RB25 on Z32 ecu pull timing, need help..........

[louiswun]

Z32 on RB25,when pulling at full throttle,
1. ECU pulls timing and did not follow the ignition map,
I have same numbers on both timing map and knock timing map,
both map's tracer where it access is O2 feedback off (numbres lower than 128)
Fuel temperature DTC code is present and I have diasble to report that code, could this be the problem ?
Any ideas how to fix it ?

2. TPS idle switch on (red), AFR alpha always 111% to 113%, actual AFR at idle is around 14.X
once the throttle open, the AFR alpha will slowly go back to 100%.

In NDS, I have tried to force ecu to running in AF base 100% (same as AFR alpha in Nistune) and I can see my idle become 16.X
The problem is when throttle switch to closed when car running (the moment TPS idle switch to red), engine reving down from around 2,000rpm, the fuel recovery kick in, the acutall AFR is too lean, car cannot run smoothly, engine stumble.
Is there any way to control the AFR alpha ?

Attached csv and bin file, please check.

[Matt]

1. Both issues discussed on here previously:

(a) Fuel temp DTC wont cause the issue and is not a problem. You can remove this DTC by putting a resistor on the fuel pump temperature pin internally to the ECU (covered in our Z32 RB25 PDF on the main forum section)

(b)

ECU pulls timing and did not follow the ignition map

False positive knock signal. Z32 ECU uses different knock sensors (SR20 style) to the RB25 engine and may be oversensitive. Suggest disabling knock feedback in the ECU if its causing issues

2. Not sure on AFR alpha. I know we are making ECU use TPS variable only input (no switch) on the RB25 and not sure if that is causing complications in this case. Make sure TPS is adjusted correctly to TPS idle lights up when throttle touched lightly

[louiswun]

1. Both issues discussed on here previously:

(a) Fuel temp DTC wont cause the issue and is not a problem. You can remove this DTC by putting a resistor on the fuel pump temperature pin internally to the ECU (covered in our Z32 RB25 PDF on the main forum section)

(b)

ECU pulls timing and did not follow the ignition map

False positive knock signal. Z32 ECU uses different knock sensors (SR20 style) to the RB25 engine and may be oversensitive. Suggest disabling knock feedback in the ECU if its causing issues

2. Not sure on AFR alpha. I know we are making ECU use TPS variable only input (no switch) on the RB25 and not sure if that is causing complications in this case. Make sure TPS is adjusted correctly to TPS idle lights up when throttle touched lightly

(a) I did that already, but may be I'm using wrong resistor.

(b) I try another setting last night after I send this thread, start all over again from a clean file for Z32 23710-41P03 (not transplanted map file for RB25), nothing changed except K value and lantency, now runing richer, timing is around 28 BTDC on max torque area at 0.6bar, it did not pull timing anymore, AFR is around 12:1. And I have disabling knock feedback, by -128 on where the timing map trace accessed area (raw value).
In the last setting (transplanted map file for RB25), timing is around 17 BTDC on max torque area at 0.8bar, pull timing to 12-13 BTDC, AFR is around 13:1.

(2) TPS adjusted to 0.46V, car is running with 444cc GTR injectors, Z32 AFM, seeing 4 bar fuel press when unplug FPR vaccume hose.
In the last setting , due to the 113% AFR alpha problem, I have lower the lantency to something around 770 to force the idle 14.7, but when low throttle, it is too lean (17:1-18:1) everywhere before seeing positive boost pressure.
In the setting of stock 41P03 file, lantency 1100, both full & low throttle fueling are fine, but the idle is around 13:1, still see the 113% AFR alpha problem, but car is running smoother except idle.

[Matt]

but when low throttle, it is too lean (17:1-18:1) everywhere before seeing positive boost pressure

Bit of a workaround but increase TTPMin to raise the minimum floor injection time so it doesnt go so lean

Interested to know what the difference between adjusted 41P03 (RB25) and standard one causing the issue is (only map changes, no firmware changes)

[bachig24u]

quote: seeing 4 bar fuel press when unplug FPR vaccume hose.

HI,
Can you advise the fuel pump part number?

[louiswun]

quote: seeing 4 bar fuel press when unplug FPR vaccume hose.

HI,
Can you advise the fuel pump part number?

It is using 255L/H fuel pump but not stock fuel pump,
something very similar to Walbro GSS341/342
4 bar fuel press is control by an adjustable FPR
(4bar at unplug FPR vaccume hose and around 3.5bar with pluged hose)

[louiswun]

but when low throttle, it is too lean (17:1-18:1) everywhere before seeing positive boost pressure

Bit of a workaround but increase TTPMin to raise the minimum floor injection time so it doesnt go so lean

Interested to know what the difference between adjusted 41P03 (RB25) and standard one causing the issue is (only map changes, no firmware changes)

The setting of TTPmin all zero, is to see any incorrect setting causing leaning problem.
The only problem I have found if TTPmin all zero is when the engine is extreme low rev (300rpm to 600rpm), AFM voltage is low, injector pluse is too short causing extreme lean like 19:1-21:1, engine will almost die and cannot go back to idle rpm, or die at once. Changing to 2nd gear at very low speed low rpm will also see this leaning problem, car stumble and feels shaking back and forth, especially when engine rev goes lower than idle rpm. I also see this problem in CA18.
Finally I have find my way to adjust the TTPmin, I try this by applying brake at 2nd gear, to force the car move very slow, and accroding to the TTPmin map scale to access between 300rpm to 600rpm, raise those number until I see 12.5:1 across those rev range.

