1994 R1100RS: diagnosing a potential lambda issue or just water in the fuel

[Ralph1212]

Hello everyone,

 

Since the last time I posted in 2019, my 1994 R1100RS has been a solid reliable ride.  The Nightrider AF-XiED O2 modulator I installed back then has been doing a great job of smoothing out any surging.  The bike has the original lambda (O2) sensor because it never gave me reason to doubt it was working until now.  The bike now has around 34,000 miles on the clock.

 

Two weeks ago I rode the RS to work as I frequently do; no issues.  I work evenings and it was a cool clear autumn night in NJ.  I suited up and started it engine and it was like a different bike.  The engine was surging, backfiring and slow to response to the throttle.  It seemed like it was running on only one cylinder.  I live about four miles from work and managed to get home.  When I arrived and went to put down the kickstand I saw that the catalytic converter was glowing red not.  I shut it off immediately.  I googled "red hot catalytic converter" and read that large amounts unburned fuel reaching the converter can cause that.

 

The following day I checked the spark plugs and the fuel injectors (aftermarket R1200 injectors from Germany; installed in 2019).  The plugs and the injectors appears to be functioning properly.  I spoke with Beemer Boneyard where I purchased the O2 modulator.  They suggested I disconnect it from the lambda sensor to see if that's the issue.  I bought a new lambda sensor on eBay, but have not yet installed it.

 

We've had a lot of heavy precipitation here and I'm wondering if water got into the fuel holding tank where I refueled before the problems started.  A friend suggested I put DryGas in the tank to eliminate water as a possible issue.

 

My question(s) are: Could water in the fuel be causing this?  Will DryGas help or do I need to drain the tank?  

When I replace the lambda sensor, will I need to disconnect the cat converter from the exhaust pipes to get at the sensor?  

 

Best Regards,

 

Ralph

 

 

 

 

[dirtrider]

1 hour ago, Ralph1212 said:

Hello everyone,

 

Since the last time I posted in 2019, my 1994 R1100RS has been a solid reliable ride.  The Nightrider AF-XiED O2 modulator I installed back then has been doing a great job of smoothing out any surging.  The bike has the original lambda (O2) sensor because it never gave me reason to doubt it was working until now.  The bike now has around 34,000 miles on the clock.

 

Two weeks ago I rode the RS to work as I frequently do; no issues.  I work evenings and it was a cool clear autumn night in NJ.  I suited up and started it engine and it was like a different bike.  The engine was surging, backfiring and slow to response to the throttle.  It seemed like it was running on only one cylinder.  I live about four miles from work and managed to get home.  When I arrived and went to put down the kickstand I saw that the catalytic converter was glowing red not.  I shut it off immediately.  I googled "red hot catalytic converter" and read that large amounts unburned fuel reaching the converter can cause that.

 

The following day I checked the spark plugs and the fuel injectors (aftermarket R1200 injectors from Germany; installed in 2019).  The plugs and the injectors appears to be functioning properly.  I spoke with Beemer Boneyard where I purchased the O2 modulator.  They suggested I disconnect it from the lambda sensor to see if that's the issue.  I bought a new lambda sensor on eBay, but have not yet installed it.

 

We've had a lot of heavy precipitation here and I'm wondering if water got into the fuel holding tank where I refueled before the problems started.  A friend suggested I put DryGas in the tank to eliminate water as a possible issue.

 

My question(s) are: Could water in the fuel be causing this?  Will DryGas help or do I need to drain the tank?  

When I replace the lambda sensor, will I need to disconnect the cat converter from the exhaust pipes to get at the sensor?  

 

Afternoon Ralph

 

It sounds more like an o2 sensor or AF-XiED issue but under certain circumstances water in the fuel could effect the o2 operation. 

 

First thing I would do is COMPLETELY disconnect both the AF-XiED & o2 sensor. 

 

If that makes it run correctly then probably not water in the fuel. If it still runs bad then possibly water in the fuel or a spark issue. 

 

If it does run better with  both the AF-XiED & o2 sensor disconnected then try running it with just the o2 sensor but  no AF-XiED.

 

You need to start somewhere so the  AF-XiED & o2 sensor disconnect is the most logical.  

[Ralph1212]

Hi D.R.

 

I removed the AF-XIED from the bike and removed fuse #5 for ten minutes (to clear the Motronic memory?).  It's still starting and running rough.  I have a replacement O2 sensor ready to install, but I don't know if I have enough clearance between the engine case and the catalytic to remove it.  I tried loosening that nut that connects the down pipes to the catalytic, but it won't budge.  Even with WD40 and a breaker bar.  Can you recommend a kind of wrench to remove the sensor?

 

Thanks,

Ralph

[dirtrider]

41 minutes ago, Ralph1212 said:

Hi D.R.

