Lossing All Power (sometimes Problem)

[map7]

I just upgraded to an Apexi Power FC & bigger turbos (Twin Trust T517Z) and I've had it tuned. Sometimes I loose all power completely and it's come close to stalling.

It usually happens just after giving it a lot of stick, then backing off and driving normal. When it's playing up it will sit at around 1000rpm or drop up and down a little like it's going to stall. If I hit the accelerator (even if i push it to the ground) the RPM does nothing, then I leave everything alone for a few seconds and it's up and going again. It's happening quite often (5 times in 50kms last night and 3 times tonight in 100kms).

It's a bit all over the place. Sometimes it doesn't play up at all.

The only mods to the car are:

Big Exhaust (from cat to back)

Pod filters

Trust Twin T517Z turbos

Apexi Power FC with Hand controller

Xtreme single button soft cushion clutch.

I have a feeling that it's the fuel pump, but I'm not a mechanic.

Does anyone have any ideas on what I could check?

I could use the hand controller to better diagnose the problem as I'm driving, is there anything I should be looking at specifically?

[map7]

I notice that sometimes my Injector Duty reaches 99.8% maybe it's cutting out.

[Beer Baron]

it definately sounds like fuel pump to me. you'll need to whip it out and test it in a bucket of fuel. you will need to find out what it's meant to flow at low pressure for the test to be really perfect or, you can try and hook the fuel return into a bucket (post reg) then supply constant 12V and ground to the pump. do it for 1 min, then times by 60 to get your litre per hour figure. if you do need to upgrade pump (you should anyway) i'd strongly suggest the nismo pump.

either way I would not be giving it any stick till this is sorted.

[map7]

I haven't tested the fuel pump but do have extra information about the problem.

My problem has been happening for 6 weeks now. In the last three days of driving this problem has happened 11 times.

It's happened with the radio and AC off.

I have noticed that when ever the problem is happening the Air Flow Meter in the Power FC drops down to around 500mV.

I've had this probem happen if i'm just cruising or thrashing it or idling. I even drove 70km at under 3000RPM and it still happened. I don't understand and don't have the tools to start testing my fuel pump but am interested in peoples view to help solve the problem.

The Power FC is not spitting out any problems what so ever.

Sometimes just before the problem happens the Exhaust gas temp warning lamp comes on? Could this be the cause of the problem?

[paulr33]

MAIN MENU, MONITOR, 4 CHANNEL

CHOOSE AIRFLOW, KNOCK, INJDUTY, RPM

PRESS NEXT

PRESS UP (so you can see max values for each)

PRESS RIGHT (resets high scores for each)

drive around and replicate the problem

note down the values for each and post them here

if knock is above 50 odd its knocking too much, take out some timing

if inj duty is getting near 98% its too high, get more fuel into the system or larger injectors

if airflow is hitting 5100mv get upgraded airflow meters

if none of those are hitting those high values then

MAIN MENU, ETC, SENSOR SW CHECK

drive around and replicate the problem

when you see the engine check light flashing look at this screen quickly and look for any sensor names that go highlighted in black, normally they back no background colour, but will if the sensor is failing or voltage is out of scale. do not confuse this with the black dots, these are relays that turn on and off.

if its not of the MONITOR 4 CHANNEL items hitting their high values and its nothing obvious in the SENSOR SW CHECK page then procced here for a well known R32 RB26 misfire bug

covered in the PFC FAQ here and R32 RB26 misfire discussion thread here

58) My Skyline R32 GTR has a wierd misfire problem, what's wrong?

[map7]

Thanks Paul,

I've ran the tests here is the info:

1st Test (maximums), 1st Run:

Knock = 36

Inj Duty = 100%

Airflow = 5115

Revs = 7200

The problem didn't fully happen, but it did miss a few beats.

1st Test (maximums), 2nd Run:

Knock = 37

Inj Duty = 100%

Airflow = 5115

Revs = 7256

No problem happened here, but I maxed out again on most of the stuff.

2nd Test (sensors), 1st Problem

Idling at 1000RPM, just after I've given it a bit, Exhaust temp light came on and the AF-1 sensor highlighted with a value of .02 to .03

2nd Test (sensors), 2nd Problem

This one happened on the west gate bridge . Same sensor highlighted and same values.

2nd Test (sensors), 3rd Problem

AF-1 again it just dropped suddenly from 1.5v to .04 whilst we were watching it and the car was just taking off in 1st gear, driving normally.

I assume that the AF-1 sensor is the Air Flow Sensor, so I suppose I need to upgrade this part first and the problem should go away when I'm just cruising or idling?

I've heard people putting in Z32-Air Flow Meters are these the way to go for my configuration?

As far as the injectors maxing out will this only affect my car when I'm flooring it? When their maxing out this much should I first upgrade the fuel pump or injectors?

Will just upgrading the fuel pump bring the injector duty percentage down?

[MBS206]

I'd be upgrading both personally.

Do fuel pump, and injectors.

Although, if you can hook a pressure guage up to the fuel line, and measure the pressure when the inj duty cycly hits 100%

If the pressure drops, throw in a new pump, if pressure stays up, throw in a new set of injectors.

AFM, time to upgrade by the sound of that.

[map7]

My mechanic has swapped the air flow meters and crank shaft sensor with the ones out of his own car, which he knows are good with my suspect ones.

I've taken the car for a drive (80kms) and it has failed three times already. The sensor test is now complaining about AF-2. AF-1 did not highlight at all, but did drop significantly in voltage when the car failed.

As the problem was happening if I hit the accelerator the car starts to die, like it's getting flooded with petrol. It stalled once and the other two times it has the same problem as before.

I also tried moving the leads around the Air Flow meters whilst the car was running to see if it was shorting out but no problems happened.

I'll do some more testing today.