My E24 is the worst thing Mpg wise i've ever driven,

[blobygook]

I absolutely adore my 5 speed 87' 635CSI but is there any way to get better than my average 10 mpg? Perhaps getting it tuned up? the previous owner let it sit for a year or so I believe.

[EvilStar]

10 mpg is terrible. Mine was getting at least 19. Just did a bit of maintenance on it so I am hoping to see it go up a little more.

[wfwright2]

My 87 automatic provided 15 to 22 mpg (US) during daily use (city/hi way commute). That being said, I did mange a couple of tanks around 4 mpg in a 535is manual during a couple of driving schools. Mileage did drop off greatly when it was time for a plug change/valve adjustment maintenance.

[alpinacsi]

How are you checking your mileage? Is you odometer correct and working properly?

[pthm]

I get 17 to 20 in the city, and I get above 30 on the highway . . . you may need to do a good tune up on your shark

[dwal95008]

O2 sensor relay and the sensor itself could be bad. I was getting 9.9 per gallon until I replaced it. You way also have vacuum leaks and or exhaust leaks before the o2 sensor.
Use this site to diagnose many running issues.

http://hiperformancestore.com/Motronic.htm

[bkats]

I can't get my auto (granted it's an '89) below 15mpg without driving it really hard. 10mpg is defnitely not from a properly-running car. A full tune-up would go a long way to narrowing it down. Electrical tune-up (plugs, wires, cap and rotor), valve adjustment, maybe a bottle of injector cleaner, and intake boot/vacuum hose inspection, check the condition of the battery; these are relatively cheap and commonly the culprit. After all that is square, then you can probably start prosecuting the O2 sensor and other things.

[pthm]

O2 sensors are $30 for the universal bosch ones. new or reman injectors particularly the Mustang ones are a HUGE improvement

[blobygook]

Thanks for the ideas guys, It has an exhaust leak somewhere I just haven't had the time to get it into the air to look at it, Its also running a little rough Hopefully checking it over and changing the oil this weekend, I've got a feeling the previous owner diddn't take the best care of it.

[GazM3]

Yes this fuel consumption is just shocking. Should be 1/2. There is a lot that can cause it. As others have said change the exhaust sensors. Also have a look at the airflow meter, leads, plugs, filter etc.

I recently mapped the fuel on my m635 and the dramatic improvements to consumption and drivability are well worth the investment.

[Dash01]

Yes this fuel consumption is just shocking. Should be 1/2. There is a lot that can cause it. As others have said change the exhaust sensors. Also have a look at the airflow meter, leads, plugs, filter etc.

I recently mapped the fuel on my m635 and the dramatic improvements to consumption and drivability are well worth the investment.

Would you pls. provide specifics of how you did this?

Also, our cars could stand some aerodynamic tweaking. Ecomodder.com has lots of info about low hanging fruit, aerodynamically and practically. The short list includes higher tire pressure, undertrays, and air dams.

For relatively little expense and effort, these cars should be getting 28-30 mpg or better at highway cruise speed.

[dwal95008]

Would you pls. provide specifics of how you did this? Also, our cars could stand some aerodynamic tweaking. Ecomodder.com has lots of info about low hanging fruit, aerodynamically and practically. The short list includes higher tire pressure, undertrays, and air dams. For relatively little expense and effort, these cars should be getting 28-30 mpg or better at highway cruise speed.

Our cars already come with rather large air dams. That said, there are skid plate under-trays that while expensive will add some aerodynamic advantage to our cars. Raceskids.com has one.
It would probably help to remove the large black rubber trim around the doors. I can hear wind noise at 40 let alone 65-70mph. Weight reduction if your desperate would help quite a bit. Idk what you would rip out to do so. Personally I plan to swap a much lighter LS3 chevy motor. Its near 200lbs lighter along with similar fuel efficiency and nearly triple the power. Also fiberglass fenders and hoods are available if youre in it to win it.

