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Discussion Starter #1
Working on a friends 2000 ZR 600 EFI, haven't had much experience with the EFI before. Problem with the sled is an intermittent miss/bog around 5-6k rpm. Sled starts fine, idles great, has good response, but has a random miss/bog and occasional backfire out the exhaust when running it. Sled has 8000 miles on it and internals on the engine are healthy. My initial hunch is the TPS is toast, how do I check this? Also wondering if the reeds could cause a sudden miss like described? What do the Cat gurus have to say here?
 

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hey there. ive had a 98 and i currently have a 02 600 zr.does the 2000 have apv valves.if it does i would seriously look into that as being a possible source.take them apart and see if you have a carbon build up issue.if so,clean them good and check cable operation.if not i would possibly suspect a flat spot in the tps.
 

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My 98 was doin that last year on my last ride. I opened it up and reamed the hell out of it and it cleared up. It was in deep fluffy powder tho I thought maybe it sucked some snow or fouled a plug. It didnt do it the rest of the night, and i traded it the next season. I dont know if i would do that to a sled with 8000 miles tho lol. My cousins did the same thing and it ended up beeing the power valves.
 

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They didn't start with Power Valves until '01 I believe, so that would throw that out.

It could be something with the ignition switch, or maybe even the throttle sensor/spacers. I know I had issues with my throttle on my '98, but that was more random. Something to look into though.
 

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Discussion Starter #5
This sled is a non-valve motor so that was easy to rule out. I still have a feeling it is the TPS, i am wondering how to check it? Someone have a procedure for this? This is my first time working on an EFI machine.
 

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I had a 98 EFI, and I'm not sure they had a TPS, the throttle bodies opened up straight off the throttle cable, I'm not sure what controls the rate of fuel injection. Likely it is not an efi ECU problem.

I would look more to a ignition problem, the classic bog- over rev- worn out throttle bushing- cut the center wire at the kill switch- deal could be what is going on here... But im not sure that this problem affected efi sleds, it for sure did on carb sleds. I would also assume you would have seen problems before hitting 8K if this was the problem.

What do the spark plugs look like, and how old are they? Believe it or not spark plugs do go bad internally, things get loose, and often times things find their own way to ground- without going through the electrodes. Then when there is no spark in the combustion chamber, fuel builds up, and ignities out of compression- which is your backfire. Each spark plug wire should measure 30k-50K ohms end to end, any higher or lower and a bad wire may be causing a misfire. It could also be the ignition coil, but AC ignition coils have not been very problematic in the past.

10 bucks says new plugs solves it.
 

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Discussion Starter #7
I wish it was that easy, but its not. I need to find a method to diagnose the TPS to validate its either good or bad.
 

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cut the center wire from the kill switch. black wirer with a white traser & tape it. under handlebar cover its a three wirer connecter.
 

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Discussion Starter #9
my buddy had mentioned he spoke to a Cat guy who told him to do something along those lines? I imagine this problem is closely related to the one Polaris has on the throttle safety switch on wedge style indys, cut the small wire going to the kill switch and problem solved. What exactly does cutting this wire do? If I do this and the problem still persists then what?
 
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