More Magneti Marelli questions
Seasoned HDF Member
Joined: Aug 2017
Posts: 7,323
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From: Omaha,NE
Do you have a good reference voltage of 5V? if you don't, you won't have good signal voltage, either. If you're positive that you're checking the correct wires, you need to verify your VREF.
Seasoned HDF Member
Joined: May 2018
Posts: 5,814
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From: Las Vegas
Have you seen this thread? good info in it --- https://www.hdforums.com/forum/touri...libration.html
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2nd Gear
Joined: Aug 2021
Posts: 6
Likes: 0
From: NC
Yes, I've been through some of the threads on the forum, no one seems to have had the same issue that I am getting though.
Any idea on how I can check the reference voltage? I'll do some googling but I'm not familiar with doing that at all.
Any idea on how I can check the reference voltage? I'll do some googling but I'm not familiar with doing that at all.
Stage I
Joined: Jun 2025
Posts: 1
Likes: 0
I know this is an old thread but did you ever get it sorted?
In have a 99 road king with the Marelli and having very similar problems. Cant afford the change to carb at the moment
HDF Community Team
Joined: Jan 2020
Posts: 1,434
Likes: 800
From: Colorado
Read, since not hard top pull the TPS apart, clean the film contacts and if swiper arms are now worn out and TPMS has to be replaced, slight tweak of the swiper arms outwards, so they apply more pressure to the film when you put it back together.
https://www.hdforums.com/forum/ignit...for-evo-s.html
If TPS needs to be replaced, your looking for the PF4C unit, but PF3 can be used if that is all you can find.
When cleaning the throttle body, make sure to shoot cleaner through the air screw channels, to clean up any carbon that has collected in them (don't change the air screws).
As for resetting the TPS voltage, need to back off the cold and hot idle screws, unplug the IAC and push it all the way in so you can close the TB vanes all the way, set the TPS voltage, then set the hot and cold idles voltages for your staring points. On cold idle with cold motor, like it to hold the idle up for only a few mins at about 1200RPM on start up, then allow it to drop to hot idle, that you want to set that to 1K RPM with motor fully warmed up.
Also to note, helps to have heat gun to check the head temp against engine temp sensor, since the engine temp sensors loves to have problems after a few years, and if temp sensor is not working correctly (will only code if its wire are broken,not if it not working correctly reading the correct temp with it resistor feed back to ECM), will leave engine is cold mode way too long, or just leave it there with engine never leaning back to hot leaner mode instead.
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MJStephens
Ignition/Tuner/ECM/Fuel Injection
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Apr 23, 2008 05:17 PM