[Dash01]

Our cars already come with rather large air dams. That said, there are skid plate under-trays that while expensive will add some aerodynamic advantage to our cars. Raceskids.com has one.
It would probably help to remove the large black rubber trim around the doors. I can hear wind noise at 40 let alone 65-70mph. Weight reduction if your desperate would help quite a bit. Idk what you would rip out to do so. Personally I plan to swap a much lighter LS3 chevy motor. Its near 200lbs lighter along with similar fuel efficiency and nearly triple the power. Also fiberglass fenders and hoods are available if youre in it to win it.

As you'll find searching Ecomodder.com, undertray can be made of Coroplast, which runs a~$25 per 4 X 8 sheet, or just recycle a politician's roadside sign. Makes the car quieter and protects the underside from road spray, while smoothing the draggiest part of the body.

E28 535i cars are surely no more aerodynamic than sharks, maybe a tad less so, and when I drove my son's for many months, it got 27-28 mpg cruising at ~75 mph. As you know, this is virtually the same car as the shark, just has two more doors. It also has bigass fog lights hanging in the breeze under the front bumper, no undertray, etc. So a shark with undertray and recessed fogs should be better than an E28 of the exact same drivetrain.

The OP should tune his car, inflate the tires to max recommended pressure, install Mustang/Bosch injectors (I got several sets of 6 @ $30/set.), liberate a pol's Coroplast sign after the election, and do the mods. With all due respect to Raceskids, that's a comparative waste of time and money.

Pls. tell us more about LS3, an idea I've also considered should my engine go south.

[dwal95008]

That race skids plate is also 3/8 steel and will save an oil pan on a lowered car. Coroplast aint saving shit. As for aero yes it it is price wise better. But who wants a McCain Palin board near their shark? Or any cheap stuff. The LS3 is a down the road plan to make my car better for a possible Motorsport build. It sits further back and weighs much less. Mwrench.com has an ls7 writeup which should be darn close to the ls3. Id match it to a t56 6 spd and a good matching rear end. Possibly corvette big brakes which are way cheaper than brembos or wilwoods. Ill have a 'Merican e24. But it will piss flames and crap excellence on the touge and the track. Hopefully. Oh and save nearly 500+ lbs when alls said and done. Thats motor swap ~200, stripped interior and replacement of hood and fenders with fiberglass and CF ~ 200, removed us bumpers and replaced in rear with sheet metal and in front with Fiberglass euro style bumper found on LBRacings M6 ~60? No sunroof~ 30? Lexan windows ~ 10? No spare tire and relocated/redesigned gas tank ~ 40, bucket seats~ 80, all the wiring from the original ecu ~ 10. But added will be a cage and harness bar ~150? Strut braces~ 15, bigger wheels to fit vette brakes ~ 25, oh cant forget lighter exhaust. If I can get the car BAR'd it will be mostly smog exempt and I can save by removing most of the exhaust. I didnt do the math but damn thats some savings. All that weight reduction will 1. Look suspicious to police...2. Save on gas and 3. Make that 450hp ls3 turn the planet underneath it. should be one hell of a custom when Im done. And something my kids can brag about to their classmates. I can just wait for "oh yeah? My dads got a fuckin crazy bmw in the garage he only brings out on the weekends." And it will still be reliable because the motor stock will make all the power Ill responsibly need.

[dwal95008]

Expense? Screw retiring when Ive got this badass car... Anyone.... Yeah I know..

[GazM3]

Would you pls. provide specifics of how you did this?

Also, our cars could stand some aerodynamic tweaking. Ecomodder.com has lots of info about low hanging fruit, aerodynamically and practically. The short list includes higher tire pressure, undertrays, and air dams.

For relatively little expense and effort, these cars should be getting 28-30 mpg or better at highway cruise speed.

I had a relativly cheap fuel interceptor that I was able to intercept the fuel signal from the air meter to the ECU. There were 127 load points you can alter. I played a little trick and upped the fuel pressure slightly and then took out fuel via the interceptor. The good thing is as you took out fuel the factory ECU adds timing, so it runs very nicely at part throttle. I tuned it on an AEM air fuel gauge, with a UEGO wideband sensor where u can tune on the fly.

The very sad thing is this Digital Fuel controller is no longer available, and Ive tried to get more with no luck.

