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Mondeo EGR valve question (long-ish!)

After various local "experts" failing to diagnose the cause of my daughter's Mondeo "misfiring" i.e. running rough / hesitating / surging at low throttle openings, I posted here a little while ago on the subject. One of the suggestions as to possible cause (for which, thank you) was an air leak, but I couldn't really find anything, so I decided to take the empirical approach by disconnecting things one at a time to see if the symptoms changed. Trying to be slightly logical (!) and still thinking about air leaks I moved my attention to any 'vacuum / air' pipes that looked like they might be possibilities. To make a long story short (oops, too late!) disconnecting the pipe between the exhaust gas recirculation valve and the EGR valve solenoid produced a dramatic improvement in smoothness of running. I verified that it wasn't my imagination be re-connecting the pipe and sure enough, the problem returned. Sealing the openings on the EGR valve and on the vacuum pipe with gaffa tape to prevent ingress of contamination (just 'cos it seemed like the right thing to do!) also brought the problem back again. Of course, I should've sealed 'em one at a time (isn't hindsight a wonderful thing) but anyway, to "cure" the problem, the vacuum pipe leading to the EGR valve solenoid mounted on the bulkhead must be left open to the atmosphere. I have yet to see what happens on a cold engine, but certainly with everything at normal operating temperature, I seem to have found the magic "cure" - which, of course is just a workaround really!

So, the question - ok, two then:

1) will there be any long term adverse effects of not having this pipe connected? 2) will it effect the emission readings on the next MOT and therefore need to be re-connected before the inspection.

Thanks, people.

Reply to
Mike Faithfull
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Mike Faithfull wrote - quite a lot!

Probably not. I removed the vacuum pipe from the EGR valve on my wife's

1994 Moandeo and plugged the pipe end (rather than leave it open to atmosphere as you have). The car ran smoothly for the ten years she kept it (apart from the usual No. 3 spark plug/HT lead HV breakdown problem at 16,000 miles).

At the same time, I owned a 1995 Moandeo V6 estate. The EGR (Exhaust Gas Recirculation) valve was not seating/sealing correctly and the engine ran really rough until I identified the problem.

This time I bought two EGR Valve to Inlet Manifold gaskets from my friendly local Ford dealer and then made up a thin (16 swg) metal plate the same shape as the gasket, but without the centre hole. I only drilled the two fixing holes. Then I used the metal plate between the two gaskets to blank the EGR valve off from the inlet manifold. I left the vacuum pipe connected to the EGR valve in this instance, which kept the EGR control system happy. I never had any further EGR valve problems after that.

With early Moandeo V6's, faulty EGR valves allowed small pieces of ceramic from the exhaust manifold pre-cats to enter the engine via the inlet manifold and wreck it. The problem was serious enough for Ford to do a recall.

I never had to reconnect my EGR valves to pass the MOT. I don't think the EGR system would normally be operational at the engine speeds used for the emission tests.

Reply to
mlv

That's very reassuring Mike, thank you very much. I'm a bit puzzled over the need to keep the pipe from the solenoid open in order to achieve smooth running, but I'm sure we can live with it!

Reply to
Mike Faithfull

Yes, having to leave the vacuum pipe open to atmosphere is a bit puzzling. I certainly didn't have to do that. AIUI, normally the vacuum pipe would suck against the diaphragm in the EGR valve, which is effectively a 'closed valve' scenario.

I still think the best option is to buy two gaskets and make up the metal blanking plate to go between the inlet manifold and the EGR valve.

That way the EGR control system can operate the EGR valve as intended, but if there is a problem with the valve sticking open or leaking, it won't affect the running of the engine. You won't suck any crud from the exhaust system into the engine either.

Reply to
mlv

(snip ...)

Sounds like a good suggestion to seal off the valve, Mike, and if the car was younger, maybe I'd do that, but it's done nearly 160K, it's "loose" to drive and probably won't last that much longer ... just until the MOT failure I expect.

Reply to
Mike Faithfull

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