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How to ? O2 Bypass

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MikeLe

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I have gleaned the following comments & information from the Mega thread, but could anyone concisly describe the connections, wire colour, etc for the correct manufacture of a homemade O2 bypass.

cheers
Mike

Quoted from yhe Mega thread:
"What wattage resistor is in the dynojet bypass, do you know? I am betting it is a lower wattage similar to the Dobeck design. I experimented with a 1/4 1k before *I ended up with the 1/2 watt 1k *and the 1/4 watt did hold up for a while. The 1/8 watt in the Dobeck was tripping mine under 20 miles steady cruise but the 1st one they sent me lasted 6k miles, weird. I also noticed the Dobeck design has the resistor encased in epoxy, heat build up maybe. My homemade ones are not encased. I sodered the resistor tails to the female brass plugs and insert the plugs down in the coupler using needle nose pliers. All is tight down in the coupler. I used plain old electrical tape and loosely wrapped it over the end of the coulper when finished jus tto keep moisture out. So far with the 1/2 watt 1k in there NO light and the bike runs great 44 mpg yesterday on a fillup. 3/4 of the tank was a long 122 mile highway stretch at 80 mph the rest of the tank was my work commute which the speeds are much slower"

from the Manual:
Measure the HO2 sensor output voltage while holding
the engine speed at 3 000 r/min.
HO2 sensor output voltage at 3 000 r/min
0.6 V and more
((+) terminal: W/G – (–) terminal: B/Br)

HO2 sensor output voltage at idle speed
0.3 V and less
((+) terminal: W/G – (–) terminal: B/Br)

Heater connectiuons
Heater voltage
Battery voltage
((+) terminal: W/B – (–) terminal: Ground)

Anyone ?
 
Look at Dobeck or PCIII site, they are cheap. Hard part of a home made one is duraibility. I have a Dobek TFI and have gone through 4 rev's of O2 bypasses. Now I have a FI light that pops up during most closed loop modes on the interstate (4.1-4.8Krpms steady), seems that this stored code is a beast to remove. I have been sent a 320Ohm 1/8 watt, (failed), 800Ohm 1/2 watt (failed), 1K Ohm 2 watt(failed) now have a 4 watt 500Ohm (? have not stripped it down yet) and still see failures. However, since I did not get this old FI light code -C44 wiped by using an 'SDS w/CD set' any one of these bypasses, excluding the first one, might have worked. Bike runs fine W/light on but it is annoying. For less then $20 you can save some headaches. Top two wires (clip down looking at bike) are the ones to bypass, bottom two wires are Vin for the HO2S and ECU return signal. Remember to insulate the resistor from shorting to the frame and hopefully you will not get the light bug.

(DoBeck now states that their O2 bypass should work W/O light issues, however, this will cost me $60 to verify (code clean = 1 hour labor))
 
Cheers Mark
Found your post, interesting the "revisions" of bypass. Not sure I understand why the stator wattage should affect things

Still thanks for the connection description. Bypass is not $20 in the UK and postage to here would probably double the price :doh:
 
MikeLe said:
I have gleaned the following comments & information from the Mega thread, but could anyone concisly describe the connections, wire colour, etc for the correct manufacture of a homemade O2 bypass.

cheers
Mike

Quoted from yhe Mega thread:
"What wattage resistor is in the dynojet bypass, do you know? I am betting it is a lower wattage similar to the Dobeck design. I experimented with a 1/4 1k before *I ended up with the 1/2 watt 1k *and the 1/4 watt did hold up for a while. The 1/8 watt in the Dobeck was tripping mine under 20 miles steady cruise but the 1st one they sent me lasted 6k miles, weird. I also noticed the Dobeck design has the resistor encased in epoxy, heat build up maybe. My homemade ones are not encased. I sodered the resistor tails to the female brass plugs and insert the plugs down in the coupler using needle nose pliers. All is tight down in the coupler. I used plain old electrical tape and loosely wrapped it over the end of the coulper when finished jus tto keep moisture out. So far with the 1/2 watt 1k in there NO light and the bike runs great 44 mpg yesterday on a fillup. 3/4 of the tank was a long 122 mile highway stretch at 80 mph the rest of the tank was my work commute which the speeds are much slower"

from the Manual:
Measure the HO2 sensor output voltage while holding
the engine speed at 3 000 r/min.
HO2 sensor output voltage at 3 000 r/min
0.6 V and more
((+) terminal: W/G – (–) terminal: B/Br)

HO2 sensor output voltage at idle speed
0.3 V and less
((+) terminal: W/G – (–) terminal: B/Br)

Heater connectiuons
Heater voltage
Battery voltage
((+) terminal: W/B – (–) terminal: Ground)

Anyone ?
Click to expand...
Search :Roy
He can teach ya somethin
rworm
I have his
 
1/2 watt 330ohm has been in mine with no probs. I've since gotten a PC-III, and the one that came with it, checks 320 ohms. Roy's kept blowing , so I'm keeping the PC one for a backup, just in case mine ever goes poof!!

btw, the connector is behind left side cover, resistor goes between the orange and white/black wires of the ECU connection side of the plug.
 
