rain/wash induced miss I can't track down

[Quick_2s]

I took a 800 mile road trip the weekend before last through the Appalachians and clocked off about 350 miles in the rain on the return end which of course in coal country made a mess out of the bike, in some of the extremely heavy patches of rain the bike did spit and cough occasionally but when its raining so hard you can barely see and you have an open style breather that is to be expected. I returned on Tuesday night late and parked it for 2 days due to more rain and the normal wear and tear on me from 800 miles on a near rigid frame. My last gas stop only had 92 octane corned fuel so I thought that maybe that was causing the slight miss  when I got it out on Friday but, refueled with good ole 93 ultimate from my normal home station and even threw in a couple oz. of Lucas octane booster to boot, and stopped into the car wash to blast away the bulk of the road grime before going home to wash the bike. About a mile from the wash I dropped down to one cylinder for a short bit due to water causing a visible spark to jump from the plug boot to the hexed part of the plug but when I stopped and wiped it off it went right back to normal....... or so I thought, it has developed a low rpm miss that appears to be electrically based due to the fact I can see a voltage drop before the miss at idle when monitoring with the tmax software.

Here is what I have chased out so far;

I have unplugged all the connectors on the voltage reg, TB, injectors, coil, and under the console, blew them out and reconnected with a dab of dielectric grease.

Changed plugs, and blew out and checked plug wires, then re-installed with a dab of dielectric grease.

Checked headlights / taillight for water and connection.

Removed and cleaned IAC valve.

Charging system is putting out 13.8 to 14.2 volts consistently.

Visually inspected, re-positioned and blew out all wiring under seat.

Pulled trap door in tank and checked for leaky internal fuel lines.

Unhooked, dry, grease and reconnect ECM connector.

Unless the short stint on one cylinder has damaged the coil or I have intermittent contact at the main breaker I am at the end of my usable knowledge on where to find the problem.

The bike is an 114" 04' FXSTDI (Deuce) platform with a laundry list of mods, still runs strong strong just have the low rpm stumble and more pronounced vibration at speed which seems to be miss related.

Hopefully this rings a bell with someone.

[Showdog75]

I had a similar issue and it wound up being where my pc plugged into the ecm.

[Quick_2s]

I had a similar issue and it wound up being where my pc plugged into the ecm.

Left that off my list of already tried, but did unhook, dry, grease and reconnect that as well.

[RainDodger]

It sounds stupid, but even though they check good, change your plug wires. I had the same symptoms, the wires checked good, but when they got totally wet I'd get some really bad missing. I put on new wires and it went away. Maybe the insulation was just bad enough that the added conductivity of the water would cause arcing or something, I don't know.

It's the easiest thing to do, so try it first!

[Horizonmech]

Try inducing the miss with the eng running and a spray bottle @ the coil and wires.......

[smoserx1]

It sounds stupid, but even though they check good, change your plug wires. I had the same symptoms, the wires checked good, but when they got totally wet I'd get some really bad missing. I put on new wires and it went away.

Exactly what I was thinking.  Seen that happen myself too.  And especially since he already saw visible tracking earlier.  I would replace the wires before anything else.  My guess is the rubber is porous and compromised.

[Quick_2s]

Changed out the plug wires to the newer 10mm SE wires, those things look huge fat compared to the last set..... now if the rain stops I can go see if that fixed the issue.

[ripp13]

Make sure that your air cleaner is not to wet from the pressure cleaner......... had a open A/cleaner on mine same symtoms as a miss when it got to wet

[Foxster]

Try inducing the miss with the eng running and a spray bottle @ the coil and wires.......

Take care doing this. A friend was doing this a few years ago and he got a shock that made him jump back across the garage.

[Eglider05]

Changed out the plug wires to the newer 10mm SE wires, those things look huge fat compared to the last set..... now if the rain stops I can go see if that fixed the issue.

I bet this takes care of the problem. I had a similar issue that was solved with new wires.

Rick

[Quick_2s]

Still no fix with new wires but.... I have noticed is I run the IAC auto on the t-max it smooths out for a short period of time but then starts up again. When I go in to look at it again it is making adjustments and the miss returns. i am beginning to wonder if my O2 sensors are on the way out and the adjustments being made are are coming from irregular readings. before I leave for work in the a.m. I am going to lock down the IAC auto adjust and see if that does the trick.... if so I can replace the sensors and all will be well. This all started after a trip by the car wash to blast off the bulk of the road grime from a rainy 300 mile trip so maybe the cooler water hitting the warm sensors fouled them up in some way or the temporary dropping of the rear cylinder gas washed out the rear one....... we shall see I guess.

[glens]

Could be the problem.  You're not supposed to direct high-pressure water at the O2 sensors.  Could also be that they're aren't any longer getting proper reference air through their wires/connectors.  And they could just be getting tired if there's 20k+ miles on them.

[crazylore]

does it throw any codes

[Quick_2s]

No codes, I have 12k on them but I got the unit used so we shall see.

[Ridetard]

Check coil connctions..

[Bakon]

You said you checked all the electrical connectors...were any wet? That is your starting point, the wet one. What does it control?

Two good observations on your part was when it stated...after getting too wet
and the IAC.... it's in this circuit more than likely and it might just be some water.

I dried an Ultra for 3 days after using S100 on it. Fans and left everything disconnected, all the connections. Threw the S100 away. Could not trust myself to not squirt too much. I will guess you did not dry something.

