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[chrisr]

Can anyone tell me what is causing my 2002 2.2 petrol to have a lumpy tickover from cold, almost to the point where it cuts out, it’s fine once it’s warmed up. Thanks

[Doctor Gollum]

ECU coolant temp sensor failing or a split breather hose.

[chrisr]

Thanks Doctor, where would I look for a split breather hose?

[cam.in.head]

not familiar with the 4 cylinder ones.do these have an idle air valve ?
if so is it working ?

[Fraggles Rock]

Have a read of these...

http://www.omegaowners.com/forum/index.php?topic=90528.0

http://www.omegaowners.com/forum/index.php?topic=90586.0

http://www.omegaowners.com/forum/index.php?topic=90597.0

The 2.2 is a progression of the 2.0 so much of the same applies.

If the breather hoses are bad, then they will either be rock hard and brittle or really soft and gooey. Neither is ideal.

[chrisr]

So I’ve put up with this problem for nearly a year (!) but it’s time to get it sorted, I’ve bought a new coolant sensor but can’t see where it goes so must be well hidden, anyone? Thanks.

[Doctor Gollum]

Back of the block.

There are two. One for the ecu and one for the gauge. The wire to the gauge one has a female spade connector and it isn't uncommon for it to come adrift, especially if you're rummaging around at the back of the engine.

There are also two thermo switches on the radiator, so you really need to be clear on what you are actually trying to fix.

[chrisr]

The gauge works fine. The car starts ok but within a minute or so the tickover is very up and down until it warms up after a couple of miles and then is fine again.

[Doctor Gollum]

That doesn't sound like a temp sensor failure

[chrisr]

Any ideas?

[cam.in.head]

hi.
if you have a new coolant sensor then worth fitting BUT just make sure its the right one. in earlier 80' & 90's bosch jetronic injection cars (carlton,manta,senator) etc there were 2 variations that looked identical but one had a single element that had a circuit across the 2 terminals but not to the body and there was a type with 2 seperate elements that each had a circuit to earth.omega ones may not be like this anyway but worth mentioning as the wrong type fitted to a jetronic didnt work !just check wether yours has anypins circuit to earth and the same with your new one.chances are the old one is fine anyway. this sensor tells the ecu how hot the engine is .if in any doubt aboutthe new one then leave the old one in !.(the other brass one with the spade is for the temp guage and wont affect running in any way)
fuel pressure could do with checking just to eliminate that side of things.
other things to check ( probably mentioned before)
plugs ,leads,coil.
breathers,hoses,air hoses,vacuum connections,servo pipe,
throttle body (often gunged up !) dont play with any of the adjustments thou !
we have to assume the actual basic engine is physically ok as well. compression test ,cambelt/ alignment,.
just a few ideas.

[Doctor Gollum]

Presumably this is one of the two previously discussed cars

[chrisr]

My main problem is I can’t find where the sensor is to try the new one anyway. As previously stated the car starts fine from cold but within about 30 seconds it seems like whatever aids the cold start is already trying to give up. Once the engine has been running for about 5 mins with the revs flicking up and down and almost stalling then everything smooths out and the car runs perfectly. When starting when warmed up there are no problems at all. It’s like in the old days if you tried to knock the choke off too soon.

[Doctor Gollum]

Again, is this one of the two previously discussed cars, and what buggering around has been done to it?

[dave the builder]

Crack in the exhaust manifold 
you should get some live data from start up ,compare to when up to temp