Hi GMTNation,
My name is Tony and I just got myself a 2007 TB LT 4x4, 4.2L I6 W/ 123,432 miles. During the 2hr drive home I noticed it didn't have the power I remember them having (borrowed one from a friend a few years back) and the gas mileage was not as great as I remember (15mpg Highway/3.42 gears).
Not having all the service records, I cleaned the throttle-body & MAF, replaced the spark plugs with ACDelco 41-103 and ensured gap was at .040, replaced all Ignition Coils and Up-Stream O2 w/ New ACDelco's, installed a Volant CAI and of-course changed all the Fluids except for the Coolant (recent Pump/Thermostat/Flush by previous owner). Finished off by running Royal-Purple Fuel Injector Cleaner in two back-back tanks of gas.
Upon logging the car during my Drives, I noticed that the Long-Term Fuel-Trims were consistently in the -7 to -12 range indicating a rich condition according to these forums. A compression test gave me 200-210 PSI across all 6 cylinders. A vacuum test gave me 20PSI of vacuum at idle and at 2,500 RPM. Blipping the throttle only quickly dropped vacuum before it shot right back up (so I'm assuming cat is not clogged). Fuel pressure is steady at 58 PSI at all RPMs (no fuel pressure regulator present).
I also occasionally get random knock while cruising and accelerating. It seems like I'm down to maybe a faulty injector/s? Below is a screenshot of my log. Does anything stand out?
My name is Tony and I just got myself a 2007 TB LT 4x4, 4.2L I6 W/ 123,432 miles. During the 2hr drive home I noticed it didn't have the power I remember them having (borrowed one from a friend a few years back) and the gas mileage was not as great as I remember (15mpg Highway/3.42 gears).
Not having all the service records, I cleaned the throttle-body & MAF, replaced the spark plugs with ACDelco 41-103 and ensured gap was at .040, replaced all Ignition Coils and Up-Stream O2 w/ New ACDelco's, installed a Volant CAI and of-course changed all the Fluids except for the Coolant (recent Pump/Thermostat/Flush by previous owner). Finished off by running Royal-Purple Fuel Injector Cleaner in two back-back tanks of gas.
Upon logging the car during my Drives, I noticed that the Long-Term Fuel-Trims were consistently in the -7 to -12 range indicating a rich condition according to these forums. A compression test gave me 200-210 PSI across all 6 cylinders. A vacuum test gave me 20PSI of vacuum at idle and at 2,500 RPM. Blipping the throttle only quickly dropped vacuum before it shot right back up (so I'm assuming cat is not clogged). Fuel pressure is steady at 58 PSI at all RPMs (no fuel pressure regulator present).
I also occasionally get random knock while cruising and accelerating. It seems like I'm down to maybe a faulty injector/s? Below is a screenshot of my log. Does anything stand out?
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