Today I was able to take the bike (97 flhtcu, efi) out for it's first ride in my ownership.

I enjoyed it, much more than I had expected, all my previous newer bikes have been much more in the sport touring mode.
My latest travelling bike being a BMW K1200RS.

I also figured out why the Harley boys seem to ride so slow, seems pretty happy around 60mph.

One thing I noticed, which I assume can't be right is , after it warms up, when I come to a stop, is it surges, regular as a heart beat, just sit at a light, and it bounces up to about 12-1300, back to 8-900, back up to 12-1300 etc, as long as I sit, it just continues.
Once I get under way it seems fine till the next stop.

Anyone have any ideas what the problem might be?

Again I assume that's not normal.

 

Its not normal but is something quite common with your type of EFI...which is why you'll find threads on converting back to carburettor on the forum.

 

I changed the fuel filter in my 1996 FLHTCU-I last week, and it really made a big difference. The filter is in the fuel tank, but was easy to change.

 

Be wary of slow Harley riders - it is a recent 'thang' in my modest experience and should not be aped. The darned things are fine at proper road speeds!

As for your surging, you may find that is addressed in your factory service manual. There are a few sensors that can disturb running, so once diagnosed and rectified you should have a sweet running bike.

We have a few MM EFI experts in here, so hopefully one of them will call by soon and help you along.

 

Thanks for the ideas so far, I read a thread about engine heat sensors causing such a problem also, hoping one of the EFI experts will chime in too.

 

Pull your codes before you do anything.

 

My bike would accelerate when I tried to come to a stop. My first thought was the throttle cable was hung up. It scared the crap out of me the first time.

97Bagger has some good write ups on what to check before you start changing parts.

My problem was the Engine Temp Senor.

 

Does this require a code reader for the 97?

I don't have any engine light on.

 

Most likely the stepper motor is engaging when it should be released from reaching engine temperature. Need to remove air cleaner cover and locate the fast idle/stepper motor on the right side of the plenom and monitor, it will move out with key on and slowly move back in with engine running as engine temperature increases, it should stay retracted at hot engine temp as the idle screw adjustment takes over. Don't move the stepper by force or most cases it will need replaced.

If the engine is at operating temperature and the stepper motor continues to extend causing the irrattic high idle problem you have then target that. The stepper motors main control is the engine temperature sensor that is the heart of the system, the ETS WILL cause a problem without a engine code because it is at it's edge of parameter but will eventually code. Most likely the ETS is the problem but sometimes pulling the ECM fuse in the right side cover will put the ECM in a relearn condition but most of the time is a bandaid.

Since a Evo eats it's own blowby, oil residue in the plenom and slightly dirty air harden and restrict the small holes and coats the air intake temp sensor, cleaning the plenom and small holes with carb cleaner helps and this would be the target if the stepper motor is ok. Cleaning the plenom and ECM reset sometimes repairs M&M issues but more than likely your ETS is out of range and the ECM is receiving a bad signal.

 

Bagger , thanks very much for that answer, I will look into all those things.

Re the plenum and carb cleaner, just a general spray, or any specific hole I'm looking for, OR need to stay away from?