bigspj

My wifes got a 1998 mondeo 1.8 and the fuel consumption seems to be all over the place sometimes good sometimes bad. She said yesterday that she did 87 miles and it went from just over half to just under half on the gauge which id expect however she came home today and said it had used quarter of a tank to do 30 miles. Car runs fine. Air filter changed christmas time recent 5w 30 oil and filter. Still on its original plugs and leads at 88000 miles (i know that doesnt help :-() I seem to see a lot of posts about high fuel consumption, Someone suggested on another site to someone with similar problem it could be the MAF so ive just gone out and unplugged it and asked her to let me know how she gets on. Will change the plugs when i get a chance but do you think unplugging the MAF will do anything. Has anybody got any experience with this matter?

tabetha

I would change the leads right away, what plugs are you using, not BOSCH I hope, if so bin them and fit ford/NGK ones in there the bosch track massively in the zetec.
The normal zetec issue is with the coilpacks breaking down, but you'd feel this easy enough.
As a rough guide my dads 2L auto gets on average 38mpg, driven gently.
If not done so change the fuel filter, and clean the MAF, use carb cleaner, do NOT under any circumstances poke the hot wires, just spray liberally with carb cleaner and shake dry.
The pull the violet coloured 3 amp fuse in the fuse box next to the battery for 1 minute, make sure the maf is plugged in, this(pulling fuse) will delete the fine trim settings stored in the ecu, and it will relearn the fine settings, just drive normally it does the rest, it can take a few miles(about 50) in that time it may be a bit lumpy.
With the age of the HT leads though I'd be amazed if you don't see a big difference right away running wise.
Get yourself some silicone grease, and smear the inside end of the HT lead plug end, zetecs can be a bit fussy and track easy if there is the slightest tear in the plug boot, for issued a TIS about this as well.
If you use a K&N filter the maf needs cleaning at least every 6 months, the oil impregnated filter's oil gets on the hot wire and of course being hot it sticks, and throws the reading out.
tabetha

bigspj

Thanks. Plugs are on my to do list as they are originals as are the leads but i was going to leave them for now. The car runs great its just the erratic fuel consumption that gives me reason to question it. I will have to get some carb cleaner too and try that what do you do just spray it in then? Car is bog standard no fancy air filters and that.

tabetha

You will need to take the maf off the car, simply unplug it, then undo the big jubille type clip on one side, and the two spring clamp bits holding it to the airbox on the other side.
Now look into it you will see two wires strung across support posts, 1 will be clean the other will no doubt be caked in grot, so spray liberally, DON'T under any circumstances be tempted to prod the wires(called hot wires), as they are fragile to physical attack!!
You will immediately see the cleaning effect of the carb cleaner on the hot wires, give it a good spray until spotless, shake the maf to get rid of excess cleaner, then put back on car etc.
Let me know how you get on.
tabetha

bigspj

Thanks. Is there any time best to spray it? Such as when cold or after a run? Ive had a look and can see the 2 wires cant really say theyre grotty as i can hardly see them lol. I just unplugged the maf and took the 2 spring clips off and pulled it out. Ill leave the jubilee clip on and try it, i think if i disturb that ill never get it looking as good again. Bought new spark plugs online today (NGK PTR5A-10) so should get them in a few days. Will buy some carb cleaner and report bac. Thanks

tabetha

Can spray anytime, it would be best to remove completely the maf, as this is carb cleaner, I don't know it's affect on the cat, as carb cars don't have cats.
The wires should be VERY easily visible but I assume it was a lack of light problem with maf still being on car ?
tabetha

bigspj

Ive just been out and got some carb cleaner. Took the air flow meter out the airbox but left it attached to the big rubber hose. As you look at it there is a resistor on the left hand side and cant make out whats in the middle, It looks like a coil wire in the bottom and further back but the top one also looked like a resistor, is it also meant to be a coil? If so its probably dirty or its my eyesight (not brill)It looked a light brown colour. I gave it 2, 3-4 second bursts with the spray but didnt notice it looking any different . Didnt pull that fuse yet as the wife was wanting to use the car so will pull it this weekend and let the ecu relearn. Will be getting my new plugs hopefully beginning of next week in the post so will change them then.

bigspj

Have just changed the spark plugs now. Plugs 1 and 3 had a 1.5 mm gap and plugs 2 and 4 had the normal 1 mm, these 2 didnt look at all bad seeing as they are the originals. Strange how 1 and 4 were bad though.