Knock Sensor on XP? Please Help!

[DenverR1]

Ok, so I got my 860 big bore back and it RIPS! We started off with 460 jets and stocker can. The mixture was a little rich but we were still breaking it in. After some miles I wanted to try my aftermarket can, so I put it on with 480 jets. It ran lean. So today I put on the can that my mechanic advised me to get, and dropped back down to 460 jets. It was running really lean again. In less than 5 miles the display then read "knock sensor" and "overheating." I quickly shut it down and had my buddy go back and get my stock can. I put the stock can back on and kept the 460 jets in. The "knock" readout continued, and about 5 minutes later I got the "overheating" again. After letting it cool down again I got back to the truck and put in the 480 jets because it was still running so lean and I thought this might cure it all. I put in the 480's with the stock can on. It continued to say "knock" and "check engine" and the power was nowhere near where it was that first day I got my sled back. What is going on here? Any input would be greatly appreciated!

 

[RKT]

Ok, so I got my 860 big bore back and it RIPS! We started off with 460 jets and stocker can. The mixture was a little rich but we were still breaking it in. After some miles I wanted to try my aftermarket can, so I put it on with 480 jets. It ran lean. So today I put on the can that my mechanic advised me to get, and dropped back down to 460 jets. It was running really lean again. In less than 5 miles the display then read "knock sensor" and "overheating." I quickly shut it down and had my buddy go back and get my stock can. I put the stock can back on and kept the 460 jets in. The "knock" readout continued, and about 5 minutes later I got the "overheating" again. After letting it cool down again I got back to the truck and put in the 480 jets because it was still running so lean and I thought this might cure it all. I put in the 480's with the stock can on. It continued to say "knock" and "check engine" and the power was nowhere near where it was that first day I got my sled back. What is going on here? Any input would be greatly appreciated!

After multiple or even 1 sever knock sensor failure.. your delaer must clear the code ... It doe snot just go away after you turn off your engine once.. It is a dealer fix item...

 

[DenverR1]

Thanks Kelsey, your 860 rips! So after I get it cleared, what can I do to prevent it from doing this again? And is the knock sensor problem the reason why my sled is running so lean? I was told your 860 is running with 420's while I'm lean with 480's. Thanks

 

[oerthtop]

860 too lean

How did you determine you were running rich or lean, spark plugs, piston wash? you need a scope or pull the exhaust valves or head. Have a look you probably have detonated. Were you lean at WOT or midrange.

 

[JohnnyH]

After multiple or even 1 sever knock sensor failure.. your delaer must clear the code ... It doe snot just go away after you turn off your engine once.. It is a dealer fix item...

Will your ECM take away timing or anything else if there is a code set?

 

[madmax]

You can only run 420's if you have the RKT ECM recurve. If you have the stock ECM run 460's.

 

[Blu Du]

my knock sensor lite up once and i didn't have to take it to the dealer. haven't seen it since

 

[trinitypowder]

I've been blown away by everybodys jetting stuff. My 860 did the same thing as yours with 480's and 470's. The mid range was especially "deto sensitive". I have since gone to an '07 needle(middle posistion-same as '08 stock) which fixed the mid range deto. But now, on 480's she's "peppering" on the main jet. I just put 500's in tonight to try out Wed. Get familar with your carbs, DenverR1!! I'm not an engine guru, but I can't figure out how a "bigger engine" with better airlfow, DOESN'T need more fuel?? I'm sure Kelsey knows I've been driving Big John crazy with phone calls. My airbox has MONSTER holes in the rear that seem to be pulling in alot more air. Let's hook up and let 'em rip! Once the jetting's fixed

 

[DenverR1]

I've been blown away by everybodys jetting stuff. My 860 did the same thing as yours with 480's and 470's. The mid range was especially "deto sensitive". I have since gone to an '07 needle(middle posistion-same as '08 stock) which fixed the mid range deto. But now, on 480's she's "peppering" on the main jet. I just put 500's in tonight to try out Wed. Get familar with your carbs, DenverR1!! I'm not an engine guru, but I can't figure out how a "bigger engine" with better airlfow, DOESN'T need more fuel?? I'm sure Kelsey knows I've been driving Big John crazy with phone calls. My airbox has MONSTER holes in the rear that seem to be pulling in alot more air. Let's hook up and let 'em rip! Once the jetting's fixed

