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Mondy Under Performing/manifold Clogged Up?

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Just looking for some advice on a very annoying problem I'm having.

Firstly, the car is a Ford Mondeo 1.8 '58 plate Zetec Diesel with 69k on the clock, which I use as a Taxi.

Whenever I give the car a bit of a kick, roundabouts, junctions etc the car will feel as if a parachute has opened up from the back. The motion is of that when you're on the verge of running out of fuel.

It will only do this when the car's been on the road for a good few hours. There's no smoke blowing and only once has the engine management light come on, when restarting the engine it didn't come on.

Tonight's the worst it's ever been, joining the motorway otw to Manchester the car was struggling to move! I was a nervous reck coming off slip roads.

Anyway, I've been to one garage (my old cab firms, which usually has a good rep) who charged me £50 to have it on their computer and road tested. No problems found, however the car was sat in their yard for 4hours before they looked at it. I tried explaining to them it only happens when it's been driven for a good few hours, 'oh' was their response.

Second garage (owned by my new cab fleet) believes the manifold has collected a lot of crap, valve too and has quoted me £250 for it to be cleaned out.

I'm not the best when it comes to mechanics, I'd appreciate folks feedback on this before I go with second garage's opinion.

Cheers for reading

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Could be the lambda sensors giving bad readings when hot causing 'bogging down' which is when the engine loses power when hot.

Get the emissions read when just warmed up and after a while when the bogging down occurs.

If the lambdas are out then the emissions will be way off.

Another thing to check may be the head gasket and manifolds for leaks when hot.

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Cheers, for the emission test is that done via the plugin computer?

Do you reckon this can lead to more major problems? I've been assured a head gasket can be quite expensive (ultimately putting me off the road).

Edit: In addition to this, when using the blowers on full primarily both front and back demisters, the car will lack power whilst pulling off :s

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If you have all the electrics on, it doesnt surprise me that you have a little less power when pulling off, but if your lacking serious power, then that may be more of a concern. The head gasket can be expensive but seldom is this the problem.

The emissions test is based on a probe being shoved in your motors tail end and having the engine revved to 2k, this will give you a reading which will be either running rich (more likely the lambda sensor as Clive said) or lean (additional air in the fuel ratio).

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The inlet manifold can get clogged up - the EGR valve deposits carbon deposits on the inside of the inlet, this mixes with the oil from the crankcase breather, forming an oily "gunge" this can "choke" the engine over time but-

There is no guarantee this is what is wrong with your engine/ what is causing your problem, £250 is a lot of money to take the inlet manifold off to clean it, a competent DIY-er with a Hanes manual should be able to do this, you could even buy another inlet manifold (for less than £100) have that cleaned (stick it to a valeter, its a messy job) and switch tem round (this way the car is off the road for the minimum time, scince its a taxi) the other inlet manifold could then be cleaned, and kept for the next time, or sold on (possibly even for a profit- scince its clean)

When a diesel is MOTd only the particulates are measured, (ie- the smoke) - the air-fuel ratio is not measured, my diesel engine does not have a lambda sensor (its normally fitted to petrol engines- i don't know if some more recent designs have them) - these things are liable to show up in the DTC codes, too

Your fault is difficult to diagnose even with access to the vehicle, (as you have seen) meny mechanics rely heavily on fault codes,- you could do the "service" items like the fuel filter (fit a genuine Ford one or "Premium" one - cheap pattern ones can cause problems) change the air filter (Ford often have exessivly long service intervals for this- i do mine every 6k/6months, whichever comes sooner) and a frequent oil/filter change is a good precaution

Does your car have a DPF? (some 1.8 mk4 TDCIs have/ some don't) this may be the source of your problem, or it could be the VNT mech getting coked up and sticking, this can cause exessive boost, the ECU can detect this and cuts the fuel to protect the engine, alternatively it could be simply lack of boost due to a leak etc which may get worse over time

Something woth considering is that the fault occurs when you "boot" the car/ floor the throttle,(due to driving conditions- eg running around town and its ok, then it "playing up" when you go on the M-way, once the engine is warmed up ) rather than after a certain amount of time, if you follow

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Appreciate the information received here. I had the car serviced on Thursday (over due by a few hundred miles embarrassingly) and had new filters fitted. Saturday night I done a 15hour shift, predominantly based in the city and had no apparent issues. I even struck luck with one out of town job and had no issues on the motorway unlike last week whereby I was struggling.

Hopefully this is the end to that problem, but shall bare all other advice in mind should it reservice!


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