2004 dyna fouling rear plug

[anthonyflhx]

My 2004 dyna started acting up today and keeps gas fouling rear plug. I swapped coil and plug wires with same results.
Any idea what it could be or where to look next?
I gassed up today with 87 non ethanol gas and she ran good for 15 miles then started lagging and running on 1 cylinder.
Wouldn't gas issue foul out both plugs?
Thanks in advance for any help.

[dogger]

Fixing the intake manifold leak took care of it for me when I had a similar problem.

[anthonyflhx]

How would i test for intake manifold leak? I just started bike and sprayed wd40 around the intake and there was no noticeable change in engine sound.

Fixing the intake manifold leak took care of it for me when I had a similar problem.

[koko3052]

Start the bike & spray a little WD40 around where the manifold meets the head. If engine rpm increases, you have found the leak.

[anthonyflhx]

Tried that and no change in engine idle. Getting a little worried here.

[barny7655]

comp test, change plug to other cylinder, check leads OHM test,is it carb, or EFI, loose injector harness if efi, cheers

[Armin]

Looks like the rear cylinder is getting an overly rich mixture so the rear injector could be the culprit or the map for the afr could have gone south if the electrical wiring is not faulty.

Armin.

[chopper]

Carb or injected?

[rbabos]

Two choices, coil or injector. Coil generally throws a no combustion code, injector won't in that case. Intake leak won't cause that situation on EFI.
Ron

[rigidthumper]

No law says there's only one problem. On a carb's bike, could be a failed diaphragm in the fuel valve (that allows raw fuel to be drawn directly into the intake manifold) combined with poor intake seals, or a poorly seating enrichner dribbling raw fuel into the port.
On an EFI bike, stuck injector will cause this.

[anthonyflhx]

Bike is fuel injected. How would you unclog injector?

[rigidthumper]

I'd swap them front to rear, to verify it's the injector and not the wiring ( a pinched ground wire will hold the injector open all the time).
Once you have found the culprit,  you can spend the $ to have it cleaned ( Marrin offers this service) or replace it ( used is prolly the cheapest, since guys replace them when doing big builds) I've seen em on eb ay for $15

[anthonyflhx]

Just did compression check and each cylinder was at about 125. Is that good or bad reading on a cold engine?

[Moparnut72]

Would be fine for a 2 stroke outboard but pretty low for a Harley. Did you open the throttle, if not you will get a low reading.
kk

[anthonyflhx]

Yes throttle wide open.

[PoorUB]

Bad gauge?
If the cylinders measure evenly I would suspect the compression is ok but you gauge is reading low. I would confirm it with another gauge before going crazy and ripping the engine apart!
How did you open the throttle? You need to open it up carefully with you fingers and jam it open with a screwdriver handle. Rolling on the twist grip will not do it.

[anthonyflhx]

Rolled the throttle. I'll try again the way you suggested and post back.

[Ohio HD]

Gauge could just read low, they're the same so I doubt the compression is a problem. I'd switch the injectors as Robin suggested.

[1FSTRK]

Rolled the throttle. I'll try again the way you suggested and post back.

Your bike is a cable throttle so rolling and locking the grip is fine.
I would try rigidthumper suggestion and switch the front and rear injectors to see if the problem follows.

[Hybredhog]

   Depending on altitude, Compression can vary widely (4psi per 1000 ft. less), So if there more or less equal I'd say move on. Another possible situation is that '04-'05 had funky guide seals, but your plugs look pretty new to not show deposits. It not a bad idea to change the intake seals for S&G's as they do get old.

[1FSTRK]

Bike is fuel injected. How would you unclog injector?

Read this thread
http://harleytechtalk.com/htt/index.php?topic=99767.msg1167272#msg1167272

[PoorUB]

Rolled the throttle. I'll try again the way you suggested and post back.

Your bike is a cable throttle so rolling and locking the grip is fine.
I would try rigidthumper suggestion and switch the front and rear injectors to see if the problem follows.

