powerc tune - are these results safe/ok ?

[paulr33]

Hey all,

I got my powerfc tuned today and after giving it a hard flogging on the way home to see if it there was any knocking/detonation or bad stuff it all seemed fine. i checked the max values on the hand controller and saw

Afm 5023mv

Injector duty 92%

Knocking 18

This was after a few 3rd gear runs to redline. I didn't get the engine flash light come up to warn of knock so I guess this is safe? It got 172rwkw on dyno dynamics not in shoot out mode. I did some searching and I was sure afm wouldn't max out at this rwkw/power level. I found a thread (http://www.skylinesaustralia.com/forums/sh...ight=afm+maxing) and it looks like he had a similar scenario. I'll go check what the mv afm value is at idle.

Anyone able to assure me stuff is ok or is it time for new afm / injectors already?

[paulr33]

at idle of 890rpm afm reads 1300mv

[Sydneykid]

Hi Paul, don't stress over the max values, they are a flash reading at a single point in time. What you are looking for is ongoing readings. The individual items;

1. Knock shouldn't go over 40, so 18 is OK.

2. Injector duty could be as a result of acceleration enrichment, don't stress until you see 90%+ holding constant speed. (ie; not accelerating).

3. AFM readings, ditto, don't stress until you see 5.1 volts when holding constant speed. (ie; not during rapid boost build).

[pnblight]

afm are right up that (5.134 v i think is max) so your like 98% of fsd

92% injector ok but again quiet high (most people like under 90%)

knock not a problem (even 30 or so is fine normally background noise) i believe 40 to 50 onwards is where you should start to worry

only my opinion

be careful shouldn't be a problem but look to upgrade down the road tho

[paulr33]

thanks for the help and relpies, clears up some concerns

[MarioGTR]

Hi Paul, don't stress over the max values, they are a flash reading at a single point in time.  What you are looking for is ongoing readings.  The individual items;

1. Knock shouldn't go over 40, so 18 is OK.

2. Injector duty could be as a result of acceleration enrichment, don't stress until you see 90%+ holding constant speed. (ie; not accelerating).

3. AFM readings, ditto, don't stress until you see 5.1 volts when holding constant speed. (ie; not during rapid boost build).

1/. Knock is engine and sensor dependant. No one can give you a safe figure, it will all depend on your particular engine and its idiosyncrasies.

2/. Injector duty at 92% means it hit 92% when the engine required 92%. Get larger injectors.

3/. Your AFM's are maxed out. Get larger AFM's - transient spikes? WTF? If the AFM recorded 5.1v (voltage ceiling) it means that more than the maximum amount of air able to be measured was being ingested by the engine - even a spike means that the Power FC didn't know for that period just how much air was present, so the engine would have run lean if the injectors couldn't dump enough to cover it - and which in his case, it couldn't do, as his injectors are reading 92%.

Maxed injectors and AFM's is a sure fire way to destroy an engine.

My suggestion to the original poster is to upgrade his fuel system and AFM's, or run lower boost until he can do them.

Mario.

[Roy]

Yeh about knock level, my car gets into the 30-40s under load from time to time. My understanding is that this is fine. But say cruising at 80km in 4th gear...when i slow on trailing throttle is will occassionaly spike...problem is when hititng peak i cant be sure whether that peak reading was whilst under load or not:(

Does anyone know if the voltage signal that the PFc uses for knock detection is a linear signal?

[Lithium]

2/.  Injector duty at 92% means it hit 92% when the engine required 92%.  Get larger injectors.

3/.  Your AFM's are maxed out.  Get larger AFM's - transient spikes?  WTF?  If the AFM recorded 5.1v (voltage ceiling) it means that more than the maximum amount of air able to be measured was being ingested by the engine - even a spike means that the Power FC didn't know for that period just how much air was present, so the engine would have run lean if the injectors couldn't dump enough to cover it - and which in his case, it couldn't do, as his injectors are reading 92%.

Maxed injectors and AFM's is a sure fire way to destroy an engine.

My suggestion to the original poster is to upgrade his fuel system and AFM's, or run lower boost until he can do them.

As much as I respect SydneyKids knowledge and experience, I agree much more with these comments. What if there is an extra extra unexpected variable? 5.1v could mean that just over the AFMs max air came in, or maybe there was 25% more.... or maybe it was right on the limit this time, but maybe another time it could go higher over that and it'll still get the same amount of fuel.

I'd definately turn the boost down in the mean time.

[Roy]

But if the thing has been tuned with a wide band lambda up its bum then surely the injector duty cycle has been set do that irrespective of the AFM volatage, boost/cfm etc the A/F will be fine.

Ok so its not perfect, but it shouldnt be too large a concern as far as balls to the wall driving. Id grab a Z32 etc as well, but from a performance aspect they wont make any difference, from an economy and driveability it would likely make a difference as it woudl make the thuners life easier....or am i way off base:)

[GunMetalR33]

But if the thing has been tuned with a wide band lambda up its bum then surely the injector duty cycle has been set do that irrespective of the AFM volatage, boost/cfm etc the A/F will be fine.

