HarleyTechTalk

Technical Forums => General => Topic started by: fbn ent on September 05, 2022, 10:25:56 AM

Title: Hot stumble issue.
Post by: fbn ent on September 05, 2022, 10:25:56 AM
'02 FLTRI, 103", TMAX. 130 K miles on most of the electrics.

Beating me up....After 80-100 miles it will develop a stumble mostly in the 2500-2800 RPM range.

I have replaced intake seals a couple times just in case and recently replaced the coil (I had a new one so why not?). Smoothed the bike out somewhat but surprised me when the stumble came back. Known good wires also.  :crook:

I will run a fuel pressure test on the road today to see if there is any fluctuation when hot.

I also have a spare crank sensor I will sacrifice although the last one went in not that long ago.

What are other possibilities? I'd like to get this straightened out before I can't test ride it in reasonably warm weather.
Title: Re: Hot stumble issue.
Post by: Hossamania on September 05, 2022, 10:29:48 AM
Venting gas cap?
Title: Re: Hot stumble issue.
Post by: fbn ent on September 05, 2022, 10:31:21 AM
Quote from: Hossamania on September 05, 2022, 10:29:48 AMVenting gas cap?

Tried a loose cap...nope.
Title: Re: Hot stumble issue.
Post by: kd on September 05, 2022, 02:21:30 PM
Head temp sensor?  If it starts degrading and kicks and pops at the lower rpm it is a good indication.

The 02 Road Kings also had a tight wiring harness issue to the front injector that seemed to wait until it was hot and on the highway.  It eventually would pull the wire right clear of the connector.
Title: Re: Hot stumble issue.
Post by: fbn ent on September 05, 2022, 02:54:28 PM
I just happen to have one....crossed my mind too.  :up:
Title: Re: Hot stumble issue.
Post by: fbn ent on September 05, 2022, 07:17:09 PM
"The 02 Road Kings also had a tight wiring harness issue to the front injector that seemed to wait until it was hot and on the highway.  It eventually would pull the wire right clear of the connector."

Yes, had that one already. Finally picked up some new pins and a connector in Sturgis to fix it right.

Nobody has parts anymore ....  :emoGroan:
Title: Re: Hot stumble issue.
Post by: fbn ent on September 07, 2022, 07:16:20 AM
It had a couple hiccups yesterday on a hundred mile run. Of course it was a nice cool day so it is not indicative of a hot day's ride. Going to get one last hot day this weekend they say. I'll hit it hard again then. Fingers crossed!
Title: Re: Hot stumble issue.
Post by: Tacocaster on September 07, 2022, 08:53:38 AM
Interesting.
I had a very similar issue (mine had a serious stumble at similar RPM's as you) with my 07 103" FLHX. In my case, I was able to remove my T-Max, re-install my stock ECM, "borrow" a buddy's in-line "fuel enhancer" (can't remember the brand right now but you folks know the owner as "Jamie" out of Las Vegas area) and voila! Gone!
Rode bike w/T-Max & stumble to Big Boyz to convert back to stock ECM. He performed his magic and bye-bye T-Max and stumble.

In between failure to resolution, I tested the living crap outta everything relatable to the problem,(Head Temp/Crankcase/Coils/Plugs/wires/Intake/Fuel- air sensors/fuel delivery) even to the point of measuring the heating circuit voltage on my Bosch O2 sensors and creating a breakout box for the T-Max before sending T-Max unit for validation test (passed, of course). Have never experienced a reoccurrence in more than 5 years now and old T-Max is still on the shelf. Wouldn't sell that problem to anyone.
Title: Re: Hot stumble issue.
Post by: Admiral Akbar on September 07, 2022, 09:06:08 AM
Try setting injector timing to 380 or 370.
Title: Re: Hot stumble issue.
Post by: fbn ent on September 07, 2022, 09:09:21 AM
Hmmm....I sure hope that's not my issue. Was yours only after a good heat soak? Stopped in at their tent in Sturgis inquiring about the issue. They talked me into upgrading my old unit to the Gen 3 for a good price. Three year warranty Blah, blah, blah. Anyway, if it is I will make so much noise they will wish they never met me. Like I said, it has improved. Just a couple hiccups last run. Time will tell. Thanks for that.
Title: Re: Hot stumble issue.
Post by: fbn ent on September 07, 2022, 09:11:20 AM
Quote from: Admiral Akbar on September 07, 2022, 09:06:08 AMTry setting injector timing to 380 or 370.
Was hoping you'd chime in. Will do....
Title: Re: Hot stumble issue.
Post by: Tacocaster on September 07, 2022, 04:18:15 PM
Quote from: fbn ent on September 07, 2022, 09:09:21 AMHmmm....I sure hope that's not my issue. Was yours only after a good heat soak? Stopped in at their tent in Sturgis inquiring about the issue. They talked me into upgrading my old unit to the Gen 3 for a good price. Three year warranty Blah, blah, blah. Anyway, if it is I will make so much noise they will wish they never met me. Like I said, it has improved. Just a couple hiccups last run. Time will tell. Thanks for that.

I hope it's not too! But if it is, you have my blessing to let 'em have it!

Yes, mine would improve as well and then come back once again. This all took place over a period of a riding season. At the onset I thought it was just a bad tank of gas.

The stumble would only raise its head ONLY after operating temperatures were reached. In my situation the exhaust tips eventually showed sooting (rich, as I was trying the variety of tests one at a time). In the end, I convinced myself it was something happening with the 5v Data bus interfering with the T-Max. I never proved it but I thought it was. Pulling the T-Max removed the issue and my focus shifted to eliminating that unit.

I'm not dissing T-Max. I think they're a nice unit and fun way to learn about mapping - at least their earlier versions of it. I've tuned 3 different bikes for guys with great results they were very happy with, just as I was.
Best of luck in your hunt!
Title: Re: Hot stumble issue.
Post by: fbn ent on July 23, 2023, 07:30:54 AM
Okay... After a long Winter and an even longer rebuild session  :emoGroan: I am back to the same issue with the stumble. I am going to follow Max's advice on injector timing and try it again. Stay tuned.....
Title: Re: Hot stumble issue.
Post by: fbn ent on July 23, 2023, 11:21:51 AM
Well, I went in to change my injector timing and don't seem to be able to change it. I only get 1024 Wideband in the tab. I have contacted Jimmy at T-Max for input.