I'm not an expert on Ford ECUs (except the Cosworth, which uses the same Weber as my Fiat) but in general, ECUs just don't fail - if they do, things stop, and that's about it. So this is a bit generic...
ECUs calculate the petrol and timing based on (a) air mass flow or (b) manifold pressure, modified by throttle position, intake air temperature, and engine revs. If any of those sensors is unhappy, the ECU will usually throw an error - red light on the dash, as a rule. You can usually talk to an ECU and it will tell you what any problems are, given the right tool. For an ECU running rich, I'd be mostly concerned about leaks around the fuel pressure regulation, or a faulty pressure regulator, or an incorrect index for the timing (I don't think Fords can do that, though). Also, it's important to make sure the cat is up to temperature - an 'Italian Tune' just before the test can improve things no end. It can also be a problem with the thermostat failing open; the engine never gets to temperature and remains in 'cold start' mode - i,e, rich. But I'll be surprised if there's an electrical problem, with no error messages from the ECU. Neil On Apr 20, 11:30 am, bilje55 <[email protected]> wrote: > I took my H4 to my local garage for the annual MOT following a new cam > belt, plugs, filters and oil. It shouldn't have failed..but it > did.....on emissions. And this is where modern mechanics enters (for > me) the realms of voodoo or witchcraft. It's a fuel injected 16v zetec > with about 40k on the clock only...with new oil and filters and a > satisfactory exhaust...but it fails on emissions? Two new sensors are > fitted...something to the block..temperature? and a Lambda sensor? The > situation improves but not enough...so a new catalytic converter is > acquired...and fitted...but the situation has still not improved > enough....so my garage man wants to call in a specialist auto > electrician, as he believes that there is some kind of electrical > fault...either wiring or (Please no) within the ECU. He (my garage > man) freely offers that he is really out of his depth...so I've agreed > to the specialist guy having a look...but he ( a travelling man who > undertakes specialist work for various small garage businesses in my > area) probably can't do the business until next Tuesday..and that's > just for diagnosis! > Friends...I need information: what is likely to be the problem here? > Should I be preparing for further expenditure on replacement parts? > Where should I start? > with thanks in anticipation.... > Bill -- You received this message because you are subscribed to the Google Groups "Quantum Owners Group" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/quantumowners?hl=en IMPORTANT NOTE: All information presented herewith is provided on an "As Is" basis, without warranty or the implication thereof. Neither the Quantum Owners Club nor the individuals associated with the Quantum Owners Club or in the preparation of the above information shall have any liability to any person or entity with respect to liability, loss, or damage caused or alleged to be caused directly or indirectly by the instructions contained within this or related message(s).
