Running rough and backfiring

[papalode]

Summer is here and this bike is not right yet. It is an '01 FI with 18k miles. A number of events have happened since the delivery of this bike. A new battery and a loose fuel injector wire had to be reconnected. It ran but seemed to be rich at lower rpm's with some backfiring. My computer had been in the shop forever so after urging from some friends I messed with the PCIII manually. Went from bad to worse. After getting the computer and downloading the right map it wouldn't take it. The factory (dyno rep) suggested I reload the software, check the wiring, etc. After reading other posts on the pros and cons of the PCIII I disconnected it. Vance and Hines pipes and a K&N filter are on this bike. Still backfires on de-acelleration and idles on the rough side. My old carburated 99 Nomad with Vance and Hines makes this one look pretty sad. I checked for cracks in the V & H pipes and smoke tested other areas of the engine looking for a leak somewhere. Nothing. I'm at a lose as to what else to look for and reluctant to take it to the shop locally (not a great reputation) I may have compromised (unknown) the performance of the bike by giving it a shot of starting fluid early on when the starting/running issues first surfaced.
Ideas anyone? Thanks

[ringadingh]

I doubt the starting fluid will have any negative effect to anything youve done on the bike. It still seems to me like you may have an exhaust leak at the header gasket, or a cracked rear pipe, you have all the symptons and V&H pipes are known to crack at the first bend of the rear cylinder.
As for the rough idle Id clean the throttle body with a toothbrush, and run some Seafoam through the tank.

[cactusjack]

Originally Posted by Ringadingh

I doubt the starting fluid will have any negative effect to anything youve done on the bike. It still seems to me like you may have an exhaust leak at the header gasket, or a cracked rear pipe, you have all the symptons and V&H pipes are known to crack at the first bend of the rear cylinder.
As for the rough idle Id clean the throttle body with a toothbrush, and run some Seafoam through the tank.

I agree with all the above and would have suggested it if Ring hadn't beaten me to it. Another cause of a rough idle could be a vacuum leak.

[macmac]

Do all the above and then yank the tank to look at the wire harness where it turns down behind cly 2. Release the lever on the factory zip tie if it is still factory. I cut mine and then saw I didn't need to.

You must lift the harness and look for chaffing.

If there fix it.

Next make sure the throttle plate sensor is on and tight, that the plug in is clean and tight.

Ride it and where ever the problem that seems rich is, shut the bike off at that RPM, and pull the plugs. Coast to a stop clutch in, and don't let the engine run, or you will get a different mix picture, than the problem. Bring tools to pull the plugs on the spot.

Either read the plugs yourself or tell us all.

After that with a mister spray bottle mist around, looking for damaged 2ndary wires and the like.

[MAS Tequila]

The crack (if there is one) can be extremely small and still cause backfiring.

Guess how I know?

The part number for the rear head pipe on the Nomad is:

K305FC-R KAW NOMAD REAR HDR TUBE $ 74.54

When I called it was a 3-4 week wait. Amazing what can be welded.

Seafoam the hell out of it. Put it in the tank and spray it right into the throttle body till it chokes and tries to die. It'll look like your fogging mosquitoes. These FI bikes carbon up very easily, especially if your running high test.

MT

[AlabamaNomadRider]

If it runs rough going down the highway and seems to miss it could also be short in the wiring harness. Or one of the pins has lost its connection.

[papalode]

Working the suggested issues this weekend. Hope to have a positive report in a few days. Thanks guys. Head gasket seems to be intact (via a stethescope listening tube) Will pull pipes and re-examine them again. Possibly a small crack got by me earlier this week when I removed them. I am assuming that a cracked pipe or vac leak somewhere not only would cause the backfiring but potentially the rough idle also(?)

[macmac]

What is power like in general? How well does the engine start?

Do you have access to a shop tach? Is there one on the bike now?

What else on the bike isn't oem?

[ringadingh]

Originally Posted by papalode

Working the suggested issues this weekend. Hope to have a positive report in a few days. Thanks guys. Head gasket seems to be intact (via a stethescope listening tube) Will pull pipes and re-examine them again. Possibly a small crack got by me earlier this week when I removed them. I am assuming that a cracked pipe or vac leak somewhere not only would cause the backfiring but potentially the rough idle also(?)

I used a mirror to find the crack in my header pipe, I didn't have to remove the pipe or the heat shield to see the crack.

[papalode]

Bike starts right up and idles smooth until it warms up at which point it idles not as smooth as I believe it should. My comparison is the old '99 Nomad I used to have. If I crank the throttle sitting there it may cough/pop slightly but not everytime. Power wise, I would say it is all there. It accelerates fine. No tach on bike nor access to one. To the best of my knowledge everything is original to this model except the V&H exhaust system and K& N air kit. The PCIII is now disconnected. After talking to one of their reps yesterday again it seems my unit may be faulty. It is a '01 PCIII and appears to have been installed years ago. There are some plugged rubber tubes that must have gone to the original air filter assembly. The map sensor is plugged into the K&N assembly as I believe is correct. Is there supposed to be an O2 sensor somewhere? I have no manual to this bike and reference "Bikebandit.com frequently for information and drawings. A re-examination of the pipes found no cracks earlier today. Tomorrow I will check the plugs, wiring and for possible vac leaks. The symptoms remind me of a possible vac leak. I did try the mirror trick but had to remove the pipes and chrome shields to satisfy myself all was well. The exhaust gaskets are new and seated snugly. Multiple test drives up the street (I live on a hill) show power as I would expect but the drive back down under no power displays the continued heavy backfiring. I will continue my investigation tomorrow and post progress as it happens. Appreciate the brainstorming guys.

