Ok guys, so I just replaced my plugs no more then 100 miles ago. At that same time I changed my COP's with Granatell's as well. So when I pulled the old plugs, two plugs on the driver's side were in bad shape. So my buddy gets home on leave from Kuwait and wanted to go for a ride in my truck. So we hope in and head on down the road a little bit to a nice straight spot. I nailed it from a roll and when I hit 80 MPH my truck started acting like it was missing. So I get back out of it and start to head back to the house, before I got there I hit it from a 10 MPH roll and around 40 MPH it started missing bad.

My question is what in the hell is going on??? I just changed these plugs!!! I went with NGK TR6 which is what I've run since the pulley swap.


So everyone is familiar with my mods here they are:
Metco 6# lower
NGK TR6 Plugs
Gates 64.5" Belt
03-04 Cobra CAI
Truc-Tracs Traction Bars
Dyno Tuned by Delk's Performance in Lebanon, TN

 

Take out the plugs and look at them, also one of your COPs could have gone bad, the Crapetelli cops have been know to be hit or miss.

 

+1 on the COP's. I was advised by my tuner not to install the set I bought because he found 1 or 2 bad COP's in every set he installed.

 

I'll try and unplug each COP one at a time and see what's going on. Only problem is, this only occurs under load when I'm building boost. The truck doesn't miss at idle.....any ideas or thoughts?

 

That is a classic cop problem, idles fine, misses under load.

 

Granatelli COP = *****

 

Ok, so how do I narrow down which one(s) is/are causing my problem?

 

Unplug them one at a time. If the problem gets worse, the unplugged pack is working. If it stays the same, that's the bad pack. Or take one of your old packs known to be good and start substituting until you get rid of the miss.

 

Well, I assume if they all idle fine and only miss under load then how would unplugging them one at a time work?

By load I mean in drive and moving, so I couldn't just hold the throttle at the throttle body and unplug them one at a time because it still wouldn't be under a load while in park no matter how much throttle I give it. I tried this already. I was revving the truck by hand at the throttle body and holding it at a set RPM and listening for a miss, never heard it miss though.

Now if anyone thinks I could find the culpert by putting the truck on a loadable dyno, I have a buddy that's got a dyno dynamics dyno. I guess I could ask him to let me strap it down after hours and have someone drive it while I unplug the COP's one by one. What do you guys think?

Now keep in mind I am no mechanic and if I could find it by just cranking the truck up, setting her in park, and letting it idle while I unplug the COP's then sorry to make this simple task so difficult.

Where's Tim when you need him??

Seriously though if I'm thinking to hard about this just tell me and I'll do the above mentioned solution provided by RustySocket.

 

This would be half hazardly, but if you can get someone you trust, if it misses during a powerstall w/o spinning the tires. Unplug them one at a time and see which one does not make the difference. Just my 2 cents.

 

I'll try, but I only have a factory convertor, so not sure it will stall high enough to build any boost.

Keep the suggestions coming guys.

 

you could try a coil pack testing tool. I know you said it wasnt missing @ idle but the tool might be able to pick up a miss that you are not hearing. check out the link, may be worth a shot.

http://www.sjdiscounttools.com/wae76560.html

I am ordering one just to be able to confirm any COP problems.