Could repeated misfire code and KR be related?
Thread Starter
Joined: Jun 2004
Posts: 5,125
Likes: 4
From: Alexandria, VA
Could repeated misfire code and KR be related? I was just thinking about how I keep getting a misfire code since my walbro took a crap and I replaced it. It keeps coming back and I'm not sure why as I thought my tuner had it all tuned out. Now, it could be that the tune just needs some work, but IF it doesn't, I was trying to think of the other causes. In dyno'ing the car we kept getting 2-3 degrees KR from 3k-5k for no apparent reason. We still haven't figured it out yet and are just ignoring it until I decide to do a 90/90 setup and replaced the knock sensors to eliminate them as the culprit. I was just wondering if this KR could be causing the misfire code or vice versa. I know it's a long shot, but I'm pretty much at my wit's end.
Thread Starter
Joined: Jun 2004
Posts: 5,125
Likes: 4
From: Alexandria, VA
I posted about my underdrive pulley possibly causing it b/c it's been on and off so many times that I thought it may have become out of round. Supposedly it's highly unlikely but I still have my doubts. I'm also not ruling out the fact that this is the 3rd engine my stock knock sensors have been in so they may have gone kaput. What do you think yours is stemming from?
I just saw your other post and u've checked the wire on the back of the altenator, but what about the one on top? I'm getting another code (P1637) and that's supposedely the wire on top of the altenator. It kinda makes sense too b/c my alternator took a crap a few thousand miles ago and I only have 40k miles. Is it related? I'm not sure. Like you mentioned in your other thread, maybe the KR and the misfires are related?
Btw...what's the difference between knock and false knock? My knock seems random and at one point spiked up to 6.1.
I'm not even sure how long I've been getting the misfire code. It could have been ever since I put my cam put in. Same with the P1637 code. I did get a so-so tune so maybe it's cause of the cam. I have MSD wires that were put in 20k ago. Maybe I'm running too hot of a plug cause I still have the NGK TR55's.
Btw...what's the difference between knock and false knock? My knock seems random and at one point spiked up to 6.1.
I'm not even sure how long I've been getting the misfire code. It could have been ever since I put my cam put in. Same with the P1637 code. I did get a so-so tune so maybe it's cause of the cam. I have MSD wires that were put in 20k ago. Maybe I'm running too hot of a plug cause I still have the NGK TR55's.
Thread Starter
Joined: Jun 2004
Posts: 5,125
Likes: 4
From: Alexandria, VA
False knock is vibrations from things like valvetrain, headers, or something like that which causes the motor to think it's detonating. Real knock is when it's actually detonating. The way to quickly find out which one it is is to run some race gas. If it's false knock, it won't go away. If it's real knock, it will, due to the higher octane of race gas preventing detonation.
As for the alternator, I did not get to check the wire on top. I couldn't quite get to it, but I will do that soon. The misfire code can easily be triggered if the tune isn't set up to handle a bigger cam properly. And your TR55's are fine unless you are spraying. Pull a plug and see if you're getting detonation (speckled plug).
As for the alternator, I did not get to check the wire on top. I couldn't quite get to it, but I will do that soon. The misfire code can easily be triggered if the tune isn't set up to handle a bigger cam properly. And your TR55's are fine unless you are spraying. Pull a plug and see if you're getting detonation (speckled plug).
You want to understand what the misfires are trying to
tell you. Single cylinder lean condition will make a single
cylinder misfire if it gets out-of-bed with the pack, badly
enough. And knock. You have to drill down into the info
(more than a code reader can, you need to catch it in
the act and dope out the cause from the effects that can
be observed).
tell you. Single cylinder lean condition will make a single
cylinder misfire if it gets out-of-bed with the pack, badly
enough. And knock. You have to drill down into the info
(more than a code reader can, you need to catch it in
the act and dope out the cause from the effects that can
be observed).
Thread Starter
Joined: Jun 2004
Posts: 5,125
Likes: 4
From: Alexandria, VA
Nothing seems to be going wrong in the engine though. Everything looks golden when it starts hitting KR from 3-5k and then it just comes back. I just can't figure out what the hell it is. On another note, my car hesitates for about half a second right after I let the clutch out in each gear and then is fine. JimmyBlue posted in another thread I was in that it could be KR as well and the system is trying to recover for that short period after engagement. I'm just wondering what's going on, what's related, and what's not. I have no clue where this false KR could be coming from.
