- Dec 12, 2011
- 4,673
I believe over the last few months, maybe more since I didn't pay too much attention when the winter blend of fuel came into play, I have lost a couple MPG's and I want to try to hunt down what may be the culprit. I want to say it's possibly fuel related but just a hunch.
I have changed the plugs (AC), fan clutch, compression is very good, vacuum good and steady needle, TB cleaned, upstream O2 replaced (AC from dealer) all new bearings at each corner. Tires are good and are LRR, MPG's were fine when I purchased the tires, brakes are not dragging.
I did reset the codes after the O2 and fan clutch but I'm letting it sit overnight with the battery disconnected.
Driving around with my OBD scanner I have been watching the fuel trims, mainly the long-term and while I'm not well-versed on fuel trims, I have a basic understanding of them. What has me thinking fuel is when I'm on a flat road, steady 60 MPH I can almost hold a steady 20 MPG on the DIC, but spends more time at 19..and mine is about 1 MPG off, reading high. I would generally hover around 22-23 between 55 & 60.
At a steady cruise at 50-65 ish my LTFT stays around -2 to -3.5 and sometimes raises to -1.7 but not for long...this is with a steady foot at 60 MPH, flat road.
I recorded some live data but don't have serial port on this PC so I need an adapter before I can post the results, maybe someone that knows the trims well enough can help. I want to look at dirty injectors, MAP sensor, fuel pressure or maybe even a vacuum leak but something tells me it's fuel related.
Another possibility is a restricted exhaust, the cat's temp last night after a drive was about 375-400 deg in and just over 600 deg out, downstream sensor stays around .475-.575V and is fairly steady. I guess this doesn't mean it's not restricted but I will test backpressure....I plan on building my own gauge from an old O2 sensor so we'll see how that goes.
Given the fact most members here are creeping up on miles here as well, hopefully this will address some MPG issues some may be having as well. I will get started on it this weekend or just before and post results as I progress.
I'm barely on the gas at 60 but just seems like I need to push on it harder than normal to pick up some speed....almost like I have 500 lbs in the cargo area. Owning this since day 1 you just get used to things and something is amiss.
All input welcome.
I have changed the plugs (AC), fan clutch, compression is very good, vacuum good and steady needle, TB cleaned, upstream O2 replaced (AC from dealer) all new bearings at each corner. Tires are good and are LRR, MPG's were fine when I purchased the tires, brakes are not dragging.
I did reset the codes after the O2 and fan clutch but I'm letting it sit overnight with the battery disconnected.
Driving around with my OBD scanner I have been watching the fuel trims, mainly the long-term and while I'm not well-versed on fuel trims, I have a basic understanding of them. What has me thinking fuel is when I'm on a flat road, steady 60 MPH I can almost hold a steady 20 MPG on the DIC, but spends more time at 19..and mine is about 1 MPG off, reading high. I would generally hover around 22-23 between 55 & 60.
At a steady cruise at 50-65 ish my LTFT stays around -2 to -3.5 and sometimes raises to -1.7 but not for long...this is with a steady foot at 60 MPH, flat road.
I recorded some live data but don't have serial port on this PC so I need an adapter before I can post the results, maybe someone that knows the trims well enough can help. I want to look at dirty injectors, MAP sensor, fuel pressure or maybe even a vacuum leak but something tells me it's fuel related.
Another possibility is a restricted exhaust, the cat's temp last night after a drive was about 375-400 deg in and just over 600 deg out, downstream sensor stays around .475-.575V and is fairly steady. I guess this doesn't mean it's not restricted but I will test backpressure....I plan on building my own gauge from an old O2 sensor so we'll see how that goes.
Given the fact most members here are creeping up on miles here as well, hopefully this will address some MPG issues some may be having as well. I will get started on it this weekend or just before and post results as I progress.
I'm barely on the gas at 60 but just seems like I need to push on it harder than normal to pick up some speed....almost like I have 500 lbs in the cargo area. Owning this since day 1 you just get used to things and something is amiss.
All input welcome.