Oops! I get hung up on the TBW stuff!

[PoorUB]

Rolled the throttle. I'll try again the way you suggested and post back.

you did it right, cable throttle vs. TBW. My mistake.

[anthonyflhx]

Just pulled the injectors and the rear looks kinda burnt. I swapped em front and back and will fire up in morning to see if the front starts fouling the plug. If so i guess i need a new injector. Then i can run her over to the dealer and run another compression test.

[anthonyflhx]

Put 2 new fuel injectors in, got her all buttoned back up and still sounds like "Potty mouth" and rear cylinder fouling out. Now it looks like front is too lean as well. Have no idea what to do from here. Man spent the whole day working on it and still back to square 1.

[Moparnut72]

Have you verified the compression readings? What you had is pretty low. You need to figure this out before you start throwing parts at it. If these figures are correct you will need to figure why. A leak down test would be high on the list.
kk

[PoorUB]

Does the one spark plug look wet and oily? Maybe the intake valve stem seal sh*t the bed and died big time and you are sucking in oil and fouling the plug. Rich would be dry, black and sooty. Oil would be wet, black and sooty.

Know anyone with a bore scope? A little mini inspection camera? Hold open the throttle and take a look down the intake of each cylinder and check over the valves and guides. If they are wet, you have a valve stem seal are guide leaking oil.

[rigidthumper]

Just pulled the injectors and the rear looks kinda burnt. I swapped em front and back and will fire up in morning to see if the front starts fouling the plug. If so i guess i need a new injector. Then i can run her over to the dealer and run another compression test.

Put 2 new fuel injectors in, got her all buttoned back up and still sounds like "Potty mouth" and rear cylinder fouling out. Now it looks like front is too lean as well. Have no idea what to do from here. Man spent the whole day working on it and still back to square 1.

Thought you were going to swap injectors? Assuming the new ones are OK, that leaves intake seal issues, wiring, or coil. I'd put the original injectors back, swapped, and check injector wires, replace the intake seals just because they're old, and try again- if same same results, swap coil with known good unit. 

[anthonyflhx]

Had issues with swapping injectors and they looked pretty bad shape. The rear looked almost broken with burned edges. Figures I'd just bite the bullet and put new ones in so i didn't have to go through that twice.
Swapped coil for working one and same issue. New plugs, new wires and flushed tank and new hi octane gas with injector cleaner. New intake seals and sprayed wd40 around intake to make sure there's no leaks. Im stuck and baffled.
Still same issue.

[rigidthumper]

So, no one has changed anything in the tune, right? No fuel pressure issues, no power commander etc? Sounds like we're down to a wiring issue or mechanical issue.  Time to pull on the injector wires, to check for a conductor broken inside the sheathing, or bad pins.  Front injector harness should have white/yellow wire, rear injector should have green/grey wire.  Good thing it's winter...

[anthonyflhx]

I tried pushing on injector wires when bike was idling and didn't hear any change in idle. I'll give it another try.
The tune was a sert tune i think from previous owner.
I was worried it might be a valve issue but tech at Harley said i would know it if it was a valve issue as it would be loud and noticeable.

[FXDBI]

I tried pushing on injector wires when bike was idling and didn't hear any change in idle. I'll give it another try.
The tune was a sert tune i think from previous owner.
I was worried it might be a valve issue but tech at Harley said i would know it if it was a valve issue as it would be loud and noticeable.

Valve seals on the rear head leaking and fouling the plug.  Bob

[Hossamania]

I tried pushing on injector wires when bike was idling and didn't hear any change in idle. I'll give it another try.
The tune was a sert tune i think from previous owner.
I was worried it might be a valve issue but tech at Harley said i would know it if it was a valve issue as it would be loud and noticeable.

Valve seals on the rear head leaking and fouling the plug.  Bob

They would not be loud and noticeable.

[anthonyflhx]

I was afraid of that. How can i confirm its the valves?
So i have to pull the heads and have the valves redone? Might as well do both while I'm at it. How much does something like that cost?

