I know that I’ve seen at least a couple members on here state that they’ve had issues with KR after pulley (ASP) installs. What I’m trying to do here is determine why some have this issue and others don’t. I was recently in contact with a friend (not on this board) who has also had this issue. Is the problem bad pulleys? Bad installs? Poorly balanced cranks from the factory showing issue with lighter weight pulleys? Too much underdrive of accessories? (20% with ASP I think??)

And also, does anyone think that having your PO300 code removed might help with this? I’ve heard that if you have a PCM reprogram and don’t get this removed that there is some crank position relearn that you have to go through. I’ve also heard that if you mess with the crank in any way and this code is still in your PCM that you also need to do the re-learn, otherwise you will have issues with it. Now, having said that, would your PCM be less sensitive to say a poorly balanced crank, or lighter weight underdrive pulley once the PO300 is gone? This is just merly speculation as I’m trying to figure out why some are having this issue.

I have an ASP pulley that I was planning to install on my car but I want to sort this out first. So everyone please give your insight, experiences, thoughts, comments, etc.

 

The KR is caused by a change in the harmonic vibration after the change in pulley. The KR sensor is spec'd for use with a specific engine configuration which includes the standard pulley. This combination generates an "normal" ambient vibration that the KR sensor can ignore. Altering the pulley can change the "normal" engine vibration and cause the sensor to detect false knock.

The potential for this to occur is increased by all of the factors you outlined in your post. There may be some minor balance variations from pulley to pulley that are exagerated by the installs. I wouldn't attribute the KR itself to a bad install (use a new crank bolt) as much as unlucky install.

The shop that did my install had done some previous testing of the leading pulleys and found that they all had the potential for this issue. I believe they also noted that it was more common on '00 and up cars. With that warning we did the install of the ASP on my '01 and we haven't had a problem.

These pulleys are hot enough comodity that if you can get your hands on one, it's worth taking a chance to install it. If it doens't work for your car, it may still work fine for another car. So I would not hesitate to try it and pass it on to someone else if it doesn't work out.

I'd warn the next buyer that I did see some KR when I tried it on my car just to be fair. <img src="gr_stretch.gif" border="0">

Rick

 

My problem was a defective Whisper pulley. The thing LITERALLY was falling apart. The dowel pins that hold it together (it's a two piece design) were backing out. I pulled them out with my fingers!

Went to an ASP and haven't had any trouble since. <img src="gr_images/icons/cool.gif" border="0">

 

An incorrectly installed pulley should be the only reason you get KR. I have installed tons of pulley's on LS1's, and never had a problem with any of them having false knock afterwards. When the pulley is properly seated and tq'd to spec, it should be smooth sailing from there.


Josh

[ February 15, 2002: Message edited by: Damian ]</p>

 

Ryan just install the damn thing aleady! <img src="gr_grin.gif" border="0">

Seriously though, I've hardly ever heard of people having KR problems with ASP pulleys. If anything it has been a slight charging problem at idle, but nothing major. Your car will definitely benefit with it.

Mike

 

[quote]Originally posted by 2000LS1Z28:
<strong>If anything it has been a slight charging problem at idle, but nothing major. Your car will definitely benefit with it.

Mike</strong><hr></blockquote>

Charging problem? Haha! I don’t think so! Thanks to MTI it idles at 850 in gear.

Are we sure it’s limited to only poor installs? Seems to me that it could be a car to car thing like was stated above.

I want some more opinions here. How about the guys who’ve gotten the KR, did you try re-installing it more carefully and see if that helped?

 

Ryan, I've got an ASP crank pulley that was installed by MTI and I've never had a problem with it. Make sure you use a new bolt when doing the install and I've heard MTI tech's say that you really have to put some effort into tightening the pulley so you won't have any loosening occur.

