar Content

  • Latest Posts

    • Yes to both! Yes to standard ECU and tune, but exhaust is aftermarket. Unsure on brand. Actually have it sitting in at my desk haha! I have to set it up on my laptop but this is a great next step, will do. So I generally try to shift before 4.5K RPM most times. I largely don't do a lot of high-rev driving, but I will take it up to red 1-2x a week max, as I know the occasional "Italian tune-up" is good for these cars.  Oh wow, is this way better than what I'm getting. Does this mean there's a good chance I have an issue?   Thanks for all the info so far guys.
    • Old Son, did you re-use the Holden ABS in the new shell or try a different module?
    • Yeah, nah. I had the actuator rod off it today. The arm will not move at all. Neither out, nor in. Yeah, you'd think so, but I've been thinking about that. Even when the actuator rod fell all the way off at the beginning of this saga, it would build more boost and faster in lower gears than it would in higher gears, and you'd think that that was the opposite of what should happen. But I strongly suspect that there is a thing with the gearing getting the revs to rise faster, that there must be some transient effect with the gas flow rate rising quickly, that you don't get with the more steady state case of the higher gears. Keep in mind - the gate is not shut in either of my weirdnesses. So things are not "normal". We normally think about a turbo spooling up (below the wastegate target) with the gate shut. I have all sorts of mental models running now where the gate is a little bit open, and having it stuck open allowing gas out while it should be going through the turbine has all sorts of weird effects (in these mental models). I'm thinking in the higher gears, the ex mani pressure builds to the point where enough gases spill out the wastegate to just prevent the pressure rising much more at all, or just creeping up, all the whole the revs are increasing and getting closer to the point where a gear shift becomes necessary.
    • Is it possibly wastegate actuator itself is sticking, or even the rod to flapper? Otherwise I reckon things are getting a bit rusty/worn   Also odd it won't boost in 3rd to 5th, but will in 1st, I'd expect the other way around with it slightly open as there's more time on your way to redline for it to spin up
    • Does anyone know ow what these two plugs are for and if they should be unplugged? Just put the dash back together and can't remember if these were plugged in before or unplugged! (Blue and white plugs) 🤦🏽‍♂️
×
×
  • Create New...