TEMPERAT PROBE 2.0 16v 155bhp keeps Going dead

sbraud · Unread post by **sbraud** » 27 Jun 2007, 19:00

TEMPERAT PROBE unit on a 2.0 16v 155bhp XU10J4 unit (1994)

I’ve replaced this unit (No 1 on pic above) twice in 6 month. It keeps going intermittent or dead and I’m at a loss as to why? When it’s intermittent engine runs rough and uneven with a loss of power and there is the smell of unburned/rich fuel vapour.

The only thing I can see when I strip down air-intake unit is a thin covering of engine oil in intake unit and over temperature probe. I was thinking the oil is attacking or causing probe to heat and burn out. The funny thing is it looks a though engine oil is supposed to access air intake unit as there is a direct pipe from oil filler cap unit to air intake hose before intake unit.

Maybe oil is red herring – Just at a loss as to why I’m getting through these probs??

Anyone any ideas.

Cheers
Steve

Unread post by **CitroJim** » 27 Jun 2007, 22:14

Hi Steve,

The oil is a red herring, the pipe you mention will be the crankcase breather drawing oil mist up into the intake tract and is totally normal.

I'm wondering if the probes you are having fail are genuine ones or pattern parts? Some pattern parts don't live as long as the pukka ones.

The probe is a bead thermister in a housing and as electronic devices go they're usually quite robust electrically and a thin coat of oil won't hurt it. The 205GTi has one dangling in its AFM and these often get very mucky. Mechanical damage can kill them as can excessive heat and shock.

A long-shot this but I don't suppose you have had any small back-fires or misfires that could possibly have ignited a little fuel in the inlet manifold? This could account for them failing.

Those that you had go could just be caused by bad connections where the cable is joined to the wires of thermister bead. It will change here from stranded wire to the very thin and delicate wires going into the thermister bead itself. Worth a check and they may well be repairable.

All a bit of guesswork really I'm afraid

sbraud · Unread post by **sbraud** » 28 Jun 2007, 08:47

Hi citrojim and thanks for detailed reply,

No both (original since new and replacement) were genuine Citroen parts. The second replacement is also genuine. I guess it’s possible first replacement was faulty, I guess I’ll find out if second goes to the wall.

Not noticed backfire or misfire but you may be right about those skinny wires going into prob.

I’ll pass on any developments.

Cheers
Steve

sbraud · Unread post by **sbraud** » 05 Jul 2007, 21:08

OK it's back... One week in and here we go again!

I guess I'm looking at the wrong part/area. It can't be the temp probe as it's a new genuine part, as was last one, and it’s doing the same as before. Symptoms are intermittent. When she warms up 80oC or above, sometimes she gets all sluggish. Loss of power and runs uneven, as if one of the ignition coil pods is duff. I can also spell rich or unburnt vapour from exhaust ??

Anyone ??

Cheers
Steve

AndersDK · Unread post by **AndersDK** » 05 Jul 2007, 23:02

Do an ohms check of the probes. If they fail - they disrupts (hi ohm). No strange values, simply a go/nogo test.

Since you can smell unburnt fuel AND the engine runs intermittent - it is in fact a sure indication of problems with the ignition.
Try run the engine with hood open in a completely dark place. Look for any arcing on the ignition components. Remove any covers necessary to do the test properly. Let engine idle until normal driving hot (fan cuts in) and check again.

A battery torch will help you to locate parts.

Any history on the spark plugs ?
Ordinary types will last approx 15-20Kmiles.
Multi electrode types up to 60Kmiles.