My 18is is consuming way to much fuel...

[Lmg]

I'm averaging 27 actual mpg, that's 60% highway and 40% local. What does your coolant gauge read, could it be an open thermostat causing the engine to think it's cold?????

+1

Does your heater blow hot air or simply warm air?

[Lmg]

Hey guys, my 18is is consuming way too much, I do not know what's going on ... Lately I will always get 11 l/100 (Or 21.5mpg for the US folks). For the type of driving I do, and the engine that it is, it's way too much. 70% of my driving is in the freeway, in 5th gear at 2200/2500rpm. little traffic. Shifting at 3000rpm. Etcetc. I may do 1 or 2 agressive starts each tank of fuel, but thats it.

Given my type of driving, i should be getting much less fuel comsumption. I have no idea what it may be, since the car was revised and changed filters 1 month ago. Do you think?

check your alignment. I just put in an e46 rack and drove on it for about 100 miles of mixed city/highway. went from 29mpg down to 20mpg. Car felt wayyy better after having it aligned and mpg has gone up.

[MTD]

Hey guys. I have another "symptom" that might give some clues on this problem.
Lately the car is having some problems starting up. Sometimes ill turn the ignition, electrical part all on, i turn the key... and nothing. I have to turn the electrics off and do it again. Sometimes 2 or 3 times. Once it starts cranking (i don't know if this is the right term sorry - english is not my 1st language) it always goes all the way and starts the car, but the problem is those times it doesn't even start "cranking".

Does this give any insight on the fuel economy issue?

[MTD]

that "new driving" principle doesn´t work on our beloved m42´s tho.. if i have to drive like they say what´s best for MPG etc i have to shift around 2500rpm.
for cruising this is sort of correct, but when you´re driving on normal roads it´s better to keep off the pedal below 2000rpm, flooring it in the low rpm range will demand way to much from our revvy and torque-less engines. this can blow you milage too.

but still i think you have a bigger problem, best to check the exhaust gasses on amount of oxigen. lambda failure or something else can make you car run way to rich. this is a sort of failsafe made by bmw, better to drive an engine rich than lean in unknown conditions.

Yeah true!
Well the car is most likely going to the mechanic soon, some new parts also arrived (suspension arm or something like that, i can't say it in english lol)

[MVincken]

that "new driving" principle doesn´t work on our beloved m42´s tho.. if i have to drive like they say what´s best for MPG etc i have to shift around 2500rpm.
for cruising this is sort of correct, but when you´re driving on normal roads it´s better to keep off the pedal below 2000rpm, flooring it in the low rpm range will demand way to much from our revvy and torque-less engines. this can blow you milage too.

but still i think you have a bigger problem, best to check the exhaust gasses on amount of oxigen. lambda failure or something else can make you car run way to rich. this is a sort of failsafe made by bmw, better to drive an engine rich than lean in unknown conditions.

[MTD]

Any update?

Sorry no updates. Didn't go to the mechanic, some busy weeks right now, exams...
One thing i did discover, on one of the tanks i filled recently i decided to "not care" and just drive harder than usual. Not racecar like, but not caring about being below 3000rpm and etc. The difference in fuel consumption was not much by surprise. From 10,2 l/100 to 11,3l/100

[gespinal0301]

Any update?

[MTD]

only waz to be sure the engine produces the power is a dyno, hiring a dyno isn´t cheap so probably not the best first option.
better go to a workshop and let them check your cilinder compression.

Thanks, the car is going to the mechanic this week, I'm going to ask him to check it out

[MVincken]

the power of the engine is ok it seems, but i didn't check by any means. How do i go about checking that?

only waz to be sure the engine produces the power is a dyno, hiring a dyno isn´t cheap so probably not the best first option.
better go to a workshop and let them check your cilinder compression.

[gespinal0301]

It was a joke. See my sig.

My first check would be the coolant temperature sensor. There are two in the M42 cylinder head, and one should have two pins and a blue connector; this is the one the ECU reads. The one with one pin is for the gauge. Make sure that one of yours has two pins, and that it's hooked up to the ECU and not the gauge. Also check its resistance. See below. If that all checks out, check the continuity of the coolant temp sensor wire; from the sensor connector to pins 78 and 43 of the ECU connector also. Check the fuel pressure if none of that pans out, and the regulator itself (pull the vacuum line and check for presence of fuel). Finally I would check the injector spray pattern. Pull the fuel rail, unplug the ignition coils, and have someone crank the car while you watch the injectors spray. Do they all make a nice conical spray? Do any leak while the system is pressurized?


