light load surge finally nailed

[Camel]

You will find most of the problem will be in low end fuelling and is usually at light throttle where the IAP A/F and TPS A/F are floating from one to the other and if the settings are not correct as they jump back and forth to each other the transition creates whats felt as surge effect.

So true, but with Gen II this is not an issue because IAP (Intake Air Pressure) has an influence across the TPS (Throttle Position Sensor) range.

[fasterfaster]

Shit !!! what are you doing up in South Indonesia!!
Mate thats further north .................. Cairns area
But sure drop in for a beer .................. and a service by the time you get here

Mark have found Gen II up to 10 to 11 % throttle still best to fuel with IAP map ............ just spent 20 hours getting the lower settings sweeeeeeeeeet and smooth on my Gen II. Found was getting the same hunting to extreme at times when certian parameters where coming together on light throttle. If you watch in the software you can get a point of transition where you can actually watch the bouncing ball jump from one to the other (IAP to TPS)
Sent new lower map down to Bruce and he loaded it and said she's now as smooth as a babies bum whilst cruzin ............. which isn't very often with Bruce lol

[Camel]

Hey Pete, is that with HO2S activated?
With HO2S on you can definately see the AFR change at 1850-2000rpm. Not so dramatic with it off.

[fasterfaster]

Mark yep OFF ................ I only ever map with it off as I want control over all parameters. Would imagine it being more obvious with it on as it try's to fights for supreme lean all the time ............... thats why I chuck it.
Got a port fueller here your quite welcome to come play with ........... fun stuff.
Cheers

[Camel]

Got a port fueller here your quite welcome to come play with ........... fun stuff.

I'm back, fuggin work gets in the way of life.

Port fueler? I'll be you were calling Mr Hahn a fahn cahn....

[fasterfaster]

Mark nice software ............................ NOT ! #@%^***% Fuggin

[THEMOTORHEAD]

On the low speed drivability on the 99/2000 they get a vacuum signal to the fuel pressure regulator which seems to really piss em off when ya mod em.
when I map em i prefer to eliminate that so fuel pressures are stabilized under vacuum situations.
one of the reasons the 01 ran better low speed

---

You will find most of the problem will be in low end fuelling and is usually at light throttle where the IAP A/F and TPS A/F are floating from one to the other and if the settings are not correct as they jump back and forth to each other the transition creates whats felt as surge effect.

So true, but with Gen II this is not an issue because IAP (Intake Air Pressure) has an influence across the TPS (Throttle Position Sensor) range.

great points as well

[rb3221]

On the low speed drivability on the 99/2000 they get a vacuum signal to the fuel pressure regulator which seems to really piss em off when ya mod em.
when I map em i prefer to eliminate that so fuel pressures are stabilized under vacuum situations.
one of the reasons the 01 ran better low speed

---

You will find most of the problem will be in low end fuelling and is usually at light throttle where the IAP A/F and TPS A/F are floating from one to the other and if the settings are not correct as they jump back and forth to each other the transition creates whats felt as surge effect.

So true, but with Gen II this is not an issue because IAP (Intake Air Pressure) has an influence across the TPS (Throttle Position Sensor) range.

great points as well

THEMOTORHEAD
how do you go about eliminating the vacuum signal to the fuel pressure regulator?

[THEMOTORHEAD]

On the low speed drivability on the 99/2000 they get a vacuum signal to the fuel pressure regulator which seems to really piss em off when ya mod em.
when I map em i prefer to eliminate that so fuel pressures are stabilized under vacuum situations.
one of the reasons the 01 ran better low speed

---

You will find most of the problem will be in low end fuelling and is usually at light throttle where the IAP A/F and TPS A/F are floating from one to the other and if the settings are not correct as they jump back and forth to each other the transition creates whats felt as surge effect.

So true, but with Gen II this is not an issue because IAP (Intake Air Pressure) has an influence across the TPS (Throttle Position Sensor) range.

great points as well

THEMOTORHEAD
how do you go about eliminating the vacuum signal to the fuel pressure regulator?

STICK A BOLT IN THE HOSE YA DISCONNECT OR AT THE T PUT A CAP

[rb3221]

Are you doing it for just the mapping, or are you leaving it blocked off?

[fasterfaster]

Was on the Gen II this topic, and on the gen I would be a little concerned (read very) that when you pulled the line and fuel pressure rises whilst mapping then drops leavin ya lean after ? Or as RB asks ................. are you leaving it off ? I'd only do it if I could monitor pressure whilst doing so as the map settings are only relative to fuel pressure at the time of setting.

[THEMOTORHEAD]

Was on the Gen II this topic, and on the gen I would be a little concerned (read very) that when you pulled the line and fuel pressure rises whilst mapping then drops leavin ya lean after ? Or as RB asks ................. are you leaving it off ? I'd only do it if I could monitor pressure whilst doing so as the map settings are only relative to fuel pressure at the time of setting.

alway map no matter what
though ramair only makes a few millibar and its a 1-1 rate so its not jack for compensation
it will be richer slightly under vaccum wich is what helps the surge

[fasterfaster]

Thats where flashings nice MH ............... simply richen up the IAP settings in the light throttle areas and she's Sweeeeeeeeeeeeeeeet as

[THEMOTORHEAD]

Thats where flashings nice MH ............... simply richen up the IAP settings in the light throttle areas and she's Sweeeeeeeeeeeeeeeet as

[Ward P]

Well I finally did it. After this intermittant light surging at cruise in top gear that has been bugging me on and off for 5 years ('99 model), I've purchased a TRE. I purchased the "auto TRE" that bypasses the GPS, but wont affect idle. I will post up results when fitted.
-why have I waited 5 years - just pig headed I guess. -and who cruises on a 'busa anyway?

2 months on and surge at cruising pace seems to be gone now. Also feels more responsive down in the low gears and off the mark.

It also occasionally used to feel like the brake was applied slightly at times as you idled off the mark. This also appears to be gone now. Am assuming that this is because the GPE was sometimes sending dodgy signals, and is now bypassed.

The problems were intermittant before, so I can't be certain that it is fixed, but for now it seems good.
- or it may be all in my head!