I have the Dobeck bypass in mine now took 3 to get one that works over a day. I still have my homemade one as a back up. I used Suzuki female brass connectors sodered to a 1/2 watt 1k resistor with no errors. The 1/4 watt model failed usually after a long ride. You need enough resistance to fool the ECM that the O2 heater is working thats it.
 
MikeLe said:
Cheers Mark
Found your post, interesting the "revisions" of bypass. Not sure I understand why the stator wattage should affect things

Still thanks for the connection description. Bypass is not $20 in the UK and postage to here would probably double the price :doh:
Click to expand...

Only thing I can thank of is that since it came encased in hard plastic the wattage rating is no longer valid, wattage rating is based on free space permeativity (? no spell check) with air. Heat can and will build up and decrease resistance allowing your ECM to see > 1V in a closed loop mode. When I decapped the second Bypass (it came in a gel casing) it seemed to work better 330 Ohm, still 1/8 watt. When the 1K Ohm 1 watt one came (3rd Bypass) and it tripped the light first ride, I decapped it as well and my light issue became intermittent. Only saw it when ambient temp was < 65 deg F. The latest rev is very fat (4-5 Ohm?) but still encased in plastic. It tripped on the first ride. Then DoBeck sprung the news that I will need to clean the stored code by using the 'SDS'. My only issue is that if the Bypass returnes the correct voltage why would the ECM trip the light? I have reconnected the stock HO2 leads and never see the light (did notice power decrease & not as smooth). ??? I also never see the FI light when I sport ride (non-closed loop). For now I am dealing with the light. However, when the light is on your ECM is seeing a lean burn event and is increasing the injector duration at the expense of fuel use.

To return to your orginal question, the Bandit has a higher rated stator
(440W?) then most GSX'er, allowing/generating more heat for the Bypass to dissipate. But I am new to all of this Bypass stuff and I could be wrong about my logic.


Cheers,

Mark
 
Last edited:
Hi again Mark
I think the relationship between the two is non existant. The Altenator produces around 80 VAC, what it produces is dependant upon engine speed, the reg rec converts this to DC at about 15V and supplies the battery as required. When the battery is fully charged, the reg reg dissapates the excess as heat. The altenative would be to over charge the battery. This is why most reg rec failures are heat related & why fitting a cooling fan is such a good idea. Read any VFR forum it is a big topic.

The O2 bypass resister must "simply" provide a voltage drop to present the required Volts back to the ECM.
Given I = V/R, thus I = 12V/500 Ohms = 0.024A.
Power = VI = 0.288W (disapated as heat).
Remember headlights are 60W at 12V = 5A and how hot they are.

here endeth the lesson :-)
 
Can anyone confirm whether the 02 bypass units being offered now by Holeshot/Dobek and Power Commander are holding up well? In other words, have they fixed the units so that you don't get an FI light on?
 
Pecan7 said:
Can anyone confirm whether the 02 bypass units being offered now by Holeshot/Dobek and Power Commander are holding up well? In other words, have they fixed the units so that you don't get an FI light on?
Click to expand...

My 3rd Dobeck unit is holding up so far. I have about 3k miles on it no FI light yet.
 
mi1lertm said:
Then DoBeck sprung the news that I will need to clean the stored code by using the 'SDS'.
Click to expand...

You don't need to do this unless you want to. Once the light goes out (because you've changed the O2 bypass, or sometimes stopping and re-starting the engine is enough if the resistor hasn't failed completely) the fault code will be stored, but it won't affect the way the bike runs. It's only when the FI light is on that the bike will run (slightly) differently.

Pecan7 said:
Can anyone confirm whether the 02 bypass units being offered now by Holeshot/Dobek and Power Commander are holding up well? In other words, have they fixed the units so that you don't get an FI light on?
Click to expand...

