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Re: more mondeo woes

O2 sensor or wire to it as it's just been disturbed (if ECU can't sense if

>wire's broken) or temperature sensor so ECU thinks the engine's cold all the >time so richens the mixture (as needed for starting). > >>>> took car for mot today (mondy 1.8 zetec mk2 p reg) failed on cat. >>>> Couple of weeks ago i replaced exhaust manifold as old one had cracked. >[quoted text clipped - 25 lines] >> >> Tim..

thanks for your replies! I have changed the o2 sensor and this morning the egr valve. i noticed that when i removed the vacuum pipe the car ran better. however after fitting the new one the bastard resorted to its usual shit!

Reply to
chunkybear via CarKB.com
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forgot to mention that the performance is still ok. well as best you can expect from a ford this age!!

Reply to
chunkybear via CarKB.com

You really havent a clue have you?

Tim..

Reply to
Tim..

youre right!! tim i havent thats why i'm on here asking questions!

Reply to
chunkybear via CarKB.com

Most likely candidate, if your particular mondy has it, is the DPFE sensor on the bulkhead, or a vacuum hose betwixt it.

Tim.

Reply to
Tim..

cheers tim, will check dpfe sensor and temp sensor. let you know how i get on.

Reply to
chunkybear via CarKB.com

So explain why they couldn't cause a rich mixture then.

Reply to
SteveB

As anyone who knows about EFI, they'll tell you that the o2 sensor output only affects mixture by around +/- 10% when running in closed loop mode.

In open loop mode i.e. when the engine is cold, (and several other conditions) the ECU fuels directly from maps stored in its memory.

Tim..

Reply to
Tim..

So I was 2/3 right then.

Reply to
SteveB

An engine running upto 20% rich will not show signs of sooting plugs / running rough- you need alot more fuel than that- around 6-7:1 as opposed to

14.7:1.

Tim.

Reply to
Tim..

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