Does a faulty MAF always give a CEL on a Boxster S 986?

[stupidget]

As the title suggests, does a faulty MAF always give you a CEL?  Reason I ask is that I've noticed that when I  accelerate (in any gear) at just over 2k RPM there is a loss of power/sluggishness until I get to 3k RPM and then everything is fine.  I looked about and quite a few people have had this and the general consensus has been 'drive over 3k RPM all the time'.

My initial thought was that it's a failed/faulty MAF, but, there is no CEL on my dash.  Would a dodgy MAF give a code that I could see with an ODB reader rather than a CEL?

[topradio]

No, I had a bad MAF on my 986 at about 60K and there was no CEL. Your symptoms do sound like it's the MAF.

[Richard Hamilton]

As topradio says, you won't necessarily get a CEL for a dodgy MAF sensor on a UK car, because the DME is programmed not to give one.  (US cars do.)  Eventually, when the fault reaches a certain point, and the mixture adjustment reaches an upper/lower limit, then you will get the CEL as it is emmissions related.  Normally, you get an ABS/PSM warning light first.  That's beacause the DME and PSM control units talk to each other, and the PSM thinks it is receiving an implausible signal.  A faulty MAF will trigger a fault code in the DME, but you might only be able to read it with a Porsche specific tester.

If you have an OBD2 reader, read off the Mass Air Flow volume.  It should be about 15kg/hour at idle, and increase progressively with engine revs.  If it reads very low/high at idle, or doesn't follow a linear increase with revs, then it needs changing.

[stupidget]

@Richard Hamilton and @topradio thanks for the heads-up on what needs doing.  I'm getting an OBD2 reader tomorrow so hopefully it'll be a dodgy MAF. Fingers crossed.

[Mr96er]

12 hours ago, stupidget said:

@Richard Hamilton and @topradio thanks for the heads-up on what needs doing.  I'm getting an OBD2 reader tomorrow so hopefully it'll be a dodgy MAF. Fingers crossed.

Easy to check without reader. 

Disconnect your maf and drive. If the symptoms gone, it will be maf.

i have not had a maf connected on my Boxsters for years. Only for MOT. 

The default program that kicks on when you disable maf is more than proficient to potter along quite nicely, as @JohnK will atest. 

[stupidget]

@Mr96er Does that mean that you have the CEL on all the time as you've got the MAF disconnected?

[stupidget]

so I've disconnected the MAF and, without wanting to over exaggerate, it's like a different car.  Revs are really smooth with no spluttering, tip gear changes smooth without delay between revs and it's great.  Question is, do I just leave it unplugged until MOT or do I get a new one fitted?

[stupidget]

used one of those ELM327 Wifi plug-in's and there was indeed a previous MAF code, among some misfire ones.  I've cleared all the codes and will give it a blast when I drive over to see my mate later. Thanks to @topradio and @Richard Hamilton for you guidance 👍

[Mr96er]

3 hours ago, stupidget said:

so I've disconnected the MAF and, without wanting to over exaggerate, it's like a different car.  Revs are really smooth with no spluttering, tip gear changes smooth without delay between revs and it's great.  Question is, do I just leave it unplugged until MOT or do I get a new one fitted?

So glad that worked out for you. I remember the new car feeling the first time I figured it out. 

Get a decent used one from Steve Strange for £30 or less and pop it in for MOT. Leave it in or go back to standard. Either way you’ll have better engine performance. 

[stupidget]

That Steve Strange ebay shop is excellent.

Just tried my EML327 after I'd cleared all the codes and it came up with the MAF one straight away.  At least I know my £8 OBD2 reader works 🙂

[Mr96er]

Winning all round 💪🏻

[Mr96er]

You’ll probably notice from cold it feels a little different. This i believe is because the maf acts like the old choke on a carb. Mixes the fuel for cold start and then adjusts. 

I tend not to notice it these days, as I get in and drive. 

I haven’t seen a check engine light since most dick was a minnow👍

[PaulQ]

Won't running without a maf f@ck your engine up eventually ? 

Sounds crazy to me just to save a few quid, but I guess you know what your doing. 

[edc]

It will run better with a good MAF than with none at all. 

[Boxstercol]

I’d worry about longer term damage running with the MAF disconnected permanently. At the end of the day it’s there to do a job. May as well just put a new one in, Bosch apparently are the ones to go for.