Hey Trinity,
You from Colorado? I'd love to put 'em side by side! From the little bit I know, we shouldn't have to be using anywhere near 480's. I believe Kelsey uses 420's in his and I've got his kit. I've got an SLP intake and also 3 flowrites on the airbox. I was pm'd by a guy that said it is somewhat common on the big bores to get this problem. And I've had the ECM reflashed. He suggested putting a small amount of silicone on both sides of the washer to make it less sensitive. He also said he has seen it mounted in different areas such as in front of the cylendar to make it less sensitive. I guess that when you are getting the knock sensor it throws everything off, like making it run lean, getting the overheating display when it's actually not. So once we get that to go away we both should be able to jet down. I'd love to be able to get it down to 420's! When I rode yesterday with the knock sensor staying on, the power was probably less than when it was a stocker 800. But the first day I had the 860 and the little biotch knock stayed away it was a ripper. And that was running it rich with 460's and not broken in yet. I can't wait to get it dialed in and broken in. I'm also going with the shockwave helix. Because that is what MPM (my mechanic) recommends, and Kelsey runs it too. Anyone else have some knowledge on this problem?
Trinity-lets run em sometime!

 

[DenverR1]

We are going to retard the timing 3 degrees. I hope that works!

 

[RKT]

VERY bad idea!

 

[Skidoox600]

If the knock sensor is hit once the light will come on. It only stays on if it is hit three times within ten minutes. That's when you need to take it back to your dealer to get it cleared.

 

[Stucky]

After multiple or even 1 sever knock sensor failure.. your delaer must clear the code ... It doe snot just go away after you turn off your engine once.. It is a dealer fix item...

Kelsey I have had mine into two different dealers and they can't clear the codes, and the knock sensor is still going off. Straight race gas too. If I was to get your reprograming of the ecm would that elimanate the codes altogether, or does BRP have clear the codes before you reflash the ecm?

Thanks Stucky

 

[triple7]

VERY bad idea!

Have to agree with Kelsey here. Take 3 degrees of timing out of it and a stocker is gunna eat your lunch!!

 

[trinitypowder]

Yep i'm from Colorado. I'm just north of Longmont, in Berthoud. 420's seem crazy low, but I guess Kelsey knows his stuff. The way I see it is if I have good plug color on 480's, why would I want 420's?? I know the DPM should take care of it, but a little safe on the main can't hurt much in the real world. On the Dyno, sure, but not out in the world of vary temps, fuel, and altitudes. My ride with the 500's will be thursday at the ears. I'm packing the 480's just in case. My timing is still stock-no ecm re-curve, no Boysen reeds. Big John and Kelsey have similar motors, but the porting is a pinch different between the two of them. Therefore, the jetting could different between mine and yours.

 

[daddy]

check out what engine tech has found out about the thermostats in these, go on arts website and have a look...we took the t stat out and problem solved

 

[DenverR1]

Have to agree with Kelsey here. Take 3 degrees of timing out of it and a stocker is gunna eat your lunch!!

What exactly will it do and why would it be bad? Bad for my engine or bad for performance?

 

[trinitypowder]

You're gonna lose power! I don't know how much, but she won't be an 860 anymore!!! Big John told me to ADVANCE 1 degree after she was broke in, but since she's still detonating, I never did. The 3 degree retarding will take care of the detonation, but will take some ponies as well.

 

[triple7]

What exactly will it do and why would it be bad? Bad for my engine or bad for performance?

It wont be bad for the motor...well, it wont necessarily be good for it either, but it will kill the power. These things only have like ten degrees of advance at 8000 rpm as it is...take 3 degrees away and you it will lose all its pull

 

[turborev]

what fuel are you running in that 860.