Quadzilla Diesel Tuner

[Bob La Londe]

I've been having a recurring P0403 code on my Duramax Diesel. In the past Fisher cleaned the EGR and then replaced it. Since the truck is no longer under warranty I decided to find out if there was a better cure. Apparently its a not uncommon problem. Mainly a sensitivity issue in the computer program of the truck. Chevy has a computer tune that supposedly reduces the problem. That was not good enough for me so I did more research.

Apparently the EGR recirculates some exhaust gas back into the intake of the truck. This can cause carbon fouling and actually reduce fuel economy due to airflow restrictions. Lots of people put a blocker plate on the EGR port on the exhaust system and then use a variety of programs, replacement computers, tuners, or special wiring harness hacks (called a finger stick) to eliminate the resulting error codes from blocking the EGR valve.

Anyway, I decide to try a blocker plate and a Quadzilla tuner (the finger stick does not eliminate P0403 codes). I needed a tuner anyway to re calbrate my speedometer for my 285 70R 17 Toyo Open Country all terrain tires.

My goals for the tuner were three fold:

1. Eliminate P0403 codes without causing any harm.
2. Get a fuel economy gain without losing power.
3. Recalibrate the speedometer to read accurately with the larger tires.

Results:

1. CODE P0403. Had the P0403 code pop up once right after installing the new tuning. I cleared it and cleared pending codes. After 3 days it has not come back, but I'll have to wait and see for sure.

2. ECONOMY. Will have to wait until I have run a tank or two of fuel through the truck. It does feel like power has picked up slightly, and it has a smoother throatier sound to it without being louder. I already had enough power to pass safely pulling my boat so that deosn't really impress me any. I do like the smoother sound though.

3. SPEEDO CALIBRATION. The tuner shows tire size in ¼ inch increments. Toyo says my tires are 32.7 inches tall. I set the tuner at 32.75 and send the program to the computer. A quick freeway check with the cruise control set at the gap between 65 and 66 (just touching the 66 mark) resulted in stop watch times of:

55.38 seconds
54.99 seconds
55.44 seconds

Seconds per hour divided by the seconds to travel a mile will give you your miles per hour.

3600/55.38 = 65.005417118093174431202600216685
3600/54.99 = 65.466448445171849427168576104746
3600/55.44 = 64.935064935064935064935064935065

Given that highway markers are not always precise, and my timing may have varied slightly in pressing the start button I figure that is close enough. Prior to the reprogram at 65 indicated I was running 70 by stopwatch with these tires.

[Bob La Londe]

Spoke too soon. It just popped up the P0403 EGR code again. I'll be in touch the performance company on monday to see what the heck is going on.