[China twin 88]

Make sure that your air cleaner is not to wet from the pressure cleaner......... had a open A/cleaner on mine same symtoms as a miss when it got to wet

You're not supposed to direct high-pressure water at the O2 sensors.

Just had this problem with a 06 with FI.  The coil had become wet from the pressure washers.  Few wash their own bikes here in China as they lack proper space and it tends to be cheap as well as the riders being mostly corporate and using their sleds mostly on Sat and Sun.  Anywho....the coil yielded some "backish rustish" substance and then with a couple days dryout, good as well almost new....just goes to show you the ole saying bout those who cant clean their own guns (bikes) not being worth the salt in their bread.... had some sound logic to it...no-one will insure the spray is not directed at sensitive parts...unless they depend on those parts to get home...

[Ridetard]

Check your coil...if the bike is dry and running ok, then take the hose out and get things wet a bit.  A motor cycle and a boat have much in common, all exposed parts are resistant to water in one way or another.

Its the coil and will be until Max says otherwise.. .

[Quick_2s]

Check your coil...if the bike is dry and running ok, then take the hose out and get things wet a bit.  A motor cycle and a boat have much in common, all exposed parts are resistant to water in one way or another.

Its the coil and will be until Max says otherwise.. .

Gonna pick up a "known good" shop coil from a local indy and see if that does the trick.

[Quick_2s]

Picked up a known good coil, switched it with mine, still same miss.

To recapp;
Changed plugs
Changed wires
Changed O2 sensors (runs much stronger but with same miss)
Changed TPS
Cleaned IAC valve
Changed coil
Went over entire wiring harness and all connectors, unplugged, blew out, and dielectric greased all connectors.

Thinking my next step is a bad injector or something inside the charging system.

Any more suggestions??

[Quick_2s]

Picked up a known good coil, switched it with mine, still same miss.

To recapp;
Changed plugs
Changed wires
Changed O2 sensors (runs much stronger but with same miss)
Changed TPS
Cleaned IAC valve
Changed coil
Went over entire wiring harness and all connectors, unplugged, blew out, and dielectric greased all connectors.

Thinking my next step is a bad injector or something inside the charging system.

Any more suggestions??

Or maybe the voltage regulator is taking a dump?

[hdtech76]

i think i missed out on the specs, is this FI or carb? if it is FI does it have a power commander on it

[sfmichael]

Quick_2s,
    I'm not a bike mechanic but I am a car mechanic and the similarities in the operating systems are fairly obvious to me. Whenever diagnosing a misfire on a car/truck, I check most of the things you've checked. If you are sure this is definitely a MISFIRE as opposed to hesitation/power loss/etc. then I'm with you as far as looking at the injectors next. If one cylinder is dead, talk to a car or bike tech and see if you can borrow what we call a 'noid' light. This tool checks for electrical injector pulse at the harness/connector.The injector can't fire if it's not being told to. Another thing you can do (depending on accessability) is use/borrow a mechanic stethoscope and see if you can hear both injectors 'clicking' while the bike is running. This usually signals that the injector is operating. As a last resort, injectors can be swapped between cylinders and see if the misfire follows the injector. Also use/borrow an inductive timing light and slip it over each plug wire to make sure both cylinders are firing.
That being said, do not overlook the ignition module. This is what my gut tells me is the problem.
Don't know about Harley's, but in automobiles, charging system related driveability problems are rare. Usually as long as there's sufficient voltage in/at the battery, the vehicle engine doesn't really know the difference. Usually system voltage has to drop below 10-11 volts before weird things start happening. And they won't start with that low of voltage. Monitoring system voltage while running should be easy enough with a handheld DVOM or equivalent and would/should rule out voltage regulator issues.
One last thing...again in cars, system grounds are crucial. The wiring can usually get the juice to the component (provided connections are good:) but often times the frame has the job of completing the circuit and one must always be sure grounds are clean and tight.
Don't know what else to tell you, barring mechanical issues, the only things that usually cause misfire are and overly rich or lean mixture in the cylinder or lack of spark. (not trying to state the obvious, just a reminder not to over think it:)
Let us know how this plays out for you. Good luck

[sfmichael]

Don't mean to "HOG" this thread (I crack myself up:), but just reread the whole thing and noticed you didn't say anywhere that you checked the intake system for leaks. It's easy to get caught up thinking this can only be moisture related but coincidences do happen (that's why they call them that:). Take a can of carb spray with the spray needle on it and spray around the intake manifold and throttle body. The engine speed and/or misfire will change if there's unmetered air being introduced anywhere in the system except from where it's supposed to introduced, which is through the TB throat. So anywhere there's a gasket, flange, sealing connection of any kind, spray the juice and see what happens.
Again, best of luck.
    Michael

[Admiral Akbar]

Its the coil and will be until Max says otherwise..

If you are talking about me.. I don't have a clue..

Actually there are probably some things to look at..

With the monitor on looks at what the Tmax is trying to set the AFR to and what the AFR samples are reading.. If they don't make sense....

Don't know about Harley's, but in automobiles, charging system related driveability problems are rare.

Yeah but they are possible in motorcycles. While I've not see it in HDs, I've seen it in other bikes that use a simple single phase alternator with permanent magnet rotors.. Others have seen it here..

One last thing...again in cars, system grounds are crucial.

Good point..

I would rule out a damaged ECM,, but it is expensive to test.. Zippers warns about water..

Max