[FXDBI]

I tried pushing on injector wires when bike was idling and didn't hear any change in idle. I'll give it another try.
The tune was a sert tune i think from previous owner.
I was worried it might be a valve issue but tech at Harley said i would know it if it was a valve issue as it would be loud and noticeable.

Valve seals on the rear head leaking and fouling the plug.  Bob

They would not be loud and noticeable.

If you keep running it with them leaking and get it hot it will grab a guide and get very loud and noticeable. Don't ask how I know.   Bob

[FXDBI]

I was afraid of that. How can i confirm its the valves?
So i have to pull the heads and have the valves redone? Might as well do both while I'm at it. How much does something like that cost?

Pull the rear exhaust and look in the port, stock heads? How many km on them and the rest of the build?  Bob

[anthonyflhx]

Stock heads 59k miles

[jamminhd2000]

Have you verified the compression readings? What you had is pretty low. You need to figure this out before you start throwing parts at it. If these figures are correct you will need to figure why. A leak down test would be high on the list.
kk

[kd]

Passing a leak down test could also confirm the compression gauge to be reading low. Then it would be worthwhile to try a known good gauge for the retest.

[nosjunkie]

A leak down would be more accurate than a comp check.. also lets you know where the culprit is...

[PoorUB]

I was afraid of that. How can i confirm its the valves?
So i have to pull the heads and have the valves redone? Might as well do both while I'm at it. How much does something like that cost?

I mentioned a bore scope/inspection camera in a previous post. Short of that, pull the intake manifold and you can get a pretty good look into the intake ports. Any oil around the valve stem should be very noticeable.

I asked earlier, is the fouled spark plug wet or dry? Oil fouling will often leave an oily film. Too much gas looks dry. Other than that either condition will look about the same.

[fbn ent]

Probably premature but....Is it using any oil? If it is 59K on the original motor and you are stuck in Winter, I would pull the top end and get a freshen. I assume the cam chain tensioners have been addressed...

[1FSTRK]

Just did compression check and each cylinder was at about 125. Is that good or bad reading on a cold engine?

Before you go tearing apart the engine slow down a little. It does not matter if your gauge is off or your compression is low, both cylinders read the same pressure yet one plug is black and one is white.
This should tell us the compression is not the main cause. In both cases of plugs you posted the one plug looks to be dry and powder black not real shiny and wet, this should mean fuel.

One of the most experienced guys here is giving you some of the best advice, slow down and follow it step by step. You may end up in the engine but at least you will not start by needlessly rebuilding only to have to go back and find the actual problem once the new engine is running. I would start with his first post here and follow this guy.

So, no one has changed anything in the tune, right? No fuel pressure issues, no power commander etc? Sounds like we're down to a wiring issue or mechanical issue.  Time to pull on the injector wires, to check for a conductor broken inside the sheathing, or bad pins.  Front injector harness should have white/yellow wire, rear injector should have green/grey wire.  Good thing it's winter...

[Norton Commando]

Before you go tearing apart the engine slow down a little. It does not matter if your gauge is off or your compression is low, both cylinders read the same pressure yet one plug is black and one is white.

This should tell us the compression is not the main cause. In both cases of plugs you posted the one plug looks to be dry and powder black not real shiny and wet, this should mean fuel.

Indeed I was thinking the same: the plug looks fluffy black and I didn't see oily threads on the base of the plug.

So at this point it appears that the problem is too much fuel or insufficient ignition on the rear cylinder.   

Best,

Jason

[Armin]

Just did compression check and each cylinder was at about 125. Is that good or bad reading on a cold engine?

This should tell us the compression is not the main cause. In both cases of plugs you posted the one plug looks to be dry and powder black not real shiny and wet, this should mean fuel.