 

I removed the AF-XIED from the bike and removed fuse #5 for ten minutes (to clear the Motronic memory?).  It's still starting and running rough.  I have a replacement O2 sensor ready to install, but I don't know if I have enough clearance between the engine case and the catalytic to remove it.  I tried loosening that nut that connects the down pipes to the catalytic, but it won't budge.  Even with WD40 and a breaker bar.  Can you recommend a kind of wrench to remove the sensor?

 

Thanks,

Ralph

Afternoon  Ralph

 

I usually use what I can get in there. Sometimes I need to cut the connector off then use a box end wrench slid over the wire pig tail then onto the sensor to break the sensor free. 

 

I like to use an o2 sensor wrench if I can work it in there but sometimes you can't get a good angle on the sensor wrench with a ratchet & extension. 

 

I have had a few stuck so tight that I needed to drop the exhaust down, cut the wire off of the sensor then use an impact wrench at 175 psi air pressure with a deep socket  to hammer the o2 sensor loose. 

 

With the exhaust in place it usually takes persistence &  trying different wrenches with the correct angle on the end (you probably won't break it free with an open end wrench). 

 

You can usually find an o2 sensor wrench at your local auto parts store for around $10.00, or on E-Bay. 

 

 

[Ralph1212]

Thanks DR.  I didn't realize such a socket existed.  I ordered one off Amazon.  Also, I have a heat gun and may try to use that to break loose the sensor (I don't have access to an air wrench)

 

Ralph

[Ralph1212]

Here's an update on what appears to have been the actual problem occurring with my R1100RS:

 

As per Dirtrider, I had intended to replace the O2 sensor with a new one I had purchased on eBay.  Since I was thinking that I may need to siphon off the "bad" fuel from the tank, I had ordered a new 5 gal fuel jug and siphon from Amazon.  I had removed and reconnected the AF-XiED O2 signal modulator I had installed in 2019.  I started the engine and it continued to run rough, surge, and make the catalytic red hot.  Going back through the forum thread I had in 2019 with other forum members, I decided to make sure the throttle bodies were clean and the throttles were not out of sync.  

Something unexpected happened when I loosened the screw clamps which secure the air intake ports to the throttle bodies.  The screw clamp which secures the right side throttle body to the cylinder head was loose, resulting in the right-hand throttle body being able to rotate on its axis.  Rotate the right-hand throttle body one way or the other and the feeder cable "travel" from the left-hand throttle lengthens or shortens. If I'm not mistaken, this throws the throttles out of sync and cause problems like surging and power loss, and confuses the hell out of the Motronic.  I tightened the screw clamp, cleaned the throttle bodies with carb cleaner, removed and reconnected fuse #5 to reset the Motronic memory, and closed everything up. After a few tries to get the residual cleaner out of the intakes, the engine kicked over and is strong as ever.  

 

I haven't drained the fuel and the original O2 sensor is still installed.  If the bike continues to run well, I'll consider myself very lucky it didn't cost A LOT more time and money.

 

A big thank you to Dirtrider for their assistance.

 

Ralph

[dirtrider]

9 hours ago, Ralph1212 said:

Here's an update on what appears to have been the actual problem occurring with my R1100RS:

 

As per Dirtrider, I had intended to replace the O2 sensor with a new one I had purchased on eBay.  Since I was thinking that I may need to siphon off the "bad" fuel from the tank, I had ordered a new 5 gal fuel jug and siphon from Amazon.  I had removed and reconnected the AF-XiED O2 signal modulator I had installed in 2019.  I started the engine and it continued to run rough, surge, and make the catalytic red hot.  Going back through the forum thread I had in 2019 with other forum members, I decided to make sure the throttle bodies were clean and the throttles were not out of sync.  

Something unexpected happened when I loosened the screw clamps which secure the air intake ports to the throttle bodies.  The screw clamp which secures the right side throttle body to the cylinder head was loose, resulting in the right-hand throttle body being able to rotate on its axis.  Rotate the right-hand throttle body one way or the other and the feeder cable "travel" from the left-hand throttle lengthens or shortens. If I'm not mistaken, this throws the throttles out of sync and cause problems like surging and power loss, and confuses the hell out of the Motronic.  I tightened the screw clamp, cleaned the throttle bodies with carb cleaner, removed and reconnected fuse #5 to reset the Motronic memory, and closed everything up. After a few tries to get the residual cleaner out of the intakes, the engine kicked over and is strong as ever.  

 

I haven't drained the fuel and the original O2 sensor is still installed.  If the bike continues to run well, I'll consider myself very lucky it didn't cost A LOT more time and money.

 

A big thank you to Dirtrider for their assistance.

 

Ralph

Morning Ralph 

 

It was probably not a rotated Throttle Body but more likely the throttle cable outer sheathing was sitting on top of the cable adjuster rather then correctly down in the adjuster (this happens a lot on the BMW 1100/1150 bikes.