02+ VFR Tuning Suggestions

[keeena]

Hey all. I recently picked up a 6th gen Honda VFR. Have an appt at Rob's Dyno to get it properly mapped in a couple weeks. It currently has Staintune slipons, Oxygen plug mod and PCII.

I have a feeling its running a bit rich, but thats just a gut feel. And it does have some odd FI in this 1 case: when cruising between 3-5k rpm for a short while. If I start to give it a little gas, nothing really seems to happen. Then all of a sudden the bike will accelerate with an abrupt jolt. This was happening quite frequently when in traffic and cruising around 40-50mph. (BTW - def. not the 7k VTEC kick...that is very distinct). So I figure a proper map according to real A/F will help sort things out.

I'm looking for breathing mods to make that may help tuning. I'll be removing the PAIR. Any other suggestions? Heading over to a VFR-specific forum, but figured I'd throw a shout out here incase anyone has suggestions. I may spring for a PCIII if it has benefits over PCII.

Oh, I already like the bike a lot. It has couple minor quirks, but a nice all-around performer. Thanks for those who recommended it in the "2-up" thread.

[benVFR]

You mean a PCIII right? There is no PCII for the 02+ VFR, only the PCIII.

Start by zeroing out the map so you're running the stock map + the O2 Sensor mod. To do this you can plug in a laptop to the PC, let it load the map out of the bike, save the map, and then put zeros in all the cells in the map and send it back to the bike.

The 4-5k "stumble" is supposed to be caused by the Oxygen sensors, if you have the correct O2 Eliminators it should go away.

Two things to check for since you didn't do the mods:

1) This bike has 2 Oxygen sensors, both right next to each other. Make sure they were both unplugged and have O2 Eliminators plugged in.

2) VFR owners are really cheap.. it's been very common for people to try and make their own O2 Eliminators with resistors from Radio Shack to try and save $10-15 dollars. Make sure they didn't do it wrong if they did it this way. The wrong resistor would definitely fuck up the bike.

Chances are good it's just a bad map.

The only thing PAIR removal will do is eliminate the "crackle" sound you hear when you get off the throttle and let engine braking slow you down. It will also damage your Catalytic converter. You don't need the Catalytic converter, but you won't get any real extra power by getting rid of it. To get rid of it you either need to be good with tools & welding and do it yourself, or you're talking about $1000+ to get headers from Europe. Practically no one in the US has the race headers for the bike, they're very very rare. (You might not even be able to get them anymore)

The bike is very very lean stock.. so the only way yours is rich is a bad map or something else wrong with it.

There are lots of maps for VFRs on the internet, with just the Staintune pipes you shouldn't have to pay for dyno tuning.

[keeena]

Thanks for the info!

This is an '02 VFR and it *definitely* has the PCII. Com cable hookup, not USB. The Oxygen plug/s are from DynoJet (orig owner gave me all the paperwork for this stuff).

The guy I bought it from had 5 bikes, barely rode this one (3.5k miles). The bike was really well taken care of, he gave me all maintenance receipts from GBMS. It did have 1 or 2 Honda recall work items as well.

I read about gutting the cat. Aftermarket full pipes are that hard to come by, huh? I'm not trying to eek every bit of performance from this thing, just want to make sure that its breathing well. I know that mfr do alot due to emissions. Other bikes I own/ed seem to benefit real well when you remove that extra stuff & makes them much easier to tune.

The stumble is definitely annoying...I'll check on those sensors.

[benVFR]

I'd consider ditching the PCII or removing it completely.. almost sounds like someone shoe-horned the wrong model in?

I don't know what the deal is but Dynojet doesn't even list that as supported... If they ever did they stopped supporting it way back in 2002. I got a 2002 in spring 2003 and by that point they already weren't supporting the PCII on that bike.

I've also never read about anyone else having one BTW.. so any map someone might have to help you out won't work, cause they are all PCIII maps. (It might be possible to convert them)

Gutting the cat is just not worth it for performance. No one has even showed a dyno graph that even hit 105hp.. it's a total waste of money IMO. With the PC setup correctly you should be able to get it running nice and smooth with pretty even torque all the way from 3k to redline, no need to mess with any other mods.

Pretty much nothing on VFRd has actually been proven to do anything, take all the mods with a grain of salt.

If the guy only put 3.5k on it it probably only went in for the 600 mile service and/or if GBM put the PCII on for him.. it's probably due for an oil change and a checkup just due to sitting 5 years.

[keeena]

Cool, I'll consider picking up a PCIII. It was most likely installed by GBM. The guy did do regular oil changes despite low miles. It didn't sit for a long period, just few & far between rides (so I was told). Also has a Scottoiler (nice automatic maintenance, but I'm tempted to remove due to the mess it makes...just do it manually). Like I said, just want to smooth the FI, not looking to eek every ounce of power.

[keeena]

Chances are good it's just a bad map.

Yup, this was the case...

I was using Power Commander's pre-defined map for my setup (I think map # was 111-004). The generated map using Dyno Link was quite a bit different...much leaner on partial throttle, not as much add'l fuel compensation as the PC map.

Bike feels smoother now, especially off idle. And that 3-5k roll-on hiccup is vastly reduced. HP/Tq roughly the same.

FWIW. Thanks again for the other info...left PAIR alone.