So, no one has changed anything in the tune, right? No fuel pressure issues, no power commander etc? Sounds like we're down to a wiring issue or mechanical issue.  Time to pull on the injector wires, to check for a conductor broken inside the sheathing, or bad pins.  Front injector harness should have white/yellow wire, rear injector should have green/grey wire.  Good thing it's winter...

If your cylinders, pistons and heads are left in stock condition your ccp at WOT should be between 155 and 165 depending on rings and cylinder wall conditions with component variances considered and I believe that 125 psi ccp is too low but, as quoted above, should not cause this uneven burning situation.


The injector receives the open command from the ECM by pulling the gn/gy wire to ground. One way to possibly find the culprit is to detach the large connector from the ECM and measure the resistance of pin 19 of the connector to ground using an ohmmeter. If it reads zero or anything close to zero steadily or temporarily then wiggle the harness holding the gn/gy wire to hopefully find a broken insulation causing the excessive injection to the rear cylinder.

Armin.

[anthonyflhx]

Ok wiring is definitely not my forte, but i gave it a shot. I used a woods analog multimeter and it has an ohm setting. The 2 omega options are 10x and 1000x. I set to 1000x and connected the red lead to pin 19 and the black to ground using frame. The needle moved to 1 ohm and stayed steady. This is with bike off and the 2 fuel injector plugs disconnected.
Am i following correctly so far? To get to the 2 plugs i had to remove the tank. So what is next step? Do i start opening threw protective tubing holding all the wires together? Should i turn ignition on to see that the ohm meter does?
Appreciate your patience and help. This is all new territory for me. Many thanks in advance.

"The injector receives the open command from the ECM by pulling the gn/gy wire to ground. One way to possibly find the culprit is to detach the large connector from the ECM and measure the resistance of pin 19 of the connector to ground using an ohmmeter. If it reads zero or anything close to zero steadily or temporarily then wiggle the harness holding the gn/gy wire to hopefully find a broken insulation causing the excessive injection to the rear cylinder.

Armin."

[kd]

Do NOT use an ohmmeter on a live circuit. It'll damage your meter.

[jls 64]

1.leak down test.
2.pull intake and take a lock
3 pull ehaust take a lock exhaust port.
4.rear inyector
wiring harness.
5.pin17 on main wire harness.

[barny7655]

gee this post has drifted away from what the first post is seems no firing rear cyl carbon on plug,causes ,1/ wiring loom, test with injector with pulse tester , 2/ change  spark plug 3/ comp test 4/ vacumme leak  test  ,5/ ignition module test , test with another if possible ,6/ fuel line to injector ,as jls has also put some ideas forward, it should still fire with new plug if oil is leaking into cyl from inlet ,try this all out ,wouldnt even look at any thing major as yet, it will be a simple thing KISS, cheers

[Hybredhog]

    '04 were not a closed loop system, maybe it is just an intake leak?

[rigidthumper]

Is there a local auto parts place that can loan you a noid tester, or maybe order one like this :  https://www.amazon.com/Astro-7898-Deluxe-Signal-Lights/dp/B00061SH76/ref=sr_1_2?ie=UTF8&qid=1543257186&sr=8-2&keywords=noid+light+test+kit 
Quick way to check wiring to the injectors.

[anthonyflhx]

What would that be used to check?

Is there a local auto parts place that can loan you a noid tester, or maybe order one like this :  https://www.amazon.com/Astro-7898-Deluxe-Signal-Lights/dp/B00061SH76/ref=sr_1_2?ie=UTF8&qid=1543257186&sr=8-2&keywords=noid+light+test+kit 
Quick way to check wiring to the injectors.

[rigidthumper]

Plug the noid tester into the connector that was hooked up to the injector, crank engine over- noid flashes if it's receiving a good signal from the ECM. HAndy to look at while tugging on wires

[anthonyflhx]

Ok quick update. Rented a compression gauge from o reillys and both cylinders measure at 145-150.

Also the ohm better was not set correctly. I adjust for 0 reading and then testing pin 19 it is steady at 3. I've wiggled and pulled the 2 wires all the way back to where the wire loom curves under center frame post. Strauss at 3 the whole time.

