Fuel Consumption

Even by 400/412 standards, that is shocking fuel consumption! I got about 8 or 9 mpg on mainly town driving but it goes up to 12-13 mpg with more high-speed action. Mine is a 1980 400i Automatic.

I'd like to improve mine, too. I think the way forward is a more modern integrated ignition and fuel injection system.

Aidan

 

Willy,

Almost all of the aftermarket ignition solutions on the market today are total BS (I am in the business and can back up this statement with data). There are a few others that do a little and claim a lot.

I would give the car a good tune up (followed by a good 'Italian tune up'): put in a fresh set of standard plugs (if you want to splurge, install NGK or ND Iridium tipped plugs); also, try adding some Lucas fuel system cleaner into the gas tank or have the fuel system and top end power flushed; also change the air, oil and fuel filters.

You may want to consider having the bottom end flushed (sludge build-up) and if it is an auto, making sure that the transmission is adjusted correctly.

Once the engine is running well (and is used regularly), your milage should come up quite a bit. Unless, of course you have a lead foot

Regards,

Art S.

 

A tune up with standard plugs and a thorough investigation of the fuel injection and ignition systems would be the place to start.
I don't know what plugs you are talking about but if it's the ones with a coil in them or multiple electrodes I would stay away. A quality plug is all that's required. Some of the four electrode plugs have been known to loose those electrodes.
Flushing the cranckcase isn't anything that will do squat to improve economy. I don't recommend that for ANY engine, especially one that will cost five figures to overhaul. This is a high profit item for hinky repair shops that serves little purpose and has the potential for great damamge.
Your mileage is very abnormal.

 

My 33' Pace Arrow R/V gets almost that mileage (your city is about my highway)...it weighs 14,000#+ and has a bedroom, bathroom, and kitchen! Oh, it can haul my race car to the track too!

Good luck with this. Let us know what improves the situation when you get it figured out.

James
Austin, TX

 

Fuel economy on a 400 series???
BAWAHAHAHAHA oh man stop it, you're killing me........




Ok on a serious note, you won't get a lot better than that but here is what you do....
1) Follow the above advice and do a "tune up".
2) Don't forget the check EVERY spark wire with an ohm meter to make sure it is flowing power at the proper level. These cars run great on 11 cylinders, but you'll think you're running on 12.
3) Shove a CO2 meter up each tailpipe and see what the readings are.
4) Now go check your 412 manual and see what range they should be. On a 400i the range is 1% to 2%. I'm not sure what the specs are on a 412. The lower you go the hotter she'll run, but better fuel economy. The higher levels will make her run cooler but eat fuel. It takes a 3mm T-handle allen wrench to adjust the mixture. Counterclockwise makes it leaner, clockwise = richer.
5) Follow the factory procedure to now set the idle and balance the banks using a vacume gauge.
6) Now go check your mileage.
7) Send me a PM thanking me because you did the above and found it helped you by 10 to 20%

 

Willy,
there is something wrong,
Filters are always a good idea.
Like Dave says it is very easy to have a dead cylinder when you have 12. Pulling the plugs first, Before you do any thing else, to let you know what is going on, and if you have a non firing cylinder and which one it is.
Good Luck and keep us informed. If you have troubles post pictures of the plugs. Of course be careful to not over tighten and use a "never seze" product on the plug threads goes generaly with out saying.

 

Dave is correct again. Tune up tune up!!!

The 365 I have burns about 5 gallons an hour going slow or going fast. If you wany better gas milage go faster.

Tune ups are always a good thing, best to do the Italian version first. Its amazing what running the engine at 5K-6K revs does for getting things back in order. Also, I always perform a compression check when I replace plugs, it takes a little while, but it gives the observent person a good trend indication of possible upcoming issues. As Dave said, these engines run great on 10-11 jugs. Spark being one area of concern, but there are several data points to look at when discussing performance of these engines.

good luck mate

 

Sorry to divert this thread, but B3tech mentioned performing a compression check. My question is the following; considering the fragility of the ignition module on a 412, mine, should one remove any cables/ wires, before cranking the engine?

 

The TR uses the same Microplex MED120B (or MED120B/D) ignition ecu, and, since that problem really hasn't been reported here before on TRs, my guess would be that it's not that risky -- but sounds like a good idea to me. Just unplug the 25-pin connector from the ignition ecu itself if that's doable (in addition to removing the fuel pump relays, of course).

willy -- Here are the fuel consumption specs that they give for the 5L TR engine in the WSM, so (unless you drive like a madman ) yours shouldn't be all that different (my own experience is that the "City" number is a little lowish -- I get 11~12 mpg; the "at 90 km/hr" number is a bit optimistic and must assume being in 5th gear; and the "at 120 km/hr" number is about right):

TR
Urban Cycle (City) = 23,7 litre/100 km = 9.9 mile/US gal
At 90 km/hr (56 mph) = 9,9 litre/100 km = 23.7 mile/US gal
At 120 km/hr (75 mph) = 11,8 litre/100 km = 19.9 mile/US gal

What is the configuration status of your 412? Is it total unmodified (i.e., no injection changes and no cats) or truly convert to "US specs" (i.e., Lambda control added to the injection system and with cats) or something else? My guess would be that if you had cats and you were putting that much raw fuel out the tailpipe, you'd already be on fire

 

There are 2 plugs in your picture which are running rich or not firing 100% of the time.
The upper left in the first picture and the 3rd plug on the bottom row

 

Well, you made me feel a little better at least - I get at best 11.5 and no more ever on my 1986 Testarossa. But usually not much less, either.

