Does a failing MAF sensor always light up the engine management light?
How fragile are these things exactly? My economy has been down since I changed the oil, diesel and air filter. :-S
I had to be quite rough and ready with the air filter housing, as I couldn't get the big pipe off the lid part of the housing, and I assume the MAF is the little sensor near there.
No warning lights and performance still seems OK. I'm still running it on 'holiday' pressures in the tyres (4 passengers and luggage) yet the trip computer still reads 45mpg average. It would be over 50 most of the time.
Only other thing I can think is that maybe a brake is sticking. It had new tyres recently, and the guy that fitted was complete moron. Only remembered he'd left the locking wheel nut key in behind the cover when I asked him where it was! I have checked them after a run and all the discs burnt my fingers by the same amount. :^D SO I don't think it's that.
Any other thoughts?
|
"Does a failing MAF sensor always light up the engine management light?"
No.
are all pipes def. connected back up properly? filters correctly fitted etc ?
trip computer accurate ?
|
|
|
You dont say what car it is ?
However, the MAF usually never lights up the EMU light.
The symptoms are loss of power, smoke and heavy fuel cons. One way to troubleshoot if it is the MAF is to disconnect it and if the car drives the same, this is the problem.
If the economy is only slightly down, it may just be the newer thicker oil causing it.
I would also try just re-seating the connector to the MAF, which as you say is on the 'post-filter' ie engine side of the air filter in a plastic tube assembly.
I would suspect that if you are reading 45 mpg even now your MAF is probably okay.
|
Sorry, it's a 2002 1.9 TDI SEAT Toledo.
Is it possible the computer has somehow become miscalibrated? Can that even happen?
I guess a brim to brim calculation is the best bet.
|
Sorry, it's a 2002 1.9 TDI SEAT Toledo. Is it possible the computer has somehow become miscalibrated? Can that even happen?
I wouldn't think so, but disconnecting the battery for 20 minutes or so makes the ECU re-allign itself, you could give this a try.
|
|
|
|
You dont say what car it is ?
I'm begining to think the sticky messages at the top of the page are a waste of time.
DD.
ps, car now added to subject header.
|
The MAF sensor DOES sometimes illuminate the Engine Management light, it did on my Astra.
The engine then goes into 'limp you home mode' with reduced economy as a side effect. Easy DIY change, ten minute job
|
My understanding is
Faulty MAF - engine runs weak, flat spots / hesitation no smoke. Unplug MAF and some of the performance returns. Thats what my Golf TDi pd did at 54K miles, no EML or faults logged. £84 from VW
|
New tyres could be the reason for the MPG drop, more rolling resistance. What make / type did you fit / replace?
|
I replaced some nasty old P6000's with Dunlop SP 'somethings'.
Still running fully loaded pressures though.
|
Higher pressures would improve economy, there's less rubber on the road, hence less rolling resistance. Its dangerous too the footprint of the tyre won't be flat against the road and you may come unstuck when the rain comes
|
|
|
|
The MAF sensor DOES sometimes illuminate the Engine Management light, it did on my Astra. The engine then goes into 'limp you home mode' with reduced economy as a side effect. Easy DIY change, ten minute job
Sorry, I was talking about VaG group cars and expecting everyone to read my mind...
|
We're all talking about VAG cars ;-)
|
Just to let you know - a dose of Millers DIesel Power Plus has brought the computer MPG average back up to 52mpg.
Real affect or duping the car's brain I don't know - satisfying though!
|
|
|
|
|
|
|
