Fuelling mods - Nitro-X and Kev mod - .: XT660.com

DaveR · # 1 01-09-12, 01:01

Hi,
This thread is a continuation of a thread which started off in the Newbies Reception Lounge. The discussion was getting a bit too deep and detailed for that forum, so I propose to continue it here.

I can't move the previous discussions (only Admin can do that) so here's a link to the previous thread in the Newbies Lounge: http://www.xt660.com/showthread.php?t=19581

Quote:

Originally Posted by DaveR

Hi guys,
A short update for any of you who may be following this thread. Well, I'm pleased to report that I installed the Nitro-X module last weekend, and it's working just fine and dandy.

I carried out a bit of lab-style testing before installation. Using a multimeter, I measured the resistance of the IAT (inlet air temp) sensor at several temperatures, cross-checked it against the sensor specifications in the Service Manual, then measured the resistance of the Nitro-X on various settings so that I could determine accurately what the "zero" setting was.

I was able to determine the actual values of the four on-board resistances and, with a little basic electrical theory for resistors in parallel, successfully proved and verified the other eleven settings available. (1/RT = 1/R1 + 1/R2 etc.)

Once the Nitro-X was installed, of course, you can just read off the temperature from the on-board diagnostics display (D05: Inlet Air Temp) which the ECU is being "fooled" into believing. All I need to do now is determine the best setting to use for my particular mods, which is the same as deciding what position to set the knob to on the Kev Mod. Unfortunately I don't have access to a gas-analyser, so it'll have to be seat-of-the-pants tests for me!

Would be pleased to share any or all of this data with anyone if you're interested, but I'll take it to one of the technical forums if you do - the Newbie's Lounge isn't the place for too much detailed info!

Cheers all!

Quote:

Originally Posted by oldf4RT

Ais mod works very well. Did mine last week and stops almost all the popping. Block the pipe off at the airbox and re-fit as per Kevs mod' guide. much better - I don't mind an odd pop but it was too much before.

The CO number can be different for each bike and can be anywhere from -128 to +128. I know what mine was originally and have increased the value by 20. I intend to put it back before using the new O2 eliminator.

Made my own Kev mod with a 1k ohm resistor from Maplin. Total cost incl' housing box, knob and wiring was less than �5. Sometimes I think it works and some days not ? I believe you need to control the O2 sensor (not eliminate it) as this senses oxygen level and adjusts at low throttle openings whatever else you do so overrides everything else. I may not be exactly correct but I've thought i'd cured it a couple of times only for it to come back.

I also think that somedays being more confident (sub consciously ?) and opening the throttle earlier and slightly harder going into the middle of a corner might make a difference. Also and I know I've said it before but chain slack and loose cush drive rubbers makes more difference than you'd believe. Several other people have pointed this out to me in the couple of days since I joined the forum.

Good luck.

Quote:

Originally Posted by oldf4RT

According to my Kev mod book the resistor is 1k ohm. On my bike that gives me 0 to -8 degrees air temp adjustment.

I think we need to move this somewhere else on the forum but not sure how. I'll ask my 16 year old son tomorrow - i can hear him even now - "give it here then - it's easy"

DaveR · # 2 01-09-12, 01:26

Hi oldf4RT,

So tell me a bit more about your fuel mod. You added a variable resistor (like a Kev Mod) but it's a 1K pot? Have you wired that in series with the IAT (intake air temperature) sensor?

If so, it sounds like a good idea because it'll both measure the actual ambient air temp, as well as allowing you to "turn down the temperature" to increase the fuelling.

In the previous post (in Newbies) Pleiades mentioned that the current Kev mod is 0 - 10K ohms. I'm therefore guessing that it's probably wired in place of the IAT, not in addition to it? According to Service Manual the standard IAT has a resistance of 2.21 - 2.69K ohms at 20C.

I've installed my Nitro-X module (as per instructions) to replace the IAT, so the ambient temperature no longer has any input into the ECU, but the more I think about this, the more I see it as a disadvantage. I like the idea of wiring the modifier in series with the IAT so you get the benefit of both.

