Marelli FI issue- see description
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6th Gear
Joined: Jul 2025
Posts: 14
Likes: 4
Marelli FI issue- see description
Hello guys. Glad to be here. Heres my issue:
2000 RKC TC88 with Marelli. Dead stock mechanicals. Just got the bike. Ran well until I cleaned the throttle body, which was pretty dirty. Since then- running like dogs posterior.
Heres the symptoms:
Low idle all the time
Miss/Chirping through the throttle body at idle and part throttle (1/3 or less)
Running rich- some soot on plugs and exhaust is strong
Above 1/3 throttle it pulls well and strong. Feels great.
Im going to check and adjust the TPS settings as needed. But this was sudden. Something seems to be telling the ECM to go rich all the time. But I dont know what. There were no pops or any issues when I cleaned the TB so I dont think I blew a seal at all- plus it runs great under heavier throttle. I think I might have somehow killed the TPS or IAT sensor.
Thoughts?
2000 RKC TC88 with Marelli. Dead stock mechanicals. Just got the bike. Ran well until I cleaned the throttle body, which was pretty dirty. Since then- running like dogs posterior.
Heres the symptoms:
Low idle all the time
Miss/Chirping through the throttle body at idle and part throttle (1/3 or less)
Running rich- some soot on plugs and exhaust is strong
Above 1/3 throttle it pulls well and strong. Feels great.
Im going to check and adjust the TPS settings as needed. But this was sudden. Something seems to be telling the ECM to go rich all the time. But I dont know what. There were no pops or any issues when I cleaned the TB so I dont think I blew a seal at all- plus it runs great under heavier throttle. I think I might have somehow killed the TPS or IAT sensor.
Thoughts?
Last edited by DinoBob; Jul 25, 2025 at 05:38 PM.
Thread Starter
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6th Gear
Joined: Jul 2025
Posts: 14
Likes: 4
Ill sniff around it with propane. But its running really rich. I have a full Marelli seal and o-ring kit. But Ive learned never to take anything apart until Im certain I have to. So Im going slow.
Thread Starter
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6th Gear
Joined: Jul 2025
Posts: 14
Likes: 4
I spent some time going through this yesterday and actually have the bike running fairly well and accelerating with no hesitation or stumbling, and have a pretty good idle. But this required setting the TPS wayyy out of whack- the initial voltage was on the order of about 1 volt.
The TPS doesnt seem to hold its initial setting as well as Id expect- so I did order a new one just because I thought that might be a good idea.
Im going to use a small propane torch to just sniff around the intake and see whether its sucking wind somewhere, but I just dont feel thats the issue.
A question is this; how long does it take for the ECM to re-learn my settings after I move the TPS?
The TPS doesnt seem to hold its initial setting as well as Id expect- so I did order a new one just because I thought that might be a good idea.
Im going to use a small propane torch to just sniff around the intake and see whether its sucking wind somewhere, but I just dont feel thats the issue.
A question is this; how long does it take for the ECM to re-learn my settings after I move the TPS?
Thread Starter
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6th Gear
Joined: Jul 2025
Posts: 14
Likes: 4
Those are pretty cheap and dead easy to change so Ive also got one on order.
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Seasoned HDF Member
Joined: Apr 2014
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From: Lititz Pa
I had one for years no trouble 58000 miles when I sold the 99RK. But if I ever had trouble I would have changed it over to a carb.
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Thread Starter
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6th Gear
Joined: Jul 2025
Posts: 14
Likes: 4
Since I adjusted the value of the TPS to this crazy value I have it at now, zero hesitation and chuffing through the throttle body. Pulls perfectly.
Stellar HDF Member
Joined: May 2015
Posts: 2,091
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From: mid Michigan
The TPS is obsolete, the aftermarket ones that fit are not correct . Maybe that's what you have and or getting . The only way to get one is on ebay buying the whole throttle body that has one. When setting the tps did it have a smooth flow from idle to wide open?