406oc.co.uk

Hi chaps and chapesses,
just wanted to now if an engine can run without the mas air flow meter connected. The one I have on now is going faulty (I think). This is the second one albeit a second hand one. When it went funny last year I got one from ebay and its worked ok till the last few weeks. I then noticed that the engine was not as smooth as before with it grabing a bit on pulling away and a bit lumpy when running at a steady speed. When I disconect it and then reconect within a few seconds it is ok for a few days but then starts again.
So if I am away down the road and it gets to bad can I unplug it and run with it off and will the fuel consumption go haywire. I am getting 45mph most of the time at the moment. It is a 406 HDI Deisel 90bhp, I know its not the 110bhp.
Thanks for any advice.

Hey,
Sorry but as yet no experiance of the 406 especially in HDi flavor, (still searching for one!) However I have a faulty MAF in my daily mazda 323, so some of this info may transfer??
My Mazda will run with it off but overfuels horrible below about 4000rpm (petrol non turbo) and this brings with it associated problems. My MAF fault is usually however caused by dirt, sensor is filthy after 150k and a broken inlet after the filter for some time.. too dirty to clean fully but a good clean usually solves the issue for a while (few weeks?) The sensor on The mazda is in two pieces a wire bridge (kind of like a fuse and very thin) and a epoxy type 'bulb' the bulb can be cleaned, VERY carefully, the wire is much too fragile, my cleaning usually involves a good spray with brake disc cleaner or isopropryl (sp?) alcohol no actual touching of the components and only using cleaning fluids designed to evaporate without trace. First time cleaning took an entire can of brake disk cleaner it was that caked.
Like I said don't know if any of this is applicable to the 406.. but may be food for thought.
I would imagine disconnecting the MAF will likely throw a code and quite possibly put you in limp mode?
Good luck,
Joe

Thanks for that joethefish, actually a lot of what you said is right. Inside the mafm it has a little rod that looks like a matchstick and two little rods under it. The inside of mine seems to get wet, or at least looks wet when I take it off. I did clean the stick thing with a micro fibre cloth but never touched the other bits. It did, like yours run for a while and started to go funny again. You mentioned the limp home mode, well I better had not disconect it then as I do travel on motorways a bit. Thanks for your reply.

Hi raccoon,
I have a 110 hdi which gave maf trouble a short time ago. It drove no problem with the maf disconnected. I believe they run on a pre programmed setting (or so ive been told) installed on the computer. As regards fault codes, im sure some were logged on the computer however the engine management light didnt come on and it didnt go into limp mode. I drove it for quite some time like that and to be honest it didnt even seem to effect the fuel economy much although realistically it was bound to be running a bit rich, which will eventually damage the cat. I know your's is a different engine but I'd give it a go.

Thanks Keppler, I think I might try it and see what happens. The thing is that I dont know how to bring it out of limp home mode if that happens, any sugestions

Ive never gone into limp mode in my car but I have on others and the only way to get rid of it was to fix the offending problem and clear the fault. Raccoon some seriously funny stuff has happened me down the years with cars as regards limp modes and engine management lights. I remember one time a friend and I changed a clutch on a nissan almera and accidentally turned the engine on without the maf plugged in. Anyway we had to drive ten miles to the nearest place with Nissan software to turn off the management light and on the way the car would randomly decide to cut out, regardless of speed. Scary stuff when on a motorway doing 120km/hr or approaching a roundabout and losing brakes and power steering.
My advice to you Racoon if you are so unsure is to unplug the maf now and take it for a spin before you attempt any long journey, at least then if there are any adverse effects you can get it to a garage to clear the code and plug in the maf.
Or you could just buy a new maf straight away at your local motor factors or ebay (£35 on ebay), to be honest if you have to get the car read by peugeot they'll probably charge you the same price as a new maf for just clearing the fault.

I think after doing some reading that I might just as well buy another MAF. I can see that will be the easiest way to go. Thanks for your time and advice.