PAIR Valve Mod VFR VTEC?
I have an ‘04 VFR and in this VFRD scenario PAIR is disabled,
1) With PAIR disabled it seems there would be less 02 in the exhaust (and quite possibly more unburned fuel too since I run a PCIII). More unburned fuel and less 02 in the exhaust means a tougher environment for the cat, suggesting risk of clogging or damaging the cat. Thoughts?
2) I disabled PAIR by plugging the fitting that goes to the air cleaner housing and by plugging the "A" port. I used rubber automotive caps. The strange thing is the idle went down somewhat. Why I wonder?
3) Some claim improved engine tractability with PAIR disabled. Thoughts?
Last edited by Chumly; 05-23-2005 at 09:07 AM.
After reading the VDisc thread I'd say they're kidding themselves as to the preceived benefits. The only real way to know for sure is to disable the system (by unplugging the solenoid) and see if it runs any better. If you do decide to disable the system I can't see it causing any damage.
Originally Posted by Chumly
I just spent 1/2 the day with the PAIR enabled and 1/2 without, AFAICT no net change.
Why do you think the cat will not be 02 starved / HC overloaded without the PAIR?
I wouldn't disable the PAIR system personally. Having the system disabled will make emission readings higher (at idle mostly)and the Cat will not light up as quickly.
Originally Posted by Chumly
Most catalytic convertors "store" O2 when it is in abundance (ie. decel) to be released when o2 is lacking (ie. WO Throttle). Since the VFR has closed loop fuel control the PAIR can't operate during cruise since the added O2 will confuse the O2sensor. This means that the Cat isn't receiving any extra o2 for 90+% of the time anyways. So I doubt that the Cat will ever be O2 starved during nomal operation because the PAIR is disabled.
As for HC overload; on a normal running engine, HC spikes the highest during decel (500% higher then idle is common). Unfortunately the PAIR system can't function during decel. If it did you'd probably soil yourself from the massive backfire it caused. So the Cat once again isn't being helped by the PAIR system.
I's imagine the only time the PAIR system is active, is at idle or during warm up.
The above info is just from my experience on automotive emission systems. The Viffer might be different, but I kinda doubt it.
Great info on how a cat works, I learned lots The VFR is different as compared to new autos in that it *only* runs in closed loop during steady state moderate throttle cruising and only for emissions. Then the VFR 02 sensors work with the ECU to lean out, all other times it's open loop.
Modern autos run closed loop much more often as I understand it. Thanks much for your views on the PAIR's interaction too.
Last edited by Chumly; 05-24-2005 at 07:38 PM.
Your correct. All cars '96 and newer (OBDII) are in closed loop at all times once the engine and/or o2(s) reach a set temperature. The only exception being at 80% or greater throttle openings, the ECM goes to open loop at that time.
The VFR is quite advanced for a bike, but it's quite simple compared to current cars (which is a good thing)
Not that I am an expert, but I am not convinced that being simple compared to current cars is a good thing in this case. Unless it is a carbureted bike like the FZ1 and you pop on Ivan’s kit for example http://www.ivansperformanceproducts.com/
The damn VFR is in the interim stage that cars were in maybe +10 years ago, where the systems would work but were not sensitive, sophisticated and smart enough to fully support the engine’s requirements while providing lower emissions.
The new VFR meets 2008 emissions with engine support technology a decade or more out of date.
Motorcycle fuel injection is fairly trick as far as PCM speed, injectors and throttle bodies. It is simple in terms of the number of different systems needed (ie no Idle speed control, no EGR system etc). The problem is that it's much more diffucult to map a small displacement, high revving engine with very little flywheel mass than it is to map a big, low revving car engine with a 40 lb flywheel bolted to the crank. Unfortunately, to meet current emission standards(which are very generous compared to automotive) and still make expected HP you need to have fuel injection, carbs can't cut it anymore.
My '99 VFR (open loop FI) is almost dead on perfect except for a bit of abruptness off idle. I know there are lots of threads on VFRdisc. about 6th gen FI quirks and from the sound of your posts you are less then pleased with your bike. What problems are you having?
Steady state moderate throttle cruising surge: solved by starter valve sync and 02 eliminators, no more closed loop leaning out during steady state for emissions and economy.
