2004 sx viper engine light problems

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Holllands16

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Hello, I’m new to these forums so please forgive me if I post in the wrong spot or anything else.

I’ve just bought a 2004 viper sight unseen (bad idea but it looked great and was a great deal with a parts sled and a trailer) so the story was that the owner had the parts sled(03 viper 700) and blew the motor, he had a shop completely redo motor top and bottom, which he then swapped into the 04 viper because the body was in good shape only having 2800 kms on it.

The sled runs great, starts up very quick, no issues with it running. The problem I’m having is that the engine light is giving me a blink code, 6 fast flashes. From what I’ve seen this is a code for knock sensor and or wiring. I’ve also read that the 03 vipers did not have knock sensors but the 04 vipers do. Is this true? Would the sled think that the knock sensor is bad because there isn’t one installed? Once again the sled runs great so I’m inclined to think that it’s a wiring problem.

Any help would be greatly appreciated, thanks.
 
74Nitro said:
Put the head off the 04 onto the the 03 engine you are using so that you can use the deto sensor.
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I wish I could do that, but when the previous owner bought the 04, it did not have a motor in it. He bought it specifically to put the 03 motor into. Thanks for the reply tho, maybe I could find an 04 head somewhere.
 
No need to do that. A lot of people that put pipes in these would disable the knock sensor.
My 2004 Viper is the same way. The sensor is wrapped up in electrical tape on mine,then zip tied between the brake and air box so it won’t move at all. There also is a ground wire that grounds it to the frame that someone added to mimic how it naturally grounds itself to the head when installed.
 
MURDER YAMAHA said:
No need to do that. A lot of people that put pipes in these would disable the knock sensor.
My 2004 Viper is the same way. The sensor is wrapped up in electrical tape on mine,then zip tied between the brake and air box so it won’t move at all. There also is a ground wire that grounds it to the frame that someone added to mimic how it naturally grounds itself to the head when installed.
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Ok so I would have to buy a sensor and wrap it up like you did? Is there any way to mimic a sensor? Like just joining the wires together like you would a fuel sensor or something? Thanks for the help
 
I worked at a dealer when these sleds came out. This is a great feature to save owners big $$$$ on potential burndown. Other manufacturers soon followed and use them to this day.
You could make a bracket to mount it on the head if you can't find a used 2004 head.
We had a few customers who would immediately want to unhook this sensor if it flashed deto. The reason it was flashing was because the engine was usually deto-ing.
Adding pipes often caused deto and burndowns, I should know as I bought plenty of pistons and cylinders over the years when I had pipes on a 700sx.
 
I have pipes on everything I got. Love them.
But, if you have a stock motor, and stock pipe,
may as well have the sensor working.
But, many will tell you, even a track that is not fully clipped can set the DCS off.
 
74Nitro said:
I worked at a dealer when these sleds came out. This is a great feature to save owners big $$$$ on potential burndown. Other manufacturers soon followed and use them to this day.
You could make a bracket to mount it on the head if you can't find a used 2004 head.
We had a few customers who would immediately want to unhook this sensor if it flashed deto. The reason it was flashing was because the engine was usually deto-ing.
Adding pipes often caused deto and burndowns, I should know as I bought plenty of pistons and cylinders over the years when I had pipes on a 700sx.
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True I could make a bracket and mount it, I just figured because the motor was not equipped with one from the factory, it would be ok to not have it hooked up. If I did mount the sensor on the head, would it throw codes all the time because the motor isn’t properly set up for a sensor? I also don’t ride a whole lot due to lack of time, had an old Mach 1 before this and only put about 1000 kms in 3 years, I am wanting to get out a bit more this year, just need the snow to do it! I really appreciate your help.
 
Holllands16 said:
True I could make a bracket and mount it, I just figured because the motor was not equipped with one from the factory, it would be ok to not have it hooked up. If I did mount the sensor on the head, would it throw codes all the time because the motor isn’t properly set up for a sensor? I also don’t ride a whole lot due to lack of time, had an old Mach 1 before this and only put about 1000 kms in 3 years, I am wanting to get out a bit more this year, just need the snow to do it! I really appreciate your help.
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As murder pointed out they can be sensitive and other vibrations can trigger them sometimes. I never had much trouble with them myself and liked the feature. Almost all the new two stroke sleds today use them, as well as the sidewinders.
The 04 engine is the same as the 02 and 03 aside from a place to mount the sensor.
I recall one time we had jetted a 2004 Viper down ONE size on the main jet and that was enough to trigger the knock light.
Put the jetting back, deto light went out.
 
74Nitro said:
As murder pointed out they can be sensitive and other vibrations can trigger them sometimes. I never had much trouble with them myself and liked the feature. Almost all the new two stroke sleds today use them, as well as the sidewinders.
The 04 engine is the same as the 02 and 03 aside from a place to mount the sensor.
I recall one time we had jetted a 2004 Viper down ONE size on the main jet and that was enough to trigger the knock light.
Put the jetting back, deto light went out.
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Ok so in your opinion the best thing to do is to get a sensor and make a bracket to mount. I haven’t looked for the plug but hopefully the previous owner didn’t just cut it off! Thanks for the help I really appreciate it.
 
Wouldnt be a bad idea.
Im always trying to do max effort stuff, so I cringe when I think something may be trying to take a few HP away, lol
But, for a rider sled, it would be nice to have.
 
MURDER YAMAHA said:
Wouldnt be a bad idea.
Im always trying to do max effort stuff, so I cringe when I think something may be trying to take a few HP away, lol
But, for a rider sled, it would be nice to have.
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That’s really the only reason I want to do something about it, idk how much performance it takes but I want it to be tip top, it’s also annoying having a check engine light on😂
 
If you have 91 octane and proper jetting, you should not see the light come on.
If you ever fill up somewhere and get bad gas, 5he light will let you know.
If the light comes on, it will pull timing out to save the motor.
You don’t have to worry about losing performance unless the light is on.
 
MURDER YAMAHA said:
If you have 91 octane and proper jetting, you should not see the light come on.
If you ever fill up somewhere and get bad gas, 5he light will let you know.
If the light comes on, it will pull timing out to save the motor.
You don’t have to worry about losing performance unless the light is on.
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Ok, so I should be running 91? My step dad has an 03 viper and he has always ran 87 with no issues. I was planning on running 91 anyway I’m just curious.
 
Holllands16 said:
Ok, so I should be running 91? My step dad has an 03 viper and he has always ran 87 with no issues. I was planning on running 91 anyway I’m just curious.
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Also, would you know what stock idle should be? Mine sits around 1100-1500, I feel like it should be a bit higher than that.
 
Update.
Got the knock sensor plugged in, wrapped it in electrical tape, stuck it kinda in behind the air box right beside the ignition, ran a ground strap over to the top bolt for the reverse lever bracket. And it works great, no engine light, only took it for a couple kilometre ride not a whole lot of snow yet, but it ran great(until I fouled a plug lol) thanks guys for the help.
 
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