Poor running when cold

[dan_b]

Hmm, help required from you engine gurus please...

The last couple of times I've driven the mighty 3B, for the first 10mins or so the car is running a bit funny. It hesitates a bit, especially on pick-up after a gear change in low revs. This goes on for about 10mins. Also, it's popping a LOT on the overrun, I've never had the car pop when cold before. This goes on for about 10-20mins. The third symptom is that the car seems to produce a rather smoky exhaust when chaging gear after giving it a bit of stick, say accelerating in 2nd to about 4000rpm, on change it smokes. This goes on for about 20-25mins.

After driving for more than about 25mins, all these symptoms go away and the car then runs fine.

Tick over is fine, smooth and at the right speed I think - around 1100rpm for the first few mins, then drops to 800rpm.

I'm running Tesco 99, plugs are about a year old. Recently cleaned the ISV, lambda was changed in the summer along with a MAF clean. The car will be getting an oil and fuel filter change at the garage meet, but I would be grateful for suggestions of what to look for so that perhaps this can be investigated in Baschurch?

My paranoia thoughts so far have been - I've killed the turbo, or perhaps its sticking exhaust valves? Could it just be the dizzy/ rotor needing replacing? The car's done 130,000 now.

[dan_b]

Help?

[Greg_S]

MFTS maybe...?

[volcano rs]

what about the water temp sensor on back of the head?

[philS2]

i've got the same symptoms as you dan exept maybe the smoke and i've just checked the temp sensor on the back of the head and it measures 4700 ohms.apparently its meant to be about 3000.think i might change it.

[dan_b]

Should I be worried about the smoke too do you think?

[philS2]

what colour is it?blue?

[dan_b]

I don't know as I can only really see it in my rear view mirror as I've not done this standing on the drive yet, it looks more black/sooty colour but hard to tell.

[philS2]

sounds like it's overfuelling then.but when i've experienced overfuelling when cold it was on k-jet and that gave loads of blue(some of that was oil as well)once i disconnected the cold start injector it was perfect.if you can get your temp sensor on the back of the head checked i'd expect to maybe see a higher reading than mine,thats if we've got the same problem.just took mine out after checking the sensor and it was loads better,but i think it's a bit warmer round here today.

[dan_b]

Is it easy to check - is this something that we could look at at the Garage Meet? Could someone do a photo with a big pointy arrow so I know what sensor it is I need to look at/ test/ replace?

Incidentally, my temperature gauge inside the car works only intermittently - is that driven off the same sensor or a different one?

[dan_b]

Oh and another thing is that my fuel consumption is falling, it's down to 20.3: it was up to around the 25-mark at Christmas, so maybe this indicates overfuelling too, along with the excess exhaust popping?

[PeteRR]

I'd point my suspisions at the MFTS (and maybe the temp. sensor at the back of the head) too Dan.

[dan_b]

Are these parts easy to change? Any BTDT advice?

[PeteRR]

Dan, the temp. sender at the back of the head is easy to change, if you can access it fully.
The MFTS (and the Turbo Pump Switch too) is more of a challenge. Access to that can be very difficult (I image it's as much of a PITA on the S2 as it is on the quattro). In theory you just remove the wiring plug and unscrew it with a spanner/deep socket (preparing for a small loss of some coolant if you've not drained a bit off).
But just getting your hand to it, never mind a spanner is an art in itself!
I ended up saying 'f*ck it!' and taking the rad out to get to it properly.
Though it may be a slightly easier job on the S2. Hope so!

[dan_b]

Worth me buying these parts in advance of the garage meet just in case do you think?