What is surging?

[ScooterCop]

I have read a lot on the topic of surging on this and other boards, but I am still not sure what it is. And I feel that it may have happened today. On my 2004 R1150R with about 5500 miles, while cruising through my neighborhood, the engine revs seemed to jump RPMs, up to about 5000. I quickly grabbed the clutch and up shifted, and everything was back to normal. It was a little disconcerting to say the least.

Was this SURGING???

[geothepencil]

Don't think so. You have the twin spark don't you ? Surging for me is a jerking at say, 3K on the tach in say 3rd gear. It lessons with engine temp and speed so that it isn't noticed at all on the highway. And of course, according to BMW, they don't do that.

geo

[jfslater98]

I think your bike dropped down a gear. That's happened to me at highway speeds, from 6th to 5th, but not at slower speeds. All the helpful tips here (less clutch, etc.) have reduced that. But it never happened at neighborhood speeds.

I think I've noticed it when cruising around 25 in 1st or 2nd, my throttle hand steady, and the engine and speed fluctuate very subtly. And it might be my brain fooling me into thinking it's surging, because I've read about these oilheads surging.

[def38]

I think I've noticed it when cruising around 25 in 1st or 2nd, my throttle hand steady, and the engine and speed fluctuate very subtly. And it might be my brain fooling me into thinking it's surging, because I've read about these oilheads surging.

That's surging.

[Sunbeemer]

You're lucky if you have to ask what surging is! What you experienced wasn't. I had something like that happen when I went over a pronounced expansion joint on the highway and it kicked out of gear altogether (Zoom Zoom, nothing... )

[def38]

You're lucky if you have to ask what surging is! What you experienced wasn't. I had something like that happen when I went over a pronounced expansion joint on the highway and it kicked out of gear altogether (Zoom Zoom, nothing... )

You mean boxers jump out of gear? How does that happen?

[Robroy]

Now that we know what this is - how do we fix it?

[ProductUser]

First, surging can occur on a twin spark.

There are several possible causes for surging, so I'll just name a few:

1) Valves and throttle bodies are out of sync. Both of these procedures must be done correctly to reduce and/or eliminate surging.
2) Air leak from one of the following places: throttle tubes; o-rings in the brass screws are worn.
3) Bad fuel can cause surging symtoms.
4) A bad coil can also cause surging issues.

Item 1 is the typical solution to eliminate/reduce surging.

ProductUser

[Robroy]

I've just bought an 02 r1150r with single spark. I'm used to riding ultra smooth Jap fours. I thought the roughness at 2000-3000rpm was my imagination unitl I read some of the threads here.
Someone suggested disconnecting the 02 sensor what ever that is.
Any help anyone?

[ProductUser]

Try using the search function re surging; you will find more information that you can read in a single day.

ProductUser

[stig]

1) Valves and throttle bodies are out of sync. Both of these procedures must be done correctly to reduce and/or eliminate surging.

In my opinion, as a 2002 single spark owner, having also come from the ultra smooth jap four, the throttle body/cables iswhere it's at>

This forum alerted me to the the cause and showed me how to fix it.

You just don't know how smooth these bikes are untill you have them setup correctly, something my local dealer could not do!!!

happy tinkering

Stig

[GTR350cc]

Surging is caused when the Motronic ECU detects conditions in the fuel/air mixture, engine temperature and strain, O2 levels, exhaust gases, and what not (technical term) that are outside the programmed range of acceptable values. The ECU reacts by increasing or decreasing the fuel supply (many times per second). Surging is the felt effect of those changes. It is recognizable mostly by a jerkiness in the forward motion of the bike at low rpm and low speeds.

Most of the above mentioned items that can be tweaked, adjusted, fixed, corrected, or changed are ways to minimize or eliminate the felt effects of surging.

The only cure is a better programmed ECU. The Germans provide one fuel map for the entire U.S. (or Canadian or Australian or ...) yet the U.S. presently markets over 40 different blends of regional/local gasoline across the various octane offerings. Ethanol and oxygenated blends are the most difficult for the ECU to manage. Bad gas being more common than we realize, contributes mightily to this performance fault.

In order of (my opinion) best results to minimize the effects of surging:

1. Buy the highest grade, non ethanol, non oxygenated gas you can find.
2. Good spark plugs. Coils, wires, etc in good condition.
3. Properly adjusted valves and synchronized throttle bodies.
4. Working O2 sensor (they go bad quickly).
5. Avoid operating in low rpm/low speed conditions (around town go lower gears for higher rpm)
6. Avoid overheating. (Traffic sucks)
7. Pull the Cat Code Plug
8. Throttle Position Sensor optimized for voltage values (don't do this unless you are very knowledgeable about it)
9. Ditch the Cat, add the Power Commander and self-tune.
10. Avoid Oilhead engines between 1997 and 2003.

[MikeCam]

As for jumping out of gear....

These are an automotive type transmission with a dry clutch. Totally unlike any modern Japanese offering.

Without getting into the mechanical stuff (others are much more articulate about those things), the gears don't always fully engage (don't feel bad but it is because of how we shift (lazy, sloppy, not forceful, not matching revs to speeds)) thus they can slip, change or otherwise do funny things. Happens upshifting, happens downshifting, happens when parts start to wear, happens when parts are still new. Think farm tractor - it's alot more like that than it is a Japanese tranny.