[1FSTRK]

Ok quick update. Rented a compression gauge from o reillys and both cylinders measure at 145-150.

Now that we have that out of the way, back to fixing the bike. 

Plug the noid tester into the connector that was hooked up to the injector, crank engine over- noid flashes if it's receiving a good signal from the ECM. HAndy to look at while tugging on wires

[N-gin]

Had this same problem.
Found out my tune would change under low RPM in closed loop. The 2-1 was ( ThunderHeader) was not working well with the O2s. I also tried a BoarZilla results were not as bad. To correct it I had to open loop the lower RPMs. Anything under 3k with the ThunderHeader, and 2500 with the BoarZilla.

Swapping injectors or replacing will require returning.

[anthonyflhx]

I don't have 02 sensors on bike. It's an 04 dyna. I unplugged ISIS and checked wiring and couldn't find anything wrong. Put her back together fired up and send to run alot better. Pulled plugs and both seemed to be burning normal.
Haven't been able to test ride yet, hopefully tomorrow.
Thanks for all the help and feedback. Praying i dodged a bullet.

[anthonyflhx]

Still acting up. Gonna try a new crack position sensor on Monday.

[JMHD]

Had a few sportsters that were 2004's that when they got to operating temp they would run rich and stumble that ended up being faulty CKP sensors.

[anthonyflhx]

I ended up taking it to dealer to see what they could find. Turns out the fuel pump hose in tank is shot and Harley doesn't have a replacement hose. You have to buy the whole fuel pump. Anyone know what size hose the fuel pump is and where to get one?

[kd]

I would be interested in hearing how the failing hose could cause the condition you are experiencing.

[PoorUB]

Doesn't sound right to me either.

You can buy fuel injection hose at most  auto parts stores.  Make sure you get hose that is designed to be submerged in gas.

Also there is aftermarket sources for the Harley fuel lines. Maybe someone will post a supplier and part number.

[anthonyflhx]

They said the spark plug wire on the rear cylinder was 3500 Ω out of spec, that with the sporadic fuel delivery or fuel pressure caused the rear cylinder to not get gas and spark at right time.
The crank position sensor checked out good.

[rigidthumper]

Its a formed hard line from the pump to the regulator, not available separately.  Entire assy can be purchased online for ~$150. I've never personally seen one go bad, but that would cause less fuel to make it to the injectors, not more- 

[rbabos]

They said the spark plug wire on the rear cylinder was 3500 Ω out of spec, that with the sporadic fuel delivery or fuel pressure caused the rear cylinder to not get gas and spark at right time.
The crank position sensor checked out good.

Pretty sure you see the problem with the statement of less fuel fouling the rear plug?
Ron

[anthonyflhx]

Yes I'm probly relating the information and correctly I believe they said that it was inner minute spark that was leaving on fired fuel in the cylinder that was fouling the rear plug but they're also happens to be a fuel pressure leak which is causing some problem or just something they stumbled across but if the rear spark Le pire ways out of sank 3500 Ω does that sound normal cars I tried 3 sets a spark plugs one of them came off another running like in the guy still running there's not wrong with his bike so if AI do all this work in it's still fouls the rear plug they eat the work until they find the culprit

[Moparnut72]

This thread keeps going on and on and on. I am not going to re-read this whole thing but I don't remember whether I saw if the valve seal has been checked on the intake valve or not. If not, this needs to be a priority. Some of the explanations I have seen are just not viable.
kk

[92flhtcu]

484235 is the Tucker/Twin Power # for the line in the tank
I am in the camp that this is not going to fix the plug fouling issue

[anthonyflhx]

Would the rear plug wire being 3500 ohms out of spec have anything to do with fouling plug?

[1FSTRK]

Would the rear plug wire being 3500 ohms out of spec have anything to do with fouling plug?

