UK Monster Owners Club Forum - View Single Post - 1100 Evo

Luddite · 18-10-2016, 01:52 PM

Problem no. 3: The dreaded lambda sensors! As the Evo has a catalytic converter, it has lambda sensors that monitor the air/fuel ratio in the exhaust. At low revs/small throttle openings the Evo runs a closed loop O2 system where the ECU monitors the lambda sensors' readings and adjusts the fuelling to get the ideal ratio for the cat (about 14.7/1). Unfortunately, this is not the best mixture for the motor and is usually leaner than is ideal for smooth running. At higher revs/throttle openings, the fuel system is open loop and fuelling is as per the factory settings on the ECU with no interference from the lambdas.

This leanness and constant adjustment of the mixture is what causes the low speed hunting and surging and that feeling of an imprecise throttle connection .

Solution: Again, there's the cheap and cheerful option and a more thorough, more expensive route.

The cheapest solution is to fit some lambda eliminators like these:

http://www.ebay.co.uk/itm/Oxygen-lam...item3cd176d4d5

These fool the ECU by sending a steady reading back so fuelling is as per the factory settings with no adjustments. They worked really well for me, resulting in smoother running and with no engine warning light either. For the money, a great little mod. Note that I don't think they work on the 2013 Evo. Check with the seller before buying.

While the eliminators allow you to remove the lambdas, they don't affect the actual fuelling on the ECU. If you want to change the stock fuelling, (which is still likely to be weak at low revs), you need to remap the ECU.

In conjunction with the eliminators, I also fitted iridium plugs (NGK DCPR8EIX) with 1 mm gaps. These give a fatter spark which are better at igniting a weaker mixture.

The ultimate solution is to have a full custom map developed on a dyno. Chris at CJS Racing in Bristol has good feedback. http://cjsracing.co.uk/dyno_ecu_reprogramming.htm

If you can't get to a dyno, a more convenient alternative is to have an off-the-shelf remap by post. After reading Chris.p's excellent thread (http://www.ukmonster.co.uk/monster/s...ad.php?t=50780) in which he explained the great results he got with a Rexxer remap from Neil at Cornerspeed, (http://cornerspeed.co.uk/tuning.php), that's what I did.

Result: Great service, great value, great results. Perfect fuelling right down to below 3,000 revs with smooth pickup right through the rev range. In addition, it allows you to remove both the lambda sensors and the exhaust valve. Note that you must unplug the lambdas or lambda eliminators. Leaving them plugged in confuses the remapped ECU.

The final piece of the puzzle revolves around the flywheel (no pun intended). Details to follow in part 2...

18-10-2016, 01:52 PM	#2
Luddite Registered User Join Date: Aug 2011 Location: Southampton Bike: M1100evo Posts: 2,465	contd... Problem no. 3: The dreaded lambda sensors! As the Evo has a catalytic converter, it has lambda sensors that monitor the air/fuel ratio in the exhaust. At low revs/small throttle openings the Evo runs a closed loop O2 system where the ECU monitors the lambda sensors' readings and adjusts the fuelling to get the ideal ratio for the cat (about 14.7/1). Unfortunately, this is not the best mixture for the motor and is usually leaner than is ideal for smooth running. At higher revs/throttle openings, the fuel system is open loop and fuelling is as per the factory settings on the ECU with no interference from the lambdas. This leanness and constant adjustment of the mixture is what causes the low speed hunting and surging and that feeling of an imprecise throttle connection . Solution: Again, there's the cheap and cheerful option and a more thorough, more expensive route. The cheapest solution is to fit some lambda eliminators like these: http://www.ebay.co.uk/itm/Oxygen-lam...item3cd176d4d5 These fool the ECU by sending a steady reading back so fuelling is as per the factory settings with no adjustments. They worked really well for me, resulting in smoother running and with no engine warning light either. For the money, a great little mod. Note that I don't think they work on the 2013 Evo. Check with the seller before buying. While the eliminators allow you to remove the lambdas, they don't affect the actual fuelling on the ECU. If you want to change the stock fuelling, (which is still likely to be weak at low revs), you need to remap the ECU. In conjunction with the eliminators, I also fitted iridium plugs (NGK DCPR8EIX) with 1 mm gaps. These give a fatter spark which are better at igniting a weaker mixture. The ultimate solution is to have a full custom map developed on a dyno. Chris at CJS Racing in Bristol has good feedback. http://cjsracing.co.uk/dyno_ecu_reprogramming.htm If you can't get to a dyno, a more convenient alternative is to have an off-the-shelf remap by post. After reading Chris.p's excellent thread (http://www.ukmonster.co.uk/monster/s...ad.php?t=50780) in which he explained the great results he got with a Rexxer remap from Neil at Cornerspeed, (http://cornerspeed.co.uk/tuning.php), that's what I did. Result: Great service, great value, great results. Perfect fuelling right down to below 3,000 revs with smooth pickup right through the rev range. In addition, it allows you to remove both the lambda sensors and the exhaust valve. Note that you must unplug the lambdas or lambda eliminators. Leaving them plugged in confuses the remapped ECU. The final piece of the puzzle revolves around the flywheel (no pun intended). Details to follow in part 2...