[macmac]

The PC III if found faulty could be a part of the problem, but this bike should have one form or another of a fuel modual for sure. Does it ping?

And yes if there is no exhaust fault, and cold it seems fine the rest sounds like a lean miss hot, so a likely vac leak.

No O2 sensor, so no feed back for a PC III. This is primitive D jetronic, a vintage Bosche system from the early 1970's re-vamped.

The engine wants idle to mid range RPM fuel the EPA cheated us of. I suspect in this range the bike stock is set to apx 19:1 air/fuel, and with a TFI/ Cobra you can correct that. Also the engine wants more fuel under hard accel. The ECU runs cruise fine the way it is.

"If I crank the throttle sitting there it may cough/pop slightly but not everytime." this says vac leak all over it.

There is 2 ports where this could take place. If this isn't a Cali bike one port on the throttle body is capped. Check that. The other port is used on all 1500, and 1600's to run the vac port to the reed valves, Check that tubing on both ends, or check the cap if the redd valves and vac pod are gone.

Other places a vac leak can occur are the throttle body throttle plate shaft seals, the body to intake manifold, the manifold to heads.

Another way to prove this is to fire the engine cold and let it run a few moments, but stop it before it gets warmed well and then yank all the plugs and read them.

Then allow the engine to warm up and become lumpy, and again pull the plugs and re-read them seeking which show signs of lean.

[papalode]

Hey Mac,
Still trouble shooting the bike based on your last input. Looks like both ports are capped off on the throttle body. No pinging by the way. One of my friends was following me a number of weeks ago and he said he could hear the bike missing. I wasn't hearing it as the V&H pipes are loud. I thought he was messing with me but now I wonder. Sitting in the driveway at a fast idle I do detect some missing. I pulled and verified the plugs as correct in part # and gap. Another frind is suggesting to lessen the gap on the plugs. They are set per label under the seat. Three out of 4 are mostly a light brown or almost yellowish on the tips and the fourth plug left side rear is slightly black or carboned up. No oil on plugs. Wiring seems to be intact and I found a small hose that was not connected to anything. I plugged it with no change in the bike performance. I've been all over suspect tubes, fittings and gaskets with my stethecope/hearing tube. Under power the right side of the bike sounds like it is sending out a leak sound from the exhaust pipe/header area. Not noticeable at an idle but under power the shh,shh,shh noise is noticeable. Will followup on this tomorrow. Not a cali bike by the way.

[ringadingh]

Sometimes a new set of spark plugs is all it takes to cure some little bugs in the engine. Even though they look ok and spark while testing, they miss during higher rpm's.
Just last week at work we had a new lawnmower that wouldn't start. It had a bad plug after about 30 minutes of use, changed it and it was hard to start, but would run. Changed the plug with another new one, and it starts first pull every time now.

[macmac]

What little hose got plugged? Where is the other end?

I don't think I like this shh,shh,shh noise, try to locate that. I hope like Doc you just have really good hearing and the noise is just the engine breather doing what it should.

BUT have a hard look at around the head gasket area just incase. I haven't heard of any problems in a general way with bad head gaskets, but it still could be. I doubt it even, but then we have head gaskets, and sometimes they are a fault.

I would quadriple check the head pipes gaskets, maybe replace them and treat the exhaust studs to a wee service.

I know tht V&H pipes at one time had no flanges with the set up and we had to use stock flanges and there was slop. The slop was taken up with another flat washer. make certain the acorn nuts are not on tight and still there is slop.

What I do is remove the head pipes, wire brush the threads by hand with a stainless tooth brush, not a power tool. I run on the acorn nuts and mark the spot on the threads with a marker.

Then with hi temp paint I paint from the head to the mark, by misting the paint into the rattle cans own cap and paint with a acid brush.

Then I anti seize the rest of the threads. I make sure the flanges are installed again nice and even. all get finger tight evenly, then snugged to tight, then a test to check for any exhaust leaks, then a test ride, for the same and a heating cooling cycle and then re-check for snug cold. Do Not over tighten cold, Do not tighten still Hot! If you over tighten you will break the stud, If you tighten hot when the stud cools it will shrink and crack over time.

I am hoping this is a simple fix still at this point.

fOR GRINS PULL THE INJECTOR CONNECTORS HAVE A LOOK AND OUT THEM BACK ON. UNLESS YOU FIND THE CONNECTORS GREEN AND CRUDY, THEN CLEAN THEM.

hit caps sorry. not pointing out much special and too lazy to fix it.

[macmac]

Another thought is move the black plug to another hole. See if the one you put where the blacker one was becomes blackend.

Would know if this bike ever got a bad dose of fuel? If it ever did, the injector spray pattern maybe different from that. The spray pattern can be critical. I wouldn't worry about that very much either, but it is possible.

So far a rough idle is not a real problem, and my best guess is it is set a bit too low. You want no less than 900 rpm. I run mine at apx 950 according to my new tack.

Sometimes it fluctuates a little, hunting at apx 50 rpm both ways. Pretty normal.

On decell I get cackel and popping unless I hold a little throttle.

right side air only, V&H baggers, TFI, coasters, both TBody ports capped off, both ISC ports capped off. (something to compare too)