I was having some issues with pinging at WOT so I added some Octane booster, 20 miles later I start to get a miss, 2 miles later when I get it home it is starting to miss pretty good. Pulled the plugs and they all look okay?? Truck only misses when it has a load, seems to run smooth at idle. Hooked up the Predator and all I see is a random misfire code. Truck is an 05 with 71000 miles and a Magnacharger. Anyobdy got any ideas??

 

you could have bad plug or plugs, maybe bad COP's

 

Plugs all looked good, is there anyway to test the COP's??

 

are you in california?

 

Negative, South Dakota

 

I had a problem like that and i had a few bad plugs, all mine looked good but a few were bad.

 

I get problems like that due to our lower octane in Alaska. I have to change the plugs out here and again.

If you are getting pinging at WOT, you are probably running too lean and need a retune.

I think I'd try a new set of plugs and hope that is a quick and easy fix on the missing, then get either the tune worked on or find a source of higher octane fuel.

 

Thanks for all the replies, I will try and round up a set of plugs and keep you posted.

 

Yes, definately check the coils and coil boots for cracks or moisture/water. Checking the fuel pressure would be a good thing too.

 

What octane booster did you use? I fouled alot of plugs do to octane booster in my Mustang, but they all looked ok. I'd replace them before getting a new COP or anything.

 

Colder weather = denser air = lean. Monitor the Air fuel ratio. A wide band o2 sensor would be a wise investment.

JMC

 

Fuel pressure is good. Finally got a check engine light, cylinder #7 misfire. hopefully the shop calls with some results on Friday.

 

Well, the saga continues. Dealership called on Friday and told me that the COP was bad on cylinder 7. They replaced that and the plug and hit me for 300 bucks. Pickup the truck tonight and the first thing I notice is no miles put on it since I dropped it off, great, sure enough I get out on the road and put a load on it and it starts missing right away. I can't believe they wouldn't test drive if after replacing the coil.

 

You installed your sc 8-2007 since then your temps in SD are much colder and your gas quality has also changed. Perfect for running lean now.
A set of tunes would allow you to change based on the situation......
Examples
Bad gas
Cold weather
race
etc............

 

wow for a few bucks more you could have had you a set of GMS coil packs, and I still think you have a bad plug or 2