"GT" > wrote in message
eb.com...
> "Catman" > wrote in message
> ...
>> On 20/01/2011 12:13, GT wrote:
>>> 156 2002, 2.0 JTS petrol. I (the car)had a splutter/cough a year or so
>>> ago
>>> and it eventually went away on its own. Its come back now and I would
>>> like
>>> to at least figure out what is causing it, if not fix it. The problem:
>>>
>>> Its independent of gear (done it in 3rd, 4th 5th). I don't tend to rev
>>> over
>>> about 4000 most of the time as its a nice torquey engine. Problem occurs
>>> under load, usually at around 2000 revs. It is repeatable - the 270
>>> degree
>>> slip road onto the M8 at the top of Livingston is about a 50mph corner,
>>> 5th
>>> gear. As I come out of it I speed up to er... 70 (ho humm!) and it will
>>> splutter most times there. It also does it in 3rd coming out of the
>>> silly
>>> little roundabouts they stick along in-town dual carriageway 40mph
>>> stretches. Its a cough/splutter, lack of power, followed by 'beep beep'
>>> motor control failure - go to dealer. As I feel the splutter starting,
>>> if I
>>> back off on the accellerator and just speed up more gradually all is
>>> well.
>>> If I drop a cog and increase the revs, all is fine.
>>>
>>> I have ruled out dirty fuel as its been through several fill ups.
>>> I have rules out engine temperature as it doesn't make any difference.
>>> I have ruled out spark plugs and electrics because the revs are low, so
>>> the
>>> demand is not so much - wouldn't this cause problems at higher revs when
>>> there are more sparks per minute?
>>
>> *maybe*
>>> I have rules out air flow for the same reason - the engine isn't getting
>>> through as much air as when the revs are higher.
>>>
>>> This (in my mind) leaves the knocc sensor, or something else.
>>>
>>> Any ideas / suggestions?
>>>
>>
>> Is it drive by wire? If so, I'd bet on the throttle pot.
>> Failing that I'd be giving the AFM a stern look.
>
> Yup, I believe there is a small computer between my right foot and the
> engine, instead of a cable!
>
> I looked at the MAF (?) sensor in the air intake when I was replacing the
> thermostat the other week. I had never seen a MAF before and was
> thoroughly un-impressed!. I covered the top of the air intake with a cloth
> to avoid any nasties getting in there, and it all looked clean as a
> whistle when I put the hose back on. All has been fine for a few weeks
> since the thermostat replacement, so I don't think its anything that I've
> introduced, but obviously I can't say for sure!

Reading around a little and there a few suggestions online that its safe to
unplug the MAF and try the car without it. That doesn't seem right to me -
sensors are there for a reason, surely? If the 'brain' can't sense how much
air is flowing, then how can it manage fuel/air mixes properly?