Disturbing VTEC transition @ 6800 under light loads, low gears; exaserbated by slow RPM sweeps through the VTEC transition range: moderated somewhat by Power Commander III and Dynojet 001 map (VTEC in it’s present form on the VFR is an irritating high tech waste of time)
Off idle abruptness: moderated somewhat by Power Commander III, Starter Valve Sync and throttle cable slack reduction (Honda needs to go dual like Suzuki)
Last edited by Chumly; 05-26-2005 at 07:47 AM.
Sounds like you've tried all the tricks, guess all thats left is custom PC mapping.
I've rode the 6th gen bike a couple times and the VTEC is awful. Honda really dropped the ball. Hopefully the 2006 VFR is improved.
I am not considering custom PC mapping because IMHO it opens a mega can of worms in which operator error, accuracy, constancy of the dyno and general working environment are too big a set variables when optimum smoothness at a presupposed ideal-best F/A mixture is one’s goal. Is an air/fuel ratio range of 13.2 to 13.5 the best for smoothness on a VFR? I don't know.
IMHO there is no way even if the all the above variables are sufficiently moderated that a dyno alone will indicate how the bike really operates on the street in terms of optimum throttle smoothness. You would need to back up the dyno testing with really accurate street testing, and then back to the dyno, and then back to the street repeatedly. Even after all that you can't exempt the VTEC transition which rears it's ugly head most prominently under light loads, lower gears while transitioning slowly through the VTEC engagement range.
To give you a more clear example of what is required for a smoothness map have a look see from a dedicated FJR1300 Dynojet man http://www.fjr1300.info/misc/PC-III.html
“The M409-MF008 map uses the foundation of several available maps that were mathematically combined trying to get the best of all worlds in terms of power, mileage and smoothness. I then took that base map and loaded it in my PCIII USB unit, put the FJR on the dyno and spent lots of time mapping cell by cell to an air/fuel ratio range of 13.2 to 13.5 from 5% throttle at 1500 RPM to 80% throttle at 6000 RPM. I then tweaked the 100% throttle numbers from 3000 to 6000 RPM. I'm a fanatic about perfect throttle and low RPM manners so the tweaking reflects this. I'm also wild about decent mileage and this map should provide that, or it should be no worse than what you have BUT all bikes are different. It could make your mileage worse or provide the incentive to use the throttle more and make your mileage worse. You be the judge. I did not tune this map for top end power. Don't expect any. My bike with this map is dead-assed smooth; the throttle is to die for — the bike lags nowhere and picks up power from any RPM at the snap of the wrist. I hope it's the same for you.”
What do you think Ryan?
I've personaly never remapped a PCIII, but if I was going to this is what I'd do:
If you spend a bunch of time on a steady state dyno I'm sure you could figure out a fantastic fuel map and probably even smooth out the VTEC transition. Of course this takes buckets of $$ and time. The best A/F for power is 12-12.5:1. I think this would be a good place to start, run a bit rich for power/smoothness then experiment by subtracting fuel a little bit at a time to regain mileage. I believe running on the rich side (12:1) from idle to 3000rpm helps the abruptness problem.
Agreed, but the buckets of $$ and time is not very appealing particularly on Honda’s techno flagship beast. The only Dnojet approved facility in the lower mainland that talked to (Future Cycle House of Speed) did not sound to me to be the brightest bulbs in the box, although their prices were electrifying. They did not even know the VFR had a cat and would need to be tested pre-cat!
Which Dnojet approved facility has the smarts and the goods I wonder?
Duncan Motorcycle Sales
1063 Canada Ave.
Duncan BC VL9 1V2
Fat Guys Racing
#114 7198 Vantage Way N.
Delta BC V4G 1K7
Fury Sports/Newman Racing
3B-35-4320 29th Street
Future Cycle House of Speed
2145-21000 Westminster Hwy
Richmond, BC V6V 2S9
Kamloops Mobile & Repair
RR 5 S2 C264
Kamloops BC V2C 6C2
Modern Motorcycling LTD
2816 Commercial Dr.
Vancouver BC V5N 4C6
11955 95A Ave.
Delta BC V4C 3W1
S & M Cycle
2758 Peatt Road
Victoria BC V9B 3V3
1107 Goldstream Ave.
Victoria BC V9B 2Y9