Probably the simplest solution would be the miller war chip. Ive never done this but you can tune the car even with the factory air meter in place (reportedly - unconfirmed) and tune same way as I did. Its a bit of a pain in the backside with the Miller as you cant do it in real time. Eventually you will get a tune that is pretty good.


TUning with a wideband sensor and AF gauge is great as you can do it on the road in real world conditions. I found it easy to tune when going up constant hills to load up the engine without going ridiculous speeds. I pretty well tuned it for 14.7 idle and part throttle, 13.0 richening progressively after 4500rpm to 12.2 as the revs rise at full throttle.

The economy is spectacular. I recently done a trip around 2500km, and got 650km (about 400miles) to a tank still with 10 litres (2.5gal) left. I have very short gears also 3.45:1 with 1:1 dogleg box so 100km/h is 2700rpm and 130km/h is 4000 so its revving pretty high on cruise. No doubt it would be better with taller gears. I like short geared cars though as you get nice violence in the lower ratios out of fairly modestly powered engines.

The miller costs about $400, (the digital fuel controller and hand controller was about $200 (unassembled) and a wideband & AF guage about $200, and allow and exhaust place to weld in the wideband bung for about $50-100. I think before I used to get maybe 350km-400km per tank so im saving money on gas while enjoying the extra power and throttle response.

You could probably get a reasonable result just by installing the wideband and gauge, and playing with the airflow meter and idle speed screw. The hex key screw will adjust idle and part throttle mixture, and you can adjust spring tension on the air meter to adjust mixtures as well. The idle speed screw also inanvertantly adjusts the mixture. There is also a rotary switch on the back of the ECU (well on the 055 one for the M88 there is ) you can alter fuel mixtures with this also but most settings are for reducing timing probably for low octane gas in certan countries. Ill try and find a list for this.

Hope all this helps.

Ill one day get on the dyno and see how much extra power I have. I originally had 240rwhp

[rlkrlk]

This one may work as a fuel interceptor. I'm getting closer to going that route. http://www.14point7.com/products/ultra-air-fuel-controller

My S14 is running closed loop WB alpha n, but bring your wallet! http://smg.photobucket.com/user/raykoke/media/IMG_0007-1.jpg.html?sort=3&o=20

Cheers,

Ray

[GazM3]

cheers Ray.

If this works with air meter 0-5v it would be perfect and low cost for us tightass DIY'ers. Ive never seen or heard of these before, but it may be a dud, or like the digital fuel controller it may be a hidden gem.

I need another one of these for my E23 project as ive put a big cam and ported B35 head, and it doesnt like the OEM mapping on idle at all. I have to dump fuel in it by moving the air meter spring tension 3 teeth wheel back to make it idle ok. This little device will be perfect as I could again up fuel pressure, then pull fuel out (by the fuel controller) which will add timing, then tune to get the right setup with sneaky added timing.

BTW i love that S14 in the 2002. Looks natural in there.

[gaspump]

My 85 euro just had a 1000 mile trip, got 30mpg. Your's needs a tune up.

[xing6666]

