I can wrench my Pan, but can't figure out computers and their sensors...

Something curious happened today for the first (and then subsequent) times, and I haven’t yet figured it out yet. My fundamental config is in my sig below. Additional info is that I rolled over 66K miles today on "Big Red" (my Ultra), the "girl" in question.

This detail is provided (sorry for the long post) for those who may be able to assist.

I was on a road trip today. Went to pull in on a secondary highway rest stop, and as soon as I pulled in the clutch (tight turn for down-shifting) the motor dies, so I ‘bump started’ it in a gear to get her running again. On my way to my destination (300 mile road/biz trip all-in today), 3 other times on the way there and 4 times on the way back, my girl died whilst coming down from speed to idle (at the random traffic lights on these country roads I was riding). After these issues, I finally (it apparently takes me a while sometimes ;-) learned that if I kept some fuel on the throttle, rather than letting the bike try to idle as she ought to be able to do, I could keep her running. If I didn’t do that, she’d die, with her final breath being a backfire out of the air cleaner…

This is an EFI model – if it wasn’t, I’d think that I had a low-speed idle problem. Since it is EFI and she’s ECM controlled, I’m a bit baffled. If there were a low-speed idle sensor, I would think that was bad, but it doesn’t seem that there is one of those. If I look at the inputs to the ECM, the only sensor I can identify that relates to engine speed is the CKP (CranKase Position?) Sensor, so for now I’m leaning in that direction.

I believe that four of the other sensors (of the six feeding the ECM) are in the “Induction Module Assembly” (FWIW that means ‘intake manifold’ to me, so please correct me if I’m wrong). To me, the intake manifold doesn’t care about RPM, it cares about mixture and the like, but I may be wrong…

The other sensor that doesn’t seem to be a part of the intake manifold is the temperature sensor, the “TP Sensor”. I don’t think it may be that, but I don’t know how these computers work…That said and for full disclosure, I did get stuck in traffic last weekend on another trip and only progressed about one mile in about 20 minutes in 90* weather…she WAS having (idle) trouble then before I detoured around the issues and was able to cool the engine. I bring that up because it’s still in my mind as I reflect on these things.

So sorry for the long narrative, but I hope it may be useful to those who know more than I. I’m thinking that I should:

· Replace my CKP Sensor
· Consider replacing my TP Sensor
· Hope for the best (?)

I’d really welcome other wrenchers’ thought and opinions, cuz this mechanical versus computer stuff really confuses me – I can work on my Panhead; cuz it's all mechanical, and hopefully not smatter than me! J.

BTW, should it be of value for those with thoughts -- I replaced the cam chain tensioners on Big Red at 30K miles when I did the big bore..

Thank you,

 

My 07 ultra does the same thing on occasion. "I" believe it is the iac (idle air control). I have read on here to remove air filter you can see the iac pindle in the throat of the throttle body. Cycle the ignition on and off and you will see it move. Cover area around and below t/body and spray carb cleaner up into iac while cycling it. You may see some black/dark stuff run out.. It is not a permanent fix but may help. I would replace the iac if I wasn't so lazy (pull gas tank) ........... you are not alone

ps mine seems to do it more after long stretches at highway speeds. if I stop for a coffee break and let it sit for a few minutes it goes away for then

 

I replaced my TP sensor on my 05, it ran fine but at idle it was rough. I think it $38 about 3 years ago.

 

It happened on my 06 2 years ago. After long runs I would come to a traffic light and she would stall. She started right up and would be fine for a week and then it would happen again. I had a fuelpac at the time and I was changing to a pcv. Once I put in the pcv it never happened again. Strange but I'm happy.

 

I really appreciate those who have responded so far, but after my day today, I'll await tomorrow to respond. Thanks again,

 

First thing I would look at is iac.

 

Same issue with my 07 a couple times. Each time cleaning the IAC fixed the problem. Cycle it with on/off switch while spraying with cleaner. If it does'nt fix it I would look at the TPS next.

 

Gents,

Thanks for the responses! I got pretty pizzed off yesterday, and didn’t want to get accused of “posting under the influence”, so I thought it would be best if I stopped for the day.

Seems like there is a consensus that I should start with the IAC, which makes sense to me. When I look at the manual, I can’t find one of those…so to confirm, is the “IAC” you talk about the same sensor as the “IAT” identified in the manual (pic attached)? And to clean it, cycle the switch, carb cleaner, and maybe a tooth brush?

Thanks again,

 

Here is the part that I will be installing on my 2007 SG.

 

It doesn't seem that that part number has fitment on the 2006's. Here's the sensor page from my manual...no IAC. I guess I'll just try to clean all the sensors I can reasonably get to and see what happens.