If your fan control is off then your on the right path by doing plugs first.

 

I'm going to do them when I add the pacesetter's. Can't wait to get the LT's on. I just saw in the dyno section someone gained 24hp and 33tq. Wow!

 

Adding the ORY as well?

 

yes! Still undecided on cats/no cats though

 

Yes its in the tuning:
There is a ignition timing table that retards the advance by 30* to 40* during A/C compresser comand on and off.

 

thanks, i know my comment was off subject but its something id been wondering about.

 

Same issue here, its a 2004 4.8. I just put tr55"s in and it seems to be a little better but my bet is that under a high load (4th gear around 60 mph light thorttle) is that one of my coils is going weak, just bought a set (well actually 7 coils) of coils from a member here, when I put them in on monday or tuesday I' will let you know.

 

thanks. Everything on my 02 LQ9 is off the 00 4.8. So stuff is getting old. But if that was the case with the coils you'd think it wouldn't run as good stop and go. It runs great all the way up to redline.......1st gear drop from 30 will light up the rears easily

 

I have seen this from experience, I'm a Jaguar Tech and the older S-types 4.0 would act the same way--5th gear cruising around 55-60mph they would hesitate. Usually when we get one of these in the shop we already know that they are in need of coils, which cylinder is it? don't know since its not a dead misfire but just a weak spark under a load and it will not flag a code.

They would run awesome throughout the RPM range but once on cruise around 1800 rpms then it would happen.

Just some info-

The coils should be here on monday and I'll update you that night.

 

very good info, thanks!