Motor control system failure

[Mash85]

Hi All,

So, I just bought myself a 156 JTS manual wagon and in less than 24 hours of picking it up I've got the dreaded motor control system failure permanently on display in the car.

Anyway, I've searched through the forums and someone noted that the oxy/lambda sensors can cause this issue and intermittently cause a stuttering at take off.

This got my attention as I have had stuttering occasionally when taking off from standstill. At first I thought it was just me getting used to the clutch (it seems to have a high take up point). So i guess I have two questions:

1: can someone confirm that the stuttering is a symptom of the lambda sensors

2: has anyone else's 156 got the seemingly odd high take up point with the clutch? I test drove one other car prior to purchasing this one and it had the same weird clutch feel so I had assumed this was a characteristic of the car and hopefully not a worn clutch! Lol

cheers,

Marshall

[colcol]

Could be a worn out Lambda sensor, as there are FOUR of them, 2 pre cat and 2 exit cat.
Best to get it scanned, so that you cut out the guess work.
They can give trouble about 80 -100k, some car makes replace Lambda Sensors as part of a programmed service.
Clutches become heavy when they are worn out, best to get opinion of Independant Alfa Romeo Service Provider, Colin.

[Mash85]

Hi Col, thanks for the great advice (again). The clutch isn't heavy, it just has an awkward (different) take up point, so that half the time I get away from the lights with a jerkiness/stuttering. My two other cars are both manual and I don't have the same issue, so I'm hoping it's not a user error!

I've got a mate with a scan tool, we're gonna hook it up this weekend and see what it says. If that doesn't net a result I'll go searching for an Alfa specialist to have a look

[Mick A]

The clutches feel heavy when they are old correct, this is usually due to a worn pressure plate, the fingers suffer from metal fatigue. Just because the clutch isn't heavy though that doesn't mean it isn't stuffed. It may have a worn friction plate. Upon releasing the clutch if you feel a shudder through the car and pedal then yes you may have a worn clutch.

The error could be a few things, but yes most likely oxygen sensors or the CAT may have a problem due to past misfires (these engines chew coil packs by the way). If you are having a hesitation under load and the engine light flashes momentarily then you may have an injector problem or ignition problem.

As already stated, get it to a specialist and have the problem diagnosed rather than speculate.

Mick.

[Mick A]

My advice is not to waste time hooking it up to your mates scan tool. Not much point in reading DTC's if you can't interpret them. Save the time just go straight to a mechanic.

[dcc236]

It can be any number of things, including a phantom error.
Check the codes, clear them and then wait to see if they reappear.
Then do something about the codes that do come back.

[bazzbazz]

Stuttering is rarely caused by Lambda Sensors.

I'll bet my broken left hand that the most likely culprit is either water or oil down in your spark plug tubes. They cause the coils to short to earth, and the bigger the load, the worse the stuttering becomes. (like as your taking of from stationary)

No need for scanners to check this. Just take out your coils and take a peek down the spark plug tubes for oil or water.

Baz

[neph]

They might of unplugged a sensor, I have this issue as mine needs a new Catalytic converter (which is in the boot), being installed this week.

[colcol]

The oil down the spark plug tubes is most likely caused by a leaking cam cover gasket.
When the cam belts are changed and the cam covers come off to lock the camshafts with cam locks, then the cam cover gasket should be changed for a new one, not reusing the old one.
Seen some JTS's with so much oil down there, you wonder how they actually run.
You say you need a new catalytic convertor, did you have it scanned or did you use a pressure tester on the cat to see if it was blocked, how many kilometres has your JTS done, curious to find out, Colin.