04 SX Viper DCS light back again..........

H

holm0069

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Ottawa, Ontario
Posted here a month ago or so regarding my 04 SX Viper with DCS light coming on every time I ride. Everyone offered lots of help which was greatly appreciated.........so I decided to take it back to the dealer for some more work. Dealer spoke to Yamaha directly and was told the wiring harness can be a problem on that model and year of Viper so they re-routed the harness. While the carbs were off they jetted them up for me to make it run a little richer as I was advised by numerous members on here as the fuel could potentially be the problem. Always run 91 octane in it and the sled only has 700kms on it......its brand new.

Carbs cleaned, powervalves cleaned.........dealership thinks now maybe sensor should be changed. I have my doubts. Light seems to come on once the sled is warmed up within a few kilometers of driving it and then from there on. If I squeeze the throttle it usually doesn't come on but when I let off and maintain RPM's around 7000 it comes on. If I let off and then punch on it then it won't come on. If I slowly increase the RPM's then it comes on.

I know this thread is long winded but I am frustrated as hell with this 'new' machine of mine. I have not been able to drive it all winter because of this issue. Not to mention I am $800.00 deep into fixing a light that is not fixed. Where do I draw the line and what step do I take next. I would LOVE some help. Thanks in advance.

P.s.- Everything is stock on this snowmobile.
 
if you figure it out keep us posted. I had one coming here all winter with the same symptoms and I hadnt figured it out yet. He ended up messing with the sensor on his own. didnt seal the threads properly and ran it low on antifreeze and blew the crank.
I'd love to find out what it was.
 
I have DCS on my 2002 SRX as well.

The system is very good at detecting detonation and protecting your engine, because of this it can be quite sensitive to any lean spot when riding. When the light flashes it is telling you the engine has begun to detonate and it has retarded the timing slightly to protect the engine from damage, if detonation continues it will further retard the ignition timing to the point that detonation is not possible and your RPM will drop right off. When you let off of the throttle the system completely resets. So the light flashing is not the end of the world it just means the system is working correctly.

Vipers have a LOT of ignition timing in the 7000 - 8500 rpm range so they would tend to detonate in that area.
Fuel today sucks... who knows what octane we are getting at the pumps and ethonal further leans an engine.
The fact that your dealer richened your jetting and you don't get the light at full throttle tells me its rich enough on the Main jets but I bet they did not richen your needle settings which controls your part throttle cruising fuel mixture.
Search needle settings for Vipers and go with what Mrviper suggests for Viper needle settings before you spend any money on parts.

JM.02c
 
I dont know. the one I was messing with I richened up every circuit to the point of being a dog and symptoms remained. I dialed in the jetting to what would normally be considered perfect. symptoms remained. I tried increasing mixtures of race fuel to premium. symptoms remained. I tore the engine down 2 times with zero signs of detonation anywhere. there was no rhyme or reason to the dcs kicking on. it would come on and hog out to 7000rpms let out and remash the throttle and no dcs. but anyways I'll likely never know what it was on this particular sled now.
hope you get it sorted holms.
 
There were a few items that I found would contribute to DCS triggering on my SRX.
-higher engine temps that occured in icy or low snow conditions or high temp spring riding conditions
-defective or out of adjustment TPS

If you can get some 100ll Av gas try mixing it 50/50 with premium gas and see if problem persists
 
a new dcs sensor and tps were going to be my next items until he blew it up.
sorry for the hijack holmes. like bob said try some higher octane fuel mixture just to rule out a fuel issue. I'd then look to testing the dcs and throttle position sensors as bob suggested.
 
Thanks for the help lads. The dealer only changed the main jets and I'm pretty sure the needles weren't touched but I'll find out Monday. It's definitely frustrating. I'll keep plugging away and keep you all posted. For now I'll be running the fields with my 1976 motoski nuvik which runs mint............WTF.
 
holm0069 said:
For now I'll be running the fields with my 1976 motoski nuvik which runs mint............WTF.
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I still have a 1972 Motoski 440 Grand Prix that runs well. After Skidoo merged with Motoski that MotoSki Nuvik is the first tear that the Motoskiis were just orange Skidoos...not unlike the new YamaCat!
Shortly after the Motoskiis were no-more...just a memory.
 
You can likely keep running it relatively safely since the DCS seems to be working properly to prevent damage.

In addition to the needle adjustment noted above, check the spark plug color after a decent length midrange run with the DCS light on then cutting the throttle and shut down. If that light is on because the sled is lean and detonating during that midrange run, seems that the plugs should show lean condition. You could try this before and after the needle adjustment. You can also do some heavy/full throttle runs where the light doesn't come on, then cut the throttle, and check the plug color. If plugs are then darker with good color than the midrange DCS-lit-up runs, your plugs are telling you to richen up the mid.

Also, if you can't get any good hi-test gas to mix with your premium, try some octane booster and see if it helps.
 
staggs65 said:
I wouldnt assume that. the one I was dealing with blew the engine with the dcs "seemingly" doing its job too
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If it's the one you talk about in your post above, you noted the owner ran it low on coolant and then blew the crank, suggesting that the two are related. I imagine the OP is sharp enough to pick up on that and make sure his coolant level is up to snuff. He needs to run the sled in order to troubleshoot the DCS, and by his description the DCS isn't on under all conditions, he has quite a bit of control over it with his right thumb. I'd be running it, keeping an eye on the plugs and making my changes one at a time to see what helps and what doesn't. I'd even be playing with the choke when the DCS comes on in the midrange, seeing if the extra fuel has any effect.
 
Sunoco gold is 94 but how fresh could it be is the ?Like how many cars in the winter use that.Would not hurt to drain your tank and fill up with a tank of 94 and try it.

.
 
1) Are your powervalves working properly?
2) Are your exhaust donuts sealing well?
3) Do you have springs that hold the exhaust firmly in place?
Check that and report.
 
does it work with stock clutching or more aggressive one ??this will raise the exhaust temp ...
 
Jetted up main carbs and light is still coming on but not as frequently and only midrange. If I backoff and hit the throttle it stays off.......when I let off and cruise it seems to come back on. I guess next step is raising the needles.........any suggestions.......were running out of snow. Thanks.
 
holm0069 said:
Jetted up main carbs and light is still coming on but not as frequently and only midrange. If I backoff and hit the throttle it stays off.......when I let off and cruise it seems to come back on. I guess next step is raising the needles.........any suggestions.......were running out of snow. Thanks.
Click to expand...


I'd try raising the needles and if the DCS goes away, go back to the original mains and see if it stays off.

From what I've read about Vipers, mid-range is ragged edge near deto and your symptom sounds like it fits.

Most have fixed the mid-range lean spot by raising the needles (per Mr. Viper recommended settings) and using an opticool base gasket for improved coolant flow helps too.
 
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