1998 FLHTCUI Missing and revving
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4th Gear
Joined: Sep 2011
Posts: 8
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From: Austin TX
1998 FLHTCUI Missing and revving
1998 FLHTCUI missing and cylinder load up. Sometimes when I'm riding the engine will stall out and start missing and popping. This seems to be related to the rear cylinder since it blows black smoke out the exhaust connected to this cylinder. Then other times the engine will rev up around 3-4k RPM. Regardless of what I do I cannot get the engine to stop reving up. After 15-20 seconds the engine will go back to idle speed.
1340 engine was rebuilt before I bought the bike, so not sure on cam or other changes. Bike has K&N air breather, Rinehart slip ons, and Revtech DFO module.
I was under the impression I got some bad fuel with some sediment, since the engine started missing and then would come back to life. However I've run about 30 gallons of fuel through it since this began. I'm of the opinion it's something more serious. If the bike is missing or revving and I shut it off and let it cool for a few minutes everything seems to go back to normal for a short time, then it's back to having issues.
I pulled the read plug and cleaned it and it seemed to make some minor improvements, but I'm not sure where to start diagnosing this issue.
1340 engine was rebuilt before I bought the bike, so not sure on cam or other changes. Bike has K&N air breather, Rinehart slip ons, and Revtech DFO module.
I was under the impression I got some bad fuel with some sediment, since the engine started missing and then would come back to life. However I've run about 30 gallons of fuel through it since this began. I'm of the opinion it's something more serious. If the bike is missing or revving and I shut it off and let it cool for a few minutes everything seems to go back to normal for a short time, then it's back to having issues.
I pulled the read plug and cleaned it and it seemed to make some minor improvements, but I'm not sure where to start diagnosing this issue.
Seasoned HDF Member
Joined: Oct 2007
Posts: 8,852
Likes: 2,493
From: Decatur, Alabama
I have the same bike.
Have you checked to see if you have any fault codes?
Mine revved up pretty badly once. The IAC was stuck. I pushed it in by hand. Another time I had a bad head temperature sensor which seems like what you could have since the problem goes away when the bike is cold and comes back after it's hot.
Have you checked to see if you have any fault codes?
Mine revved up pretty badly once. The IAC was stuck. I pushed it in by hand. Another time I had a bad head temperature sensor which seems like what you could have since the problem goes away when the bike is cold and comes back after it's hot.
Thread Starter
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4th Gear
Joined: Sep 2011
Posts: 8
Likes: 0
From: Austin TX
Carlgrover, I haven't checked to see if I have any codes. I would assume so since the engine light comes on sometimes when I'm having issues, but it's not consistent.
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Seasoned HDF Member
Joined: Oct 2007
Posts: 8,852
Likes: 2,493
From: Decatur, Alabama
If the engine light comes on, you have trouble codes. It doesn't have to be on all the time. Get a factory service manual and it will show you how to retrieve the code, what the code means, and how to fix it.
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check engine code first. no tools required..off/on sequence with-out starting but with fuel pump priming..this sequence done three times will show code....consider review of engine temp. sensor..when the temp sensor goes bad the bike runs super rich and lean back/forth and generally runs **** poor...the cam position sensor in timer cone melts over time in this year..visual check(no tools) of melted goo exiting wire hole under timer cover...original is usually biege/tan...also clean throttle body..may bikes have NOT been cleaned..all three items above can be checked and or replaced with minimal tools once a diagnosis is reached...i am betting on the engine temp. sensor based on the minimal information available..check fuel lines also as the M & M two line hoses breakdown from inside out and sometimes leak at the swivle under tank.