I think.....both file got the same 113% AFR alpha problem,
When using the transplanted maps file, I have lower the lantency to achive 14.7 on idle, but raise the VQ map numbers anywhere between AFM signal 1.1V to 2.4V to gain more fuel before boost, adjust the VQ map AFM signal 1.0V - 1.1V to reduce the fueling on idle, by the time I make these adjustment, I did not know there is 113% AFR alpha TPS idle switched red problem.
although I can make it run richer than 17:1-18:1, I can tell the result is not good, the exhause sound is weired, very minore poping if holding the throttle at any rpm no load fixed rpm reving, even if the AFR is adjusted to 14.7, exhause sound good (no minor poping) only at AFR 12:1 - 13:1
Low throttle to full throttle AFR transistion is not smooth enought (VQ map not smooth enought)
http://www.youtube.com/watch?v=A7DbgAhXQok

When using the 41P03 stock file, I have ignore the idle AFR (TPS idle in red, 113% AFR alpha, around 13:1 AFR), untouched Z32 VQ map, raise the lantency between 1100 to 1200,
The low throttle to full throttle AFR transistion is much better, vaccume mixture now is anywhere between 14.X to 16.X, boost transistion AFR is from 13.X to 12.X
No more minor poping on no load fixed rpm reving, exhause sound is better and healthy.
Sometimes the 113% AFR alpha probelm will gone after a full throttle pull, idle could stay around 14.x:1-15.x:1, but the AFR alpha will slowly go back to 113% in 10 seconds.
Please ignore the misfiring in this video, I think I have to change the coil to get better result.
http://www.youtube.com/watch?v=1vMyHYgtbjQ

[louiswun]

This is the TTPmin map now I have.

[louiswun]

The pull timing problem might be cause by misfiring,
The engine that I'm tuning, sometimes it will not misfiring, when it is not misfiring, the actuall timing and fueling is exactlly what I have inside my maps.
(for unknow reason, sometimes it can pull great from 2,000rpm to 7,000rpm, but ususlly missfiring when boost pass 0.9 bar)
But when it is misfiring, the timing report from both nistune and apexi multi checker is pulled around 5 -7 degree, I still not sure the pull timing is cause by misfiring, or the the misfiring cause pull timing, will see result after changing the ignition coil.

[bachig24u]

With the FPR disconnected from vacuum (@atmosphere) and the TPS 'off' (say 1200-1500rpm) do you see a change in fuel pressure from 4bar?

[louiswun]

With the FPR disconnected from vacuum (@atmosphere) and the TPS 'off' (say 1200-1500rpm) do you see a change in fuel pressure from 4bar?

No, it won't change....and why change ? no vaccume and no boost, it always stay at 4 bar.
The 4 bar base fuel pressure is to make the injector flow more than what it should.
I usually do this on the very begining of tuning, especially on the car without fuel pressure gauge, no load fixed rpm free rev do not consume that much of fuel and causing fuel pressure drop.
I usually removed the vaccume hose and adjust to 4 bar fuel press, connect the FPR with a hand held vaccume/pressure pump to verify the rising rate of the FPR.
In case if 4 bar base fuel pressure(@atmosphere), to see if I have 1.2bar of engine boost, will the fuel pressure raise to 5.2bar, if any pressure less than 5.2bar, I will adjust the FPR to achive 5.2bar (when applying 1.2bar of simulated boost pressure)
I always think, if the injecors usually flow test at 3 bar, to maintain proper flow quantity when engine on boost, the fuel pressure (when on boost) must be at lease the boost pressure + 3bar, if the fuel pressure is any less than boost pressure + 3bar, the injector cannot maintain proper flow rate when on boost.

[bachig24u]

FP will change on cars with specific fuel pump control modules.
If that was the case the Fuel Pressure would go ridiculously high (gain 25-30psi)
thus, causing the flow rate to drop anywhere up to 30% causing the misfire underload you described.
This could be detected momentarily by a knock sensor if the engine ran lean for a few cycles.

if the FP isn't rising when TPS is off then your Fuel pump circuit is not affecting the problem you are describing.

[louiswun]

FP will change on cars with specific fuel pump control modules.
If that was the case the Fuel Pressure would go ridiculously high (gain 25-30psi)
thus, causing the flow rate to drop anywhere up to 30% causing the misfire underload you described.
This could be detected momentarily by a knock sensor if the engine ran lean for a few cycles.

if the FP isn't rising when TPS is off then your Fuel pump circuit is not affecting the problem you are describing.

Do you know is there a fuel pump control modules on R33 GTS25t ?
I'll go check the fuel pressure again tomorrow !
How to check ? Just unplug FPR hose and rev up ?
Today I have pull out the plugs to check and found that no.5 and no.6 coil has problem,
I have change that 2 coil and go for a short run in 2nd gear only (due to heavy rain).
The misfiring is gone, but need to check again if tomorrow no more rain.

[bachig24u]

I believe they do.

the fuel pressure is not your issue though..

those plugs were drowned at some stage.

[louiswun]

This is the plug pulled out after full set of ignition coil changed, after full throttle run.
The misfiring is due to weak performance coil, and the misfiring is gone, will test at higher boost tomorrow.