03 lb7 lopey idle, surge and knock
 

Just recently bought at auction 2003 crewcab longbox 4wd duramax. I have no history on unit. There is an edge product(chip?) called the juice made in 03 vers 4.61 installed on it. The truck starts and idles great with no/limited smoke, slight puff of blue then clear. After warming up for 5 to ten minutes and heading down road, all seems fine. As truck gets warmer, about 3 or 4 miles of driving, it surges, has a clattering knock under acceleration. If I back off of accelerator and gradually speed up and I mean gradually, it sometimes bucks and knocks slightly and then seems to clear up after a few miles, never smokes black or anything like that. It is intermittent, sometimes takes longer to happen. First time was 30 miles from auction. On flat ground not accelerating is better. Going up slight incline starts to knock and surge. If I give it wot it seems as it is running out of fuel and knocking, but then sometimes chugs through and clears up. Have changed fuel filter. Old one had no water in drain. New filter never made difference. Have added diesel injector cleaner to tank and liter of dexron 3 atf as per heavy duty mechanic friend. There is a toggle switch mounted in dash behind signal switch. In one position the truck gives all these symptoms. In other position, the truck gives same symptoms but with very limited power. I am assuming that this swtich powers up the edge. I can hardly get 50 mph with switch in one of the positions. In the other position it has a fair bit of power, but still less than my dad's 04. Other replies to posts leads me to injectors, and lopey idle leads to fpr. I know need to get friend with reader to check codes and fuel rail pressures/balance. Have not had time to check wiring from switch to see if it goes to edge. Any ideas appreciated.

you put atf in fuel?

Yes, my friend who is a journeyman heavy duty mechanic as well as a journeyman automotive mechanic told me that the detergents in it will clean the injectors as well as lubricate them.

YOU DONT PUT ATF IN COMMON RAIL ENGINES that run at 27,000 PSI of pressure to the rails. Thats a old school mechanical injection system trick and on common rails the best thing to do is run fuel additive. But more than likely what your loping issue and everything is is being caused by the FPR or the injectors.

Thanks for the reply, I am leaning towards replacing the fpr for the $300 and hope it cures the problems.

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Got my friend to scan codes and P0500, P1235, P1244 came up. I think they were vehicle speed sensor, #5 injector and #8 injector. We then removed the chip (edge the juice) and miraculously the truck runs great. Still has lopey idle, but no knocks, or anything bad, just a little doggier. When testing truck balance rates were good, so hopefully no more issues. Just add stanadyne fuel additive to tank and go! It is so nice when it is the simplest fix.

sounds like the fpr or the cp3 could be slowly taking a dump on you. with all those codes you should contact edge and see what the deal is with that.

You know i auctully saw something like this at a buddys on youtube. The "switch" was ran into an electrical line or something like that for one of the injectors.. but the truck did not have an edge box. The guy in the video used it for a "lope tune" and trying to save money and not buying an auctual programmer. I couldnt tell you what the video was call it was a good while back... but that is just an idea to see if this "switch" is or not