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AFM Max Values

tang0

By tang0,
in Engines & Forced Induction

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tang0 Proficient

tang0

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ok, so I know (i think) that the AFM gives an output of between 0 and 5 volts, 5 volts being at the max of its range ... looking at the stats from my consult port logging, I can see that the afm is VERY close to the 5v mark on quite a few occasions ... 4.90 being the top end so far - my injector pulse width being in the 15-17.5ms mark and a duty of between 60 and 85%

so the question is this : What needs upgrading first

fuel pump ?

injectors ?

afm ?

any thoughts anyone ?

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Sydneykid Grand Master

Sydneykid

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ok, so I know (i think) that the AFM gives an output of between 0 and 5 volts, 5 volts being at the max of its range ... looking at the stats from my consult port logging, I can see that the afm is VERY close to the 5v mark on quite a few occasions ... 4.90 being the top end so far - my injector pulse width being in the 15-17.5ms mark and a duty of between 60 and 85%  

so the question is this : What needs upgrading first  

fuel pump ?

injectors ?

afm ?

any thoughts anyone ?

How many rwkw?

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tang0 Proficient

tang0

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i have no idea how many rwkw it has now, or what i want to get

to be honest i'm not really interested in looking at what the numbers are, i am more interested in driving it bloody fast (on a private track of course) and also being drivable on a day to day basis - not to be spitting flames at every gear change.

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Sydneykid Grand Master

Sydneykid

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i have no idea how many rwkw it has now, or what i want to get

Sorry I can't really help you then. All the components for upgrading are rated and, based on a large number of cars, I have a rule of thumb wherebye I can tell what part is capable of what power. It is pretty stupid to have a 400 rwkw capable fuel pump, 300 rwkw capable injectors and only a 250 rwkw capable turbo. Stupid = wastes time and money and is limited by the weakest link.

i am more interested in driving it bloody fast

To many people a 200 rwkw Skyline is "bloody fast". Others need 400 rwkw to get any jollies at all. Some think anything less than 1,000 bhp is plain whimpy.

I have a personal preference for 2wd drive Skylines to have around 250-270 rwkw, that's enough for a high 11 at ~200 kph. Over that and they get a bit cranky in traffic, tricky in the rain and you get a pretty poor return for your money (lots of $'s per kw). For 4wd Skylines, add another 50 rwkw or so, as the wheelspin problem is covered.

Hope that helps :P

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  • 2 weeks later...
b2barker Enthusiast

b2barker

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Tang0 : Mine goes as high as 4.96, with 80% duty (mods exhuast, filter stock boost control).

I have major hesitation issues from 5 to 7k RPM. I think the solution maybe AFM or piggy back with Z32 AFM. I sent you a PM

SydneyKid : Do you know what sort of rwkw you would reach where you would be maxing out the stock R33 AFM? I though it was in the 200kw range, but I would be suprised if mine pulled much more than 150kw atw with only exhaust and filter and stockish boost.

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Sydneykid Grand Master

Sydneykid

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SydneyKid : Do you know what sort of rwkw you would reach where you would be maxing out the stock R33 AFM? I though it was in the 200kw range, but I would be suprised if mine pulled much more than 150kw atw with only exhaust and filter and stockish boost.

Hmmmm, an unusual combination. If the numbers are all as you say, I suspect something is wrong. I haven't seen a R33 GTST go that high in AFM voltage until over 200 rwkw. Maybe try cleaning the AFM (brake clean is the go as it has no residue) and checking it's connector. Then check the voltage with a multimeter, as a few spots in the rpm range, that might help narrow it down. :D

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Beer Baron Grand Master

Beer Baron

Posted
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It's about 1.1V at idle. Should it be lower?

You may need to re-ground the MAF. I've heard of this problem cropping up a number of times of GTI-R SR20s. Adding another gounding point to the MAF should help. You will need to identify which wire is the negative earth and then CAREFULLY solder another wire to where it fits on the AFM, then ground the other end to a good ground place on the chassis.

HTH.

Richard

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b2barker Enthusiast

b2barker

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The ground to the AFM is switched off the ECCS relay, and connected to the CAS sensor and the ECU on multiple pins. I am unsure what other things may be affected by wiring another ground in parallel. Personally I would want to disconect the existing ground first. See atached schematic.

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tang0 Proficient

tang0

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well, hopefully this can now be solved, I have ordered a PFC from nengun, and am awaiting its arrival ...

I don't have the consult plugged in at the moment as was fed up with it sliding around behind the gearstick ... will plug it up at the weekend and see if I can get some logs off it ....

now to read up about the pfc ..

gah

so much to do

so little time

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The Mafia Grand Master

The Mafia

Posted
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Hey guys did the re-grounding work ?

I haven't done it yet, but the problem is shitting me off to the max.

I have 1100mv on the powerFC at idle (700rpm) and at 2000rpm in 5th gear on flat highway, its at 2500mv - 2700mv

****en big cough at around 6500rpm gearchange if changed hard..

this is what I am gonig to do, find the earth, chop it off the AFM and wrap it up, and then solder a new earth onto the AFM and ground it somewhere on the motor or the chassis.

Anyone know a good spot?

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MM2death Grand Master

MM2death

Posted
Posted

My AFM goes the the max value on the data consult port display all the time when i get up it (5.11). It also says my injectors are in theory going up to 125% duty cycle.

Car is R32 GTS-T with around the 200rwkw mark. On dyno it shows there is still plenty of fuel. Sydneykid you have seen my dyno graph. Any idea on all of this. Car runs great.

Regards,

Scott

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