FAQ: Fuel cutoff rpm's - Honda Prelude Forum

Absolut · 09-11-2002, 12:14 AM

Per my 1993 Honda factory service manual, page 11-48

Fuel Cut-off Control.

During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at speeds over 1,100rpm.

Fuel cut-off action also take place when the engine speed exceeds:
F22A1 (S): 6,600rpm
H23A1 (Si/SR): 6,800rpm
H22A1 (Si VTEC/SR-V): 7,700rpm
regardless of the position of the throttle valve, to protect the engine from over-revving.

Lots of intresting stuff in here, everybody should have one of these manuals.

red92si · 09-11-2002, 12:38 AM

but you gotta add in the extra 200rpm to account for the tach innacuracies.

Satan_SRV · 09-11-2002, 07:35 AM

Okay answer this as well. VTEC engagement is at 5000? That's what it looks like on my dyno sheet. But I always hear people say 5200...maybe that's just fifth gen?

U.K VTEC · 09-11-2002, 12:11 PM

Mine hits at 5000 too, at least that what the needle tells me...

brendon2k · 09-11-2002, 01:13 PM

Quote:

Originally posted by red92si
but you gotta add in the extra 200rpm to account for the tach innacuracies.

he could make a side note saying that the fuel cut off might appear to be at a differnt rpm on your tach but I think the point of the post is to tell people that 8k on their tach is only 7700rpm.

Absolut · 09-11-2002, 02:17 PM

Mind you, this is what the ecu is programed to do, the tach needle is driven off a completely different circuit.

I will check on the VTEC x-over point when I get home.

Forbidden · 09-11-2002, 02:27 PM

VTEC x-over is at 4900RPM page 5-7 in the helm (93)

also there's two other thing you need so VTEC engages:
the car has to go over 19MPH/30KPH
the engine coolant temp has to be 140oF/60oC or higher

Absolut · 09-12-2002, 12:14 AM

Quote:

Originally posted by Forbidden
VTEC x-over is at 4900RPM page 5-7 in the helm (93)

also there's two other thing you need so VTEC engages:
the car has to go over 19MPH/30KPH
the engine coolant temp has to be 140oF/60oC or higher

And more then 57psi oil pressure.

4thGVtec · 09-12-2002, 07:45 AM

unless you get a vafc, then the vafc will activate vtec at over 50% thottle and your set rpm. and i can say the rpm cut off on a 4th gen is 7700... the vaf said 7703 when i bounced... judging by the stock feel of vtec engagment, and tach needle postioning(autometer), it looks to be around 5050-5100 rpms on a 4th gen.

Forbidden · 09-12-2002, 11:47 AM

Quote:

Originally posted by Absolut

And more then 57psi oil pressure.

oh yeah I forgot about oil pressure