ECU cut out/Boost cut at 9.5psi?? Or faulty coils? R33

[HKS-R33]

I was getting rich and retard at 12 psi, so we dropped it down to 10psi on the dyno and still the same prob. So we ended up just leaving it at 12psi. Nothing a power fc wont fix. When my car was getting rich and retard it didnt feel like a miss, u could just see it in the dyno graph, there was dips all over the place.

Mike

[benl1981]

Hmm - so the rich an retard can't really be felt that easy? I can feel a definite hesitation in the power delivery above stock boost. Around 7-8psi it is fine - very smooth. Boost it and you can feel it isn't as smooth, kind of a little jerky..

I might leave the boost up to around 10psi and take it to somone to check.

Mine is series 1 though..don't know if the rich and retard is different for this..

[matthew33]

I realise that this is a late response to the problem but I have the same problem - especially as the car comes up to temp. It just felt electrical. Anyway I changed plugs and thought the coils looked a bit sus' - similar looking burn marks. I asked a few people including a workshop and auto electrician and they all said coils. So I forked out a grand for a set of spitfires and the car was no better. I thought I'd run some injector cleaner thru then change the fuel filter after. Still no better. The car doesn't loose coolant and as the compression in each cylinder is OK I can assume the head gasket is. I swapped the air flow meter (with a borrowed one) and changed the O2 sensor in despiration. Finally after checking air fuel ratio with a meter, it would appear that the ratio goes way lean as it misses. The O2 sensor looked like things were lean. Anyway I'm still struggling (and a bit poorer) so be sure before you fork out the $$ for the coils.

Plus if anyone has any clues why it goes lean I would be gratefull.

[Sydneykid]

I realise that this is a late response to the problem but I have the same problem -  especially as the car comes up to temp. It just felt electrical. Anyway I changed plugs and thought the coils looked a bit sus' - similar looking burn marks. I asked a few people including a workshop and auto electrician and they all said coils. So I forked out a grand for a set of spitfires and the car was no better. I thought I'd run some injector cleaner thru then change the fuel filter after. Still no better. The car doesn't loose coolant and as the compression in each cylinder is OK I can assume the head gasket is. I swapped the air flow meter (with a borrowed one) and changed the O2 sensor in despiration. Finally after checking air fuel ratio with a meter, it would appear that the ratio goes way lean as it misses. The O2 sensor looked like things were lean. Anyway I'm still struggling (and a bit poorer) so be sure before you fork out the $$ for the coils.  

Plus if anyone has any clues why it goes lean I would be gratefull.

What the fuel pressure like when it goes lean?

[siksII]

another late addition:

i believe the tune of my powerfc is way too conservative/rich as injector duty cycle reaches 98% at around 6500 and the car runs a much slower mph(8-10mph) and slow time when compared to stock ecu equipped cars with same mods but stock computer.

im not sure but could this be related to AFM, as my AFM maxxes out around the redline and i dont think this should be the case at only 10psi (other mods include full exhaust, fmic, exh cam gear, splitfire coils, shielded pod)

anyway so i thought i would swap the pfc for my stock ecu to see if the car is quick like others i am comparing too, and seems to go into rich and retard at anything above 4500rpm even in 1st.

there is a sudden jerk in accelleration, then the car starts revving up very slowly to the redline. im assuming this is R&R? maybe what ben is experiencing?

[benl1981]

Siks mate. Thanks a lot for that post.

Thats like what I get sometimes. Feels slow to go to redline and a bit jerky. Depending on loading/outside air temp and what gear I'm in affects how jerky it i, ie.e whether it was a sudden cut or just not real smooth when you rev it out.

I have got the boost at around 8psi and appears to be smooth almost all the time. 10psi was causing some problems on cold nights etc

Handy to know that yours with splitfire coils is the same. I think I can rule out coils as my problem aswell. Its either SAFC style gizmo or PFC it seems

[siksII]

yep sounds like we have similar problems it has to be the stock ecu as mine is fine with the pfc plugged in

untill i can get a retune, i might turn the boost down a bit to see if the problem with the stock ecu dissapears(as im assuming it will, as it did in your case)

[benl1981]

wierd even tonight running just over 8psi I can feel slowed acceleration when foot flat to the floor. Much faster at 1/2 throttle.

I have an R34 intercooler and full exhaust..maybe the extra airflow from these and the cold nights lead to a steep increase in airflow and cause the ECU to freak out at the readings?!!

Like to know how you go siks!

[siksII]

hey

i have not tried to wind down the boost yet, but i am sure my AFM is stuffed anyway. with the stock ecu it does not idle properly, it hunts and idles high most of the time, then goes into r&r after 4 grand and sometimes switches off

the pfc seems to hide the problems better than the stock ecu

so yeah i need a new afm AND probably a retune, so i dont even know if i will bother playing with lower boost!

[siksII]

ok i put the boost down to 8psi and it goes rich and retard, but at 6000rpm instead of at about 4600, the afm has to be reading high otherwise the car shouldnt go into r&r at only 8psi with my mods.

also with the stock computer compared to the pfc when i back off there is a lot more popping from unburnt fuel in the exhaust.

ill be trying another afm soon ill see how that goes