What happened to my King?!?

First issue I've had with this 2005 King Cat. Brought it out to go riding the other day for the first ride of the year and couldn't get it to rev over 5,000rpms! Sled started easy, idled fine while I was dropping the ramp door for the trailer, came back to the sled and went to put it into the trailer and buhhhh...buhhhh at the 5k mark. Throttle response is still pretty crisp up until that point and it just cuts out like a governor. It seems like my PTO cylinder isn't firing because the plug comes out clean and there is LOTS of unburned fuel coming out that side of the y-pipe, plus that cylinder is pretty cool while running. I put in new plugs (no difference), swapped the ignition coil out with one from a 2002 ZR800 (no difference), pulled the injectors out of the throttle bodies and cleaned them and the fuel passages (no difference), completely disconnected my Boss TFI box which is only used for nitrous (no difference), cleaned exhaust valves (no difference). I feel that it should not be an exhaust valve issue being the rpm cut off is so low. I also pulled the fuel pickups that attach to the fuel pump (in tank) and verified that they weren't restricting fuel flow. I have spark with the new plugs but it certainly could be weak. I have compression and I have fuel. I'm leaning back towards the ignition side of things thinking I'm either looking at a stator or coil or maybe a bad plug wire that isn't allowing full current to transfer. Does anyone have the resistance and voltage specs so I can verify that my stator and coil are functioning correctly? Any other ideas? I also pulled the drive belt off so the drivetrain is not affecting my symptoms.
One last thing that I found interesting, with the drive belt off and everything hooked up correctly, I'd let the engine warm up idling and when I'd hit the throttle, rpms would quickly jump to the 4500 mark and then make it to 5k about 1 second later, then drop back to 4500, then back to 5k creating a surging pattern, exactly how a governor would cut power, then allow it, then cut it, then allow it. The sled ran awesome last year and I've never experienced a problem like this with any machine I've owned. Please help as I need to get her up and running. Engine is all stock, just a gutted airbox and a can for modifications to the sled and I ran this exact setup all last year flawlessly. It also has fresh gas.

Thanks for your input!

unhook your exhaust and try it mice plugged mine once

Thanks for your response markeo. The y, main exhaust pipe and can are all clear.

Did you check for a broken reed?
Take the cover off the servo to see if the EXH valves are actuating. Check cables and cable adjustment.

I did not look down the reed cages, I will check that out tomorrow. It is my understanding the the exhaust valves don't trip until around 6500 rpms on this engine, which should waive them from my list of possible problematic suspects.

Your getting one wet cylinder, this is why I went to the reed valve. That hole loading up.

I have a PDF on powervalve cleaning but it is too large to attach. I can email?

"The APV system has a self-cleaning and self-testing mode built in. Every time that the engine is started, the servo will cycle once, and this will wipe-off the carbon that has accumulated on the exhaust valves. The CDI unit also monitors the voltages at the servo during this cycle to assure they are within operational tolerances. If all voltages are within tolerance, the system is ready for operation. If the voltages are not within tolerance, the servo will cycle two more times. If the voltages remain out of tolerance, the system will not operate."
"TROUBLESHOOTING (EFI Models)
The APV system used on EFI models is very similar to that found on carbureted models. The self-cleaning and self-testing modes are much alike. The main difference between the two is the higher total electrical power required by the EFI and APV systems combined. Because of these more demanding power requirements, the EFI APV system gets power from the stator lighting coil. The ECU constantly monitors the power output of the lighting coil, and if the lighting coil output gets too high or too low, the ECU will activate the “limp-home” mode. The “limp-home” mode is an ECU operated engine RPM limiter. When activated, the “limp-home” mode will be seen as an immediate loss of engine horsepower.
For example, if the headlight and taillight are disabled, the ECU will sense a high voltage condition and activate the “limp-home” mode. Adding more than 4 amps of accessories will create a low voltage condition and activate the “limp-home” mode."

Hope some of this helps.

It would certainly seem that I'm in "limp" mode. That makes quite a bit of sense; especially as to how I was describing that the engine would spike to 5k and then drop back, then hit it again, then drop back. I can cruise uncomfortably at about 20 mph, but almost ride a wheelie out of the hole. I'll have to look into this further but certainly appreciate your help.

The only other thing would be low voltage from the stator lighting coil. Still doesnt explain the wet cylinder.
Sounds like you might need an analyzer hooked up!

the efi does not cycle the power valves at startup on efi models, only the carbed models do this. the efi's cycle the valves at 7100 rpm, if it cycles once things are fine if it cycles 3 times there is a problem as per the service manual.

