Originally Posted by Littlewaco

I've got the same problem pretty much other than my truck is basically stock other than my trucks only mods are diablo programmer, cold air intake and exhaust nothing major. Should I look at checking the same things you have or what? My truck jus started this last week and it is getting worse everyday I even went back to stock tune. Anything I should check first? Truck has 145000 miles.

Originally Posted by Holty

Ok, well, the verdict is in (kinda) lol.

I think the problem was the valve springs. I took the time this weekend and finally changed them out even though i was pretty sure it was not going to fix the problem seeing that visually, the comp 918's (new version) looked fine. I broke down and bought a set of PRC double springs that cost me right around $300 with shipping. After my wife royally chewed my *** out about spending the money i decided if this did not fix it i was going to throw in the towel for this season. Anyways, i spent the a couple hours on sat and the majority of the day sunday swapping them out. Didn't run into any problems at all, the hardest part was getting the air compressor adaptor/fitting screwed into the spark plug holes. Didn't even drop a single "keeper". Below are a few pics i took, not really sure why i took them, but you can see the difference between old springs and the new ones. Although, the old springs are really not that old, less than 10k miles on them.

Went out for a test drive after letting it warm up a few mins. FIrst thing i noticed is that these new springs are LOUD. MUCH louder than the comps. I drove around easy for about 10mins or so than eased into the throttle. No misfire. Went into the throttle a little harder, still no misfire. I took it WOT up to about 120MPH letting is shift through the gears. NO MISFIRE.

I don't know what to say here. I'm pretty disappointed in the comp springs at this point. My cam is not big by any means and these springs should have been fine. I'm still not convinced that fixed ALL my problems though.

I still have a top-end hesitation that has been there ever since my truck was rebuilt back in 2008. Its very slight and hardly notieable by anyone other than me, but i'm certains its adding a tenth or two off my 1/4 mile times. I always used to think it was a fuel pressure issue. But thats not the case

Anyways i'm happy for now and the truck seems to be running well. Now time to start troubleshooting my N20 that has been installed for two years and has yet to work lol.


Attachment 143569
Attachment 143570
Attachment 143571