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Discussion Starter · #1 · (Edited)
Hi

My R34 GTR had an engine change after a conrod bearing damage, the engine fitted was a standard R34 GTR vspec engine with approximately the same mileage of the car.
The GTR is fitted with some GT-SS turbos, nismo 600cc injectors, nismo fuel pump, nismo fuel regulator, hks exhaust and decat pipe, apexi power fc with commander and boost control kit.

With the new engine fitted, the gtr was tested and driven for one week,
the engine is running fine, oil pressure is good, they just had to adjust the idle that was a little too high, adjust the power fc map, and all the knock, wideband and other measures are ok.

Now after driving the car for one day, after one hour driving on the highway,
it started to do some short misfires, similar to a boost fuel cut, sometimes around 4000rpm and not under full load.

When doing this the engine check light was sometimes coming on for less than one second, without flashing at all.

Anyone has some suggestions on what it could be?

It was also raining, I don't know if this could have caused some water to get in the AFM's with the standard airbox, or if it could be something else, injectors, spark plugs, coil packs or just something wrong in the power fc settings but it shouldn't have driven perfectly for some time.
 

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i had similar probs last night (r32)

even after fitting brand new coilpacks

there was quite abit of water in the engine bay as i had it just valeted

just taken it for a spin this morning , and its 100%
 

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I have had these problems for weeks now and its really annoying me. You can try all the usual checks first like:
AFMS
Inlet manifold leak
Plugs
Coilpacks
Ignition amp
Injectors

Let us know how you get on.
 

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Discussion Starter · #4 ·
What I would like to know is why the engine light comes on, as it detects that something is wrong, so maybe it shouldn't be something like a spark plug as it wouldn't probably be detected by the ecu, but something like the AFM would.
 

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Discussion Starter · #7 ·
No I didn't check the earthing.

I don't know if it would do an angine light if it's just earthing.

Anyone who uses a power fc know what it can be when the engine light just come on for one second and doesn't flash?
 

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missfire

I have a uk R34 which had a missfire which i put down to low milage and lack of use! I took the car to middlehurst for a service and asked them to change the spark plugs to try to cure the missfire, this did nothing so they put the car on the fault finding machine (whatever this is!!!) and this turned up a oxygen sensor fault. they changed the sensor, which cured the high tick over and stopped the missfire-car now runs 100%. who says middlehurst knows nothing! they certainly did a good job on my car.
 

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Discussion Starter · #11 ·
I opened the airbox, and the air filter was slightly humid, and a very small amount of water was in a corner of the airbox, I cleaned it and I cleaned the AFM's net, and I noticed that the bottom net was more wet.
I cleaned them and I started the car and rev it some times, after that the botttom AFM net was slightly wet and there were some little splittings of dirty water. The maximun AFM voltage value on the power fc now shows around 5115 when before the problem it was never going above around 4900, so probably it's an AFM problem.

I would still want to know why the engine light comes on and what exactely is causing the fuel cut at around 5000rpm, is it the power fc that cuts as it doesnt get some value frome the AFM or is there some cut in the fuel supply caused by the AFM?

I will try some other standard AFM this week.
 

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Discussion Starter · #16 ·
It was probably the airflow meter that get some water.
I opened the airflow meter and it wasn't wet, but I ve resoldered 2 weldings that looked slightly less nice, and I also cleaned it with some brake cleaner.

When I fitted it back it just did the engine light once when the AFM value on the power fc went over 5000mv, maybe as the brake cleaner was not completely dry, then it worked perfectly.

I will probably get some nismo or other afm anyway as the standard ones are almost at the limit of their range.
 

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It was probably the airflow meter that get some water.
I opened the airflow meter and it wasn't wet, but I ve resoldered 2 weldings that looked slightly less nice, and I also cleaned it with some brake cleaner.

When I fitted it back it just did the engine light once when the AFM value on the power fc went over 5000mv, maybe as the brake cleaner was not completely dry, then it worked perfectly.

I will probably get some nismo or other afm anyway as the standard ones are almost at the limit of their range.
I've had water droplets hit the AFM on my car and the symptoms are exactly as you describe. When I checked the datalogging the AFM signal was spiking to just over 5 volts which caused 'boost cut'. Eradicated the water ingress and its been fine since.
 

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Discussion Starter · #19 ·
Ciao Carlo,

Yzr is coming here tomorrow and he's bringing your afm so we can try them,
Thanks a lot.

Is the "boost cut" made by the power fc when going over the max voltage of the afm, or is it made because the fuelling is wrong because the afm readings are wrong?
 

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Mine is doing the same thing and has been for a while. Cleaned the AFM's a couple of weeks ago and it ran a lot better. Now its up to its old tricks again, losing power at random times and bogging down completely. Usually doesnt stall, just fluctuates around idle for a few seconds. If you put your fot to the floor on the throttle to try and break through the spluttering it almost dies.
I've also noticed of late that the EGT light flickers ocasionally (1 or twice) when its bogging down.
Also my fuel ecomony is horrendous( even for a GTR!!) which leads me to believe that when the AFM's are 'doing their thing', it leads to massive overfuelling. I say this as, if I keep it in a lower than normal gear and keep revs high, its less prone to bogging down.....

Luckily, i've got some NISMO AFM's ready to go on. Gonna get some Sard 700's and a Tomei rail first before I send it away for remapping.

TT
 
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