During this week whilst the wife was driving, the car decided to stall on a couple of occasions at low speed and was a bugger to get started. Luckily not in too much of a dangerous position to be broken down in the middle of a busy roundabout!!!!!!

Well i hooked the car up to my diagnostics and was showing on average 40,000kPa fuel pressure on Idle. going up to approx 75000 kPa at half revs OK??

Approx 850 rpm at idle OK??

2.2 g/s @ idle then a maximum of 14.5 g/s at half revs registering in the MAF (which i thought was low, and no change when i disconnected it)

I swapped the MAF for a different, known working, one. It then registered at 18.4 g/s @ idle BETTER

I know it will obviously make it very hard to start or even impossible to start but can a faulty MAF cause the 2.5 + 2.8 Crd to stall? Just serviced it today and i didnt notice any issues with the fuel system and according to the diagnostics it all seems well.

I still have P0403 EGR fault code on key dance but I'm happy with that as i have blanked it off.
Did have P1130 on key dance but believe that was because it stalled as, when I deleted it, it never reappeared.
Then P0103 on the diagnostics which is the air mass circuit. I believe it has gone but will check again later. Just waiting for the car to cool down to then check again under different conditions.

Any insight in to this would be great.

Cheers Dan

 

Looks like your on for a few pages on this. Classic Fuel pressure fault with air in fuel. Injector or bypass valve leak dropping pressure. Maybe crank/cam sensor. Fuel filter letting air in. Where do you want to start.

 

Have you cleaned the old MAF with some CRC or electrical contact cleaner spray? I take it the air and fuel filters are both good? And that the fuel filter us tight on? But as goggs has said above! Where do you start! Simplistic 1st... and then go frim there. My guess is the fuel filter housing has a tiny fracture and letting air into the fuel line...

 

Air filter and fuel filter were changed yesterday during the service. Filter put back on tight and primed ok. Hand primer still solid after eventually starting and shutting off. I cleaned the MAF to start off with and didn't make much difference but when I put the known working MAF on there was a marked improvement on the diagnostics. Couldn't notice anything different apart from the car actually starting first time however the engine was still at running temp? Waiting to go out in it this morning to see if she starts ok in the cold. Will have to monitor mpg to see if it has a marked improvement as I'm only getting around 24.5-25 mpg at the moment.

Not too sure if it could be the cause for stalling but will have to see how I get on from now. If the problem reappears I will then thoroughly inspect the fuel filter housing. However the P1130 fault code hasn't reappeared as of yet. I have a working MPROP valve which I may swap out to check also.

 

the fuel pressure readings look normal. Not sure what the volumetric efficiency of the engine is, but the readings from 2nd MAF look about right.

Never known of a MAF causing a stall, but there is always a first.

Regards

Richard

 

Cheers for the reply Richard.

It is a new one for me also. I'm pretty sure this isnt the only issue with the engine as when i disconnected the old MAF it ran the same, so not sure. I know it can massively affect starting and idling and absolutely trash mpg but stalling the engine is very strange. It only happened at low speeds, fastest being approx 20mph. obviously depending on what gear you are in this speed should be below the turbo range so the ecu is still relying on the MAF?
The volumetric efficency should be somewhat better after blanking the EGR but may have to do a compression test to see if im losing much there. It didnt splutter to a stop it was more of an electrical cut out as if the fuel cut off solenoid was engaged after turning the ignition off so i am assuming some kind of electrical demon.

Cheers Dan

 

Electrical should be logged as a fault, what scanner are you using?

Regards
Richard

 

I was using WOW diagnostics. It logged up as an air mass sensor fault P0103 but hasnt returned as of yet. Car has started first time except for earlier tonight i went out to try again. let all the lights go out and to do its check, turned over and it eventually fired but didnt relly want to. kind of spluttered its way to idle speed??

 

can you scope the fuel rail pressure sensor during cranking and starting?

There is a reference waveform on the picoscope website for a 2.5VM engine. Mainly you are looking for a nice quick rise time.

Regards
Richard

 

Unfortuneately I haven't got access to a scope. Not used one since my electronics days back in college. I may have a working sensor I can temporarily use for fault finding purposes. Could the fuel rail pressure sensor effect fuel economy? im starting to think it could be cam and/or crank sensor. If these are faulty they can cause poor starting, random stalling and reduce fuel economy but then so can a few other parts!