UK-POLOS.NET - THE VW Polo Forum

http://www.tigerstyle.co.uk/poloforum/v ... php?t=7458

Anyone know about the Polo GTI cold start / auto-choke? Other members have the same issues, so it seems to be a common problem. Cheers.

Er, as it's GTi, it doesn't actually have a choke. It's all controlled by the engine management system, which can finely control the input of air (via ISV) and petrol (through the injectors) and the ignition advance, while checking the output via tacho, lambda sensor etc to keep it running at a level pace with much more accuracy (and flair, panache!) by altering these variables on a spark-by-spark basis.... much more so than a crude old choke, whether manual (set by a human tugging on it randomly every few minutes) or automatic (set to full by a human flooring the pedal when ignition's off, then slowly coming back down controlled by a thermostat of all things).

Therefore running much above the normal idle speed (that ol' 850rpm for a great many VWs) even from cold is not necessary as the engine can still function reasonably ok. Which improves the engine life (not running consistently fast before the oil's started moving, unless the driver chooses to drive away immediately) and reduces emissions / consumption.

Does mean it takes a bit longer to warm through, however...

Thanks Tahrey1043.

Well, the GTI warms up really quick! And it runs okay from 850 revs cold, but labours the engine slightly if you put the A/C on immediately.

Yeah, I guessed it must be dealt with by the sensors (electrics ECU etc) as was my last car, but I wondered why there was such a discrepancy as to why the Revs sometimes went to 1100-1200 Revs when cold started and why it sometimes starts cold and immediately sets to 850 Revs. There seems to be no way of telling what makes it decide.

Sometimes it starts at 850 Revs from cold, yet at other times it starts at 1200 Revs from cold. I always start the car the same way: turn ignition key, wait for the fuel pump to prime the engine. turn on ignition (without pumping the accelerator pedal). Yet, this provides inconsistent results. Therefore I considered it must be measuring the air temperature somewhere...

So, where is this air temperature sensor I was wondering... I was thinking it may need a clean occasionally (as my last car did)?

mm, mine can be b***h as well

seems to always hover around 900 when it should be 750

and sometimes a shakey 800, sometimes 1100 or so. dont quite understand its wily ways, just try to ignore them.
but at least its not humming along at a super rich 2000+ like the badly choked (manually set - idiot at the wheel) Maestro that passed me coming out of a carpark i walked past today - cough cough, hack, a shout of put your bloody choke in you idiot, its not december yet.... (and whaddya know.. he did )

thems were the days... not.

Thanks Tahrey1043. Apparently there are problems with Golf's and Polo's cold start due to a air flow or oil temp sensor going faulty. Golf's need them replacing regularly the VW dealer tells me.