Technical Multipla JTD 1.9 Diesel MAF Sensor Question

[BC Yoko]

Hi all

Just joined this forum to try to help out my Dad who has a Fiat Multipla 1.9 JTD and is ripping his hair out with frustration!! :bang: (he doesn't have the net so I'm employed as his 'finder outer of things'.

He's done the following;

Mapping done
new MAF
new EGR
All filters changed

The original problem was the lack of power, as if the car was 'holding back', which is now cured. But under acceleration, like when you leave a roundabout and accelerate again to normal speed, the car stutters slightly as if it was misfiring but this has been checked by the garage and isn't the case.

The question is, as he has a new MAF sensor, is there a particular way to programme this - he briefly read somewhere on the net at a friend's house something about running the car for a time/distance, then leaving it to idle for a certain time. Does this sound right and does anyone know specifically what the procedure is for doing this?

Sorry if this has been covered elsewhere, I've done a search but can't find the answer to this specific question

If anyone can help, it would be massively appreciated as the garage can't find the problem, even with diagnostics machine, and my Dad is swiftly losing the will to keep this car!!!!

Thanks in advance

 

[Shepherd]

Hi,

I have heard that when a new MAF sensor is fitted the ECU goes into a re-learn mode and this can take quite a few miles for it to fully learn the correct settings. I have read before that this can take quite a few miles and the process could result in the engine not running as smooth as it should do. This may/may not be your dads problem but I thought I would share it anyway.

I am currently running with my MAF disconnected as I bought a third party one last year and after fitting it I had problems so I just disconnected it and it has been as good as gold ever since.

Jim

 

[BC Yoko]

Hi Jim

Thanks so much for the reply - I'll give him a ring and pass that on. I'm not sure when he had the new MAF fitted, but I know that it was a while ago and he's been back and forth to me (1 hour journey each way) at least 3 times since plus a trip to London from Norfolk, so not sure how many miles the people were saying might be needed

I've read about disconnecting it and interesting that you're finding that it helps so much. Doesn't this affect the air that's coming through the filter in a negative way (this is where I'm not clued up so forgive me if I'm talking rubbish ) I'll tell him that you've done this and are finding it works well. I think we talked about this and he was worried about doing it but maybe his mechanic can put his mind at rest about it. I think he was worried that if Fiat had put the part in, that suggests that it's needed (to which I said, yeah but you can live without your spleen ) LOL.

Thanks for your reply - will give him a bell and pass this on

 

[disgusted]

When I had my EGR valve de-sooted, they did the same to the "turbo actuation valve (!?).

I don't know what this is, or even if it's really called that.


Massive difference when it was done.

 

[BC Yoko]

Hmmm, have never heard him speak of the turbo actuation valve, will ask if he's had it looked at /replaced - thanks

 

[umberto]

I've read in the past that the accelerator pedal potentiometer could be doing strange things. There is a wiring loom that runs from the potentiometer along the floor to the passenger side footwell and it's coupled via a multipin connector. Unplug it, squirt some contact cleaning fluid and plug it back up. Unique to R/H Drive versions only i suspect..

 

[MultiPa]

I ran my Alfa diesel with no MAF for 12 months or more - the flat spot was really bothersome on a short break in the Lake District (all those hill and corners were just frustrating in a coughing car!) so I unplugged it. It ran so well that I left it like that, never intending it to be for long, but I sort of forgot I had done it. Might be worth getting your dad to unplug his and see if it makes a difference - I guess there is a chance his new one was faulty? Mine was instantly better - it seems that the 'default' settings I presume it uses when there is no MAF signal at all work pretty well.

I've had the throttle pot problem Umberto mentioned too, although in my case it resulted in a high idle and occasional surges in revs so the car felt lke it was running away - the opposite problem I suppose, but then I guess a faulty connection could give any result. I didn't even clean mine, if I'm honest, I just pushed the plugs together and gave them a jiggle.

I've had the codes read on my car today as it happens - I have a sticky EGR, for which the symptom is a slight falling away of power, then the engine management beep, then a huge loss in power. Sometimes it almost immediately comes back, and sometimes it doesn't. The engine management light goes out again if you stop the car for 30 seconds or so and then restart it, and the faults tend to come in batches as the car keeps re-trying, until it gives up for a few weeks.

In trying to diagnose that fault (because it doesn't save the code - I was lucky today in that the fault occurred only a mile or so from my local garage and the traffic was slow anyway, so I limped there and left the engine running) I've read that similar symptoms can occur if there is a leak in the pipe to the turbo.

Hope some of that might help - let us know how he gets on.

 

[disgusted]

I first had a throttle potentiometer fault when the car was new (about 6 months old) coming back from Stansted Airport. Car went into "limp" mode. Still usable though. Clearly, under guarantee at the time, the dealer replaced it.

By the next time that it happened, I had given up on the Dealer (they were truly useless) and Gonnella's of Catford were my fettlers of choice. Their fix was less reliant on new parts, they just took it off and cleaned up the contacts. My records show that this was at 36k miles. The potentiometer has been working without trouble now for 138k miles since that fix.

 

[bifter]

I replaced mine yesterday ,just took off the old one and fitted the new one and that was it ,drove it for 10 miles no problems