Overfueling in M20 engine

[Yaninnya]

The problem is in my other car ('87 E34 520i with M20 engine)but because this engine was used by BMW in E30 too, I'm asking here:
The problem that I have is a little bit strange. I was reading foult codes several times without sucsses but car is very badly overfueling all the time. The niddle on econometer usually is out of scale. The economy is around 10 mpg during very slow normal driving. I have checked HT leeds, rotor arm, distributor cap, replaced spark plugs and it is still the same.
Any sugestions?
Cheers,
Jan

[georob]

blocked in jector

[c76jon]

there is a sensor on left hand side of engine in a water pipe

in fact there are 2 together if im correct

one brown which is temp guage and a blue one which senses temp of water and sends info to ecu

if cold then this will tell ecu to richen mixture ie choke

these fail a lot and when they do they give wrong info to ecu and engine will run rich all the time

worth a try

john

[georob]

check the plugs for fouling first before changing any sensors

[jmc330i]

Is the blue temp sensor a dealer only part, or can I get one from GSF/ECP?

Also, any idea on price?

[georob]

sensor is around a tenner iirc

i had the same prob and cost me a fortune in bits unitl i cvhecked injectors to find one clogged hence causing the rest to overfuel

[c76jon]

its about 15 quid all in i think

its worth doing anyway if the one in it has done 10000000000 miles and is 15 years old imho

john

[jmc330i]

Everything else was changed on mine when I fitted the engine to the touring, so its an idea to change it. Have noticed its not doing great on fuel at the moment.

Off to the dealers tomorrow then

[Richy325iTouring]

there is a sensor on left hand side of engine in a water pipe

in fact there are 2 together if im correct

one brown which is temp guage and a blue one which senses temp of water and sends info to ecu

if cold then this will tell ecu to richen mixture ie choke

these fail a lot and when they do they give wrong info to ecu and engine will run rich all the time

worth a try

john

ive tried telling one of the boys this but he wont listen

[DanThe]

If your car has a cat then it could be a faulty lambda,

Ive been having the same with mine recently, mpg gauge seems to like 12mpg most of the time, disconecting the lambda gives the ECU a default mapping to protect the cat. I did this and according to the mpg gauge I was getting much better fuel economy, it also idled better

This is an M50 engine but it should be the same sort of thing with your M20

[Yaninnya]

check the plugs for fouling first before changing any sensors

As I wrote spark plugs are replaced allready.

[Yaninnya]

these fail a lot and when they do they give wrong info to ecu and engine will run rich all the time

Thanks for that advice. Do you know what impendance shoud have this sender when hot and cold?
Jan

[Yaninnya]

If your car has a cat then it could be a faulty lambda

No, no lambda sensor.