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Car: R34 GTT

Problem: TPS light, Skid light and Check engine light are on and car is running sluggish and idles a little higher then it should 1,200

I installed a friends stock R34 ECU into the car and it fixed all the problems and cleared all warnings idle returned to normal.

So what is wrong with my Power FC?

*Is it blown?

*Is there settings that can be changed to fix this?

*What was the cause?

Has any one experienced this problem before? I don't know what caused it but I just want to know how I can fix it.

I don't have a hand controller but can possibly get access to one.

Thanks in advance

Is it 2nd hand?

You may possibly have the wrong afm setting, this will cause some crazzy running conditions.

You really need a hand controller to see what all the settings are, and to see what all the feedbacks are doing.

The power fc was purchased and tuned for this car. I don't know what the previous owner had done tune wise or anything like that but the car has since been in storage over a year not really moving.

The slip and tc lights seem to be a common problem with the power fc. Someone asked similar questions not long ago. Had the tcs and slip light as well as the check engine lights on with the power fc but nothing with the stock ecu. Not sure if an answer was found

Given those three systems complaining at the same time, their most significant intersection with respect to the ECU is the TPS, and possibly the auxiliary throttle used by the TCS system. The other significant option affecting all of them is the vehicle speed sensor.

  • nicksamaniac: Thanks for your advice. I am trying to get hold of a hand controller as we speak.

I think I found the thread about it( http://www.skylinesaustralia.com/forums/topic/407575-tcsslip-light-on-with-pfc/ ) . I have messaged the guy to see if he had any luck fixing it so hopefully he will reply. On last look he had every signal symptom I am experiencing but no solution. He even had the car tuned and they couldn't figure out the cause of his problem.

Would the above mentioned such as speed sensor be affected all the time not just with the power

If you're asking me if the problem would be there all the time with any ECU or only with the PowerFC, then my suggestion would have to be that I would be looking to the PowerFC as being the problem. TPS for example is something that has a threshold setting to set idle (for example) and the threshold could easily be different between a PowerFC and a stock ECU. The VSS comes from the speedo head to the ECU and is then passed to the other control units (HICAS, ABS, TCS, etc) and if the PowerFC has a different pullup resistor behaviour or something then it might interfere with the way that the other control units see the signal. There are all sorts of things that can go wrong, and to a certain extent, good luck trying to figure it out!

If it were me tuning an R34 (and it is, I have a Neo transplanted into my car) then I would use a Nistuned factory ECU over a PowerFC simply because of these seemingly random problems that the PowerFCs seem to cause. You take a bit of a hit in how hard it can be to tune a Nistuned Neo ECU (they're not as simple as older ECUs or PowerFCs)....but they work like the original ECU does because they ARE the original ECU.

GTSBoy: I appreciate your input and to correct my self in my previous message to you I forgot to finish my sentience it was suppose to say Power Fc but I am sure you understood me.

So because I have checked over the car plugs top to bottom and with the fact that the stock ECU is having no issues I can conclude that connections should be good.

I would love to solve this problem by just purchasing the Nistune how ever this is the ECU that has been tuned and for the moment at least its all I have got.

From reading the other post and talking to tuners I have come to the conclusion that this is not something that will be fixed by a tune or a setting with the exception of the check engine light.

* Is it possible spark plugs are causing this problem? i checked the coil packs and they are all fine so I replaced the spark plugs with what was already in there .7 could this be the problem? Because the power FC is tuned to much higher power.

*Fuses I am pretty sure I have checked the car over for blown fuses but maybe I should double check some people say that power FC can only run on a specific current and a blown fuse can disrupt this?

* Active LSD people with R33's say there is a problem with the power fc going funny after time recognising the active LSD and it plays up I am not sure if I am experiencing this and have not read any where of R34's having this problem.

*Could a damage piece of suspension cause this error?

Any additional advice is welcome thank you all

Edited by Rps13

Due to having a PFC you can't have the system diagnosed with a consult unit, so you are stuck diagnosing it manually. Not much we can do from here.

If with the stock ecu everything is working, I can't see it being an external sensor fault... It is inside the PFC.

Do you have the hand controller for the Power FC? If so you can check a few things like how your TPS is behaving and if you have any sensor or switch problems

From memory the other person experiencing these issues had no problems but with the sensors etc. Not sure if TPS voltage might be too low on closed throttle, should be about .45V - .55V from memory

Surely it isn't a problem with Power FC's in general if they are made for the 34, which all came with T/C (I think?)

Could spark plugs be the problem? I know in some strange way most problems like this come back to spark/coil packs. Now I know my coil packs are fine but when I changed the spark plugs I replaced them with the same ones that were in there and they had a .7 gap. I was reading some where that with more power you need a larger gap.

My theory is that the power Fc should be tuned for around 240kw and when the stock computer is in because it is running standard power no codes are thrown so when I plug in the power fc and it requires larger gapped spark plugs?

I don't know and can't find much information on the symptoms of running spark plugs that are too small in a R34 but as I am clutching at straws it seemed quite logical approach.

  On 09/04/2014 at 11:41 PM, GTSBoy said:

No, not suggesting it is a problem with all PFCs. But would strongly suspect that in this case the PFC is where the problem is occurring. They're just electronics, like any other ECU. Something is always ready to go wrong.

Yeah all good, I just wonder why there is the odd Power FC for 34 that seems to have this issue, but it cant be too much of an issue or the forum would be littered with threads about it and alot more answers.

Not sure what the go is, but if the stock computer works fine and the Power FC doesnt, it seems very likely that there is a problem with that specific Power FC

And spark plug gaps, as said, dont make any difference at all. They may make a difference in power output, but wont log faults etc

  • Like 1

I know what you guys are saying I just feel like i am chasing a needle in a haystack. Clearly something is wrong with the ECU but people have had no luck fixing it with the hand controller or playing with settings with a computer or tuning. So the only thing i can think of is something that the power fc might be over sensitive to or is having trouble interacting with due to the power of the tune. Clearly it's not a plug or something that is broken. I just don't know where to go from here with this problem.

Previous people haven't found a solution so while it is a rear problem the solution eludes us all for the moment.

It's probably the same PFC being handed around over the years with similar problems on every owners cars. :P

My suggestion is to lash out a few hundred extra on the Adaptronic, or Haltech/Link if you have the coin. PFC is old tech.

I'd suggest contacting apexi support and seeing if they can shed any light on it. Otherwise finding someone who can actually check/repair any circuitry that might be wrong with it (not quite so easy)

  • Like 1

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