The Nitro-X module contains four resistors which, through setting a four-position DIP switch, allows a variable resistance from 1.259K to 6.830K ohms. From my tests, this allows selection of inlet air temperature from +37C to -4C. Choosing anything above actual ambient temp (say 16C today) will therefore weaken the mixture, of course, so that's of no benefit for our purposes, but choosing anything between 16C down to -4C will progressively richen the mixture.

When you say "Sometimes I think it works and some days not" it makes me wonder if this is due to the change in the ambient temperature? If I set my NitroX to fool the ECU to get 16C when the true ambient is 21C then I'm getting 5 degrees of enrichment, but if the true ambient falls to 16C then I won't be getting any enrichment at all!

I don't really want the hassle of continually tweaking the setting according to whatever the ambient temperature happens to be that day, so that's why I like the idea of wiring the IAT in series.

For the most part, my bike is running really well now (anything over 5-10% throttle) but I still have slight glitches at small throttle openings, in fact as you so aptly put it: "...can't get clean throttle response coming off closed throttle entering corners. Very annoying as it upsets balance and also my confidence."

waynovetten · # 3 01-09-12, 10:35

I've seen little on the Nitro X,the time honoured way is DNA 1 and 2,Kev's mod,remove snorkel,drill holes,go to a PC if you want a touch more go and also gets rid of the snatch.

It's the route I went and I've a Kevs fuelling mod if you want to loan it to compare.

oldf4RT · # 4 01-09-12, 10:58

Dave,

You're exactly right. My 1k resistor is wired in series with the air temp sensor. When monitoring via the dash display it gives me zero to -8 degrees adjustment against CURRENT AMBIENT temp. This means that when set to say -5 it fools the bike and makes the mixture richer and will always do so at whatever the ambient temp is. I believe that the statement that the current Kev mod is 10k is incorrect. It is 1k.

My hunch (and it only a hunch) is that even with this active - when at low throttle openings the oxygen sensor reads the exhaust gas and cancels out the air temp adjustment that we have made and thus causes hesitation due to weak mixture.

I'm away in the US for a couple of weeks now and when I come back my plug and play oxygen sensor eliminator will have arrived from Kev and I'm hopeful that this will work. If not then a Power Commander will be the only way.

The new plug and play oxygen sensor eliminator is more sophisticated than the current one and is also easier to fit as it plugs directly into the harness in series with the O2 sensor. It adjusts the O2 sensor signal to richen up the mixture rather than trying to cancel it out altogether.

This is Kevs reply to my questionregarding the cheap,plug in O2eliminators you can buy on ebay. It's very much consistent with my hunch about the O2 sensor. Do you understand the closed loop and open loop ? I assume when closed loop the circuit is completed by the O2 sensor and gets feed back from it and when open it doesn't ?

The resistor type O2 eliminators do not work on the XT660X,R or Zs we have
proven this on the Dyno, the only 2 that do work is Dynojet's O2 Optimizer &
my O2 eliminator. I now have a new plug & play version O2 eliminator for the
X & R models, photos attached.

My fuel mod, a PCV or PCIII can only adjust the A/F ratio in the open loop,
as soon as you start cruising the closed loop comes into play & takes
readings from the O2 sensor & will lean the A/F ratio out again no matter
what fuelling device is fitted to your bike. To completely control the A/F
ratio you will require an O2 Optimizer or one of my O2 Eliminators[/COLOR]

waynovetten · # 5 01-09-12, 11:53

Even though I have two bikes with PC's fitted I wouldn't buy one now unless it's cheap,my K1200 which has dubious fuelling at best has needed sorting for a long time,this last week has been a 9.9 on the Richter scale because aftermarket fuelling is changing!!! the days of bolt on fuelling mods are on the way out,the difficulty for me was beleaving it, which I didn't a week ago,it's been a shock to say the least.

Pleiades · # 6 01-09-12, 13:08

Quote:

Originally Posted by DaveR

In the previous post (in Newbies) Pleiades mentioned that the current Kev mod is 0 - 10K ohms. I'm therefore guessing that it's probably wired in place of the IAT, not in addition to it? According to Service Manual the standard IAT has a resistance of 2.21 - 2.69K ohms at 20C.

No, the Kev fuelling mod is/should be wired in series. It does not replace the IAT sensor.

