Technical MultiAir unit fault?

[gengis]

Hi Troops,

I’m looking for a bit of advice/help in diagnosing a fault on the wife’s 500x 1.4T Multiair 2016 40,000 miles. It all started to misbehave a couple of weeks ago, the fault presents itself on a cold start and sounds and feels like it’s running on three cylinders also brings up a standing engine lamp. After it’s been idling for a few minutes and a couple of increments on the temp: gauge are showing… if I turn off then restart, the car runs perfectly all day with the engine lamp sometimes extinguishing …until another stone cold start.

Now…I’m a bit of a home mechanic, but a bit of a dinosaur having a couple of 124 Spiders and a 128 I belong to the analogue world of motoring. Suppose I’ve been lucky up till now! I have now bought a code reader…see below the codes been transmitted, the last code I have only captured intermittently.

• P0304 - misfire cylinder 4 (performance or incorrect operation component or system over temperature, misfire 1000)
• P0300 - misfire random (performance or incorrect operation component or system over temperature, misfire 1000 or misfire 200)
• P0130A - misfire 200 (component or system over temperature)
• P106B – cylinder 4 UniAir actuation electro-valve signal (Actuator stuck open)

Work so far…swapped coil pack 4 for 3 – fault did not migrate. Changed all plugs, changed oil + filter with correct spec: oil, withdrew in-head oil filter for MultiAir unit and cleaned.

The fault conditions have not changed, although the engine runs smoother. This is where I am now…Do I have a misfire (ignition fault) or MultiAir unit fault. Could the ECU be sending corrupt signals to coil pack or actuator or both?

Any help deciphering my fault would be appreciated.

 

[s130]

Those codes are related.

Here is the diagnostic info for P106B-00

Others are below

 

[gengis]

Excellent information there s130…Thanks.

It raises a couple of questions in my head though. Please excuse my ignorance…The Powertrain Control Module is that located at the centre of the bulkhead just under the scuttle panel in the engine bay, and has a left and right multi-plug? Do you have information regarding the pin-outs for these multi-plugs? So I can identify the appropriate coil/solenoid. I have started checking the battery/alternator condition.

 

[s130]

I get also confused with some of Fiats terminolagy. I think the Power Control Module is the main Engine ECU.

I'm not sure I have direct one-to-one pinout/function for the ECU. You may be able to find this on the WEB.

The modern Key Learns are more orientated to Fiats diagnostic kit where I think more detailed information will be servied directly.

I'll have a look to see if I can find pin/function info for you. No promises though!

 

[gengis]

Thanks again s130.

I think the PCM and the ECU is one and the same thing…well for the time being I’m going to assume that. Possibly the PCM is referring to the output side of the ECU…?

I’ve checked the battery and the alternator which are fine. I also withdrew the multi-plugs from the ECU/PCM cleaned the terminals and put a very light smear of contact grease on the terminals. We’ll see if there’s an improvement on a stone cold start tomorrow morning. In fact I think I’ll monitor the battery volts on a cold start tomorrow.

 

[gengis]

Morning,

Well…four cold starts later and looks like the fault has been resolved, cleaning the ECU multi-plugs has done the job. Runs sweet as a nut, with no misfires and no engine lamp. Thanks for your help…watch this space.

 

[s130]

Morning,

Well…four cold starts later and looks like the fault has been resolved, cleaning the ECU multi-plugs has done the job. Runs sweet as a nut, with no misfires and no engine lamp. Thanks for your help…watch this space.

Really pleased this appears to have resolved your issue.

As an aside, so many "places" will just blindly use diagnostic kit and tell you "you need a new this, new that, new other". For them it is a quick diagnostic, a component sale, and all at your expense. Not all are like this but ....

 

[gengis]

Yeah, hopefully things have settled down. I was fearful of getting into the situation of playing “parts bingo” but having the MultiAir unit costing £1k+ focuses the mind somewhat! Treating the control system as a whole, rather than individual components, helps when trying to diagnose faults.