 

I had an ASP pulley on my car for two months and the entire time the pulley was on the car I would get missfires on 1,3, and 8 between 5k and 5700 rpms, the above that the motor would start pulling hard again.

put the stock pulley back on and no more problems <img src="images/icons/confused.gif" border="0">

 

[quote]Originally posted by Bad Habit Bird:
<strong>I had an ASP pulley on my car for two months and the entire time the pulley was on the car I would get missfires on 1,3, and 8 between 5k and 5700 rpms, the above that the motor would start pulling hard again.

put the stock pulley back on and no more problems <img src="images/icons/confused.gif" border="0"> </strong><hr></blockquote>

Not to sound like an *** here, but how “careful” did you install the ASP? Did you use proper torque specs? Or was it a shop that did it?

Not trying to be disrespectful, just looking for facts <img src="gr_stretch.gif" border="0"> Thanks.

And thanks to all who have replied so far. <img src="gr_stretch.gif" border="0">

 

Anyone know how to get an ASP puleey off without bending it up? I'm taking my car back to stock and would like to try to resale it if I could keep from fu(king it up!!! <img src="gr_eek2.gif" border="0">

 

I've got two-dozen witnesses who'll tell you that my car had no knock before and after the pullies. Now, I may not be a good barometer for what you're describing, because I put the ASP pullies on incidental to a cam swap.

BUT... both times, before the install, and after the install... I dynoed my car. Neither time did it make an audible sound, and I ran it to just shy of the stock rev limiter. Some of the other LS1's dynoed that day sounded like they had marbles loose in the crankcase... one of the mechanics at the shop was amazed that the cars were making 300+ rwhp with detonation that prominent.

And my car is running the hotcam on stock programming... I just installed the mods in the sig. Not a single problem yet. I was the only LS1 to dyno that day (out of about a dozen or so) that had absolutely no audible knock. I've never autotapped the car, so I don't know beyond what I've posted here...

 

Bluestreak...Thanks for the info. I’m planning to put mine on during the cam swap too, as I hate to put sock parts back on that have been removed when I can upgrade instead.

Keep the info coming guys.

Anyone else have KR issues after pulley(s)?

[ February 15, 2002: Message edited by: RPM WS6 ]</p>

 

Ever since I had someone put the ASP crank pulley on my car it has KR @ 5300+rpm, a local shop did mine and they have done a ton before and their responce was some are good and some are bad. They re-used the stock bolt with red locktite. It seems to ramp faster than the stock pulley did even with the KR. <img src="gr_sad.gif" border="0">

 

Matt,

No, you don't need anything special for the new pulley. And, the ASP can be removed with any small block balancer puller at a later date.

When installing, make sure you use the old balancer bolt to seat the new pulley all the way on the crank snout. Then, remove the old balancer bolt and install the new one, torque to spec and you're done. I think the torque spec is 37 ft-lbs. + 120-degrees, if memory serves me... someone please correct me if I'm wrong.

 

Bluestreak,
Thanks for the info. I'm sure the new pulley will come with torque specs, so I can double check whan I receive it. I don't mean to sound like a dumb@ss but I've never done any work on a LS1,but I've built quite a few smallblocks, so I'm learning as I go.
Thanks for the info.

Matt

 

I feel pretty lucky, mine has been on/off the car four times and I have no knock at all.

Ryan I have all those tools, the Kent Moore GM ones, if you want to rent them for a small fee.

 

I put mine on during a cam swap as well and the autotap is not showing any KR,, I had always thought that these were the only pulleys that didn't mess up. Bluestreak is right on the tq spec for the install but to seat the original pulley with the original bolt you have to torque it to 240 ft lbs of torque <img src="gr_eek2.gif" border="0"> I have an M6 and I had it in 5th and when I got to around 230lbs the car was lurching forward at me. This was with E brake on and jack stands blocking the rear tires.

 

installed mine 2 weeks ago, and i atapped 20 or so times this week... no KR at all... she reads 0 all the way down the list for KN <img src="gr_grin.gif" border="0">

wish i could help, but everyone i know with the ASP hasnt had any probs... well in Va and Md anyway <img src="gr_images/icons/cool.gif" border="0">

 

i know this is a bit off ,but how about wrapping the knock sensor threads with teflon tape ( that white plumbers tape) to help dwell the harmonics????

 

I have 0 KR with the ASP crank pulley on my 99 TA. <img src="gr_grin.gif" border="0">