Temperature Issue (GTI 8v)

[alien.46.uk]

rubjonny:

Been thinking about what you've said and I'm curious. Why would this bad fuelling only occur once the engine has reached 90-100*C water and about 75*C oil temp? I would of thought the warm-up stage would of been completed by then as most cut off from warm-up before 60*C water roughly.

Up to the 90-100*C point, she fuels fine even with the sensor plugged in and idles spot on, its only at those temps when everything goes to pot.

Thanks once again.

[rubjonny]

I'd leave the CO allone for now and check the ignition timing with a timing gun, though as you say its a bit odd that its fine up to 90degs? if you dont have access to a co meter dont bother trying to fiddle with it as you'll probably just end up making it worse!  if there is idle adjustment its worth setting that up, but thinking on it now im pretty sure there isnt

main issue is with the sensor unplugged revving it to 3k 3 times in a row buts it in CO adjustment mode, which could be possible in norm al driving which would make strange things happen i bet 

was the sensor a genuine VW one?

[alien.46.uk]

Apparently, the car has been driven with the sensor disconnected for some time now. Unless its gone into set-up and tweaked whilst driving without the previous owner knowing on the daily commute, could this happen? And if so, could it be a case of simply setting it up again? But then I get into the point of it only happeneing at a certain temperature again ... This is really quite an odd one and I cant get my head around it.

Just re read what you wrote and about normal driving. It runs absolutely fine with it disconnected, apparently it "pulls like a train" (Just watch some 16v and VR6 people jump all over that comment now ).

And yes, as far as I'm aware it is a proper VW sensor yes, same as the one pulled out. Same o-ring and clip supplied with it as well.

[rubjonny]

ok cool. i havent actually driven a digi car with the sensor unplugged, for it to pull like a train with it unplugged id guess the timing is well advanced past where it should be, as disconnecting the sensor pulls the ecu advance right back so you can set it up properly.

The advance should be 6 degrees BTDC at 2.25k rpm with the sensor unplugged, and it should advance 30 degrees when you plug it back in.  Thats a big difference, so I imagine if it was setup right it would be very sluggish with the sensor disconnected.

The above is only a theory though as I've never actually tried it myself

[alien.46.uk]

All theorys welcomed and thanks once again for yours and everybodies suggestions so far.

It may be eating into any profit from this car, fiddling with everything, but as per useual, I'm thoroughly enjoying it. I useually take in bikes, sort em and sell em on, but I'm wanting to do some cars now (obviously) and this be the first.

Worked on plenty of other cars both at Uni and family and friends who dont know much, but none admitedly have been VW's or even Golf's, so learning little niggles with any car I enjoy.

I went out again just now for a play (weather's getting on my nose a bit now lol) and did the same, but noticed it did it from within a few seconds from cold, was warmed up hours ago, so porbably not totally cold, but colder than its useually decides to drop one. Which I thought odd. Turned off an on, was fine again, untill again slightly lower than useual but not far off this time, it does it again, turned off and under the bonnet I went for a fiddle.

Upon fiddling around the dozzy area I found on of the HT leads was very corroded at the Dizzy end and the pin on the dizzy doesn't look to healthy either, neither does it "pop" on properly. So wiggled it I did, started and was fine, upto 110*C Water, 80*C Oil, when out it went, wiggle I went, start-up ... fine again. And sat there nicely for 2-3 mins on 110-W 80-O.

I dont suppose this is a simple case of nackered HT leads?

For that to be true, I must of flicked the HT lead enough each time I took the water sensor off to sit it right again. And once the sensor was plugged back in whilst running, it must have eventually dislodged again for the issue to come back as when it was running I would plug the sensor back in again for it to be fine only to drop one a few minutes after.

I guess the only real way is to get myself some Leads and a Cap to try this out.

My heads all in a mess after having such a drawn out plan of action.

Think when I do get a Car Lic. the first car shall have to be a Mk3 GTI no matter how many years it is untill I get one.

[rubjonny]

yeah that would be a good starting point, wont cost a lot either
http://www.vwspares.co.uk

[alien.46.uk]

Right, got some other cables, from a Mk2 and a Mk3 1.4 or something CL at breakers, same cables, got the dizzy caps from both but not tried them, did the cable change but no joy. About 80*C ... Off she goes funny again (Sensor plugged in).

On thinking, I dont think it can be the cap, but will change it anyway, dont think the ones I got are the exact model number, but fittments and connections are all the same, so should be fine. At least for testing, might get some new HT leads anyway. The ones I got needed the pop on fitments on the plugs removing so the thread parts were exposed. Fitted nicely after.

Will have a look at the advance when this weather goes past, bleedin sunshine untill 30 mins ago when I could hear thunder whilst basking in sunlight only for it to change in seconds and heave it down!