Just as a side point, I have a maintenance notebook and write down miles, MPG, and fuel amount on every fillup since I have had the car - does anybody else go to that extreme? I thought it might be useful to observe trends, and perhaps to serve as proof of my mileage & maintenance if I ever want to sell.

 

I LOVE IT!!!!! That's great advice!!! So if he goes 20 miles per hour, he only gets 4 miles per gallon (20 miles/5 gallons) but if he kicks it up to 100 mph, his mileage increases to 20 mpg! Take it up to the top speed for a 400i of 150 mph and you can just hit 30 mpg!

Next time you get stopped by the highway patrol, all you need to do is explain that you were trying to be eco-friendly since by driving faster and faster, the better the gas mileage.

<GRIN>

Now we return everyone to more serious and technical programming advice, sorry for the diversion.

John

 

My wife has done that for her last 3 cars (all bought new). That covers her for about the last 18 years or so! She can tell you how much she paid per gal, how many miles she went, how many gallons she pumped and what the mileage was! A little to AR for me. I wish she was as neat as that in the house and would wash her car from time to time...I guess she is spending so much time writing down all this info she can't wash the car...

James
Austin, TX

 

Well, I never did this before I got the Ferrari - not for the 9 Porsches, 8 Corvettes, other cars, and not even for the Airplane. Just got into Ferrari Obsessive mode, I guess.

However, I have not been writing down how much I spent on the gas - too depressing these days.

 

Willy
You got lots of good suggestions. When I received my 400i the CO was running 5-6%. When I reset to 1-2% the mileage improved and so did the response. I also found my timing was about 20 degrees off when I got it.

This past weekend I ended up slugging it out in traffic for a half day and mileage dropped under 10. When on the open roads I was up in the 12+ range, maybe even 14. My average over 4000 miles last year was well above 12.

Now for your plugs. Dave is suggesting two possible problems for the "dark" plugs. They do not exactly look like over rich or unfired plugs. They look for oil fouled which is more ominous but not life threatening. This could be valve guides or bad oil control rings. Do the checks DAve and others suggest before you worry about bigger issues.

My plugs are 100% uniform, but unfortunately a bit on the white side for my comfort. The damn alcohol in our fuel is putting us all a bit lean even with our CO adjustments.

Keep us posted.
Ken

 

Exactly!
But for your sake we're all praying for bad spark plug wires on these 2 cylinders and not oil fouled plugs.

This has been a good thread. I'm betting that if you follow the advice given here you'll get your mileage up to 10 to 11 mpg (when you keep your foot out of it) which is as good as you're going to get. Some other guys will tell you they get better than that but just remember one thing.......they are measuring thier miles with 25 year old Italian speedometers (silly boys)
We all know they aren't even close to being accurate.

10 to 12 average mpg on a 400 series car? You're a happy guy.

 

Dave seems to be looking for a job in my engineering dept. Several good points made. Willy you are going to be doing a comp check soon, and please report your results. Make sure to get several movements per cylinder when checking. Also get all the plugs out of the engine. After comp readings are posted we can help with diagnosis.

If your traffic patterns are like mine in SFO. they are TERRIBLE !!!! Dave is very correct, 10-11 will be the best you can look forward to achiving. As the person with the TR stated, when you go faster milage gets better. No worries, you own a Ferrari, burn some gas DUDE !!! (hahahaha)

can't wait to see the comp readings.

 

Your company hires cranky balding drunks? Cool!

 

If one is always getting single digit mpg there are probably issues as pointed out elsewhere in the thread. But, expecting a 400i to sip fuel is optimistic.

My 1982 Automatic slurps up the fuel around town. 9 to 12 observed MPG in stop and go and excessive idling--my foot may not help much. The times I've driven mostly highway miles between fillups the observed can crawl up over 15 MPG. I live in the Portland Oregon area and have to go through the sniffer every two years. So the regulated imperative to make sure it is burning cleanly provides a regular cycle for my tune ups. I think one is about due even.

-steve

 

Steve

One thing I never expected was for my 400 to sip fuel! It drinks like a fish. It had a full tune up and valve adjustment last year, so it runs sweetly.

Aidan

 

Just make sure that you shut off the engine when filling up the gas tanks, otherwise the gas pump will never catch up with the consumption!

John

 

Darn, I knew I was doing something wrong. Thanks for the tip, John!