Is the isv pipe connecting to the bottom of the inlet clamped

I'll have to double check in the morning when it's light again, I had wondered if it could've been something to do with the ISV

Have you cleaned the air fuel screw on the tb and set ut to the right place

ISV was all clamped up

I cleaned it all out and set it up before all the problems occurred (about 300 miles ago)

have you tried driving those 300 miles in reverse to see if the probelm solves itself?

I've not quite resorted to those extremes yet! Luckily I was able to send it to a garage before I properly lost my mind on! It'll probably come back as some really small, stupid issue that I've overlooked!

You said it bogs down when the 2nd butterfly is opened - that's what my GT did intermittently on the motorway; felt like 3 cylinders or a smaller motor.

This was caused by a combination of both a worn TPS and lambda.

The worn TPS would cause a bottleneck around the 2nd butterfly point where air continues to be sucked in but not matched with appropriate fuel due to the duff sensor. Would stop accelerating until pedal past that point. New sensor fitted, code cleared, smooth throttle.

The lambda was a more gradual state of affairs; the symptoms ramped up rapidly toward the end; beginning with an occasional refusal to start, all the way up to black smoke, drinking fuel and intermittent low power on a motorway. New lambda, code cleared, been right as rain ever since. It's like a new car - much much better drive. No need to change gears as much due to more torque.

Try running again with the lambda disconnected on a combination of B-roads and steady cruises on an A-road/motorway - see if the car feels different.

Then try with both the lambda and TPS disconnected. Then try with lambda connected but TPS disconnected. It should run OK with any of these combos (though nowhere near optimally).

It's better to have a code-reader so that the ECU can be reset for each combo, otherwise the sensors can't be isolated properly each time and it'll be much harder to get a feel for what's going on with service modes and stacked error codes interfering.

It might of course be something different without possibly knowing service history but these symptoms seem to be a combination of things - all the sensors are interdependent and when you have one or two that are duff, it brings the rest of the system down.

It's definitely down on power, I haven't taken it for a run with the lambda out but I've been pottering around in it with the TPS diconnected and it works but definitely down on power, feels like a stock 1.0 with the occasional burst of proper power. I've bough the suggested code clearer (I think it may have even been you who suggested it) which is the Vgate VS450 one and I'm going to have a tinker with it before sending it into a garage as I'll have a bit more free time in the coming weeks. Hopefully I'll clear all the codes and some clear faults will be thrown up after running for a while so I can start replacing bits and get the ol' girl running how she should. I was having a look at lamda sensors today on euros but I haven't had a look for TPS yet. Is there an especially good and cheap place to get the two from that anyone is aware of? I know there are a few used TPS for sale about but I'd rather get a new one so long as it isn't like £100!

any chance of some pictures of this bay so we can have a look

Can I have a link please on the vgate vs450 that you brought ? is it this one Bluemarktwo ?

Edited 3 December, 201510 yr by 1vw2many

Lambda sensor here http://www.ebay.co.uk/itm/Lambda-Sensor-VW-POLO-86C-80-1-3-CAT-Hatchback-75-BHP-Top-German-Quality-/400777933608?hash=item5d5039f328:g:uIoAAOSwfcVUIZax

TPS From the Club Polo Shop http://shop.clubpolo.co.uk/gt-3f-throttle-position-sensor-22-c.asp

I'll get some pictures of the bay to you in the next few days.

1VW2Many that looks like the right one, here's the link to the the one I bought:http://m.ebay.co.uk/itm/VS450-Vgate-Fault-Code-Reader-Scanner-Engine-ABS-AIR-BAG-For-VW-Audi-Seat-Skoda-/281280086251?txnId=1458080479018

Thanks for the links, kwijibo, hopefully I won't need both!!

Top man thank you..

If your engine keeps throwing up codes or it feels like it's struggling to keep running try checking fuel pump relay mine went and it still ran for a long period of time after but once replaced made it run 10x better than it ever had and it had similar problems to what you have now although I've now got another issue with mine 😓 Gts are just no fun unless they work that is for sure good look on fixing it bud 😊

Thank you simon, it usually stays running fine as soon as it gets warm but the idle drops under breaking and bogs under acceleration. Fuel pump relay will be my next thing to check if I have no joy with the scanner and sensors

Went out for a quick spin today with the lambda and TPS unplugged and it ran far better. It idled a lot lower but ran and picked up better. Can't say it was a great test as my scanner hasn't turned up yet so there will probably be a load of fault codes in the ECU

You might need the little 2x2 adapter to connect the scanner to the Polo loom by the bonnet release too; I'm not sure it includes this adapter.

Thank you, I already had one of those adaptors lying around. Looks like the scanner will still be a few days. Damn pre-christmas postal rush!

Got my scanner this morning! Plugged it in and the ECU was chock full of fault codes. It now runs 100 times better than it did! I've been our for a drive and started it a few times, no more codes being thrown up.

It's starting better but still really struggles if parked facing up a hill or steep downhill or with the car leaning to the left (cambered streets). Also still won't idle until up to temperature but then idles fine at about 920rpm

Still not throwing up any more codes. Starting from cold it will hold a 1k idle for about 30 seconds but will gradually drop and then start to hunt for an idle. At this point it is very difficult to keep it from stalling. Still fine once the temp gets about about 70 on the gauge

Edited 12 December, 201510 yr by Bluemarktwo

Better or worse with the lambda sensor unplugged?

Was worse with the lambda unplugged, it didn't clear up when it got to temperature solid couldn't hold an idle. It also didn't throw up an error code when it was unplugged

Could it be a poor earth from the lambda maybe? I can't think of anything else that would cause a problem that's so temperature dependant seeing as it's a new blue sensor as well

even if the lambda wasnt earthed out it still shouldnt be hunting for idle although if it wasnt earthed it would throw up an issue on the code reader