D1 fuel economy

terryjm1

Well-known member
Jan 23, 2011
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324
keep in mind the odometer is about 10% fast with factory tires, so adjust MPG claims accordingly

It is perfect with 235/85s
I’m running 245/75s. The speedometer app on my phone seems to be just about spot on with the speedometer in my D1.
 

terryjm1

Well-known member
Jan 23, 2011
1,389
324
Isn't the barometric sensor there to reduce fuel at higher elevation? At the very least, the fuel rail pressure regulator.

FYI- this is a 99% off topic reply…

A long time ago I had a 1980 Triumph TR7 and a 1981 Fiat Spider at the same time. Both had Bosch L-Jetronic EFI systems and 2.0 liter 4 cylinder engines. I really like those EFI systems as they are incredibly simple and extremely reliable. In that era they were installed in just about every European vehicle. Even the Japanese cars had what I believe is a cloned version of that system. I took both EFI (Fiat and Triumph) harnesses out of cars at a self service salvage yard to see if they could be easily interchanged. The answers is, yes they can with very little modification. The only major difference is the Fiat has a barometric pressure sensor. I took the Fiat harness, barometric sensor, and ECU with me and stored it away planning to someday swap it in my TR7, which I still have. Now that I live at high elevation I have a pretty good reason. The ECU part numbers were consecutive with the Fiat being one number later.

Over the years I purchased a lot of NOS EFI parts on ebay (for cheap) made for many different European vehicles as I determined which parts would work with the TR7. For example, back when cold start injectors for TR7s were around $350-$400 you could buy the BMW version for $30. It’s the same injector clocked 45 degrees different but the BMW version will fit the TR7. Cold start injectors get clogged with prolonged inactivity which is kind of typical of what happened with old TR7s. Another example, the idle air valve is basically the same valve used on a VW bus but was 1/10th the price back then. With any luck I will never need to hunt for EFI parts to keep my TRs on the road.

Even further off topic, Triumph had a lot of problems with Lucas electronic ignition. After a few bad years of warranty claims they decided to lean on GM. At first they went with their distributor design with a GM ignition module. At the end, just before they shut down, they went with a completely GM distributor and HEI style coil like what was used in 70/80s model GM cars. It worked well but the coil that was installed in the distributor cap in GM vehicles, was mounted with the ignition module on a small heat sink on the fender well. The coil used a unique direct wired pigtail that over the years dried out, cracked, and shorted out. I have yet to find a direct replacement and the TR version of the coil has long been obsolete with no replacement. No problem! The Fiat version also uses the GM ignition module mounted with the coil but on a larger heat sink located on the fender well. However, the coil used is the basic and extremely common cylindrical coil common to numerous older cars and trucks. I can walk into any Autozone, Napa, Oreilly’s, and many more and buy both the ignition coil and ignition module off the shelf. Another bit of useless information… the GM / Delco parts TR used were made in France.

More useless information… Saab 99s used a GM points type distributor. The TR7 and Dolomite engine is based on the Saab engine. Not surprisingly, in a Saab that engine was incredibly durable and reliable but when Triumph made a slightly different version it became notoriously unreliable. I cant recall if Triumph or Saab originally designed the engine. I think it was Triumph.

Many TR7 owners swapped in the Saab points distributors when the Lucas electronic version failed. The points used were common GM parts used in 60s era vehicles. The aforementioned electronic Delco HEI/CEi distributor TR switched to at the end uses the same body and ignition rotor/cap as the old Saab points distributor. To get back electronic ignition you could buy the Pertronix and Lumition kits made for the Saab distributor.
 
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discostew

Well-known member
Sep 14, 2010
7,617
983
Northern Illinois
keep in mind the odometer is about 10% fast with factory tires, so adjust MPG claims accordingly

It is perfect with 235/85s
I’ve never heard that. The 10% seems high. So if that’s true Land Rover got out from under about 4800 miles of warranty repairs across the whole market? Accidentally on purpose maybe?
 

robertf

Well-known member
Jan 22, 2006
4,753
338
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I’ve never heard that. The 10% seems high. So if that’s true Land Rover got out from under about 4800 miles of warranty repairs across the whole market? Accidentally on purpose maybe?

its true, take a GPS and verify. Interestingly the OBD2 reported speed is accurate, so yes, they knew.

I've been told by a former sales guide in the area that a customer threated legal action when LR tried to get out of expired warranty work on a D1 because they knew about the fast odometer.
 

DarylJ

Well-known member
Apr 3, 2011
440
24
Doylestown, PA
its true, take a GPS and verify. Interestingly the OBD2 reported speed is accurate, so yes, they knew.

I've been told by a former sales guide in the area that a customer threated legal action when LR tried to get out of expired warranty work on a D1 because they knew about the fast odometer.

I did notice OBD2 was accurate (now high in my case) but never noticed if the odometer was accurate with the stock tire size or not.

