[i-am-iron-man]

Hi all,

As an IT worker I am frequently presented with 'how long is a bit of string'-type questions. Not looking for any smoking-gun answers, but any opinion on root cause and remediation is welcome!

I have an '04 GT V6. It has had stacks of work done and has had a completely problem-free year.

Long stretch of road, bright sunny day, know the area well, what can I say? - I was already at reasonably high revs in 4th and made a poor decision to give it more beans in 3rd. The vehicle did not take this well. I can't remember the exact series of events, but I immediately got the motor control failure light. Not seen that since I had a 147

Car seemed fine but quietly turned itself off when I slowed down to take a junction. It got me home after that, but on the motorway it beeped at me again and gave a 'low voltage'-type error.

A few days later and the car is ... broken. ECU code is P0100 / mass airflow circuit failure. The engine won't stay running for more than a minute or so before it dies, so driving it to the nearest garage was a colourful experience at best. Did I mention I'm not much of a hands-dirty type of IT-working Alfa-owner?

So, the facts:
- P0100 / mass airflow failure
- The garage couldn't read the code, even though I did using a cheap reader and Torque app...
- The garage also says they had trouble keeping the car idling, even with the MAF disconnected.
- I am getting the other MAF symptom: the fuel gauge works on MAR, but stops working when the engine is started. The trip / MPG computer isn't working either. I've read that these are very typical symptoms of MAF failure.
- The garage indicated I should get an electrician. I did, and it was a very difficult experience. Thought he was going to work out if I do just need a new sensor, or if I have something more elaborate (wiring, ecu...). He didn't do any of those things - he read the fault code (the one I already told him about), said he wanted to trailer the car somewhere else, then hoofed me for seventy quid before driving off into the distance with my money. Robbed!

The garage has agreed to check the MAF circuit / pipes / check voltage on the MAF, but a local Alfa specialist also mentioned I might need an electrician. I'm off on holiday today, MOT is imminent, and I have a car that doesn't behave when I try and use it.

Any similar experiences, or any thoughts on how I broke it?

 

[ransoman]

A tricky one. I would be looking at earthing faults first and just looking over the general condition of the wiring loom.

If the Maf is original and/or has done more than 80'000 miles then it would be worth replacing. Search this forum for a cheap repair using a vauxhall agila sensor in the v6 tube.

Also search the GTA section for ECU failure. I don't want to put undue worries on you but it may help prove the ECU and if it is faulty, I believe there is a solution there.

From my experience working on the v6 so far, the wiring is very "Old fashioned" so I wouldn't be surprised if there is some damage to the loom somewhere. Especially above the toasty rear bank exhaust manifold.

 

[i-am-iron-man]

Fitted a new Bosch MAF and cleared the fault code ... and it came back straight away.
Just having a re-think on working through what it could be vs parting company with the car as it is ...

 

[ransoman]

What about the rest of the suggestions in my post?

Some of what you have described as "Maf failure symptoms" in your first post are ridiculous. A failed Maf won't cause a fuel guage to stop working for example, nor would it cause the trip computer to stop working.

 

[Aramis]

did you change any settings with your el cheapo EOBD connection and torque? Cammon, be honest, IT guys like to fiddle with the software settings.

 

[badgerdom]

I'd confirm if the replacement MAF was bosch original or a pattern part and if the garage did the MAF circuit/voltage checks and what the results were.
If the voltage etc was checked and came back OK, then I'd be suspecting either the replacement MAF is faulty (unlikely but possible) or the fault lies elsewhere.

I personally would be checking the airbox and lid is secured and following the air flow to the engine, ensuring there are no leaks/holes etc.
Then checking the electrics - MAF plug pin check for voltage, etc etc. tracing back from there to the relevant earthing point, etc.

I wouldn't think that the electrical feed for the fuel gauge etc would be reliant on the MAF sensor, but could stretch to them using a common feed.
Otherwise, as ransoman suggested, I'd be looking at the wiring loom, earthing points, and the points in the MAF plug too.

In true IT form (being in IT as well) I don't suppose you've tried a battery disconnect for 30-60 minutes as a bit of a system reset?

Trying to rule out things for you from a general POV, having no actual experience with the engine/electrics of a GT...

 

[mjaz101]

MAF failure on my GT V6 did cause the fuel gauge and trip read out failure!
However mine ran fine, well mostly, until I replaced the MAF (same as a Panda 1.3 jtd if I recall - half the price just need to change the housing)
Good luck!

 

[badgerdom]

MAF failure on my GT V6 did cause the fuel gauge and trip read out failure!
However mine ran fine, well mostly, until I replaced the MAF (same as a Panda 1.3 jtd if I recall - half the price just need to change the housing)
Good luck!

