gpr
February 5th, 2018, 11:34 AM
I have a 2002 Silverado with 5.3 lm7 engine. In the last 6 months I have noticed the fuel mileage has gone down. When i first got the pickup i would get 15-16mpg almost all the time. Now I'm getting 12, but don't know why. It had 90,000 miles when i got it and now has 157,000 miles. It is pretty much completely stock, and I have tuned it and turned off most of the torque reduction etc...
I did a quick scan today and LTFT, maf and map seem inline. What else should i check? I pulled the intake and cleaned the maf wires. I did notice when cruising down the interstate that i got a slight bit of KR. Not sure why, and I was wondering if it was real or false knock. Attached is a screen shot of it as I had cruise set. I'm running the stock spark tables
I had serviced it up a few years ago and put new iridium plugs, MSD wires, knock sensors, fuel filter, and o2 sensors. I was thinking i could replace all of those again to service it up, but don't think that would help any as I'm not seeing signs of it missing etc...
I have noticed once in a while while idling it seems to idle maybe 200rpms higher then it should, but doesn't do this all the time, and I was thinking vaccum leak. However, there is really only two vaccum lines, one for the brake booster and one for the fuel pressure regulator and they look fine.
I was wondering what i should log to see if there is a sensor or something that would cause this? Or how would I know if maybe the intake has a leak?
I did a quick scan today and LTFT, maf and map seem inline. What else should i check? I pulled the intake and cleaned the maf wires. I did notice when cruising down the interstate that i got a slight bit of KR. Not sure why, and I was wondering if it was real or false knock. Attached is a screen shot of it as I had cruise set. I'm running the stock spark tables
I had serviced it up a few years ago and put new iridium plugs, MSD wires, knock sensors, fuel filter, and o2 sensors. I was thinking i could replace all of those again to service it up, but don't think that would help any as I'm not seeing signs of it missing etc...
I have noticed once in a while while idling it seems to idle maybe 200rpms higher then it should, but doesn't do this all the time, and I was thinking vaccum leak. However, there is really only two vaccum lines, one for the brake booster and one for the fuel pressure regulator and they look fine.
I was wondering what i should log to see if there is a sensor or something that would cause this? Or how would I know if maybe the intake has a leak?