A bad plug wire could cause the plug to not fire under load and gas foul. Didn't you say you tried a different set of good wires from a running bike and it made no difference?

[anthonyflhx]

Yes 3 sets. Gonna be interesting to see the results here in a couple days

[jls 64]

In my case it  was a.bat coil.not the wire

[kd]

Wouldn't it throw a code for that?  Was the 2004 ECM capable?

[jls 64]

I Think since  2005 .will send a code

[anthonyflhx]

Turns out it wasn't the fuel line or rear plug. Now they say it's the ecm. Swapped out with a spare one and it didn't foul plugs.
When i complained about going off course and chasing the leaking fuel line and wasting 2 days for that part to come in they got pretty defensive saying that was still part of the "run ability issue".
Soooooo now we are at new ecm and new flash tune and a more expense than i was expecting. I pick her up in few days so we'll see how she runs then.
Thanks for all the help and feedback.

[Hossamania]

That happens during troubleshooting, often other issues are found, maybe causing or contributing to the problem, maybe not, but need to be addressed either way. Once the problem was found, that leaking hose would have come into play anyway.
It often costs more than you would hope, sometimes it's a simple fix like a loose plug wire, sometimes it's a little more complicated like a new ecm.
Either way, you'll be up and running and having fun again.

[PoorUB]

It is funny they would assume the leaky fuel line would fix it, it was flooding, not running lean! I would have told the owner I found a problem, but I doubt it is the cause of the plug fouling, but either way it needs to be fixed too.

[N-gin]

Wasn't there an aftermarket company that did these pieces parts for cheap.. fuel smart?? Or  something. I believe FSG posted once.

[anthonyflhx]

Got the bike back and am surprised there's no decel pop like before. It almost feels like the flash tune is a tad bit rich, but it's been colder than usual here and i wonder if that's helping any.
Pulled plugs and the tips look pretty clean. What do you guys think?

[1FSTRK]

Unless you are running the corresponding SE components the flash tune is no tune at all.
The flash changes the tune and it could be rich where it was lean or lean where it was rich or both but it does not necessarily match your combo any better than a stock tune would. 

[PoorUB]

Unless you are running the corresponding SE components the flash tune is no tune at all.
The flash changes the tune and it could be rich where it was lean or lean where it was rich or both but it does not necessarily match your combo any better than a stock tune would.

Funny how that works. For example, I have CR570-2 cams, gutted head pipe and Fulsac recore kits in my 2016 Limited. Street tuned with a TTS. I decided I wanted the quiet mufflers so I put the stock muffs back on. Now I have a lean hesitation until the engine gets warmed up. One would assume that more restrictive mufflers would richen up the AFR, but it is leaning it out at low RPM. So yeah, flash tune? 

[anthonyflhx]

So do the plugs look that bad?

[1FSTRK]

So do the plugs look that bad?

I understand you spent a lot of money on this already but it is next to impossible to read plugs with today's EPA fuels and totally impossible to do it with an internet picture.

That said I can tell you that you need a tune.

[PoorUB]

So do the plugs look that bad?

I don't think anyone commented on the plugs, but they look a bit rich to me. Modern nolead fuel makes it tough to take a spark plug and get a good idea if it is rich or lean. If it seems to run well and get decent MPG and you are satisfied I wouldn't worry about it. If you want it to be correct you need to find a good dyno tuner and get a proper tune. Good dyno operators on this site have proven time and time again that you can tune a stock bike and gain HP and torque. Is it necessary? Only you can judge that. If you like to putter around and never ride the snot out of it you most likely will never appreciate a proper tune. There are millions if stock bikes out there with crappy factory tunes that the owners never do anything with them.

The comments were more against the flash tune which could be richer or leaner than the stock tune at various RPM and throttle positions. They may as well have left to tune stock.

[Hossamania]

The plugs obviously look better than they did, especially the rear.
But, as mentioned, a good tune will go a long way to getting it running right, and give you peace of mind that it is right.
Without monitoring the afr, how would you know if it is right or not?