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[Mark_L]

Hello....help please to solve a permanent engine mgt alarm on my 3 litre Elite estate, 1996, 75k miles.

A professional checker indicates the air inlet temperature sensor. Testing it reveals no problems - the resistance varies with temperature OK.
The paperclip test shows the same thing plus an oxygen sensor issue.
I've just MOT'd the car. The emissions readings were OK but the lambda reading is 1.028 [ie only just inside the upper limit of 1.03]. This is a change from previous year's readings which were virtually 1.
The car starts and runs fine - no issues at all and no change to the performance as far as I can tell.
I've just had lots of other expense on it [air-con pump, exhaust, tyres...] so I don't want to be buying lambda sensors from Vauxhall quoted at £125 each unless I am very sure they are at fault. I have also found that the connectors are very, very difficult to get at - at least with my mitts....
I'm off on holiday in it soon so I want to fix this quickly - preferably without recourse to the pro's and lot's of cost...

Any ideas please?

[nixoro]

If lambda sensors are your problem try www.autovaux.co.uk they supply GM kit mostly but can supply a good substitute if needed.

Best to ring them as they are busy and email takes a while for responses.

HTH

[Omega VT3000]

Mark,

Just because the ATS resistance varies it doesn't necessarily mean it is OK if it is starting or ending at the wrong resistance.You should be able to see what value temperature it is recording at startup. For example, the ECU will compare the startup air temperature with the water temperature and if it sees a big difference it will register a fault. On my LC you could also verify the wiring was OK by reading the temperature on a Tech 1 by shorting (-39 degs) and going open circuit on the connector (140 degs).

The sensor may be fine but the wiring may be duff. I don't know where the wiring for that particular sensor runs but I have heard of wires being trapped after cam cover/cam belt changes.

Also bear in mind that when the ECU goes in to limp mode it may well assume an average set of values for various paramaters and will probably use a generic fuel map, i.e., it's providing too much/too little fuel which will throw your lambda sensors out.

[JasonH]

What exactly are the fault codes?

You may have an exhaust leak (before the lambda sensor) or a loose connection or two.

I found changing the lambda sensor quite easy really. Mine was £50 delivered from here:

http://www.gendan.co.uk/product_LB1010.html

[Marks DTM Calib]

Remembr that a fault code is an indication of a sensor reading being out of range, this could be the sensor, wiring, connectors or even th ECU (unlikely).

The Multiram and air temp connection havn't been mixed up have they?

[Mark_L]

thanks all for your replies....

James - do you know what the resistance of the sensor should be at say 20 to 30 deg C. ?
I read somewhere that it should be around 4 to 6kohm and so I tried a 5k fixed resistor across the connector pins - that made no difference so I'm now thinking it could be the wiring.... I shall have a further play with it later.

I don't think the connectors have been mixed up as no work has been done on the car in that area to necessitate removing the wiring.

I was coming up with codes 69 and 13 using the paperclip method....

regards

Mark

[Marks DTM Calib]

As a check the wire colours for the temp sensor are

Brown/green
Grey/Red

Just pulled the one out of my inlet trunking, once its at room temp (which is about 28-30degC at the mo) I will measure it for you.

At the moment its measuring 1K and is rising so your original values are clearly wrong.

[Marks DTM Calib]

Now reading 1.5K

[Mark_L]

thanks for doing that - mine's now reading 1.7k at 25degC which doesn't seem wildly different to yours but yes - the values I looked up are clearly well out. Next stage is definitely to check the wiring loom.......oh joy.....

[Marks DTM Calib]

Check it back at the ecu connector, its pin 44 (Blue/Red wire) and pin 30 (Brown/Green wire)


Also have a good look at the ecu connector, I have seen them with water damaged pins before...

[v6man54deg Geffd]

I have seen that one before - the white plug is the air temp one!!!!!!!!!!

Remembr that a fault code is an indication of a sensor reading being out of range, this could be the sensor, wiring, connectors or even th ECU (unlikely).

The Multiram and air temp connection havn't been mixed up have they?

[Mark_L]

 [smiley=laugh.gif] BRILLIANT!! SUCCESS!! that's the answer - the connectors were swapped over - I assume when I had the air-con worked on but can't think why as the pump is on the other side of the engine but never mind....it's fixed and I much appreciate all your help.

Mark

[nixoro]

Good to hear you got it sorted