R32 GTR RB26DET need help, any idea ?

[louiswun]

I'm recently having trouble on a R32 GTR RB26DET,
Car is almost fully stock, stock injecotrs, stock AFM, stock turbo...etc
Car run extreme rich on idle, TP read at 6X, only 500rpm due to too rich and a lot of black smoke on exhause.
Gear box "In Gear" switch works normal,
TPS idle switch normal, TPS 0.46 V @ throttle full close, 4.XV on full open throttle.
Intake air temperature sensor normal
Water temperature sensor normal
Rpm reading is normal (suppose crank angle sensor is normal)
Start switch is normal
Tried remove the ECU and AFM to another R32 GTR, work fine and rev freely without smoke, without any fault code. (suppose this ECU and AFM is good)
Tried swap another CAS, 6 X Ignition coil, 3 pair of AFM, same result,
Tried to rewire the AMF to ECU signal and signal ground, same result.
Checked the fuel pressure, normal at 3 bar, still hold pressure when engine is off, suppose it is not injector leaking.
Checked ECU valotage is around 12V.
Checked injector resistor at around 7.5ohm.
Checked Injector +12V power pin to car battery +ve side have 7.5 ohm (suppose injector resistor wiring is correct).
Swaped to another ecu harness (enigne to ECU, good harness without any wire cutting), result is the same.
Unplug HICAS ECU, same.
Car can start for few miniutes and stall due to too much unburnt fuel create carbon on the plug, remove all plugs to clean, reinstall, and it can idle at extreme rich for another few miniutes.
When idle, both AFM voltage is around 1.4V-1.6V, injector opening at around 6ms -8ms
No fault code.
Any idea that how or what factor affecting the injector duration so long?
Any other system on this car will give false load reading to the ECU ?

[skylinegtrhr]

Sorry not direct help but some general directions in similar problems:

Checked for boost leak ?
Lambda sensor OK?
Engine leak down test and compression test?
Air filter clean?
exhaust manifold and turbos OK?
Timing belt alignment verified?

[PL]

Hi Louis,

I'd be having a close look at AFM voltage and inj time on a good GTR and then compare these figures to the rich car.

PL

[louiswun]

Hi PL,

Thank you for your help !
Sorry, found out it is loose intercooler pipe, but I still don't understand how it make the injection pluse so long.
I my mind that if the intercooler pipe is loose, there shoud be some air go inside the engine without pass through the AFM,
it should be lean !

What I guess is if engine on idle, if the engine cannot maintain the same rpm on idle rev target map, it will give more fuel and cause this trouble.

Louis

[PL]

Yeah, weird that it was so rich from an air leak. As long as it fixed the problem...

A problem I've seen with these is that the throttles don't seal properly and so they idle very high - which can't be fixed without somehow re-sealing the TB's. This can really mess them up.

My friend finished up sealing his by very carefully wiping the throttle butterflies with silicon sealant (after coating throttle bores with a smear of grease). I've since seen OEM butterflies with a similar treatment on injected m/cycles. This is almost a surgical operation (he is actually a doctor so I guess it's only fitting!) which required complete dissasembly of the inlet. But he reckons this transformed the driveability of the car.

PL

[steve_s13]

mmmmm i may give that a go myself Pete cheers for that tip