Sigma very lumpy

[Macchiman]

I’m having a problem with my 2007 140 SV.  Was going great, but suddenly became very lumpy, though not missing.  A trawl through past postings suggested Lambda probe.  I disconnected it and engine back to normal!  Noted part number and got a replacement Bosch part from on-line supplier.  Fitted it and now back to very lumpy engine.  Took to local garage to see if their diagnostics kit would identify the problem.  They could not get any readout from the diagnostic port.  Car is fitted with MBE 36L038A ECU.

I know that It’s not possible to access the mapping, but should it be possible to get a diagnostic readout?

Thanks

Peter

 

[simon_h]

The MBE doesn't have obd like a road car. You will need to find someone with the correct lead and program to look at it really.

[elie boone]

Can it be that the wire to the Lambda sensor are to close to the exhaust and are fried somewhere ?

[ChrisC]

You need someone with the MBE lead and the knowledge to diagnose the problem.  Even if you purchase the lead yourself it will save you money in the long run (and it can be sold when you sell the car).   

It’s possible you have a new faulty lamda sensor, if the wiring was causing the problem it wouldn’t matter if it was connected or not.  Was it a Bosch or Ford part?

[Macchiman]

The lead to the lambda sensor is OK.  Well secured and not fried.  The original sensor was marked Ford, but was made by Bosch and had a Bosch number  0258 006 599/600.  I spoke with the Technical Dept at Bosch, and they said that part number was deleted in 2016 and the direct replacement was 0258 006 605.  After fitting I disconnected the battery, and then re-connected to see if it would "re-set" the ecu.

If I purchased the MBE lead, would that  allow an auto electrician to use standard diagnostic kit?

[ChrisC]

No. A standard auto electrical will be used to getting codes telling them the sensor is not working.  The lead will show you live data coming from the sensor, so you have to determine if the sensor is working or not.  You also get a trace (think f1 style telemetry) which you can use for diagnosis.

For example a mate had a problem where the engine died for no reason.  I could see via the lead when the engine died the lamda voltage showed a mixture getting leaner, but the fuel pulse getting longer pointing to a fuel supply problem.  A deeper dive into the data showed just before that the battery voltage increased as the fuel pump switched off.   The problem was traced to an intermittent inertia switch.

basically good diagnostic skills are needed.   Glad you went for a good quality part ;-)