14+-4 F (-10+-1 C): 8200-10500 ohms
68+-2 F (20+-1 C): 2200-2700 ohms
176+-2 F (80+-1 C): 300-360ohms



Let's just say I'm in boost a lot. I tuned it myself, I do all my own work, and occasionally build a megasquirt or tune for someone. I don't want to hijack this thread, so PM me about your swap if you have any questions.

If I ever get serious about it I'll start bothering you lol. I've made up my mind that if the m42 lasts 3 more years than she has earned the right to a rebuild. Ive been watching wayyyyyyy too much petrolicous on YouTube which kind of reminded me that our car is a one year wonder so I want to keep it as original as possible.

O.P. any luck by testing the sensors?

[varg]

What the hell, is this a chronic thing on 18is's?

It was a joke. See my sig.

My first check would be the coolant temperature sensor. There are two in the M42 cylinder head, and one should have two pins and a blue connector; this is the one the ECU reads. The one with one pin is for the gauge. Make sure that one of yours has two pins, and that it's hooked up to the ECU and not the gauge. Also check its resistance. See below. If that all checks out, check the continuity of the coolant temp sensor wire; from the sensor connector to pins 78 and 43 of the ECU connector also. Check the fuel pressure if none of that pans out, and the regulator itself (pull the vacuum line and check for presence of fuel). Finally I would check the injector spray pattern. Pull the fuel rail, unplug the ignition coils, and have someone crank the car while you watch the injectors spray. Do they all make a nice conical spray? Do any leak while the system is pressurized?


14+-4 F (-10+-1 C): 8200-10500 ohms
68+-2 F (20+-1 C): 2200-2700 ohms
176+-2 F (80+-1 C): 300-360ohms

How hard are you driving it?? I was wondering where'd you got it tuned by the way I'm just looking for decent shops in case I ever have to do a swap

Let's just say I'm in boost a lot. I tuned it myself, I do all my own work, and occasionally build a megasquirt or tune for someone. I don't want to hijack this thread, so PM me about your swap if you have any questions.

[MTD]

When's the last time the car had a tune-up? Spark plugs, air filter, fuel filter, diff fluid change, tranny fluid? It wouldn't solve your problem, but it would help eliminate some things

about 1/2 months ago...

haha he trolled you, he has a turbo on it. than everybody would get 19mpg because fun :)

I filled it up yesterday and it was around 25-26mpg (11km/l) and I hit it hard on the mighty autobahn everyday. (not so smart with nankang 165/55 wintertyres )
I think if I would drive like a normal person i could easily hit 30+ (13 km/l or more)
buttt, i overhauled my complete engine before i put it in.

how is the power of the engine? maybe you have a piston with halve compression, forging the engine to work harder for same speed and so lose mpg

oh ok, i fell into that one

the power of the engine is ok it seems, but i didn't check by any means. How do i go about checking that?

[MVincken]

What the hell, is this a chronic thing on 18is's? When i was resarching the best engine for me, everybody suggesting this one for mpg, now that i have this problem i find out lots of people have it as well... damn

haha he trolled you, he has a turbo on it. than everybody would get 19mpg because fun :)

I filled it up yesterday and it was around 25-26mpg (11km/l) and I hit it hard on the mighty autobahn everyday. (not so smart with nankang 165/55 wintertyres )
I think if I would drive like a normal person i could easily hit 30+ (13 km/l or more)
buttt, i overhauled my complete engine before i put it in.

how is the power of the engine? maybe you have a piston with halve compression, forging the engine to work harder for same speed and so lose mpg

[gespinal0301]

Something's wrong with mine too. If I'm lucky I get 19mpg. Completely baffled

How hard are you driving it?? I was wondering where'd you got it tuned by the way I'm just looking for decent shops in case I ever have to do a swap

[gespinal0301]

When's the last time the car had a tune-up? Spark plugs, air filter, fuel filter, diff fluid change, tranny fluid? It wouldn't solve your problem, but it would help eliminate some things