re read the thread again, thats quite some work you put into the rover.

Thought about getting a tune done by someone with hptuners?

 

This is probably the point at which I start talking about something of which I have limited knowledge. I have a Jet Programmer which does an excellent job of resetting the computer to run without VATS, EGR, Rear O2s, Cats, Purge Valves and a bunch of other stuff that is still on the truck at the junkyard. It will also reprogram VSS output to correct the speedometer for Rear end ratio and tire size. It will reprogram shift points, line pressure and a bunch of transmission parameters. (I try to leave those alone unless there is a problem). You can really help yourself a lot by sourcing a transmission and engine combo from a similar style and weight vehicle. This will almost certainly result in much better performance (and tune) at the first startup. Having said that, there are plenty of other methods to get the "Right" tune for your needs.


1. Just drive it. After about 4 tanks of gas, the computer has learned enough about its new home to adjust the Long Term Fuel Trim for a compromise of fuel economy and performance. By the way this is also how you "Reprogram" a LSx to run Regular fuel that came from the factory requiring Premium.
2. Copy a known good set of parameters from another similar computer and flash this tune to yours. This is a mail order tune. (Internet tune I guess, now that we are well into the 21st Century).
3. Hire it done by a "So called Professional". Most of the professional tuners out there (from my limited experience) have no problem tuning for performance at the expense of fuel economy, usually on a dyno. They will take your money and give you a tune, but probably no better than Option (1).

I use option (1), way cheaper, cause I'm a tightwad.


Almost 1000 miles on it now and still running great. I have a few things to sort out, but so far all is well. I will post again and go through some of the most recent issues.

 

18-20 mpg hwy?

 

The low fuel light just came on today on the way to work. This is really the first tank that I have run thru it that didn't have a couple of hours of idling in the shop checking stuff. So, when I fill it up today at lunch I will have the first good MPG number. I was hoping for 20, but from the miles on this tank it looks like 17 (combined hwy and putting in the yard). I will know for sure after lunch.
I hope the computer just needs to do a little more "Learning" and it will improve.
I am 100% sure it will be better than the MPG from the Rover V-8.


By the way, temps are running 194 - 199 hwy with the stock thermostat from the GMC LM4 motor (probably a 195 deg).


In case I never mentioned it, I am using the stock cooling system from the Rover, minus the water pump and thermostat of course. Stock radiator, fan and fan clutch(hayden), shroud (slightly modified), reservoir tank, heater core, and the stupid plastic lines are now rubber hose. Temps are steady and perfect for an aluminum block.


Also, if it matters to anyone, the LSx motors (like the Discovery) also use a bypass system for quicker cabin heat. It is inside the water pump housing. The thermostat looks very similar to the guts of the Discovery external thermostat. The LS aluminum motors run so cool, that this is the only way you get any heat for the first 10-15 minutes after start-up.

 

Ok, I will have to say I am a little disappointed with the first MPG calculation.


Here it is: 16.55 miles per gallon combined back yard and mostly highway.


Mostly 70 - 80 miles per hour (With the Discovery V-8 I never went over 70 for fear of shaking it apart)


This is also using regular Gas, way cheaper than Premium.


No AC (still trying to get that going...looks like it is a bad compressor)


Hopefully it will improve over time, maybe....


Overall it is still a win, this is at least 1.5 - 2 mpg better than the original V-8, it has MUCH more torque and power, it will go faster, when it breaks it will be easier and cheaper to fix and it's still AWD.
Plus, the truck is not in the scrap heap.

 

not bad. no trade off there. I'd be willing to lose some mpg if I get on the highway without putting about, like I am on the way to to a blue hair bridge tournament. and you are right, prolly get better.

 

i guess it is kind of hard getting MPG's when your pushing a 5000lb billboard down the road no matter what is pushing it.

 

80mph is too fast. The Discovery's have a tall, flat rear end, which creates a suction and decreases mpg quite a bit. I can pull 16-19mpg on a long freeway trip with the 4.0 as long as I'm going 65mph, any faster than that I'll get 14 below.

 

I guess I'm afraid of coming in last!

 

Did your MPG reflect the hours of idle time you had it running in the garage? Or was your MPG figured on a new tank after the rebuild?