Light throttle hesitation / flat spot FIXED?

[Mark_A]

Cleaned the throttle body on my VRS this morning and initial impressions are good

Probably need to do a few more miles yet before claiming victory though I guess...

Bit of background:

Been driving the car every day for two weeks now and the only running issue I've had is a pretty consistent flat spot on steady light throttle openings at between 1500-2000 rpm approx. Car is completely standard and has done 68k. The throttle body had clearly never been touched from new.

Basically if pulling away in first on a tiny bit of throttle and holding the pedal steady, the revs would rise smoothly until 1500-2000rpm and then it would jerk as though I'd lifted my foot sharply off the pedal, stutter a bit and then pull cleanly again once above that rev range.

Having read the various threads on running issues on here, i decided to start trying to resolve this with a TB clean, but not having access to VAGCOM, I had no means of aligning the TB afterwards.

Since I have access to another vehicle should the Octavia be undrivable after cleaning without a TB align, I decided to give it a go anyway..

With the hose from the intercooler removed the TB didn't look too bad, but some deposits were evident close to the butterfly

With the TB removed, the true state of it was clearly obvious though

Now I had read about opening the butterfly by hand, some people having done it without apparent problems, others advising against doing so...

I pushed on the butterfly gently and slowly increased finger pressure until it started to move. It has a pretty damn strong spring loading to keep it in its default closed position. I took the view that in order to overcome that degree of spring pressure and operate quickly and reliably enough in day to day use, the stepper motor and any associated gearing must be pretty tough, so opening it manually shouldn't cause any problems. Just my personal opinion - don't sue me if you do this with yours and it breaks!!

Anyway, rather than fight the spring tension, I cut a short length of rubber hose and used it to lock the butterfly open thus

This also meant I wasn't opening and closing the butterfly manually more than necessary and it made cleaning the stubborn deposits on the throttle body and the butterfly (particularly the edges) simple.

To clean it, I sprayed carb cleaner onto a cloth rather than directly into the TB, though I couldn't see how any substantial amount could enter the motor assembly since the only route would be via the butterfly spindle, and that should have near airtight tolerences to prevent any boost being lost.

Once cleaned, I simply reassembled everything, started the engine (from stone cold, first start of the day) and went for a drive. Cold idle was 1250ish settling down quickly to a steady 800 +/- the thickness of the tacho needle when warm. No flatspot and I think better response on all throttle openings of less than about 1/4 throttle - though some of that could be placebo effect of course!!

Will have to see how it goes over the next few days and weeks as per my original caveat of course, but my initial conclusions are:

• If the only running issue is a flat spot aound the high teen rpms then a throttle body clean is a quick, cheap and easy starting point.
  
• The butterfly can be opened manually so long as care is used - it requires effort but not brute force to do so.
  
• A throttle alignment is not strictly necessary - I disconnected the connector from the TB whilst cleaning it, but left the battery connected throughout.
  

Thanks very much to everyone who has posted on this subject previously, the links and guides I found here gave me the knowledge and confidence to have a go