Jerky shift fix

[GLRT]

For years people have been commenting on poor shifting, jerky shift and general clunky transmission performance. And of course the cure / fault as usual is oil or some new more slippery brand.
In all cases the symptoms are the same - good shift while cold but jerky when warm. For me the problem has never been transmission related, it's always been fuel mapping and that off idle stall which is a factor in all gl1800s.

Here is the test - when cold the bike shifts fine at all speeds however as it warms things get a bit jerky. Under moderate to hard acceleration things also work well but shifting under low acceleration is a hobby horse affair.

The fix

You can change oil every 10 minute and use any brand under the sun but the problem will not diminish as this is not a transmission problem but rather a result of an over rich idle mapping. The transmission works fine when the engine is cold not due to oil but rather due to the fact the engine is cold and requires that richer mix. Once warm however the mix is to rich and an off idle studder develops which leads to the jerky hobby horse low end shift problem.
So how do we fix this? Pull out your wallet or credit card, go down to Radio Shack and buy a 2200 ohm resister ( 1/4 watt is fine)
Pull the top shelter and locate the air temp sensor which is plugged into the air box. It is located just forward of the fuel cap.
Strip the wires and place the resister in parallel with the sensor. Solder and tape it up.

What this does is fool the computer into thinking the incoming air is hotter than it really is so the ECU will remap a leaner mix. The low end stumble is now gone and that occasional galloping idle will also disappear.

One thing you will want to do is unplug the ECU fuse and turn the ignition on. You can immediately replace the fuse and go for a test ride. The ECU will recalibrate and the change should take place quickly. No need to let it idle until warm as the ECU is designed to remap under normal conditions.

This fix only affects the low speed mapping so no improvements or changes in fuel economy will be realized. I did the fix last year and for 9000 miles I never experienced any idle surging (gallop) nor did I ever experience the jerky shifting.
It's a less than a dollar fix that really works.
This exact alteration is used by car buffs to increase low end horsepower, the difference being they put the resister in series to richen the mix and add a bit more pull off idle. So it's nothing new just reapplied here.

[peppilepew]

Did you check the normal range of resistance for the sensor? 2200 ohms? You have basically set the input, which should be variable to a maximum fixed value of 2200 ohms.

[GLRT]

The resistance is not fixed at 2200 ohms it is the average of the two units together - 2200 ohms and the sensor. As the sensor changes values the average resistance also changes however it does so in a new range.

[bill jamison]

Could you post a schematic of the resister in parallel? Thanks.

[GLRT]

Could you post a schematic of the resister in parallel? Thanks.

You really do no need a schematic - there are two leads running to the sensor just attach one end of the resister to one of the leads and the other end to the other lead.

All this does is lower the average resistance the computer sees and consequently the idle mix is slightly leaner resulting a crisper off idle responds. It's a cheap fix that I have used on many other models of motorcycles and cars.

[bill jamison]

Thanks. I am going to try this when I change the air filter during Spring break.

[goodolboy1]

Wow....
I have this same problem. Thanks for sharing a fix, I'm
going to be doing an air filter change in the near future
and will give this a try. Thanks again...

Roger

[Darksider 562]

Thanks for the info, I'm sure going to give this a try. A question though, you say to remove the ECU Fuse, and turn the ignition on. Could you help with which fuse is for the ECU, as it doesn't show as ECU on the fuse panel.

Thanks, Phil.

[WingAdmin]

Thanks for the info, I'm sure going to give this a try. A question though, you say to remove the ECU Fuse, and turn the ignition on. Could you help with which fuse is for the ECU, as it doesn't show as ECU on the fuse panel.

Thanks, Phil.

It depends on the year and model. Look in your fuse box for "FI Unit" or "FI IGN" - that's your ECU. It's also called ECM in some places.

[Darksider 562]

Thanks WingAdmin, that's easier, got that one.

Phil

[GLRT]

It's just the main fuse in the block - should be on the left side of the fuse block. Pull the main fuse and then turn on the key to drain the ecu circuits.
Put the fuse back in and start up the machine and ride on. No need to wait until it's warm as all this does is set the ecu to base config and it will program and tune itself as you ride.

I tried running mine without the 2k resister and found it just did not run as well so I put it back in and once again things are good. MPG is still in the 37-40 range which is really good for a trike

[waituntilthebeep]

Does this jerkiness apply to the 2012 as well? I have not felt any issues with mine that I notice. I came from a 1500 that throttled and shifted like hell compared to this 1800 so I probably wouldn't realize it if it was.

[GLRT]

I am unsure on the 2012 as the fuel map was changed on later models. If it's fine then I would recommend just leaving it be.
I setup mine with remote wiring so from inside the fuel door area I can change or disconnect the resister for real tuning ability. What I found again is when the resister is removed the idle will hunt a bit and low end shifting is again jerky. Hooking up the resister and the idle drops about 100rpm and smooths out like silk. Low speed shift is clean and non-jerky.

My GL shift every bit as smooth as my Valkyrie 1500 and I have had zero complaint, Fact is the GL shifts better than any of the over 100 motorcycles I have owned to date. It always has except for the engine mis-map slight problem.

[waituntilthebeep]

What I found again is when the resister is removed the idle will hunt a bit and low end shifting is again jerky. Hooking up the resister and the idle drops about 100rpm and smooths out like silk. .

That is why I asked... my idle when cold is smooth but when it steps down to standard idle condition it seeks. I can't tell if it is jerky or not because my 1500 shifted poorly. The idle seeking tells me something is hinky.

[keithg64]

This is an old post but may still be relevant today. I have a 07 that has a surge problem at idle when the bike is warm. A buddy has an 08 with a stumble problem when taking off from a stop when the bike is warm.

Have other guys used this and your thoughts on it.

[Joen]

Has anyone tried the 2K Resister to the IAT sensor? The idle surge issue is an ongoing problem that has not been resolved.

Thanks
Joe

[waituntilthebeep]

It's been forever and a day since I was asking about this but whatever the issue was initially went away. I suspect it was due to break in as at that point, the bike was still less than a 1000 miles. Ive put nearly 70k on it since then and it ran smooth at idle within weeks of my last post.

[Joen]

I’m surprised that no one has come up with a remedy there are many with this issue lots right out of the box from dealer some reset the ECU others are living with it... Thanks for reply..
Joe

[Ravyn]

I have a 2002 gl1800 with a little over 100,000 miles on it and I have never had any of the problems you guys are talking about ??
I do believe if you want to reset you computer start your bike but do not touch the throttle and let it warm up until the fans come on and then shut off. Turn off your bike and restart it. Your computer will have rest itself.
If I'm wrong on this please let me know.