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Discussion Starter #1
Here's the challenge, we are considering a 2003 Road King Classic with a S&S 106 kit, stock throttle body and injectors, Thunder Max Auto Tune ECM, Super Stocker 89cc S&S heads and S&S 585 gear drive cams, Fueling race cam plate, oil pump, and pushrods (S&S lifters). I was out riding, had a hard hot start and loud exhaust back fire. After that the bike seems to have a break on. Lost power (as if running on one cylinder but not), tons of pinging on acceleration while going down the road, rough idle and very rich condition on the rear cylinder. Had a throttle body replaced by dealer after finding broken one on road trip just prior (about 1500 miles ago) to all the issues. Found the Idle Air Control module had been left loose by repairing dealer and replaced with a new one, no change. Remapped and recalibrated ICA and cruse control, no change. While remapping found faulty engine temp sensor and replaced, no change. Checked wiring for loose/bad spots and connections, did compression check (130 both front and rear), checked plug wire spark with sparkers (good), new plugs, checked scavenge oil in cases (good only a few ounces), checked for manifold leaks (none) however can blow air through one injector (rear), no faults/error codes listed on Thunder Max. Have remapped to original map several times as well as ICA calibration. Issues occur with motor warm or cold. Ideas??? I am at a loss.........
 

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Just Ride
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3,264 Posts
Let's see, rear cylinder acting up and injector for the same sounds like it's bad. Do the math.
 

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Retired citizen
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A couple things come to mind:
1) Check the front injector wiring at the connector, history of wires breaking inside the jacket due to harness tie strapped to the frame too tight. Disconnect the injector connector and pull on the wires, if the jacket stretches the wires are broken inside.
2) Stock '03 throttle body and injectors. Install the SE 25 degree injectors.
 

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Discussion Starter #5
Ok guys, thanks for the responses! FritzHD — I thought exactly the same thing, rear cylinder problem and injector I can blow air through (I think that means they are bad?) duhh bad injector, however.....brought the injectors home from my buddy's shop and cleaned them with a syringe and lighter fluid and battery, and walla no more blow through! Put the stuff back together and same seeming brake sound/feel issue......could the rings have washed out of the rear cylinder due to all the fuel??? Should I do a bleed down test??? What are the possibilities???
misinlink — I also thought about the Tmax issue and sent two different running logs to them and the computer/ECM seems to be doing everything it is supposed to plus. By plus I mean it is doing everything it can to adjust for the problem/issue the engine is going through. They suggested mechanical trouble.
SCHMIDTYS — the wiring I have checked, but will sure enough double check. The SE 25 degree injectors is an interesting suggestion, why??? Will they fit a stock throttle body???
Again thanks guys for the help with this!!!
 

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Retired citizen
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The 25 degree injectors were a moco fix for driveability issues on pre-'06 injected TC engines. They fit all TC engines. They were originally only installed on CVO engines but came stock later on.
The front injector wire breaks inside the jacket and can't be seen, gotta pull on the wire to see if the jacket stretches. The moco issued a tech tip on the subject. No recall tho.
 

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Discussion Starter #7
Thanks SCHMIDTYS! I will replace the injectors with the 25 degree ones. I still am wondering about the possibility of having damaged the rings in the rear cylinder. Your thoughts please??? Like I said I cleaned the old injectors and seemed to have stopped the blow through issue. I put the one that was in the rear cylinder (blow through one) in the front cylinder and there seems to be no change in how the motor runs......
 

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Retired citizen
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To check for ring damage do the compression test, compare the front to the rear. Should be like within 5% of each other.
Also use a small light and look thru the plug hole at the cylinder wall.
 
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