Thanks for the heads up on that Mjaz101 - interesting to know how the fuel gauge/trip is wired up if the MAF is part of the circuit!

 

[i-am-iron-man]

Thanks for all the attention y'all

did you change any settings with your el cheapo EOBD connection and torque? Cammon, be honest, IT guys like to fiddle with the software settings.

Ha! These days I spend all day making sure nobody fiddles with anything ever. Mess around with settings and it'll break and sad-faces all-round. No tampering on this car!

Some of what you have described as "Maf failure symptoms" in your first post are ridiculous. A failed Maf won't cause a fuel guage to stop working for example, nor would it cause the trip computer to stop working.

I'd seen quite a few threads where a MAF fault causes the same symptoms I'm seeing - dicky fuel gauge, trip computer reads "-------", stalling. I know you really shouldn't believe everything you read on the interweb, but someone somewhere once said (to another guy with the same car / where the gauge works until the engine is started) that The gauge will not work because for some reason it is earthed through the ECU, to the MAF, back to the ECU and then to the engine, so if the heater breaks in the MAF then your fuel gauge will go wonky. ... but obvs I have no way of substantiating this claim.

I heeded your words about the ECU.

I'd confirm if the replacement MAF was bosch original or a pattern part and if the garage did the MAF circuit/voltage checks and what the results were.
If the voltage etc was checked and came back OK, then I'd be suspecting either the replacement MAF is faulty (unlikely but possible) or the fault lies elsewhere.

It was a pukka Bosch item, and the garage reported they'd checked the circuit before they replaced it. The car remained in an unhappy state with the old one unplugged and with the new one in place.

I've had the battery disconnected, as turning things off and then back on again is by far the most consistently successful fix for anything that goes wrong at work (well, that and asking if anyone has been interfering with something). As for the rest - especially the electrics - I've just taken the car back to the same Alfa guy that did some work on it before I bought it, so at the minute I'm holding out for his prognosis.

MAF failure on my GT V6 did cause the fuel gauge and trip read out failure!
However mine ran fine, well mostly, until I replaced the MAF (same as a Panda 1.3 jtd if I recall - half the price just need to change the housing)
Good luck!

Thank you Sir.
When you say it ran mostly fine, was it stalling? Just done thirty miles in the car and it behaved perfectly tonight ... other than the flashing fuel light and the gauge reading zero always in the corner of my eye, so I couldn't shake that sickly-anxious feeling that I'm about to run out of gas on the motorway.
Last time I drove an Alfa on a motorway with odd readings on the dash it was my much-loved and immaculate 145QV just before it caught fire

 

[halftone]

Hi all,
...

Car seemed fine but quietly turned itself off when I slowed down to take a junction. It got me home after that, but on the motorway it beeped at me again and gave a 'low voltage'-type error.

Did you look into this? I wonder if it's no longer charging properly since you thrashed it and the low voltage is letting the gremlins out to play.

 

[i-am-iron-man]

Did you look into this? I wonder if it's no longer charging properly since you thrashed it and the low voltage is letting the gremlins out to play.

I certainly did. When I first got my 147 the battery was knackered and the dash kept lighting up like a Christmas tree, so I've seen the battery weirdness before and I was hoping that's what it was...
I checked the voltage with the car off and with the engine running and got 12.something and 14.something, so it doesn't look like it's that

 

[Chris155]

The mcsf error first occurred after you dropped it in to 3rd and presumably over revved it?

By how much did you over rev it?

If it was significant, you could have damaged the valves or worse which may explain MAF errors and an inability to idle.

However, such mechanical damage would in all probability have been apparent immediately after the over rev incident.

 

[Chris155]

Have they checked battery voltages? Engine on/off and engine on with electrical load?

Otherwise, try changing the MAF (IIRC it's the same element as a 1.0 Meriva) and the battery.

 

[ransoman]

When was the timing belt last changed? I suppose you could have jumped a tooth.

 

[mjaz101]

I seem to recall that when the fuel gauge and trip computer 'failed' I still managed to use my GT for my 60mile daily commute without any misbehaviour. I did get the MAF ordered and fitted straight away though, so prob drove 150-200 motorway miles between diagnosis and rectification.
Good luck!

 

[Aramis]

first time I connected my cheapo el EOBD it gave me engine failure warning, guess she didn't like being penetrated by El Cheapo..

Check battery voltage as has been said, even a minute drop plays haywire with your system. 12.7V I think was proper?

 

[i-am-iron-man]

In the interests of finishing-up the thread: everything was the MAF.
New one fitted and all problems are resolved!

Soooo ... new MAF and 12 months MOT. Black, tan leather, GTA alloys ... anyone up for buying it?