8 replies to this topic

[Emmet]

Hi I have a 1993 Mini Cooper 1275cc. It is doing very bad mpg bout 100 miles to a tank. It is running rich as you can smell the unburnt petrol. When i have been driving it for a while the engine temperature guage will only rise to the middle of the blue rectangle, it used to go to half way.
I recently had welding done on the exhaust manifold as it was broken and the car was running very rough. I changed the spark plugs and they were all sooty again telling me its running rich.
The engine has full water and the oil is up to max.

Has anyone come across this before?

[Big Man]

I had the same problem (92 Spi Cooper) and changed both the engine temp sensor and the air intake sensor both for under £20 and it solved the problem. I did both at the same time so cant really say which one it was but also made sure all my vaccum pipes were ok and correctly fitted as the joint fittings are prone to cracking.

BM

[Emmet]

I had the same problem (92 Spi Cooper) and changed both the engine temp sensor and the air intake sensor both for under £20 and it solved the problem. I did both at the same time so cant really say which one it was but also made sure all my vaccum pipes were ok and correctly fitted as the joint fittings are prone to cracking.

BM

I have just had a look to see if anything was unusual about the inlet air sensor and i noticed there is a very thin black pipe that comes from what i can only guess is a sensor to the back left of the injection port but isnt connected to anything else.

If that isnt the problem where is the engine temperature sensor? to the left, right, middle of the inlet manifold?

[Big Man]

I will pop my bonnet and see where my black\ pipe goes so to speak and let you know..... think that could be the problem as it all feed data to ECU that controls the mixture.

Oh and Temp sender is on the rear of the engine and you need really really small hands to get to it!!

[Big Man]

black pipe could either go to the flame trap (black box on bulhead) or it could go to ECU check to see if its a long pipe and if there is a spare "hole" on ECU... BUT dont plug it in until were sure!! Need to wait for an expert me thinks!

[Emmet]

I was told it may be the thermostat?

Yes the black pipe comes fron the small box on the bulk head, about 2 inch by 1 inch?

Also when i turn the engine off there is a sound right as it stops like pressurised air escaping.......

[Blatherskite]

black pipe could either go to the flame trap (black box on bulhead) or it could go to ECU check to see if its a long pipe and if there is a spare "hole" on ECU... BUT dont plug it in until were sure!! Need to wait for an expert me thinks!

The thin tubes should lead from the manifol to the trap, then the trap to the ECU. Its a vacuum pressure gauge, for inlet pressure. If you take it off and switch off the engine, I guess the manifold vacuum will leak in with a gasping sound...

Somewhere in this forum, some wonderful person has posted Chapter 14 of the Rover MEMS manual that describes what and how all the sensors do in signalling the EMS, and it is really helpful in diagnosing faults with fuelling, etc. Cn't remember where the post was, but was at least smart enough to download it, so if yuo can't find the copy (search on MEMS??) then maybe I can send it out by email?

[Emmet]

Thanks everyone for your help, i plugged the little black pipe into the ecu nnd noticed a difference straightaway!! Instead of using 2 tanks a week to get to work i only now use 1!! so big savings there, Also i had warm air in the car for the first time in ages!! It still makes that escaping air sound when i turn the engine off though.

Thanks again

[josh_crf450]

Thanks everyone for your help, i plugged the little black pipe into the ecu nnd noticed a difference straightaway!! Instead of using 2 tanks a week to get to work i only now use 1!! so big savings there, Also i had warm air in the car for the first time in ages!! It still makes that escaping air sound when i turn the engine off though.

Thanks again

Iv just started having the bad mpg problem with my mini spi and like you I can also smell unburnt petrol ect and also have bad idling but dont have the leaking air noise. For some reason some of the replies to your thread wont display on my computer > could you please run though what you did again? Sorry for the inconvenience. Your help will be very much appreciated. thanks.