Engine reving high, won't slow down-any ideas?
Thread Starter
|
Stage II
Joined: Aug 2008
Posts: 2
Likes: 0
From: Fennville, MI
Engine reving high, won't slow down-any ideas?
Started up my '98 FLHTCI this morning and everything was good. Half a mile down the road it started revving real high and wouldn't slow down. Turned around and took it home, still revving high the whole way. Any idea's of what could be going on? It was a little above freezing this morning if that makes any difference.
Thanks, Rob
Thanks, Rob
Stellar HDF Member
Joined: Jan 2009
Posts: 2,578
Likes: 463
From: On a Lake, not far from the Gulf
You may want to have this moved to the EVO section.
1998 is M&M EFI. There are a few reasons to get a high rev. First thing is to pull any codes that are stored. The service manual will tell you how to do that. After that list them here. You can also reset the ECM by pulling the fuses, or diconnect the battery for 30 min to 1 hr. then resynch the Idle Air Controller to the ECM. But pull the codes first otherwise if you have a more serious issue it will only happen again.
You also clean out the Throttle Body intake and pay special attention to the two small holes on the inside, top of the intake. Spray them out with throttle body cleaner well until they run clear.
Other reasons for high idle are failing Engine Temp Sensor, IAC, TPS, or intake leak. You have to chase them down one at a time.
1998 is M&M EFI. There are a few reasons to get a high rev. First thing is to pull any codes that are stored. The service manual will tell you how to do that. After that list them here. You can also reset the ECM by pulling the fuses, or diconnect the battery for 30 min to 1 hr. then resynch the Idle Air Controller to the ECM. But pull the codes first otherwise if you have a more serious issue it will only happen again.
You also clean out the Throttle Body intake and pay special attention to the two small holes on the inside, top of the intake. Spray them out with throttle body cleaner well until they run clear.
Other reasons for high idle are failing Engine Temp Sensor, IAC, TPS, or intake leak. You have to chase them down one at a time.
3rd Gear
Joined: Jun 2013
Posts: 7
Likes: 0
From: Ontario
Having the same issue with my 97 Ultra. I too need to do my homework, but I believe it might be related to the temperature sensor. Dealer reset idle settings and that didn't cure it. Runs great in warm weather, but in cold.... well, high idle is a kind description.
Road Warrior
Joined: May 2012
Posts: 1,423
Likes: 535
From: Oregon
I went through 3 temp sensors on my '97 RK. There have been several up grades to the sensor. Make sure you have the latest one.
Trending Topics
Seasoned HDF Member
Joined: Apr 2012
Posts: 9,982
Likes: 5,219
From: Michigan
On an EVO of that age I'd definitely recommend new intake "O" ring seals.
You could have throttle cables issued and they should replaced also.
(I had mine replaced just as PM).
Hopefully you'll find simple problem such as a ETS or a TPS and not a serious issue with the MM EFI.
Good luck.
You could have throttle cables issued and they should replaced also.
(I had mine replaced just as PM).
Hopefully you'll find simple problem such as a ETS or a TPS and not a serious issue with the MM EFI.
Good luck.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Stellar HDF Member
Joined: Jan 2009
Posts: 2,578
Likes: 463
From: On a Lake, not far from the Gulf
Having the same issue with my 97 Ultra. I too need to do my homework, but I believe it might be related to the temperature sensor. Dealer reset idle settings and that didn't cure it. Runs great in warm weather, but in cold.... well, high idle is a kind description.
The test for the IAC is a simple Go/NoGo test. With a cold bike tun the key switch on while observing the IAC. Does it move? Then start the bike while watching the IAC. Shortly after starting the bike the IAC should move in (toward the TB) and the idle should drop down. If the IAC does not step then it needs to be replaced.
If neither of these tests show a faulty sensor then you check you leaks.
Thread
Thread Starter
Forum
Replies
Last Post
