Fault Code 44

[Ellie]

After persistent intermittent Check Engine Light (CEL) illuminations I have finally got Elanscan working and first results seem to indicate Fault: Oxygen Sensor Lean.

ALDL & Jumper (paper clip method) to confirm.... fault code 44 (Lean exhaust - per WikiLEC info).

All I need now is what to do to fix the problem! Anyone got some ideas please????

[GeoffSmith]

Mike,

If you zip your ES log and post it up (you can't post Lotus Elan logs on LEC!), I can have a look at the signals from the O2 sensor for you when I get home.

Geoff

[Ellie]

Thanks, Geoff - I shall email you (the file is small with just a few minutes of idle : no fun in the sun at present for it's been persisting down for many days (4" in 1 hour this morning)).

[GeoffSmith]

Oh dear. It's raining in Oz. I feel so, so sorry for you.

I've had a look at your log Mike and the O2 sensor is varying between ~1V and 3.7V. On a healthy sensor, it is typically between 0.3 and 4.0V so I think you're right in concluding you need to replace the sensor. I've sent you a copy of a technical article on O2 sensors in case you're interested - it looks like there is a gain of about 4 to 5 between the sensor and the ECU ADC.

Geoff

[Dave Eds]

Oh dear. It's raining in Oz. I feel so, so sorry for you.


Geoff

But it aint raining in Bishops Stortford Mike

Dont you wish you were still here?

[Ellie]

Only if I can drive your Elan(s), Dave.

Oh dear, Geoff, the rain's stopped and the sun's out... and so is the O2 sensor (came out easier than the sunshine).


Seems that code 44 = Oxygen Sensor Knackered - get another.

[Enright]

In that case go to Rockauto unless you're made of money.

(And search for 1991 Isuzu Impulse RS in the Emissions section. You need the 3 wire kind)

[Ellie]

In that case go to Rockauto unless you're made of money.

(And search for 1991 Isuzu Impulse RS in the Emissions section. You need the 3 wire kind)

Thanks for the advice... found it at http://www.rockauto.com/catalog/x,carco ... ttype,5132 but this brings more questions as there are several O2 sensors listed: what's the one to get? (The one I removed is [Nippon Denso] ND 065500-8290 5L 897018-5870). USA supply: http://www.automedicsupply.com/catalog. ... ey=1176173 http://www.racepages.com/products/?N=16 ... 1+9166+773

[Ellie]

Interesting: Source: http://www.lambdasensor.com/main/mfaults.htm Common Sensor Faults. B: Rich Fuel Mixture This will cause a heavy black carbon layer to form on the sensor element. Rich fuel mixture is usually caused by a failure in the air/fuel metering system.

The sensor I removed today has the heavy black layer (rich mix) yet the fault code says LEAN.

Could code 44 mean a failure in the air/fuel metering system?

[GeoffSmith]

The sensor I removed today has the heavy black layer (rich mix) yet the fault code says LEAN.

[Ellie]

The sensor I removed today has the heavy black layer (rich mix) yet the fault code says LEAN.

A longbow guess... maybe the carbon/soot layer prevents the electrochemical reaction (oxidisation) of the metal surfaces, preventing proper voltage output which presents as a 'lean mixture' (but then why not the fault for 'rich mix'?).
I'll have to deep read the sensor info now (to the music: 'Lambda hope & glory').

[Enright]

Groan.
Moderator? Moderator! Banish that user for crimes against hilarity!

[Ellie]

Well, it's extremely bad weather again and I needed something to relieve the tediom of learning all about these sensors and this damned code 44!:banghead:

Having read the complexities of oxygen ion transfer through zirconia dioxide layers and such trivia, and plunged into lateral thinking mode, the possibilities may be:
1) a leak in the exhaust flow between the cylinder head and the sensor, allowing air into the exhaust flow and increasing exhaust O2 levels, causing the sensor to read a lean fuel/air mixture;
2) a blocked or reduced reference orifice thus causing a bad/false outside (external) atmosphere reading, upsetting the external/internal O2 ratio (the fundamental premise on which the sensor operates);
3) the sensor elements (and in the case of a 3-wire sensor such as this one, the heater element) have a bad or intermittent electrical earth return path between the sensor body and the manifold mounting threads (or manifold-engine earth);
4)the sensor elements/coatings are simply no longer in an optimum operating condition either due to wear & tear or some other engine fault.

A natural consequence of a sensor reading lean should be for the ECU to increase injector dwell timing to improve the fuel/air mixture, which would in turn, be more fuel than really needed, thus causing the sooting.

An expert I'm not. Any assistance appreciated.

[GeoffSmith]

Likewise confused Mike. Can't see oxygen leaking into the exhaust (it tends to be at a higher pressure than atmosphere - well at least in the Northern hemisphere) so I think your last three are nearer the mark. These sensors are obviously very prone to degradation/failure due to contamination.

[Rap mode on]Oh to be an expert: I wouldn't feel like a lamb ta tha slaughta. [/Rap mode on]:-D



What about turning the ignition on without running the engine? You don't get much leaner than that! If you don't get close to zero volts then you've probably confirmed it's knackered.

[Ellie]

I was going to do a 'lambda the slaughter' joke earlier, but I don't want to get sensored by Mr. Enright!

The top shroud air paths seem to be fine, so I'll discount reference air.
The sealing ring contact area 'shiny parts' are not as good as I'd like to see, and the threads are all rust/corroded without shiny areas, so the earth path could well be bad. Since I suspect the sensor is the original, active service since '94 means it's pension time for the blighter.
I'm going to test as you suggest, just to find out, but ultimately renewal is the answer methinks.

Some excellent info including how sensors work; faults; how to replace; Bosch reference No.s (1st part of catalogue)... here: http://www.bosch.com.au/content/languag ... index.asp# [then select 'car parts & accessories > engine management systems > oxygen sensors > catalogues/brochures)

[Ellie]

What about turning the ignition on without running the engine? You don't get much leaner than that! If you don't get close to zero volts then you've probably confirmed it's knackered.

Yep, did several logs with key to 'ign' position, and a quick drive around the locality. Every dataset has the fault log "oxygen sensor lean', and I got the ECM light + 5000 revs limit kick in. Cheched earth path with multimeter - was fine before anything done and I cleaned the sealing ring + manifold contact area. I hereby declare the o2 sensor 'knackered'.
(Bloody glad I got back in time to avoid the tennis ball size hailstorm 2 mins later - lots of cars got major damage).

[GeoffSmith]

You obviously need to check some logs with a new sensor. If you're running rich it's important to cure the source of the problem otherwise you could loose another sensor.

[Ellie]

New oxygen sensor in place.
Rain started, Elanscan started, Elan started.
Dataset collated & analysed.

I think it may now be officially declared - Fault Code 44 = O2 sensor knackered - get a new one.

Notes:
The vehicle performance seems to be better than it has ever been since I have had it over the last 8 years - so the sensor has probably been deteriorating for a long time. If you are experiencing performance below par then I'd suggest having a good look at the o2 sensor - ELANSCAN IS ESSENTIAL for diagnostics.

The LEC forum has been an utterly indispensible tool in the diagnosis and resolution of the fault, and learning so much more about the vehicle.
An open and very loud thank you to all who assisted via LEC, and to there's only on f in Geof Smith in particular.

[Sy V]

Oh, don't say that - he's unbearable enough as it is!

[DaveT]

to the music: 'Lambada hope & glory').

Now that sounds much more stirring!!!!