I had a relativly cheap fuel interceptor that I was able to intercept the fuel signal from the air meter to the ECU. There were 127 load points you can alter. I played a little trick and upped the fuel pressure slightly and then took out fuel via the interceptor. The good thing is as you took out fuel the factory ECU adds timing, so it runs very nicely at part throttle. I tuned it on an AEM air fuel gauge, with a UEGO wideband sensor where u can tune on the fly. The very sad thing is this Digital Fuel controller is no longer available, and Ive tried to get more with no luck. Probably the simplest solution would be the miller war chip. Ive never done this but you can tune the car even with the factory air meter in place (reportedly - unconfirmed) and tune same way as I did. Its a bit of a pain in the backside with the Miller as you cant do it in real time. Eventually you will get a tune that is pretty good. TUning with a wideband sensor and AF gauge is great as you can do it on the road in real world conditions. I found it easy to tune when going up constant hills to load up the engine without going ridiculous speeds. I pretty well tuned it for 14.7 idle and part throttle, 13.0 richening progressively after 4500rpm to 12.2 as the revs rise at full throttle. The economy is spectacular. I recently done a trip around 2500km, and got 650km (about 400miles) to a tank still with 10 litres (2.5gal) left. I have very short gears also 3.45:1 with 1:1 dogleg box so 100km/h is 2700rpm and 130km/h is 4000 so its revving pretty high on cruise. No doubt it would be better with taller gears. I like short geared cars though as you get nice violence in the lower ratios out of fairly modestly powered engines. The miller costs about $400, (the digital fuel controller and hand controller was about $200 (unassembled) and a wideband & AF guage about $200, and allow and exhaust place to weld in the wideband bung for about $50-100. I think before I used to get maybe 350km-400km per tank so im saving money on gas while enjoying the extra power and throttle response. You could probably get a reasonable result just by installing the wideband and gauge, and playing with the airflow meter and idle speed screw. The hex key screw will adjust idle and part throttle mixture, and you can adjust spring tension on the air meter to adjust mixtures as well. The idle speed screw also inanvertantly adjusts the mixture. There is also a rotary switch on the back of the ECU (well on the 055 one for the M88 there is ) you can alter fuel mixtures with this also but most settings are for reducing timing probably for low octane gas in certan countries. Ill try and find a list for this. Hope all this helps. Ill one day get on the dyno and see how much extra power I have. I originally had 240rwhp

We need to talk.

[Dash01]

My 85 euro just had a 1000 mile trip, got 30mpg. Your's needs a tune up.

This from a car with more power than the stock US version, and so, presumably, a somewhat higher burn rate.

What one Shark can do, others can do. And should.

Would you pls. tell us how you're doing this?

[EuroGeorge]

This from a car with more power than the stock US version, and so, presumably, a somewhat higher burn rate.

What one Shark can do, others can do. And should.

Would you pls. tell us how you're doing this?

I have seen 24-27mpg from my '84 Euro for 13 years.

[rlkrlk]

My friend Jake likes the 14point7 stuff. A page from his website: http://www.classicdaily.net/category/current/blunttech-s85-e30-m3/page/2/

I think that controller is a relatively new item for them. I think I'll drop them an email and gather some details. EDIT: the manual is here: http://www.14point7.com/pages/software-and-documentation

I suppose a WB O2 readout would be needed to properly tune on the road. Barring that, a dyno with a WB sensor in the tailpipe...

... My M635 got 26mpg at a constant 60mph; 23.5 at average speed of 74 over 150 miles. Not bad I think.

The M2 with 2.5l S14 gets about 25mpg at 80, with a 4.10 diff. Acceptable to me :-)

Cheers,

Ray





cheers Ray.

If this works with air meter 0-5v it would be perfect and low cost for us tightass DIY'ers. Ive never seen or heard of these before, but it may be a dud, or like the digital fuel controller it may be a hidden gem.

I need another one of these for my E23 project as ive put a big cam and ported B35 head, and it doesnt like the OEM mapping on idle at all. I have to dump fuel in it by moving the air meter spring tension 3 teeth wheel back to make it idle ok. This little device will be perfect as I could again up fuel pressure, then pull fuel out (by the fuel controller) which will add timing, then tune to get the right setup with sneaky added timing.

BTW i love that S14 in the 2002. Looks natural in there.

[gaspump]

My car is a 85 euro, somewhere around 220 hp. I was told by the PO that it had "autobahn" gearing. I dont know what that means but I thought he meant a 3:07 ratio. This trip this weekend consisted af driving into Chicago, then to Elkhart Lake wi. for the weekend. Thur, fri, sat, was around town. Then back on the interstate through Milwaukee, so not just all interstate. From the track to my house, 13 gallons, 400 miles. 75 mph mostly in Indiana. Why do I get such good mileage I don' t know. I got 28 mpg to se sharkfest this spring, but that was mountains, towns, etc. I hope you can find better mpgand I wish I could help more.

[CW6er]

It sounds like you need to do a full Phase II inspection which goes over everything. Do you have a Bentley manual? It has the Phase II in it. Check out the "Goodies Page" for links to Factory WorkShop Manuals, Wiring Diagrams (ETM's), Factory Parts Catalogs, parts Suppliers etc.:
http://bigcoupe.com/phpBB2/viewtopic.php?t=10410

The Goodies Page has info on the Bentley.

