Testing Cas (and Other Problems)

[Mullett86]

I was wondering if anyone had a way to test the CAS for proper function? I'm having a high-rpm problem with my R33 GTS-T. Basically 5k-redline it pulls and surges a little, boost pressure rises and the power drops noticably in spurts and surges up to the redline. It has new coilpacks and a new fuel pump, so I'm starting to run out of ideas. Maybe 02 sensor? But I didn't think that impacted full-load fueling. I've cleaned the AFM and checked for vacuum leaks...Any ideas?

RM.

[simonr]

i dont know about skylines speciffically, but that sounds like leaning. are the injectors thmselves flowing well and consistently

[Mullett86]

i dont know about skylines speciffically, but that sounds like leaning. are the injectors thmselves flowing well and consistently

That's another possiblity, it sure feels like lean out. I have no idea about the injectors, although there's a chance it has a z32 AFM on it, and the ecu wires have been spliced in the past and then snipped. So maybe it has a bigger AFM (I have no idea how to tell them apart, does anyone know part numbers?) and haas been re-tuned in the past and then the interceptor has been pulled out. I'm starting to think it's a bit of a bitsa.

RM.

[jeffworld2]

sounds like you are running too much boost for the ecu to handle. look up rich and retard. if your lucky your afm may be the problem showing high volts or its the wrong part. it should ahve a part number near the power plug on it

[Mullett86]

sounds like you are running too much boost for the ecu to handle. look up rich and retard. if your lucky your afm may be the problem showing high volts or its the wrong part. it should ahve a part number near the power plug on it

Good stuff, keep that info coming! I'm only running about 8psi of boost, and the symtoms occur even at the competely factory boost setting. I can't find a P/N on the AFM, not on the top anyways. All it has is the 'Nissan' symbol. Apart from that, near the plug, it's blank. The plug has 5 pins, but only 4 wires. The connection missing is the one closest to the air filter. Does that help at all? Maybe it isn't a standard one. Today was warmer, about 30deg, and the car runs awfully. Good boost, but bugger all power, and revving it past 5 just isn't an option, it feels BAD.

RM.

[MrStabby]

Just to check - have you changed the fuel filter and spark plugs?

If its over-fuelling you'll have black crap on your rear bumper, and probably be able to see it in the rear view mirror. Maybe get a mate to follow you to look for black smoke. What boost are you running? If its not stock, pull it back to stock and see if the problem goes away.

[Mullett86]

Just to check - have you changed the fuel filter and spark plugs?

If its over-fuelling you'll have black crap on your rear bumper, and probably be able to see it in the rear view mirror. Maybe get a mate to follow you to look for black smoke. What boost are you running? If its not stock, pull it back to stock and see if the problem goes away.

The plugs have been done, but not the fuel filter. There's a small brown burn on the rear bar, but not a trace of black smoke on acceleration. It behaves exactly the same on stock boost, which makes me wonder. And the problem is definitly far, far worse on a warm day (30-odd today), it's almost undriveable at anything more than 20% throttle. No power, surges, it's all over the place. Driving me insane!

RM.

[Psymon]

I had a similar problem to what you are describing in my 32. I did fuel pump and bigger injectors in one go. One of them fixed it. Since you are only running std boost maybe your fuel pump is dying.