What Is Your Max Load Ignition Timing Like?

[benl1981]

Just been playing round with the PFC etc.

I have stock turbo and just over 170rwkw tuned with 10psi.

Lately I have been maxing out the AFM a lot. About 5500rpm I get the 1 check engine flash and look down and

AFM: 5095mV

InJ: ~76%

I have had that 5095 figure about 3 times. So I wonder if this is the absolute max it can read??!!

Maybe its the cold weather.

But anyway I ran some 95 octane the time before last fill and most recently filled up with 98 octane. Still getting a bit of knock.

I dialled out 5 deg timing and was finding full throttle from about 3500rpm onwards I was seeing 17 deg timing most of the way up..so normally that would be 22deg. Seem like normal to you? Looking at other PFC maps looks about right I guess..

Also the Powerfc when you look on the map trace etc it only has I think 15 or 16 load points on the vetical axis but in the tuning maps there is 20. Can you not use the last 4 or something?

Thanks

Edited June 16, 2006 by benl1981

[paulr33]

5100mv is the absolute max of the airflow meter. i would suggest turning off the AFM warning under ETC as it will just keep flashing and mistakely alert you, when you may think its knocking.

my max load IGN timing is near 19deg on full load.

the reason its running across the 15-16 load axis is because for 3.84 4.48 and 5.12v brakets cor airflow correction you will have something like 80% or thereabouts, which affects the final plot point for engine load. if they were all 100% it would drop near 18-19 on the load map.

[benl1981]

5100mv is the absolute max of the airflow meter. i would suggest turning off the AFM warning under ETC as it will just keep flashing and mistakely alert you, when you may think its knocking.

my max load IGN timing is near 19deg on full load.

the reason its running across the 15-16 load axis is because for 3.84 4.48 and 5.12v brakets cor airflow correction you will have something like 80% or thereabouts, which affects the final plot point for engine load. if they were all 100% it would drop near 18-19 on the load map.

Thanks Paul.

I think before the tune or anything it would only got to 15 or 16 on the load axis though!...

Cheers

[chrissso]

Hey Ben,

I remembered this from another post. Acording to SK, or someone like that,

air flow maxing out at 5500rpm is OK. If it's maxing out at 4500 rpm, then it is a problem.

You need considerably more airflow to push the voltage up higher at the top of the volt range.

Another thing, my airflow is maxing out at 5500rpm as well, and the tuner said that it's no problem at all either. However, if I chase any more power at all, get the Z32 maf.

[Cubes]

What car/pfc Ben?

If its an rb25 then I've seen power readings from around 180rwkw right up to 210rwkw using up to load point 16.

220rwkw pushes load point 17 that interpolates with 18. Its damn close to 18.

Close to 180rwkw is where I saw my std AFM maxing out.

[benl1981]

Hey guys - thanks for the replys

Car is an R33

Std turbs

3" full exhaust

R34 SMIC

10psi

high flow panel

PFC ver 2.32a I think

Dyno tuned to 172rwkw

AFR leaned out from about 9.x:1 to 11.8:1

Hey Cubes.. how can 220rwkw + send it to load point 17 or 18?? If you are already maxing out the AFM at load point 16 how would it know to go to 17?

Chrissso - I found an article in HPI that sort of explained a similar reasoning to the one you point out. The air flow meter was maxing out yet the AFR and ignition timing was ok at 220rwkw..WIth fuel and igniton changing only due to the rpm increase because it no longer had resolution on the AFM.

Does this mean that from 180rwkw to 220rwkw you can not tune it very well. I mean if I wackedon a slightly bigger turbo would you wack in more fuel at load point 16 to adjust for the extra airflow?

Not really sure how it can control it that well.

I find it odd mine maxed out at only 172rwkw. Maybe mine reads a little higher or I was dynod on a lowish reading dyno ...

[paulr33]

hey ben,

have a read of the djetro vs letro conversation currently happening. you will realise why one tune drops to load point 15 and others drop to say 18 or 19 and vice versa. a very good read

[benl1981]

Thanks Paul - yes I read that so mine most liley hitting 16 load point at 5.1v wil l never get to load point 18 (as mine probbaly has the correction in there).

Still struggle tosee how the engine can be tuned effectively from 170rwkw if AFM is maxing out.

[paulr33]

all that happens when the AFM is maxing out is that the AFM can show anymore airflow increase to the ECU. which is basically the same as MAP sensor style. it will shoot across the horizontal access from the point it maxes at 5100mv. you can make upto 250rwkw on the stock AFM if you can deal with the maxing out. even maxing it out 3500rpm, simply means from then onwards it will shoot across as apposed to diagnoally down.

[Cubes]

Hey Cubes.. how can 220rwkw + send it to load point 17 or 18?? If you are already maxing out the AFM at load point 16 how would it know to go to 17?

Its not one individual car.

The 220rwkw car is running a q45, mine now runs a z32.

I find it odd mine maxed out at only 172rwkw. Maybe mine reads a little higher or I was dynod on a lowish reading dyno ...

Most likely just the dyno, unless its running no ignition timing and or afr's are really rich. Which its not.

[siksII]

im pretty sure the figure i see when mine maxxes out it 5115, definetly not 5095.

[benl1981]

hmm thats strange - ive seen that value about 3 times

[paulr33]

what value ?

[benl1981]

5095mV

[paulr33]

what about it ? the afm max is 5100mv

[Busky2k]

You're pretty much there. My mate in his R34 is doing the same on his AFM with the std turbo.

[siksII]

what about it ? the afm max is 5100mv

mine shows 5115 as said before...

[paulr33]

right so we are talking about 0.01 of a millivolt. whats the problem? its somewhere near 5100mv