All of these things are accumulative, and generally it is not one thing that is the cause, but in your case with such a low MPG, a Previous Owner (PO) may have screwed around with something which he didn't know what he was doing, bless his pointy little head.

But the first step is to do a Phase II and get the car to a known baseline.

P.S. Don't use the $30, single wire O2 sensors which don't have heaters. Your '87 requires a heater because of it's location in front of the Cat, so far from the header, so you need the 3 wire O2 sensors.

[GazM3]

My friend Jake likes the 14point7 stuff. A page from his website: http://www.classicdaily.net/category/current/blunttech-s85-e30-m3/page/2/

I think that controller is a relatively new item for them. I think I'll drop them an email and gather some details. EDIT: the manual is here: http://www.14point7.com/pages/software-and-documentation

I suppose a WB O2 readout would be needed to properly tune on the road. Barring that, a dyno with a WB sensor in the tailpipe...

... My M635 got 26mpg at a constant 60mph; 23.5 at average speed of 74 over 150 miles. Not bad I think.

The M2 with 2.5l S14 gets about 25mpg at 80, with a 4.10 diff. Acceptable to me :-)

Cheers,

Ray
They look quite cheap so I guess one could purchase it any see how it goes.
Just done some conversions from l/10km to mpg USA
E24 M635 20-23mpg
E23 735i 21-29mpg
E34 540i S/C 15-22mpg
E36 M3 Evo 18-30mpg

[Dash01]

My car is a 85 euro, somewhere around 220 hp. I was told by the PO that it had "autobahn" gearing. I dont know what that means but I thought he meant a 3:07 ratio. This trip this weekend consisted af driving into Chicago, then to Elkhart Lake wi. for the weekend. Thur, fri, sat, was around town. Then back on the interstate through Milwaukee, so not just all interstate. From the track to my house, 13 gallons, 400 miles. 75 mph mostly in Indiana. Why do I get such good mileage I don' t know. I got 28 mpg to se sharkfest this spring, but that was mountains, towns, etc. I hope you can find better mpgand I wish I could help more.

Thanks, gaspump, you've helped a lot already:

You weekend trip works out to ~30.8 mpg mixed highway and town driving, mainly highway. If so, your purely highway portion is probably closer to, say, 33-34 mpg.

I suspect your autobahn gearing/3.07 ratio has a lot to do with it, along with better aerodynamics of the Euro cars: The big, fat, ugly, clunky ("bfuc") bumper on US cars traps more of the bow wave under the nose, rather than shedding it. The bfuc bumper on US cars probably also lifts the nose somewhat at highway speed, jamming more air under the car and causing more drag and increasing effective frontal area into the bargain. Euro bumpers are probably less bad, it's hard to imagine worse than the bfuc US versions.

What tire pressure are you running?

Front tire width?

Tire type and model?

Deep dish wheels, or not?

Is your car lowered?

Higher tire pressure, low rolling resistance tires, narrower front tires with less draggy frontal area in the breeze, flush outer wheel surfaces such as pizza-pan covers, and a lowered car with less frontal area and so less airflow under the very rough belly = much improved highway mileage.

I suspect your car is in pretty good tune.

What kind of plugs? Plug gap?

Valve adjust gap?

Fuel type and octane rating?

[gaspump]

Car lowered--yes, Eibach springs. Running 235/45/17 continental extremes on 17x8 style 5. I run 89 octane. Standard spark plugs, gap ???. So nothing extreme on the car. I do run high tech racing air in all 4 tires, summer blend this time of year. Its hard to find here locally.

[tschultz]

I noticed improvement in mileage with cheaper all-season tires (less grippy and not as wide). Also slight increase on highway mileage with the mustang/ford injectors.

OF course it's all a moot point with lots of stop and go driving or a heavy foot!

