x1 hard missfire at 2800-3100

[Vtwinsuicide]

my 99 x1 has a really bad misfire right around 2800-3100 rpm. the bike starts/idles/winds out just fine, it only happens when cruising at that rpm range between 40mph and 60mph. if i try to hold a steady speed in 5th at 3,000 rpm it gets really choppy on me, if i downshift into 4th and bring it up above 3,000 rmp it cruises perfectly smooth.

the problem doesn't worsen or improve regardless of what i do to the fuel maps in that area.



a little info about the bike, it has a ham can intake on it V&H exhaust. recently put a race map on it, i've run it with the stock map and it does the same thing. brand new spark plugs. I've reset the TPS about 10 times with no improvement. checked the static timing, which if i was doing correctly, it looked slightly advanced. I marked it and retarded the timing a little bit and saw zero improvement.

also, it is popping out of the intake while misfiring, which to me says lean or spark is too advanced?

I'm not used to bikes with FI and stupid electronic sensors on them so if anyone has advice on what to check next it would be much appreciated


thanks -Brad

 

[newyorkbuell]

popping yes thats lean. My father has a 2002 x1 with a forcewinder and a jardine pipe and had the same kind of studder/flat spot trouble. I started with the stock map and added 2 to everything then datalogged and it wanted more fuel and ever since it has been good. With the cams you deff will need more fuel then what just the race map is giving you. Hopefully one of the better tuning guys can help you but i would add more fuel.

 

[Vtwinsuicide]

adding fuel to that rpm/tps range made the problem worse, but leaving the race map as is and riding in closed loop steadily at that rpm bumped my AFV up 130?? so it feels lean, the computer thinks its lean but adding fuel makes it worse? someone remind me how DDFI is better than carb

 

[knwyman]

Does it happen when the bike gets warmed up or is it always happening? That sounds somewhat similar to what my S3 did when the head temp sensor went bad. It would seem to run fine, then get hot & all hell would break loose! COughing, farting back through the intake, bucking, etc.

Your AFV is pretty high, though. Race map is quite lean in the map area of normal riding. You sure you have no intake leaks?

 

[Vtwinsuicide]

i did the spray test for intake gaskets, didn't do seem to do anything, but i've had them go on my 86 evo and not respond to any sort of test. i'll probably throw new ones in tonight just to rule it out.

head temp sensor seems to be reading correctly judging by the feedback ECM spy is giving me. ive compared what its reading to what my temp gun reads on the jugs/head and the numbers are pretty close.

 

[Vtwinsuicide]

So while tearing into the bike I noticed there is a small vacuum line connector on the bottom of the throttle body that is not connected to anything. Intake gaskets are fine but I I'll replace them anyway. Injectors looked a little dirty but not too bad. Think the vac line connector could be my problem?

 

[knwyman]

I just looked in the S3 manual & I'm betting you have a CA spec bike. That hose is supposed to go from the charcoal canister to the bottom of the throttle body. If the port on the TB is not plugged, that could be a problem...

 

[NwRider]

I recall reading that as well. That fitting was for ca. Emissions and is capped off on the 49 staters. If memory serves me correctly it didn't cause a noticible difference when capped off again. Cap it and report back.

 

[Vtwinsuicide]

looked a little deeper. Wire loom for front injector was totally chewed up and resting against the throttle cable. When I twist the throttle to about 20% (right about the position a was having a bad misfire at) the cable presses against the wires where they are bare. I can't believe the thing ran at all with how chewed up they are, not to mention it actually ran pretty well at every other rpm [confused]

 

[Vtwinsuicide]

Also, would a cali spec bike have made it to Minnesota? I got it from the original owner.

 

[knwyman]

Not sure, ask the original owner. Just make sure that port on the bottom of the TB is capped tightly... It sounds like you found the problem though. Get those wires fixed & go for a rip. Then re do your fuel maps, you won't regret it...

 

[NwRider]

I doubt a cali bike would make it that far but ya never know. Sound like it does not have the emissions junk on it or it was removed. I have heard of the vacuum caps falling off though. Cap them and maybe use a tiny zip tie to be sure it doesnt come off again.

I have heard of many different electrical problems due to poor routing and chaffing. Every time I work on my bike I poke around and overuse zip ties to keep everything in order. I even have a spare new harness I found on ebay a while back just in case. If I get around to a complete rebuild (want to change the frame color eventually) I will probably use the new harness.

Glad you found the problem.

Oh.. if you want to confirm its a 49 state bike you could probably call the HD with your VIN.

 

[Vtwinsuicide]

being a moron i broke one of the terminals inside the connector for the front injector. being that the harley dealer nearest to me was lost when i ordered intake gaskets, i don't even want to try them with this one.

anyone know a part # for those things? or if maybe an automotive connector will cross reference to it? it looks similar to a lot of GM fuel injector pigtails i've seen

 

[NwRider]

Iat sensor, o2 sensor and maybe the tps all share automotive applications. It wouldn't surprise me if that connector is the same. I'd take a trip to your local Napa and check it out.

 

[Vtwinsuicide]

it is indeed the same as a GM multi-port FI solenoid connector. got one from napa after a whole lot of "what kind of car is it for" questions.

if i can avoid shooting myself in the foot again, maybe i'll get it back together tonight

 

[NwRider]

Haha... Nice... Good eye!

What is the part# just for the record.

 

[Vtwinsuicide]

think i already threw away the box. I know they're the same for all GM MPFI fuel injection systems. i think i just told them i needed one for a 95 lumina with a 3.1 v6 and they were able to find the part.

bike runs great now. still had to tweak the map in that area to get it to cruise perfectly. after a 50 mile ride AFV was still at 100%, but it has been throwing a code for "o2 sensor always lean" now [confused] do i have a bad o2? wouldn't it be bumping up the AFV if it thought it was lean?

 

[obstin8]

Same type issue. Gas. The ethanol in the fuel screws with the ecm. Find a pump with gas only. Finally did find an outlet and it runs like new. No more sputtering, backfire, or getting passed by that minivan.

99 X1 Carbon Fiber #195 of 250

 

[Vtwinsuicide]

being that i do 15-20 long distance trips a season i'm probably not going to depend on the availabity of non-oxy gasoline.

That really seems like putting a band-aid on the problem. yes, today's pump gas is terrible awful *****. That aside, under normal circumstances, you should be able to dial in almost any fuel delivery system thats worth a damn to run on it.