I have a 2018 Harley Road Glide special with a 107 M8. Bike was stock other then 4” Rinehart Slip-ons installed prior to recently purchased upgrades.
Bike ran perfect before upgrades but now not so much...

After installing head pipe, air breather and flashing the ECM with the provided FM tune. Now the bike starts with an excessively high idle and then slowly drops down to a low rough idle. Crank the throttle and the rpm seems to linger up and come down slowly then idle low and rough. Any advice would be greatly appreciated. This is my 3rd personal bike build with a Power Vision tuner and never experienced this problem. The map/tune was provided by Fuel Moto and Pre loaded into the Power Vision. Before going into the garage I uploaded another similar map/tune into the PV along with updating the PV firmware. Then after installing Exhaust and Air Breather I Married the Power Vision to my bike and flashed the pre loaded FM tune. Bike did exactly what I described above. So I tried the Map/tune I downloaded from Dyno Jets site and same results. Then I re-flashed the ECM for a 3rd time re-installing the ORIGINAL factory map/tune and again same results. Nothing seems to work. Any advice would be greatly appreciated. Ive also reached out to FM and waiting their reply. Thanks in advance!

Prior to upgrades: Stock 2018 RG 107 M8 with 4" Rinehart Slip ons when running 100%

Installed upgrades:
1) Fuel Moto Jackpot Head Pipe,
2) Arlen Ness M8 Big Sucker
3) Power Vision PV-2 with Pre-Loaded FM Tune/Map

 

Sounds like you may have an intake leak somewhere . Double check your gaskets and make sure there sealed properly .

Dumb question , but did you leave the support bar , above and behind the air cleaner on it ?

 

Yes, I left the support bar. Watched several videos and at the end just followed the box instructions and left it in place. Unless I missed it in the instructions and was supposed to remove it ??. As far as leaks too intake, do you mean the air breather gasket? I actually was thinking I missed something of one of the breather bolts was not breathing so I also tried running it without the air filter of cover to let more air in....nothing.

 

Yes , sorry , the bar is still supposed to be there , had a friend take his off , big mistake . It could also be possible that you may have bumped the connector to the TPS , check it and make sure it's plugged in all the way . You could also try resetting your idle and see if that solves the problem .

Run switch on ,
Turn on your ignition on and wait ten seconds
Then turn ignition off , wait ten seconds
Do this 4 times in a row , then wait a few minutes before starting .

What type of header gaskets did you use , most aftermarket gaskets are flat with a square edge , oem would be tapered .

Are you getting any codes when it's running , red key light staying on ?

If all looks good and everything is sealed up the way it should be , I would call FM and talk to them personally , they are without a doubt great to work with .

 

You should have gotten new breather bolts with the air cleaner , they should have come with 4 o-rings , 2 for each side . Pretty simple and not to difficult .

 

I will check the TPS. As far as the head pipe gaskets, my son is the one who installed the head pipe while i was at work. He said he used the stock flange parts unless he FORGOT THE GASKETS!!!

 

PS: Yes, I personally installed the new breather bolts and all for front and rear plate o-rings. As far as what I just said.. I will check the old stock head pipe the gaskets are in it. No check engine light that I was aware of either.

 

Right on , you want to be sure your using the correct gaskets ... Hope that's all it is . Best of luck . Keep us posted !

 

If the throttle body support has not been removed this is for sure the problem as this will cause a direct air cleaner and will 100% cause the idle to hang. Removal of this bracket is noted in Step 2 (Picture 1) of the Arlen Ness install instructions. If you need any additional assistance feel free to reach out to us.

 

Jamie. I definitely DID NOT remove that plate. Wow...I just checked the instructions and totally overlooked that step! What a bonehead move. I will get right on that and remove it asap. So it must be sucking air from improper fitment causing the idle to raise at initial start and then run rough. I will keep you posted, I usually never have to do things twice but in my defense I just turned the BIG FIVE OH and must me losing memory