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Help! Fuel problem?

HONEYMON57ER

HONEYMON57ER

New member
My '99 996 has just started playing up.
Here's the symptom:
Loss of revs for between 3-5 secs in any gear
then kicks back in
No warning lights on
Engine sounds normal
Oil pressure normal
This seems like intermitant fuel starvation.
Coincidentaly I have just filled with BP standard
unleaded 95 Ron but usually use Shell V Power stuff.
Any ideas?

Cheers, Barry
 
You did tighten the fuel cap?

Otherwise, if I were you I'd get a diagnostic check done, as it's the only way you are likely to get to the bottom of the problem quickly. Could be a number of things - MAF, fuel pump, an air leak, etc.

 
Hi Richard,
If it is the MAF, would I have a warning light or
not always? This item looks easy to clean or replace as a
first step


Thanks, Barry
 
No, you won't necessarily get a CEL with a MAF fault on a UK car. (You will on a USA car). I had a faulty MAF which showed a fault in the computer, but no CEL. A first step might be to clean the MAF with an electrical contact cleaner, but my experience is that it doesn't last all that long. If you get 50-60,000 miles from a MAF then you have done well.

If that doesn't work, I really think you need to get a diagnostic check on the car. There is no point in throwing £150 away for a new MAF if it doesn't need it. Where are you located - if you are near me I could help.
 
I agree with Richard, your problem could have so many causes that you need to get the car hooked up to a tester (PST-2, PIWIS) to find out what is going on. Loss of power mid range could be caused by, MAF, lambda sensors, variocams, crankshaft Hall sensor, fuel pump, fuel filter, contaminated fuel, e-gas, plugs, coil packs etc. etc. I don't think you'll find the answer to this one by chance.

One thing worth trying before going to the stealer / indy is just to reset your DME and see if it clears the fault. To do this you disconnect your battery for a few minutes (usually 10 will do - I always allow 30 though). Procedure as follows:

1) Turn your ignition to 'on' - all dash lights illumiated but engine OFF. This prevents the alarm going off
2) Using a 10mm spanner, loosen the negative battery terminal and detach. Leave for 30 mins. (You can remove the key from the ignition now)
3) Re-attach battery terminal - do not overtighten, it's only made of soft lead.
4) Start you engine and leave to idle for a couple of minutes
5) Reset your OBC setings / radio code / radio settings / dash light settings
6) Run your windows up and down a couple of times to re-enable the one-touch facility.
7) Drive normally

This procedure resets all the cars electronics to factory spec and your engine electronics back to their base maps. If there is a sensor at fault, it won't make any difference as the DME will immediately register the fact it's getting no reading from that item (or a reading ouside the permitted range) and still run like a dog! If it was just adaptation related, it will clear things up. Worth a try for 30 mins.
 
Thanks for that guys , I'll try both suggestions (after the Grand Prix
of course) If I have no luck I plan to take it into Parr as they are
nearest.

Richard, I'm in Smallfield nr Horley
 
MAF seemed so new it didn't need cleaning. I think
it must have been replaced already at some point.
Just disconnected the battery to try reset.
 
This is now one of those "worth the membership alone" threads.

I'm pleased to say that after the battery disconnect everything is
back to normal. I've just been out for about 25 miles for a blast
with the only problem being a little hunting on idle when I stopped
at a junction. I'll keep a eye on it but I'm happy again as this was
ruining my weekend

Thanks Ian, thanks Richard [:)]
 
You should find that the hunting idle should disappear as the system adapts after a several miles. Hopefully your problem won't come back......
 
Well, almost 2 years later and the problem returned on Saturday evening on the way home from a trackday at Bedford.
I put up with it for about 10 miles or so and then the engine cut out at some lights. I thought it was probably exactly the same
problem so I tried the same solution (battery disconnect for 30 mins). Co-incidentally I had put some fuel in at the circuit and
it wasn't the V-power I usually use.

The car started ok so I thought I had solved the problem but it promptly gave up the ghost about 100 yds down the road.
Greenflag got me home (97 miles) on the back of a flatbed. I called Parr and they picked the car up on Tuesday morning
and phoned later in the day to say that they can't find any fault!! They did 2 long test runs and hooked it up to their diagnostic gear
and found nothing. I picked it up today and its back to normal.

I'm guessing it may have been some dirty fuel or something that cleared itself now. At least one good thing came from the visit to Parr
(they are really good by the way) they fixed my windscreen chip when Autoglass came out and said I had to have a new screen.
 
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