EFI Troubles Harley EFI & Harley Carb Discuss EFI Troubles in the Harley Tech & Harley How-to forums; 02 Ultra 88 cu. in. What I'm doing is trying to track down an intermittent miss. I took it to the dealer when it first occurred, they said they saw ...

[shovelmike]

02 Ultra 88 cu. in. What I'm doing is trying to track down an intermittent miss. I took it to the dealer when it first occurred, they said they saw no trouble codes, charged me $100 and changed the spark plugs. The trouble first occurred when the bike was bone stock, now I'm running TW21G cams, Ness Big Sucker A/C, and Rush slip-on's 1.5" baffles, and PCIII USB. I loaded the map for the intake and exhaust combo and added 5% fuel at low range, 10% at mid range..all was well all last Summer following the mods. now were back to the miss. At 60-70 mph all is well, around town it's missing, lurching, popping out the exhaust.
I have sprayed WD40 around the manifold-head juncture and throttle body-manifold juncture and have seen no sign of leaks. Any help would be appreciated. Sincerely: Shovelmike.

[Tbone]

Looks like no one knows a solution yet Mike.

I've been thinking about what could cause this (with regard to how little I know about repairing engines).

Miss before spark plug change. Miss after spark plug change.
Not the spark plugs (unless you were unlucky enough to get two bad sets in a row).

Miss before and after the changes in exhaust, cam and air cleaner.
Not the exhaust, cam or air cleaner.

Miss before and after the changes in fuel mapping.
Not caused by fuel mapping.

Doesn't miss at high speed. Only at low speed.
Could be electrical.
Start at the stator. What is the output at idle or low rpm compared to high rpm.

[Wrightturn]

Hey Mike,

I think Tbone is on target. Charge the battery then let it rest for an hour. Read the voltage at the battery with the engine off and then with the motor running. Check the ground cable at both ends and consider adding a second ground cable. This made a major difference on my 02 FLHP.

Next use your VOM to check the coil. I have had to replace the coil on both my 99 FXDX and the FLHP. You can spot the problem with the VOM before a trouble code shows up. If the coil reads bad you can get OEM from J&P and save almost $40.00 over HD.

Good luck

[milindh]

Hi Mike

The most interesting thing in your post was, "all was well all last summer after the mods. Now we're back to the miss."

That makes me think it's all related to weather conditions. Might have something to do with enrichening circuits in your EFI. Maybe more likely is an electrical glitch like a bad connection or a bare wire that grounds out in moisture. Sounds like Wrighturn and Tbone are on the scent here. At any rate if it's weather related it's either about heat or moisture. Weak electrical components are effected by both. Also if your system voltage isn't up to par it would probably have an effect on your EFI brain.

Good Luck Dude

[evoKENevo]

Here's just another one of my long shots
As noted here the air around us is denser in cooler & damper weather than in warmer & dryer weather...
Could it be that last season you were running on the edge of too lean (low-mid range) and that the COLD weather now has you temporarily a little over the edge.
Was the lowest temp when you rode it last season...as cold and/or damp as it is now ?

[unclepsycho]

As I read the reply's, I too think the cold temps have something to do with it. Some things shrink in the cold.... uh, like wiring? or in the coil, the cold weather could make the insulation pull the ground wire or something away from it's position.
I had a truck that cut out and misfired when I hit the turn signal..... it was a bad ground that did that. So maybe you have a bad ground somewhere that is affected by the cold weather ???

Good luck

Tbone:
I like the way you think... using the process of elimination to find out what is NOT causing the problem.... and letting that point you in a direction that can lead to the solution
I gotta remember this...

[shovelmike]

Thanks guys, you gave me some good ideas and some things to check out. On the off chance that I was borderline lean and affected by a change in the weather as suggested by EVO I printed out my Power Commander maps so I could really look them over how much fuel was added at certain RPM and throttle openings. I have been running M807-059. I found that M807-016 supplied more fuel at the points where I'm experiencing the most trouble, so I installed that map and it seems to have improved somewhat.
I'm going to take a look at the charging system and battery ground situation as you suggested, Wright.
Thanks guys, I'll let you know what I find. Ride safe and GOD bless, Sincerely: Shovelmike.

Shovelmike, I have an 03 Ultra, w/35k miles, for the past few winters when the bike was cold it did not want to idle properly, or run at low RPM's. Felt like riding a horse bucking, shakin etc. Took it to the dealer to have the front forks serviced, told them about the problem. When I got the bike back they had found a couple of pin holes in the fuel line in the tank, from the check valve to the fuel pump. Tech told me you would only notice it at low RPM's, enriched state. (cool weather) When the engine warmed, or when you opened the throttle enough fuel would flow to overcome the leak. Just a thought.

[shovelmike]

Thanks, Graybeard, I've got about 32 thou. on mine, the manual calls for fuel filter canister replacement at 25 thou. (I haven't done it yet). It requires removing the canopy from the top of the fuel tank, so it's an excellent opportunity to take a look at them. Ride safe and GOD bless, Sincerely: Shovelmike.

[shovelmike]

I changed the ignition coil on the Ultra in case the windings were getting bad and put in a new battery just for good measure (since the old one was 7 years old) Awesome Spring weather today, about 72 degrees! Hopped on the Ultra with the intent of delivering an item to my wife at work, making a stop at the nursing home where my mother resides, and then put some serious miles on the bike. It was running terrible, bucking, missing, and popping out the exhaust. I dropped off the stuff the wife needed and rolled into the dealer’s service department just as they opened. I figured I’d let them see what they could find.
They got the bike right in. They rode the thing all over creation and couldn’t get it to miss a beat (of course). They called me out to the shop area, hooked the bike to the computer to verify that the map was OK, tweaked a couple of cells, gave me some pointers on tweaking the maps, and verified that the fuel pressure was OK.
I had them change the fuel filter and take a good look at the in tank hoses, which proved to be fine. I stood there and visited with the tech while he did the job. He demonstrated to me how he powers up the fuel pump while holding up the canopy so he can check for pinholes in the pressure hose once everything is all hooked up.
I think it’s cured! (cross my fingers, toes etc..) I got out of there for about $145. Considering the time they spent sorting it out and the info I picked up I didn’t think that was too bad.
My theory is that I had some debris in the filter, I do know that I have gotten a bad tank of gas here and there filling up in unfamiliar towns.
Thanks to everyone for the advice along the way and we'll hope all I have to do now is RIDE....I'm ready!