Overfuelling

[ianswebb]

Hi guys and girls!

Im running a '99 1.4 with 160k miles on it, it runs and drives as sweet as a nut, except it overfuels beyond belief! All the obvious things have been checked, air filter is clear, dizzy and rotor arm are clean and not worn, leads are good and spark plugs are new. Exhaust has no leaks either.

Ive run it through VCDS lite and all it showed was a lambda probe fault. The probe has been changed and the code cleared, yet i am still getting heavy carbon fouling on the plugs and even a soot mark on the floor when its throttled up hard.

So im thinking the only other option seems to be knackered injectors? Does anybody else have any other ideas or possible causes? Also has anybody else had to do this, if so do you have any helpful tips?

Ive got a feeling i may be in a minority!

Thanks in advance.

Ian

 

[Chrisbee]

could be a knackered cat, a petrol wont leave soot marks even if its over fueling, as it'll usually pop and bang as the fuel ignites.
when the cats get clogged up they stop the flow of exhaust gases which may casue carbon deposites to be blow out.

Also do a compression to test make sure the valves are closing properly as this can happen on old engines.

might be worth chucking some redex in to clean the injectors while your at it.

 

[Seatmann]

Any grey coloured smoke when it's idling?

 

[ianswebb]

Thanks Chrisbee. Clogged cat = an obstruction.. Hadnt even though about that! A new cat will be required anyway, because if it wasnt clogged up before, it certainly is now! And it doesnt have to be type approved, so for £60, i can afford to knacker it! I dont supose you would you happen to know what sort of pressures i should be expecting? Its an APQ engine, if that changes anything.

Hey Seatmann, thanks for coming in on this too.. Nope! Just a little puff of oil when you really give it some welly! Which i believe is due to a wearing valve guide on cylinder 1. The oil has no white spots in, and no mayo under the oil filler cap. The coolant is clean also, so that should rule out head gasket failure.

 

[Seatmann]

I was thinking poor spark caused by a faulty distributor but what about the plugs, are they the right ones? Hot enough rating? Try a new air filter too if you haven't already.

 

[Chrisbee]

I'd have to check the database as to what kind of pressure you should be getting, although they all should be reading around the same so if one is out you'll know.

 

[ianswebb]

Seatmann, the dizzy is fine, no cracks or corrosion on either side. Not sure if the plugs are correct, they are NGK R BUR6ET's, but in going to bin them off in favour of some standard plugs dye to the amount of fouling. The air filter has been changed for new. I have the stock air intake system, with no performance filters.

Crisbee, id be everso grateful, should you get a chance.

Any thoughts on a shot auto choke? The temp sensor is new, and it idles at around 800, so im kinda guessing not that either!

Ian

 

[Chrisbee]

It could also be the EGR valve, they get clogged up after a while.

There is a "how to" on club lupo on taking it apart and cleaning it.

 

[ianswebb]

No EGR valve on mine, that must have come about on the later models.

 

[ianswebb]

I havent had a chance to work on this since my last post.. Shes now laid up on the drive looking unloved :-(

Roll on the finer weather!

 

[ianswebb]

So!.. after new valve guides, cambelt and water pump change, fresh oil, new filters, another lambda sensor and a good purge of the fuel system, we are back in business. Its now MOT'd taxed and back on the road.

Done a good 1500 miles in it and it hasnt skipped a beat.. until today.. when it kept dieing. No coughing or spluttering, just conking out,both at lights amd junctions etc and whilst driving along.

Out come the spanners again then!.. i will not be beaten!