[GazM3]

Just ordered one of those 14.7 fuel controller things I'll try it on the e23 735i as it's a good candidate. Just installed an upgraded b35 head and 292dibilas cam dual valve springs and b34 intake manifold.
It runs ok on the std tune but I had to screw the hex key right in and move the spring tension about 4 teeth richer to make it idle ok. It's using about 18l/100km approx 12mpg and due to the richness makes only moderate power as when u dump fuel in it kills timing also.

Just at have to wait for shipping from Toronto.

[Dash01]

Car lowered--yes, Eibach springs. Running 235/45/17 continental extremes on 17x8 style 5. I run 89 octane. Standard spark plugs, gap ???. So nothing extreme on the car. I do run high tech racing air in all 4 tires, summer blend this time of year. Its hard to find here locally.

Ah, that rare Midwest racing air, from the Windy City, no doubt.

With my E34 and E36, found that premium fuel gets better mileage, more than offsetting its higher cost per gallon, so premium winds up being a tad cheaper per mile.

[gaspump]

Well, the summer air is funny, but I've used shell high test (93+), and found it does get better mileage than others.

[EuroGeorge]

Well, the summer air is funny, but I've used shell high test (93+), and found it does get better mileage than others.

Bill, If you add a can a beer per gallon of high test, you will get 47-50 mpg. Problem is, it will only run about 120 miles before it takes a dump. I'm tryin to work out the kinks :beer

[CW6er]

........ Problem is, it will only run about 120 miles before it takes a dump. :beer

Everyone knows you can't buy beer .... you can only rent it for a couple of hours !!? http://bigcoupe.com/phpBB2/images/smiles/eusa_doh.gif :shifty :redspot

[EuroGeorge]

Everyone knows you can't buy beer .... you can only rent it for a couple of hours !!? http://bigcoupe.com/phpBB2/images/smiles/eusa_doh.gif :shifty :redspot

Yeah. LOL so true :beer

[rlkrlk]

Keep me posted. I'll likely go the same route.

... I have a friend in Melbourne if you need someone to scare on a drive ;-)

Cheers,



Just ordered one of those 14.7 fuel controller things I'll try it on the e23 735i as it's a good candidate. Just installed an upgraded b35 head and 292dibilas cam dual valve springs and b34 intake manifold.
It runs ok on the std tune but I had to screw the hex key right in and move the spring tension about 4 teeth richer to make it idle ok. It's using about 18l/100km approx 12mpg and due to the richness makes only moderate power as when u dump fuel in it kills timing also.

Just at have to wait for shipping from Toronto.

[GazM3]

If it works I'll do a write up.
Interceptor devices usually go ok on old ecu's as they don't have any self learning or adjusting programming. The more modern ones can learn there is something unusual going on and correct to a certain extent around them

[pthm]

May actually have an issue then with the motronic on these, they do learn but no idea if it will notice a inline on it

[rlkrlk]

Nope.


May actually have an issue then with the motronic on these, they do learn but no idea if it will notice a inline on it

[pthm]

Nope what. Are you saying no problem or that it doesn't learn?

[GazM3]

I done this on my 055 Bosch and the tune hasn't mioved a whisker in 3 months. Just nice consistent power and economy.

[rlkrlk]

I'm saying both.

Based on my 14 years experience with S14's running alpha n in both closed loop and open loop, sending NBsim signal to stock Motronic ECUs. And also on Jim Conforti telling me that this generation ecu does not "learn."

And also on my experiences having always owned (3 different) M635's since 1996, along with having all of the M-Register newsletters of the time, and being a member of the Yahoo S38-M88 group since 2003.

Upon what are you basing your statement?

Cheers,

Ray



Nope what. Are you saying no problem or that it doesn't learn?

[pthm]

Damn your kind of bit but at any rate. According to bosch. Motronic 1.3 is adaptive at learning and compensating for component wear. That's based on 8 years of working on bmws from 1976 to 2006. As well as directly from the motronic 1.3 spec sheet from bosch. Being a little nicer would have been expected and nice.

[pthm]

And for the sake of It I was just asking if you had intimate knowledge that I had missed.

[rlkrlk]

I'm saying this generation Motronic does not "learn" and "adapt" to the detriment of piggyback systems I'm aware of using, which is what your brief post intimated to me.

