8.62 mpg city...mega squirt?

[bandit86]

That was my last fill up in my 95 land river discovery. No extended idling. Then yesterday I drove 250 miles plus a by of city and got 16.4mpg. On the highway I was throttle conscious, I'm thinking something might be wrong with my truck, but instead of trying to troubleshoot it I was thinking of ripping out the ecu and going with mega squirt, a DIY programmable ecu setup. That way I could adjust parameters on the fly, adjust the fuel maps, maybe convert to wide band o2 sensor

I'm thinking leaning a bit at part throttle and idle, since the engine is 3.9L I does not have to work very hard to push the truck along, must be a horribly inefficient design

[Kodak]

How long are your typical trips? A little 2 mile city commute with a cold engine can yield some extremely low mpg results.

[drmiller100]

8.62 is just flat horrible for city driving. something is wrong with the rig.

16 is about what you should expect with a 4500 pound huge SUV with terrible aerodynamics.

Megasquirt is a great system, but I think you are not going to get much better mileage with it until you fix what is wrong with your city mileage.

[leg0man]

If you try to fix mechanical hardware problems by tuning them out through software, things will only get worse with time. Unless troubleshooting shows your current ECU is faulty and the cause of the problems, just installing megasquirt and leaning out the tuning to save fuel is a bad idea.

[spacer]

I was upset with 16mpg when I had my 4.2L Trailblazer. I don't think the Rover would be *that* much worse.
I usually could nurse 21 out of it on the highway, btw.

[bandit86]

I'm out of the city. About 9 country blocks, one and half mile each country block with 50mph speed limit then stop sign. Passed the emission test no problems and no codes so it cannot be too far out. Runs and sounds good. I kno my 01 jeep hated hills and would adjust power to maintain rpm and sometimes double my FE without me wanting it, I figure this one is doing it. I have a scan gauge but it is too old. I found my mpguino just need to wire it in. We get enough snow Regularly that i am very thankful for 4x4 and winter tires but maybe I should get a 99 Porsche 911 gt3 as a daily driver?

[E4ODnut]

First a few questions.

Have you had the vehicle long enough to tell if this mileage is normal, or if it has deteriorated suddenly?

If this is a sudden deterioration, then it would be simpler to find the problem and fix it. If it has always been this way, have you had much mechanical and engine tuning experience?

If the answer is no, then it would be simpler to find the problem and fix it. If the answer is yes then Megasquirt might improve things for you , if you can tune it right.

Before jumping into it, I'd suggest buying a good quality wide band and read out so you can see what your operating conditions are now. You'll need it for MS if you go that route anyway. If the numbers are fairly normal, then MS probably won't do much for you. If they are way rich, it might.

A word of warning. MS can be very addicting or extremely frustrating, depending on your talent and patience.

[bandit86]

New to me. Had one the same model same year, stock drivetrain on 33 inch tall mud tires. I was getting similar mileage. I thought if was because ofthe tires, they were 10% taller than stock

[320touring]

Originally Posted by bandit86

New to me. Had one the same model same year, stock drivetrain on 33 inch tall mud tires. I was getting similar mileage. I thought if was because ofthe tires, they were 10% taller than stock

What engine is it? the 3.9 V8? or the 4.0 V8?

[bandit86]

3.9. Heard both are the same but the 4.0 has different ecu. Use the numbers to keep the models easier to distinguish