[gdaf]

I have the old Motor Control System Failure - go to dealer message, and had it scanned today with 'Oxygen Sensor 2' returning a few issues. After reading extensively about the causes, the first thing I want to try is cleaning up the connections that have been described as being 'at the back of the engine' with some electrical contact cleaner. Can somebody better describe where these are, or even better, post a photo of what I should be checking for and cleaning up?

Note: Car has a brand new battery.

Thanks!

 

[Artermis]

what year is your car?

That will determine how many exactly lambda sensors you have. CF2 motors have 2, CF3 motors have more like 5 I think. That will tell you exactly which sensor you are referring to.

if you only have 2 lambda sensors then you will have 1 pre cat and 1 post cat. Pre cats are the ones that make the most difference to the running of the motor.

as the CF 3 motors have 3 cats you have more lambda sensors, they are typically referenced by bank numbers.

the connector you are referring to though is directly behind the engine block, should clip onto the fire wall / bulk head and be a 3 wire weatherproof connector block.

from memory these are grey and clearly seperate the 3 pins, probably about an inch wide.

 

[trashbat]

He says a JTS so it should have five. I'm not familiar with there being a connector at the back other than the two 20-odd pin ones for the main loom - purple and brown.

From my thread:

If you look at the top of the radiator they are some wires, one goes to the fan, one drops at the gearbox side of the engine and goes though the heat shield, and the 3rd one drop downs near the timing end of the engine and goes though the heat shield. Its those two that go though the shield we need to look at.

Recently helped Ross156 who has got a JTS, he had the MCSF lambda and coolant temperature fault. I think he got all four lambdas changed.

I think I've ID'd these but there's quite a few connectors around there. Failing anything else I will try and take photos tonight and someone else can annotate them.

 

[gdaf]

Car was built in 2004. Photos would be great - thanks!

 

[trashbat]

You might as well find the four connectors at the front - 2x four wire with yellow seals, 2x six wire with grey lego-like clips - and clean those up. Fairly sure those are lambda connectors.

That and the rear ones I mentioned - the bracket they fit into slides sideways and then you can remove them.

Please let me know how you get on - my ongoing saga is here: http://www.alfaowner.com/Forum/alfa-147-156-and-gt/296908-strange-156-woes-post-misfire.html and so I'm currently in the same state as you.

 

[Sooty Si]

Good luck sorting it, let us know how you get on...I've got the same problem, read the codes etc., had all 4 connectors apart, cleaned with electrical contact cleaner, still have the MCSF. A chap at an Alfa specialist told me its a very common problem with the JTS, and he's seen all sorts of "fixes" from cutting off the connectors and soldering the wires, to cutting off the connectors and replacing them with terminal blocks. Just need the time to give it a go myself.

 

[trashbat]

Didn't manage to take any photos tonight I'm afraid, too busy faffing with my car to no avail.

Both of you: what are your symptoms, apart from the MCSF?

 

[Sooty Si]

No symptoms whatsoever, no stalling, idling probles, misfires or anything, just the MCSF and engine light after anywhere between 20 and 120 miles of resetting, totally random. Had it diagnosed and a lambda replaced with a new Bosch one from AlfaShop in Norwich, but fault is still there. It's got to the point where I prefer the light to be on, then I'm not dreading it coming on after I reset it, lol.

IIRC the code was P0420 (high signal on Bank 1 Lambda 2). I read somewhere, maybe on here, maybe on Alfa156.net, that the ECU takes it's reading between something like 30 to 40 mph. So if you reset it and avoid dawdling about in that range, it takes longer to reappear

 

[Guest]

The ECU takes readings every 400th of a second, otherwise you'd be waiting an age for the MAF to regulate air mass, volume and temperature, fly-by-wire throttle to open accordingly in the correct position, the injectors to regulate the pressure and volume needed and the O2 sensors to read the Co2 content expended...

Check, remove, clean and refit your earthing points and battery connections:thumbs:

 

[gdaf]

No other symptoms here either - just the light that comes on with starting, and beeps and it stays on the whole time. Had it scanned and cleared, and it came on around 100kms later. I'm determined not to spend money on it only to fail again, so want to eliminate all the possible causes and apply the relevant easy fixes prior to ordering parts. Thanks for replies. I'll let you know if cleaning up fixes.

 

[Sooty Si]

If you turn off the buzzer feature on the Infocenter menu, you don't get that annoying BEEEEEEEP when you start the engine.