Quote:

Originally Posted by oldf4RT

My hunch (and it only a hunch) is that even with this active - when at low throttle openings the oxygen sensor reads the exhaust gas and cancels out the air temp adjustment that we have made and thus causes hesitation due to weak mixture.

Your hunch is right - the closed loop governs fuelling up to 3000rpm, small throttle openings and while on the cruise.

Kev · # 7 02-09-12, 00:22

Correct the air temp is always been read even in the closed loop, but any adjustments made to the AT sensor will be over ridden by the closed loop circuit.

My fuel mods have been update with 4 different versions over the past 6 years it is connected in series to the AT sensor, I know of better ways to build the mod but it's all about the cost of the mod in the end, the main purpose of my mods is to make them as cheap as possible to the guys that can't afford expensive fuel mods. I removed all the info on how to make your own Kev fuel mod from the open forum because there was member on this forum that decided he would mass produce my fuel & spacer mods & start to sell it for himself. The info is still avaiable to supporting Forum members to make their own through the ASK Kev section.

I always offer proof of my mods by means of Dyno runs or other means.

http://www.youtube.com/watch?v=glkdBO8aZm0&feature=channel&list=UL

Part of a discussion we are having in the ASK KEV section at the moment were I cover this type of info in detail.

There are 2 sides to a fuel map, closed & open loop circuits.

A Power Commander or any other type of fuel mod can only adjust the fuel map in the open loop, the open loop circuit is when the the ECU sees sudden acceleration, any RPM above 4500rpm & all throttle openings over 20%, cruising or not cruising.

The closed loop is used for emission control, it comes into effect after a coolant temp of 70 degrees C, when the ECU sees a constant throttle opening of below 20% & below 4500rpm, the ECU takes voltage readings from the O2 sensor & will lean the A/F ratio out until it sees a A/F ratio of 14.7:1.

The resistor type Eliminators do not work we have proven this, at the time of proving they do not work Dynojet pulled all the XT660 resistor O2 eliminators from their for sale lists. The ECU constantly looks for 0 to1 volt square wave signal, by unplugging the O2 sensor & fitting a resistor it sends a constant voltage signal to the ECU, after a few min's the ECU see this as an corrupt signal & then constantly switches the A/F ratio up & down, in this state the bike is not tuneable. Below the You Tube test is with a resistor type eliminator connected & the A/F ratio has been data logged.

http://www.youtube.com/watch?v=ZwTfuwZZ848&feature=channel&list=UL

The only 2 types that have been proven to work are Dynojet O2 Optimizer & my O2 eliminator/controller.

I have 2 types of O2 eliminator/controller one completely turns off the closed loop circuit & the latest type controls the O2 sensors voltage outputs.

By controlling the closed loop circuit we are able to reduce the surging when you are cruising, with one of the latest O2 devices when the ECU switches between the open & closed loop circuits the transition is much smoother as the A/F ratios are closer to each other, see table below.

Open loop for most HP & Torque= 13.2:1
Closed loop A/F ratio = 14.7:1
O2 Optimizer or kev's latest O2 controller = 13.6:1

Pleiades · # 8 02-09-12, 00:53

I think what he (oldf4rt) was implying with his "hunch" was that whatever he does in adjusting the fuel mod the closed loop will always cancel out its effect (that of adjusting the fuel mod), I don't think he meant that the ECU isn't taking a reading from the intake air temperature sensor?

Xia Kun · # 9 29-03-13, 08:06

Checked the ECU, it's 5VK-8591-01.

Took it out Yesterday, with CO up 8 places & AIS done. Seems to be better. Have increased the CO up another 2 to make that 10 in total. Any limits on that increase? Still getting a lot of back fire. But that doesn't really! worry me too much. It's more the fuel delivery.
Will get back on how this runs again.

Kev · # 10 29-03-13, 10:29

Quote:

Originally Posted by Xia Kun

Checked the ECU, it's 5VK-8591-01.

Took it out Yesterday, with CO up 8 places & AIS done. Seems to be better. Have increased the CO up another 2 to make that 10 in total. Any limits on that increase? Still getting a lot of back fire. But that doesn't really! worry me too much. It's more the fuel delivery.
Will get back on how this runs again.

A 01 ECU would have been changed under warranty.

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