It's pretty typical to have a speedo read low and I think the manufacturers default to that because it's better than reading high. Or at least that's how it was in ye olden days of mechanical stuff. Seems like they could be dead on if they wanted to now.
 

discostew

Well-known member
Sep 14, 2010
7,617
983
Northern Illinois
its true, take a GPS and verify. Interestingly the OBD2 reported speed is accurate, so yes, they knew.

I've been told by a former sales guide in the area that a customer threated legal action when LR tried to get out of expired warranty work on a D1 because they knew about the fast odometer.
I believe it. Back in 96 I didn’t have a smartphone that would do that. GPS hand held units were available but mostly boat guys had them. All that sounds familiar but so long ago I really don’t recall it.
Now I have people coming in because the app is telling them about some old historic fault. Or the app tells them you haven’t really been working on it because it’s been parked and locked the whole time. Better still when some kid takes a rich guys car thru the McDonald’s drive thru. Nobody likes that shit. I wouldn’t either.
Done with my rant, you guys get back to the whole 10% thing. From the car company that sells Castrol oil at 3 or 4 times its real cost, just so they can add the dye to prove you’ve been using oil from them. They suck worse every damn year. You can buy better but you can’t pay more.
 

terryjm1

Well-known member
Jan 23, 2011
1,389
324
Castrol is bad? I just ordered some of their 20/50 high zinc oil.

Edit -never mind, I read that wrong.
 
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luckyjoe

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Oct 10, 2004
430
97
New Jersey USA
Over 16 years my D1 peaked at 15mpg, regardless of how it was driven. The best I have personally experienced was my '95 RRC 4.2L at 19mpg (all highway, one stop, driving through two tanks of fuel).
 
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terryjm1

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Jan 23, 2011
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Today’s fill up calculated 16 mpg on 87 octane with moderate AC usage. Seems that is pretty much what I should expect. I will admit, it’s hard to keep a light foot with the manual trans.
 
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kris812

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Jun 11, 2014
180
64
Tucson AZ
1996 Disco 1 SE7 145k on the clock.. Drum roll and the winner of the Disco's... 8.15 MPG on todays fill up 87 octane, AC on all the time, windows down, 100% city, mostly short 5-15 mile trips, heavy footed (new exhaust do you blame me). LTFT is at 0.78%, STFT +/- 5%, New heads, new o2's, new Cats. Just replaced the brake booster to get to those LTFT numbers down from -24% so hopefully next fill up is better! GAS PIG, best I've seen in last year with heat on and windows up was 10mpg.. BUT All these numbers should be +12%ish more MPG as I have larger tires.. NOTE: 40mph ECU is 45mph GPS speed with my tires
 
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robertf

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Jan 22, 2006
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1996 Disco 1 SE7 145k on the clock.. Drum roll and the winner of the Disco's... 8.15 MPG on todays fill up 87 octane, AC on all the time, windows down, 100% city, mostly short 5-15 mile trips, heavy footed (new exhaust do you blame me). LTFT is at 0.78%, STFT +/- 5%, New heads, new o2's, new Cats. Just replaced the brake booster to get to those LTFT numbers down from -24% so hopefully next fill up is better! GAS PIG, best I've seen in last year with heat on and windows up was 10mpg.. BUT All these numbers should be +12%ish more MPG as I have larger tires.. NOTE: 40mph ECU is 45mph GPS speed with my tires
Are you running 35"s with stock gearing?
 

1of40

Well-known member
Oct 23, 2017
229
55
Va
It’s a stock but low miles (27,XXX) 4.0. The only non-stock aspect that may affect fuel economy is it has new Ford type injectors that produce a finer spray pattern.

On the 16 mile 5000 feet drop the accelerator pedal is never touched. Engine braking is standard just about the whole way. down. Going back up it really works hard, probably 50% accelerator in 3rd gear mostly and a few short runs in 4th on the less steep sections.

The most recent trip on that route, I went back uphill with the AC on and it moved the temp gauge past the halfway mark, close to 5/8 I’d say, and made me a bit concerned. In the 1000 ish miles I have driven it since I got it back on the road, I’d never seen it go above the 1/3 point. I pulled over for about 5 minutes and is cooled back down and stayed down the rest of the climb. The area I stopped, about half way, is also where the outdoor temperature really starts to drop. Where I started it was 93 degrees. It is in the high 60s by the time I get to the top. It’s the first time I made the climb with the AC on but also the first time with 87 octane. I wonder if there is any correlation to the octane. The AC fans were operating. The coolant tank was where it should be as well. The radiator came out of the same donor vehicle the transplanted engine came from. It looked very clean from what I could see from the hose ports. I’m going to repeat the trip soon but with my scanner plugged in so I can see the actual digital temperature.
Got a part number on those injectors? My NAS 90 with 200K miles is on its OG everything. If/when it needs head gaskets done I may try a new set of injectors.