200 HPDI Dropping Cylinders

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ofishal

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I have a 2000 200 HPDI and it is dropping cylinders while running. It runs fine at the dock and will get up to about 1500 rpm's and then it starts dropping one cylinder at a time. I know this because I had it hooked up to the computer. Generally it starts with 2 and 3 (normally dropped in idle) and then 5 then 6 or any combo of those. I have a O2 sensor that tested bad and I should be getting a new one today. From my understanding this wouldn't cause the engine to drop cylinders.

I had a tech talk to Yamaha and they said that it could be the wiring harness. I am ok with replacing the harnesses but there are 3 of them and they are quite expensive.

Just wondering if someone has any insight before I drop a bunch of money and start tearing the wiring harness apart.

Thanks
 
cousinabe

cousinabe

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Re: 200 HPDI Dropping Cylinders

get a new tech.

at idle in nuetral the Z motors drop cylinders 2-3,in gear ALL 6 hit regaurdless of engine speed until the rev limiter gets you.
during cranking all 6 cylinders fire until the engine is running then the ecu looks at the shift switch position and determines is it in nuetral.
if ya really want to watch something silly,throttle it up in N and you will see 2 more cylinders drop off as engine speed approaches 1800 or so.
whats amazing is the amount of folks,both online and in the shop,talk about it will hit 4000 RPM in Nuetral on 2 cylinders.
however I can never see a reason to throttle up an EFI or DFI motor in nuetral.

http://forums.iboats.com/showthread.php?t=275779
 
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ofishal

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Re: 200 HPDI Dropping Cylinders

thanks for the reply. I was aware of the Z motors dropping 2 and 3in neutral. My problem is that when shifting to forward, 2 and 3 start firing again, so I'm running on all 6, then as i slowly throttle up it starts dropping one cylinder at a time until i'm running on 2, which is usually #1 and #6.

thats my problem. it runs great in neutral on 4 cyl and fwd idleon all 6.

Any other insight?
 
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rodbolt

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Re: 200 HPDI Dropping Cylinders

carefully test the shift adjustment and the nuetral switch.
if it detects nuetral and you attempt to throttle up the ECU will start dropping cylinders.
it could also be the ECU trying to protect the engine.
can you post a printout of the lap top screen while its shutting cylinders off?
 
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99yam40

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Do you expect these people to be still on this forum after 9 years?
 
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