Hi Everyone , I'm new here to the forum . I could really use some help and guidence Please !

I have a 99 FXD twin cam ,, when the check engine light is off , the bike runs flawless , nice smooth through out the rpm range. When the Engine light comes on it seems to hesitate , gets louder ( Exhaust Wise ) , seems like the engine is being held back , when reving up to switch a gear as soon as I let of the throttle it'll back fire and pop and it'll stay running like this until the light goes off on its own , then it acts like a totaly different bike. when the light goes off it instantly runs smooth , gets quieter and picks up speed with out me giving it more throttle. the light comes on and off randomly and varies how long it stays on.

I know I should bring it to the dealer and have them put it on the machine.

I figured I'd ask here 1st to see if anyone else encountered this same problem and could possibly help me diagnose it .

The engine is stock with 15,000 miles on it.

Your input , help and guidence is greatly appreciated !

Thanks Randy

 

If it's intermittant it might be an ignition problem. Have you checked your plugs, wires... etc Maybe work your way back from there.

 

Check connections on plugs, on coil from plugs, connection to coil from ignition module, and connection from crank position sensor to harness. The crank pos. sens.(CKP) is on the front of the engine right by the end of the oil filter. Then check cleanliness of the battery connections. The first sensor I would change is the CKP. Carb bikes are relatively simple compared to EFI engines.

 

Thanks , I'll check that tommorow, I did look at the plug wires and they look new , no cracks or dry rot and the connections are clean and tight into the coil and in the boots onto the plugs. I haven't pulled the plugs yet , I will tommorow . I know I hit the crank sensor a couple times taking the oil filter off with the wrench . I'll trace the wiring to thanks again , I'll let ya know how I'm making out .

Randy

 

also check the cps if it still has one

 

I pulled the plugs , the front cylinder plug was clean , but not shiny clean, the rear cylinder plug was black, but not filthy and oily , kinda dry black. all wire connections are intact. could my coil be on it's way out ?

Thanks Randy

 

If you happen to have a manual it will show you which terminals to put a jumper wire on in the electrical panel which will flash a light sequence on your speedometer which you look up in the book to find the fault. Sorry this is not more specific but it's been about three years since I've done this.

 

Check your battery terminal wires to make sure they're tight.

 

If the engine light makes it run bad just remove the light. j/k I think the light comes on cause it senses somethin amiss. Not becomes amiss 'cause the light is on. Sorry I am of no real help here. Hope you get it straight. Does sound like a bad connection somewhere.

 

Using the manual , ,I jumped the #1 and #2 ports on the diagnositc test plug. it did flash codes , the only codes it flashed was

code #12- map sensor and code#42 - cam position sensor

it says in the manual though that the map & CMP sensors are connected to the same reference line. if the reference line goes to ground or open, multipule codes will be set ( trouble codes 12 and 42)

so could my map sensor be triggering my cam sensor or vise/versa ??

Has anyone encountered these codes together at once and if so what was done to correct the problem ??? Help Please !!


Thanks Randy