You suggested there "may" be an issue, without any substantiation. That's what rankled me. :)

I've learned that if I'm offering a specific opinion on the internet, I ought to quickly follow it with back up. Lest such as in this case someone may walk away with the "knowledge" that early ECU's "learn" more than they do.

Best,

Ray

[GazM3]

After pressing "lock" on my tune 3 months ago the A/F ratios have not moved any perceivable amount. My car is the one with the "non catalysed" engine. The m30b34 is same. All designed for leaded gasoline.
Anyway I should have the device shortly so we will see how it goes.

[pthm]

Sorry I was replying via cell phone so my typing is worse than normal.... As for what I was saying is that I know for fact that motronic 1.3 is adaptive in the means that it compensates for component wear with things like the CTS and even the O2 sensor. Thats all. Knowing that if you run any inline anything with the electronics that it will change the resistance suddenly and presumably the DME would compensate. That is all. but I have never broken into how the tables are built for it when it is looking for and compensating for wear. I was just saying it "may" recognize the change and try to compensate for something that is not really happening. As if it is expecting 5 ohms of resistance across a 12ga wire but you splice two pieces of 12ga wire together so it would inherently cause the resistance to be halved. so the brain would try to compensate for the change in expected resistance. I was not trying to cause a stink just applying a little bit of knowledge of the system with a little bit of electrical engineering that I assumed the Bosch engineers would have been working with,

[rlkrlk]

Yep, fair enough. But the piggyback systems I am familiar with of course provide signals Motronic is looking for. For alpha n I don't believe the CTS is intercepted.

Cheers,

Ray

[pthm]

I need to double check now but I wonder if it "learns" the AFM as well for wear pattern. Doubt it but I will have to look

[rlkrlk]

If you have some good links to the mysteries of early Motronic, I'd be interested to read 'em!

Cheers,

Ray

[pthm]

http://www.tonybmw.co.uk/Downloads/Bosch_Fuel_Injection.pdf is a very great booklet on most early motronics but only hits lightly on the adaption capabilities of 1.3. I have the over book I was reading on my desktop and will try to post that later today

[rlkrlk]

Cool, thanks!

(Apologies to the OP!)

Ray

[youngbimmer]

Haha, the E32 735i I owned for a brief time got 9MPG. But it was in such crap condition, I wasn't really surprised. EML light on, check engine light on, reeked of gasoline.

[sdam87]

I absolutely adore my 5 speed 87' 635CSI but is there any way to get better than my average 10 mpg? Perhaps getting it tuned up? the previous owner let it sit for a year or so I believe.

Do plugs, wires, cap n rotor. Get some techron and dump it in the tank next time you fill up. Also get a new air filter and a oil change.

[blobygook]

After oil change, Seafoam treatment, Tachron, and air filter cleanout im up to 13ish,

[rlkrlk]

What type of driving, and how are you measuring the mpgs?

Cheers,

Ray

[sdam87]

*Off topic* Hey man, tryed to reply to your message..your inbox is full.

[blobygook]

well through mileage and the checking the on board mpg computer,

Also sdam fixed

[mitch5]

I get 25 mpg on my 535i with a b35

[GazM3]

I finally got my 14point7 fuel interceptor in the post from canada. Ill plumb in the wideband first and see where it is (on the M30b34 high comp, with cam) and then wire in the interceptor and start playing with it. Baseline economy after running the fuel dumped "tune" has been 16.3 l/100km (14.43 us MPG / 17.33 europe MPG). Before cam was 12.0 ave (19.6 US MPG / 23.54 europe MPG). Best economy I used to see on a trip was in the high 7's. If I can get anywhere near where it was with the big cam/B35 ported head ill be pretty happy.

[rlkrlk]

Keep us posted!

Cheers,

Ray

[GazM3]

run a 5 core wiring loom today. Just got to break into the air meter wire, tach, and give it power and ground. Ive run it into the engine bay and will prob take power somewhere locally. The tach signal ill get straight from the coil.

The pain in the butt thing is i need to get a bung welded on my exhaust as mine was the high comp "leaded" gasoline model so no narrow band sensor.