Dynojet haven't, or hadn't a couple of months ago when I enquired - they're still using a 330ohm 1/4 watt resistor. Mine blew. I haven't been able to do many miles with the 1kohm, 1w resistor that I used instead but there was no indication of a problem in the few hundred miles I covered. I haven't cleared the fault code - that can be done next time the bike's in a dealer.....if it ever goes back to one.

MikeLe said:
Bypass is not $20 in the UK and postage to here would probably double the price
Click to expand...

Dynojet UK charge £17.63 for an O2 bypass. Not extortionate, but making your own is (in my experience) likely to prove more reliable in the longer term.
 
I'm not so sure about that. I have not blown the resister but during 80mph vaunts down the interstate I will get the light. When I turn of the bike and restart it the light is gone stating that the resister is functional. How ever per 'DoBeck' there is still a stored code in the ECM. They were not able to clear it with any of the tricks of the trade such as connecting the two battery wires and turning the key to the on posistion. They stated that their version of the 'SDS' was the only way to erase the code.

However, I am still wondering why I can not get the light to come in when I reconnect the stock HO2 sensor? Only when I used one of the four that I have received from them. I still believe that when they wrap these O2 bypasses in plastic or gel that there is a heat buildup causing a resistance drop which will have the voltage spike over 1 volt.

Are you saying that when you used your homemade verison that you never see the FI light anymore?
 
My resistor didn't blow straight away. Every now and then the FI light would come on at a steady motorway speed. Stopping and re-starting the engine put it out again. This was only occasional but the frequency started to increase. Eventually the light came on and no amount of on/off (or even leaving the bike overnight) would get rid of it. At this point I tested it and the resistor was open-circuit.

The theory that heat build-up causes the resistance to drop, triggering a warning, seems plausible. Well, eventually that heat build-up kills the resistor completely. You obviously haven't reached that stage yet, but it's probably only a matter of time.

You can't get the FI light to come on when you re-connect the O2 sensor because your sensor is functioning properly! The FI light indicates a current fault only - once it goes out (because the fault is no longer apparent) the fault code will still be lodged in the ECU but only as 'history'. SDS is the only way to clear this history, as Dobeck told you, but clearing it is optional and doesn't affect the way the bike runs.

I've not seen the FI light since putting my own, higher-wattage, resistor in as a bypass.
 
It's been a while since any O2 sensor issues have been mentioned. As I recall there were a lot of folks that were getting FI warning lights thrown up as a result. Has all that been resolved? What was the final cure?
 
Brass said:
It's been a while since any O2 sensor issues have been mentioned. As I recall there were a lot of folks that were getting FI warning lights thrown up as a result. Has all that been resolved? What was the final cure?
Click to expand...

I haven't had any problem, but the cure is simply to replace the resistor if/when it goes bad. Mine is 330 ohm, 1/2watt.....still working fine when I put it up for the winter a few weeks ago..
 
I suspect the 'cure' recently has been riding in cooler conditions. As the failures seem to be heat-related, cooler ambient temperatures mean that failure is less likely to occur.

I don't want to be branded a pessimist, but I expect the issues to return with the warmer weather, at least for anyone still running with a low-wattage resistor in the bypass. Roll on summer :lol2:
 
My latest Dobeck bypass is still working. I have had since August I think. I have not rode the 1250 much since I got the B-King:doh: I know it's a sad existance. It needed a rest anyway with 20k + miles on it. I still have my home made bypass in the tank bag just in case;-)

On a related note I find it interesting that the B-King with a O2 sensor and cat does not exihibit the surging the 1250 did in closed loop. I can't tell the B-King even has a closed loop system it works so well. Something must not be just quite right with the 1250's ECM processing unit or a sensor just not calibrated properly. The 1250 should operate just like the other Suzuki closed loop bikes. The GSX-R1000's with closed loop don't exhibit surging either.
 
Roy said:
On a related note I find it interesting that the B-King with a O2 sensor and cat does not exihibit the surging the 1250 did in closed loop. I can't tell the B-King even has a closed loop system it works so well. Something must not be just quite right with the 1250's ECM processing unit or a sensor just not calibrated properly. The 1250 should operate just like the other Suzuki closed loop bikes. The GSX-R1000's with closed loop don't exhibit surging either.
Click to expand...

The Hayabusa is Suzuki's flagship bike (if you ignore the race reps, but they probably have the same electronics) and has as sophisticated an injection system as is feasible for a production bike. So the B-King does as well. The Bandit is a budget bike with, one has to assume, a corrrespondingly budget injection system. I don't think it's any great surprise that the bargain basement bike has fuelling quality to match, or that the B-King has immaculate fuelling - at that price you'd expect it to! At the price the Bandit sells for I guess people are willing to be more forgiving....or to spend a bit of time and money to improve things as a lot of us here have.

