Yeah I may take it out tomorrow and run some miles on it, stopping and turning it off after 30 miles or so, restarting and continuing on and monitoring them to see. 2.3 is pretty good and combined with STFT fluctuating in the low positives to 0 to a few negatives means that LTFT and STFT combined is staying pretty close to 0, which is good.

I did retorque the new plugs. A couple of them had soot around the washers (but not the electrode) so they may have not been at the correct 15lbs. Probably not enough to induce any air seepage but who knows...

The replaced MAF made it run like doo-doo and kicked up STFT to over 25%, but idling a bit and a drive around the block a few times sorted it out.

There's a guy on DISCOWEB that has made a program to reset adaptive values using a cheap OBD scanner but I haven't got the program to work yet. That should help, too, once I can get them reset.

 

I'm not one to throw parts or suggest to do so but I had a gut feeling based on my own experiences with MAF's. Electronic devices do degrade and the Rover ECU has a pretty high tolerance and won't throw a CEL until it's bouncing off the absolute limits. What's the IAT reading, pretty close to ambient? Is the CEL staying off when cold starting?

 

I keep throwing "Rough Line Low Fault" I think it's a P1317 on occasion but that's been a long-time problem. I have new ABS sensors but holding off until I replace the master cylinder and do my front brakes and new rotors. I have my ABS fuse pulled though since I was getting random pulsing through them. But since the sensors are still in place I guess it's throwing codes.

Haven't thrown a multiple cylinder misfire code in a couple days now.

IAT staying close to ambient, yes, but so was my other one (give or take). It definitely wasn't the -36 that the shop that ran my diagnostics said it was so no telling how they got that number.

 

85 mile round trip.
LTFT started at 3.9
End: 4.7

IAT: 62 degrees. Actual air temp 40.

12 mpg round trip average. 65 mph cruising. 2300 +/- rpm

 

I can tell you from experience any changes you make will take awhile to start showing clear results. LTFT can take 100 miles of driving to average out. It's increasing towards lean which is fine but it may signify that you may need another bottle of Techron at the next fill-up. It took me two tanks before I started seeing good results. It's a start, you know you have good parts and no vacuum leaks. I was reading up on LTFT and came across a test for vacuum leaks;

For a suspected vacuum leak, note the fuel trims at idle and increase engine speed to 2500 RPM and hold. If the STFT immediately decreases and moves to acceptable levels and the LTFT slowly starts to come back down, you have a vacuum leak. After the repair, reset the KAM and start the vehicle. Monitor the fuel trims to make sure they are within the normal ranges. It could take up to 10 miles of driving for an accurate LTFT reading.

 

Since it was still warm I ran out and did that test quickly. My STFT actually increased initially and then came down so that pretty much confirms no vacuum leaks.

Could just be an old coked up motor I guess. I have a 16 hour round trip coming up this weekend so I'll just pour techron through it the entire way and see what happens.

 

Good deal, I know that has been bothering you so it's confirmed. Only after I replaced my head gaskets did I start getting 17 mpg highway because I cleaned the pistons and combustion chambers in the heads. The adaptive resets help to clear what's stored and start fresh so the ECU can relearn. I highly encourage you to read hhowards thread on it, not hard to do. Do you still have catalytic converters?

 

It has about 25k miles on new heads, gaskets, timing chain and gears, camshaft, lifters, magnaflow Y pipe and NRP muffler and exhaust, and new cats at that time. Less than 500 on new plugs and new wires. I didn't do the work but bought it off a meticulous owner (and professional machinist) so I'm doubting that it was slapped together. I would assume, though can't confirm, he wouldn't have just let the piston domes stay coked up when he did the new heads.

I am running 255/85/R16s and a lift kit so I know I'll never get the 18-19 that it presumably ran stock, but wouldn't think it would suck 7-8 mpg due to the tires.

New 02 sensors in front. Maybe the rears have to be replaced though I read they don't affect the fuel trims and only show whether cats are working.

Perhaps I have a tired and slow ECU? It has moved, in the last year, from Portland, to 6000' at Montana, to 2000' in WV. I'm still waiting to get the adaptives reset. The plugs looked fine yesterday when I pulled and re-checked them.

Previous owner did state in Spring/Winter he would get 240-260 miles to the tank
Summer would pull 185-215.

I'm getting 140 at best per tank, though once on all highway I did get 180.

I do plan on getting another car to use for my winter commute since it's a bullnonsense 2 mile commute I can't do via bicycle - in summer I use the motorcycle, but winter's here are usually rainy, icy, and horrible. I know that quick back and forth is choking up the motor for sure, esp when I can't get out once a week just to drive it for the sake of putting highway miles on.

 

Have you checked to see that your odometer is reading correctly. With the taller tires your odometer may be reading less than the distance actually traveled. This would affect your MPG calculations.

I didn't read back through the entire thread, so if this has already been addressed, please ignore.

 

My scanner is showing me running about 6-7 mph less than the speedometer is showing - so if it shows 70 mph my scanner is showing around 63-65.

Good input, thanks. No idea how to correlate that into an ODO reading though. I paced myself with mile markers and as I recall it was pretty accurate there.

Note: I haven't used a GPS to determine actual speed, just what the OBD scanner shows is my speed.