993 engine issue/ expert advice needed

[carkid]

I have a 1996 varioram 993 C2 manual.
It runs very well most of the time however intermittently
when I accelerate hard it sputters and feel's
a bit croaky as if it's not getting enough fuel.

I've cleaned the idle control valve and fitted a new fuel pump
along with new spark plugs - all to no avail.
It never completely cuts out and stalls, it just sputters sporadically-

Anyone experienced this and know a likely cause?

Any help much appreciated.....

 

[AP90]

Hi CK

Could be electrical, check the condition of the distributer caps and the rotor arms also the condition of the spark plug and coil leads

Fuel filter may also be worth a look if it feels more like a fuel issue although if only under load sounds more electrical

I had my distributor refurbed, I had about 130K and it was well 'run in' as it were, I was under the impression that the advance/retard chutney may have been a bit gooey at this mileage, which may also cause the symptoms you describe may also be worth a look whilst you're in there

Have you just bought the car?

 

[carkid]

I bought the car about 9 years ago.
I'll look into these possible causes- thanks

 

[IMI A]

Totally off topic is your bread van as fun as your 993 down a b road?

 

[andyp]

Sorry, I'm no expert, but does this happen at low revs or further up the Rev range?

I had a similar sounding issue which felt more like a misfire, but at medium to high revs under load. Turned out to be faulty O2 sensor.

 

[Gwsinc]

If its only on acceleration then I've heard of this kind of issue being caused by a faulty/corroded/damaged Throttle Position Sensor.

Easy to replace on non-vario but suspect a little more difficult to get to on vario cars. Part is about £50 for a decent Hella replacement or more for Bosch/Porsche.

Best way to test is to get the car clagged up to an OBD reader (or T-OBD) and see what the TPS reading is, from memory it should be about 5-8% with foot off the accelerator and about 85% foot to the floor. An OBD reading will also identify if the other sensor readings are in spec.

Could also be a vacuum leak from one of the many rubber connectors in the engine bay (and one under the dash), always worth checking these if you haven't before. If problem persists and you can't find any defective vacuum connectors then an intake smoke test will identify any leaks.

 

[carkid]

Totally off topic is your bread van as fun as your 993 down a b road?

To be honest there's no competition- the Z3mC is far more fun to drive.
I love the 993, it's such an iconic design etc but it feels like a heavy touring
car compared to the Z3mC.
I had Centre Gravity refresh the suspension on the Breadvan, bilstein B6 fitted etc and it handles so crisp and agile, go cart like.
And the S54 M3 engine is quite rightly very highly regarded- it's superb.
I'm a die hard Porsche enthusiast, however I really do think the Z3mC is something special- considering what they cost vs performance and rarity I think they are totally undervalued. You virtually never see one in the wild- there's only 123 RHD S54 UK cars.
I'd recommend anyone to get one !

 

[nk993]

I actually debated getting the breadvan instead when I bought the 993! My choice would be red, for no other reason than that was the car I saw when I was a kid.

 

[xbox]

I bought the car about 9 years ago.
I'll look into these possible causes- thanks

I have a similar issue with my C2, which incidentally, looks almost identical to your car!

It occasionally kangaroos, which I can now reproduce between 1500-2k rpm, in a high gear, with low engine load.

Also noticed that if you completely lift the clutch in reverse, it all gets very bouncy.

Any ideas?

 

[berni29]

Hi

Have you inspected your engine mounts? If yours are worn you should consider the RS versions.

All the best

Berni