Ok so its not perfect, but it shouldnt be too large a concern as far as balls to the wall driving. Id grab a Z32 etc as well, but from a performance aspect they wont make any difference, from an economy and driveability it would likely make a difference as it woudl make the thuners life easier....or am i way off base:)

I agree with Roy to an extent. If your tuner maxed out your AFM on the Dyno then he would know the load point on the fuel map where it occured. This means that at that Max out point the fuel grid would flat line from left to right. If you know this flat line point then you can "guess" how much fuel will be needed after the max out point by following the pattern of duty increases from bofore the AFM Max out. Just to be safe you add a little more fuel to each cell after the flat line which means at full boost when you max out your afm you might be running a little rich...

I should say that I think this is only possible with a standard turbo setup due to the linier boost curve, as a steady curve allows you to guesstamate load after a AFM Max out. Turbos with a steap boost curve are harder to predict.

My 2 cents

[Mik]

The injector duty depends on what the tuner set the injector duty at. If he set it up as say 80%, then a reading of 92% on the handconroller is only really 0.92 x 80% = 73.6%.

You can check this by looking it the injector settings (if your tuner didn't lock your handcontroller)

[GunMetalR33]

can you lock a PFC HC ?????

[Emre]

The injector duty depends on what the tuner set the injector duty at. If he set it up as say 80%, then a reading of 92% on the handconroller is only really 0.92 x 80% = 73.6%.  

Not quite mate,

The correction on the injector menu is to accomodate aftermarket injectors.

If you have 550 cc injectors, the correction value is %80.

The duty cycle will still read correct, if it shows %92, that means your 550cc injectors are operating @ %92 = 506cc of flow.

GunMetal,

The hand controller can be locked with a laptop software.

It would still monitor, but you wouldnt be able to see and change any parameters on the settings menu.

[GunMetalR33]

 GunMetal,

  The hand controller can be locked with a laptop software.

  It would still monitor, but you wouldnt be able to see and change any parameters on the settings menu.

 

Now that would be tight of the tuner

[Emre]

Well, some tuners may see it as their own propety, even though you are paying for the tune. Best is to check before proceeding even though it's not very common.

It would also stop curious fingers playing with the settings just to see what it does.

Worst case scenario is when the cars change ownership; I've read about a couple of dramas in the past.

[fresh]

just got mine installed today, didn't notive the AFM voltage but i did notice that in second gear at 6900rpm my injectors hit 99.6%.........so basically this is saying i should turn the boost down or........... would a bigger fuel pump do the job ??? the car is running upto 14psi at the moment...i don't mind losing some boost for some safety, would i need a fuel reg or sumthin with a bigger pump.....where do i go from here.

also its not fully tuned at the moment, will that make a difference ?

[pnblight]

just got mine installed today, didn't notive the AFM voltage but i did notice that in second gear at 6900rpm my injectors hit 99.6%.........so basically this is saying i should turn the boost down or........... would a bigger fuel pump do the job ??? the car is running upto 14psi at the moment...i don't mind losing some boost for some safety, would i need a fuel reg or sumthin with a bigger pump.....where do i go from here.

also its not fully tuned at the moment, will that make a difference ?

You need big injectors

( a pump and reg can help get a bit more out off injectors but its like a band aid solution ,injector are quiet cheap my 700cc sard were $115ea)

and you may need pump to go with it depending on how far you want to go and the std system in place ablilties (is this gtr,gts or something else)

plus i would think you would be very close to afms maxing out ,if your maxing injectors and i would recomend doing a peak hold next time you give it a good boot full to see how high the afms volts are going. Upgrade for gtr are the rb20/25 80mm afms at about 150ea second hand and the gts is the Z32 80mm afm that can be bought through Repco (std bosch part)with plug I guess for around $400 dollars(i got cheaper but a friend worked there)

hope this help

[fresh]

yeah sorry its a gts-t. do many other people have this problem, i don't really have $700 for injectors + pump + reg + everything else, i just don't have it, me tihnks lower boost will be only go for now

but...how do u do this peak hold thing u speak of, is that where the little black boxes appear on the side which hold peak values ???

also, does anyone have a pfc manual, cause i have no idea how to read those graphs, and is there anyway to review them, say after a drag ???

[paulr33]

wow thanks for the stack of replies and extra info guys. has been a great help

[MarioGTR]

I agree with Roy to an extent. If your tuner maxed out your AFM on the Dyno then he would know the load point on the fuel map where it occured. This means that at that Max out point the fuel grid would flat line from left to right. If you know this flat line point then you can "guess" how much fuel will be needed after the max out point by following the pattern of duty increases from bofore the AFM Max out. Just to be safe you add a little more fuel to each cell after the flat line which means at full boost when you max out your afm you might be running a little rich...

 

I should say that I think this is only possible with a standard turbo setup due to the linier boost curve, as a steady curve allows you to guesstamate load after a AFM Max out. Turbos with a steap boost curve are harder to predict.

 

My 2 cents

You should be on TV with talent like that - you're talking out of your arse.

There is no way in hell anyone could do what you propose. It is impossible to control how much fuel is required for the air that is being ingested without accurately measuring it - if you exceed the voltage ceiling for the AFM's, the tuner has no control over anything at and past that point.

As load increase, air ingestion does, so what happens if you tune like you propose and the guy is driving up a steep hill in 5th gear? There is no way in hell the fuel system could put enough fuel (especially in this case with injectors so close to their limit).

Infact, the Power FC is usually set to dump fuel when it detects the AFM voltage ceiling; just as it does when it detects what it believes to be knock (>= 60).

Mario.

[edit: spelling]