Fuel Consumption Problems B20F...

[Daniel M]

Hi People....

I know that a 2.0i can be a thirsty car, if driven the wrong way-ok, i do stick my foot down occasionally, but who doesn't! It's a 1994 440 2.0i, B20F engine. When i first got the car, i seemed to average around 32-38mpg-quite good i thought, but lately it's been getting worse. I had the petrol needle about 5mm of the red mark on Thursday, so i put £20 in, as usual, but unusually it only filled up to half the tank-it usually goes a bit higher. My needle does have a tendancy to be rather slow sometimes, so i thought it might creep up, but it didn't. Tonight (Friday night), i have covered a total of 51 miles since Thursday, and the needle is sitting at well below a quarter of a tank-nearly back to just off the red. I've cheked the engine for petrol leaks, had a good old sniff and checked the floor-everything dry as a bone and smelling normal.

Does anybody have any idea as to what might be going on? I seem to recall a conversation somewhere-be it here or with a mate even, that perhaps getting a new fuel filter will help-that the older they get the worse they become? The car has only just done 73k, and has been serviced every 6k from new.

Any ideas or suggestions appreciated.

Cheers, Dan.

[Peter Milnes]

Did you check the tank for leaks and the rubber connections at the tank end of the fuel pipe? Your figures suggest 200 miles per tankfull which is not that good. I think the correct engine designation is B200F unless it is a Renault engine which could be B20F.

All the best, Peter

[Dave M]

Now the bad news....;-)


The car is a 1994 440, therefore it will have a catalyst fitted to it, Contact German & Swedish for a new Lambda probe, my guess is that the sudden failure to obtain the mpg is due to the Lambda probe on it's way out! It's only £25+vat and is easy enough to install as it screws into the exhaust.

Other things to look for are...

1/ When was the last time the car had a "complete" service? It is quite possible that the air filter needs changed and has become choked, have a look in the air filter box at the filter, If it's black then bin it and replace with a new one!

2/ What miles are on the car? again, as the car is fuel injetion, probably single point, remove all connections to the throttle body, and clean thoroughly using some form of carb cleaner like Wynns available from Halfords and clean until spotless, the rim of the butterfly should be clean, then lubricate using 3in1 oil on the hinges and re install.


Try these and let us know how you get on...

Regards
Dave M

[Daniel M]

Hi...

The car has just done 73k. I service the car and follow all the instructions of my Uncle, who has been a Mechanic all his life. The last service was about 1000 miles ago-everything was replaced with new ones-filters/plugs, the usual. My engine has had a complete oil flush with Wynns engine flush, and previous service to that it had a bottle of Wynns injector fluid flushed through it. The engine is a multipoint Renault lump-the B20F.

Everything is clean-it's had alot of TLC this summer. Just have to see how it goes. Sometimes the petrol needle has a tendancy to get stuck-it's been like it since i got it, so perhaps it just needs a little tap. I'll see how it goes.

Cheers for the suggestions.

Dan.

[Dave M]

Hi Dan,

Take care doing the engine flush, I'm told horror stories of engine damage due to the sedement that the flush leaves in the sump. What I do to overcome this is to use a crap new oil and a second oil filter, run it until hot then redrain and put in the proper oil and filter as required.

Hope this Helps.

Regards
Dave M

[Citizen.Agfa]

Without wishing to sound too pompous, you can only "guesstimate" consumption figures unless you follow this routine:-
Brim the tank;
Zero the trip meter;
Drive;
Brim the tank;
Read off trip and work out your average; anything else is wishful thinking,i.e. "Coo, I've driven nearly two hundred miles on that last fiver of four star, I must be driving really economically!"
Good luck, Nick H.