[Sunbeemer]

I must apologize for not answering Def38's question sooner, but I didn't notice it until just now...The jump out of gear could have been my foot hitting the shifter when I went over the bump while accelerating onto the highway (quickly!), and it happened on my Nighthawk!

Sorry if that was confusing.

Also, I'd like to mention something about GTR 350cc's post that I've read (in several places) that pulling the Cat Code Plug (CCP) will cause the Moronic 2.4 ECU to create a richer mixture than the catalytic converter was designed to handle, and could (some say "will") cause a decrease in gas mileage and damage not only the catalytic converter, but foul the Oxygen sensor. I don't know if that ends up costing anything down the road - so to speak

[def38]

Not all boxers surge. The surging problem is most often found in single spark 11XX models. It is this boxer series that is dealt with herein.

What is surging?

Surging occurs when your boxer engine is operated at moderate RPMs (1500-2500) with little or no load in lower gears. If your boxer is prone to surging, you can produce surging when running the engine at 2500RPM in neutral on the stand, no load. With a steady throttle position, the engine RPM varies slightly producing what we know as surging.

What causes surging?

The simple answer is too little fuel. This can be brought on by a leak in the intake air system, dirty fuel injectors, low fuel pressure or poor engine adjustments. What happens is that at light or no loads, the ECM selects a MAP. The MAP is a set of fuel delivery instructions stored in the ECM. This MAP is factory-preprogrammed information in the ECM’s memory. The single spark boxer ECM is not addressable. The MAP selection is based upon several parameters such as:

1- CAT code plug.
2- RPM.
3- Model year (Firmware revision programmed into the ECM).
4- Air temperature.
5- Throttle position sensor signal.
6- Lambda sensor output (closed loop operation).

If the fuel delivery rate remains perfectly controlled and there are no changes to the inputs to the ECM, surging will not occur. However, if one parameter changes even slightly, the system can be driven into instability. This unstable condition is cured when engine RPM slows just a bit. However, the fuel delivery again changes based upon the lower RPM and the situation occurs all over again.

The condition occurs because the engine is running lean of stoichiometry. Any small upset in fuel, air, exhaust backpressure, load or RPM can drive the engine into the condition that causes the surge.

How to cure it?

Keep valves adjusted to optimum. Keep the intake runners clean and leak free. Keep the air filter clean and spark plugs gapped properly. Check and adjust ignition timing. Perform the zero=zero adjustment (Hint: Do not undertake this adjustment unless you are knowledgeable and skilled. Incorrect adjustment could cause engine damage). If these adjustments fail to cure your surging, an electronic fuel controller may be your only option.

Things which should be avoided if your experience surging;

1- Changing your exhaust system…a reduction in back pressure or changing the exhaust system pulse waves will most often exacerbate surging.
2- Adding an aftermarket air filter. Again, the OE unit is best and very effective at providing clean air to your boxer. Don’t change it.
3- Riding at low RPM in lower gears with no load…severe surging can damage driveline components if left uncorrected.

Remember, surging may increase if you commute or ride mostly in the city. Carbon deposits tend to exacerbate surging. Use only high-grade fuel from brand stations that turn over their fuel routinely. Do not use less octane than called for. Keep you bike in good tune.

[TicTac50]

What is "Lambda sensor output"? Does it effect cold start problems

[def38]

What is "Lambda sensor output"? Does it effect cold start problems

Lambda=oxygen. It does not effect cold starts. If you have cold start problems, check the following;

1- Spark plugs.
2- Fuel (grade and age)
3- Injector condition (dirty or gummed with varnish).
4- Battery charge/condition.

[boxermania]

Ahhhh....surging, what an interesting topic.

Surging = running at constant speeds while the ECU is attemping to get as close as possible to an A/F ratio of 14.7 to 1 (lean mixture)

The ECU oeprates in two modes, open loop and closed loop. Open loop is anytime that the throttle is being opened (the 02 sensor is out of the circuit and the ECU selects a richer fuel map). Closed loop is when the bike is running at steady speeds, where the 02 sensor instructs the ECU to lean the mixture (doing so improves gas mileage).

However as the mixture is leaned out the combustion becomes somewhat irregular and surging takes place, this is further exarcerbated by the makeup of the fuel in the diferent areas and the amount of carbon deposit on the piston/combustion chamber.

[def38]

Ahhhh....surging, what an interesting topic.

Surging = running at constant speeds while the ECU is attemping to get as close as possible to an A/F ratio of 14.7 to 1 (lean mixture)

The ECU oeprates in two modes, open loop and closed loop. Open loop is anytime that the throttle is being opened (the 02 sensor is out of the circuit and the ECU selects a richer fuel map). Closed loop is when the bike is running at steady speeds, where the 02 sensor instructs the ECU to lean the mixture (doing so improves gas mileage).

However as the mixture is leaned out the combustion becomes somewhat irregular and surging takes place, this is further exarcerbated by the makeup of the fuel in the diferent areas and the amount of carbon deposit on the piston/combustion chamber.

Closed loop operation takes place above specific RPMs to the best of my knowledge. Also, it differs with different ECM program revisions.