'98 electra glide with poor running condition and really bad fuel milage. shop said most likely the ecu. anybody upgraded to a newer system ie. thundermax and hod do u like it. looks pretty interesting to me. just don't want to dump hard earned money into the marelli system and still heave a junk system.lol. any and all info. would be very much appreciated. thnx. what i'm a do.

 

If you have the money to take it to the dealer and get it diagnosed,you won't have to start guessing whats wrong with it. It's probably a Throttle Position Sensor or Head Temp Sensor but don't start replacing parts to get to the right one. It gets expensive.

 

How many miles on your bike?

 

60k mi. its been very reliable and metucullously maintained. idles hi. bogs really bad after warmed up. terrible fuel milage. I had a very reputable shop investigate. all sensors are reading properly. their opinion is the ecu may be bad. looking for a tunable upgrade if i have to spend.

 

Check on getting an 02 Delphi ecu.

 

When's the last time the fuel filter was changed? Hard to believe it would be an ECU as they normally either work or don't. Have you had the injection system cleaned? Sometimes a bottle of fuel injection cleaner can help. You can spray carb cleaner around your intake areas and if it causes a change in idle you'll know you have an intake gasket leak. A couple easy things to check....

 

Careful w/the "reputable garage"...when i first got my 01 roadking (also magnetti equipped) I took it back to the dealership because once warmed up it sputtered and backfired pretty bad. I was told by the service manager (after the techs checked it out for an hour or so) that I had an aftermarket fuel injection system that they don't service. I had a feeling this wasn't right and took it to the next nearest dealership.
It turned out that Harley switched from magnetti marelli to delphi efi in 02, this happened to me in about 06. As hard as it is to believe, the service manager @ the next dealership said that the other shop probably had newer techs only trained on delphi so they didn't know how to service it! Luckily the 2nd shop had a guy who could work on my ancient 4-year-old STOCK efi!!!
It was just running lean, bought a sert and had the 2nd dealership make the adjustments. Good luck, hope its somethin simple.

 

thnx for info guys. the fuel filter hasn't been changed but I will be doing next weekend. that might fix the problem. I don't let just anyone work on my scooter. But I won't take it to a dealer.

 

Invest in a can of throttle body cleaner and clean the throttle body. Concentrate on the two holes near the opening of of the throttle body. One in each throat. They are the idle air control passages and can become gummed up.

Also check that the IAC motor is working. A simple test with a volt meter can tell if the TPS has a voltage spike. Check that the nut on the throttle shaft is tight.

Not many indy shops or harley dealers really understand the M/M system.

M/M system can be adjusted without special equipment if all the sensors are working properly.

Does the check engine light indicate a fault code?

 

EFI troubles, like exotic sports car electronics, are one place where you WANT an authorized dealer diagnosing your problem. They have the equipment and experience to quickly diagnose failures in EFI systems. The MM is no more nor no less prone to problems (other than a tricky cold-idle setting which is no big deal) than the Delphi system is, HD switched because they had to: 2006 Federal Mandates required throttle-by-wire and closed-loop EFI systems to further limit emissions and the MM was never designed to do that.