Can I get the output voltage range and wire colors to test the stator's lighting coil please?

Based on BigTwin's post earlier regarding too high or low of voltage being sensed by the ECU, I should also mention that I have a 4-window Digatron unit monitoring both EGT's, water temp, and tach on the sled too. I had the Digatron on it last year when everything was working perfectly. The only new add on is the Boss TFI box as I converted my Boss Noss to the new style system using the TFI box. I guess it would make the most sense to simply remove that entire setup and then test the sled.

Also, can the ECU be "reset" to try and illeviate the "limp mode" after resolving the faulty circuit or does the faulty circuit have resolved and then it will automatically correct itself?

900KingKitty
Both EFI and Carb cycle at startup. If you would like a copy of my shop EPV manual PM me and I'll email it to you in PDF format.

TurboDS1300
Once you remove the box, fire up the sled. If your voltage is in the operating parameters the ECU will read this and all should be fine. I will look for the light coil output.

PM sent. I'll tear the BossNoss electrical off of it tonight and hope for the best. It would seem pretty odd to have the light coil output shift out of spec during the offseason being it was not used at all and stored in a warm, dry place. Is there stator issues with the 900's? I haven't heard of any and my sled has less than 1000 miles on it!

Big Twin said:

900KingKitty
Both EFI and Carb cycle at startup. If you would like a copy of my shop EPV manual PM me and I'll email it to you in PDF format.

TurboDS1300
Once you remove the box, fire up the sled. If your voltage is in the operating parameters the ECU will read this and all should be fine. I will look for the light coil output.

Click to expand...

sure! i sent you a pm, in my 04 and 05 manauls it says carbed models will cycle at startup, but efi only at 7100rpm will cycle once, if it cycles 3 times to check cable length or ispec powervalves, could see where it states what you read. but would like to see it as maybe i over looked it, and i am trying to make sure i am no having any problems myself, but don't wanna hyjack this thread so i will post my own on this issue.

thanks

KingKitty,
I was just reading the the APV manual as well and would like to confirm if both the EFI and Carb models will cycle upon startup because I am interpreting it the same as you
are based on what the manual says.

Reed cages checked out perfect. I disconnected the Boss Nitrous TFI box and voila! it runs perfect. As soon as I plug the Boss TFI box back inline with my injectors it gets the 4500-5000 rpm bog! The TFI box has power when plugged in and appears to function as expected so I'm not sure why it is putting my King into limp mode once plugged in. Another consideration is that the Boss Nitrous system I'm using is powered off of the 8AA batteries on the Boss kit, not off of the stator.
As a downer to the story, I took the King out for a quick ditch race against a M7 and a Summit Rev 8 and the King smoked'em, however I got carried away and road a wheelie over a "wooden" stake which turned out to be a "T" style metal electric fence stake and took out my bellypan, exhaust pipe, hood, and other components. Looking to the positive side, I'm wondering why my Boss TFI box is doing this to my sled and what can be done so I can ride with my beloved nitrous? Thanks for everyone's help so far as it runs great...I'd just like to get my extra 50 shot when I need it.

Well, I have isolated the problem to the wiring harness that plugs inline between the TFI box and my factory injector harness. I didn't think of it at the time either but the Boss TFI box is powered off of the 8AA batteries that run the solenoid so that should not be adding ANY load at all to the sleds ECU. Has anyone else had issues with the harnesses that plug inline between the ECU and injectors?

Big Twin said:

900KingKitty
Both EFI and Carb cycle at startup. If you would like a copy of my shop EPV manual PM me and I'll email it to you in PDF format.

TurboDS1300
Once you remove the box, fire up the sled. If your voltage is in the operating parameters the ECU will read this and all should be fine. I will look for the light coil output.

Click to expand...

i shot you a pm the other day with my email address so i can check out your info , check your pm.s

900king Kitty is correct on the EFI's not cycling the APV's at start up, this has been beat to death on hear for years and I confirmed it on several different 04-05 EFI 800,s and 900,s Glad you found your problem, usually its the last thing you did which is usually the culpret with a problem like this!!!!!!!!!! Sled on!!!!!!! HAPPY NEW YEAR

Happy '09 to you all as well. Sled ran great past few days. I'd sure like to get the NOS back in action if anybody has some good tuning info on that Boss TFI box. Something is up with the harness, which is supposedly brand new too, as I already explained that the nitrous solenoid is on its own power source and functions properly. There sure does NOT seem to be much info out on the Boss TFI boxes, at least from my searches. I've also tried contacting Boss directly and I have repeatedly come up empty even getting someone to answer the phone. Do any Boss dealers on here have experience with the new TFI boxes?