I just wish Suzuki would come out with the perfect compromise bike - the practicality of a Bandit with the engine, electronics, suspension and brakes of the B-King.........and a price somewhere in the middle. I for one would willingly pay half the difference for that much of an improvement. Yeah, I know - dream on........
 
sproggy said:
I suspect the 'cure' recently has been riding in cooler conditions. As the failures seem to be heat-related, cooler ambient temperatures mean that failure is less likely to occur.

I don't want to be branded a pessimist, but I expect the issues to return with the warmer weather, at least for anyone still running with a low-wattage resistor in the bypass. Roll on summer :lol2:
Click to expand...

I would gladly risk it for a little of that summer heat! It's in the teens here, and had snow and freezing rain last night. Gawd I miss riding!
 
Since registering with TWT, I've read of this "surging" in quite a few threads; but I have yet to feel anything to complain about. I've also read of the (frequent) need to synch' the carbs, and how my CA model should have had the carbs synch'ed at 600 miles..... Well, 4,000 miles later with no TB synch', I still don't feel anything about which to be concerned.

I had a BMW R1150RA, and THE biggest complaint voiced by it's owners was the Roadster's "surging". The following model year, BMW added another pair of spark plugs to the mix. The intent was to help burn any remaining fuel and arrest this 'surge', however some people still found reason to complain. As it turns out, BMW had a contractual obligation to (continue) to use an old (Bosch?) fuel injection system. By today's standards the brain of the (old-fashion FI) system took readings far too slowly/infrequently to work efficiently with the demands of EPA's standards for a lean running & environmentally "green" burn. Thus the "surge".

I feel very little 'surge' on my Bandit 1250, and I didn't complain about my Roadster's surging. I think in large part my lack-of sensitivity to this surging must be a result of my riding style.
- I very rarely 'cruise' at steady throttle,
- I generally select a gear to ride in from which I can expect a spirited response,
- and I dance all over the gear box.
I must admit that the linear power available from 3,000 to7,000 rpm is starting to change my riding style. If I start to 'cruise' more and dance through my gears less, I may actually start to 'feel' this surge spoken of.......

In the mean time, the roads are dry, the rain has lifted, and I think I'll dress warmly enough to go "dance" in the 33* weather out there. I need a fix, I need a spin on the Bandit, I need to RIDE!
 
Fittysom'n said:
In the mean time, the roads are dry, the rain has lifted, and I think I'll dress warmly enough to go "dance" in the 33* weather out there. I need a fix, I need a spin on the Bandit, I need to RIDE!
Click to expand...

The weather here won't allow a ride. Thanks to a cold front coming down from Alaska, it's currently -15c (5f). Earlier in the week it was down to -28c (-18f). If the reason for the O2 bypass failures is what Sproggy says, there is no danger of them burning up out here now.

Spring won't get here soon enough.
 
(whew.... I couldn't last more than a 100 mile sprint through the foothills.

The bike was running good, the tires a bit stiff from the cold, and my toes are not YET thawed out! Two pair of socks, the wool worn thin from years of use. Leather boots nine years old. the sole of which was flapping in the 39* wind. I'm gonna hafta rethink this.... )
 
I've felt a touch of surge in my Bandit cruising at the 3500 to 4000 rpm range. Heck, that's 60 to 70 mph. Had a bit of surge on my DL1000 at the same speeds. My BMW R11**s surged more than that and that still didn't bother me enough to get excited about doing something about it. Like my ex BMW mechanic told me once when I was concerned about the cam chain noise on my R1150GS. "Nothing to worry about, Go ride that thing and do the miles". :rider: :rider:
When I sold the bike at over 50,000 miles, it was still ,. " Nothing to worry about" . :lol2:
 
I just got around to adding a Dobeck O2 bypass to my ’07 Bandit and it felt like it made quite a bit of difference. I only have 1700 miles on the bike and always thought maybe my throttle control was a bit shaky. Now, with the O2bypass, my low speed/low RPM cruising feels 100% smoother. My O2 bypass is only 3 weeks old but I might make/purchase a second just-in-case.

I wish Dobeck had a part # on their Web site. I have to call to order the O2 bypass for the Bandit. I wonder of the PCIII folks have a bypass I can order. I'm getting a PCIII one of these days.

Ol dave
 
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