UK-POLOS.NET - THE VW Polo Forum

For a while the tickover has been all over the place, especially on a cold start. Recently the car just refuses to start at all. Have replaced temp sensor, fuel pump relay and auxiliary air valve. It seems to work OK for a bit, then refuses to start. Any ideas before I push it over a cliff?

leads, plugs, dizzy cap, rotor arm

Does it misfire or just idle all over the place ? does it drive ok ?

The idle was all over the place, but actually seems to have settled down now. It did seem to be working for a few days, but then then it refused to start up. After swearing, head scratching wiggling wires and relays it did eventually start again. It usually goes like a rocket, but has been missfiring after refusing to start. The biggest problem at the moment is the random not starting.

.....

Get one from a breakers or a scrappy. Shouldn't set you back more than £30.

Karl.

Karl_CLCoupe wrote:Get one from a breakers or a scrappy. Shouldn't set you back more than £30.

Karl.

I think you'll pay more like £50, maybe more, for a GT ECU - as they're rarer. That's assuming the scrappy know what they're selling. Anyway, ECUs rarely go wrong - to me it sounds like you might have a dodgy hall sender in the distributor.

to me it sounds like you might have a dodgy hall sender in the distributor.

Would that cause the intermittent output from the ECU? The garage have had the ECU apart and checked all the connections. They seem to be OK, but the output is still dodgy.

Can you replace the hall sender or does it need an entire distributor? And how much is it likely to be?

yeah the hall effect sender is the primary sensor that controls the ecu. it tells the ecu that the engine is working, so if its not giving an output signal it will shut the ecu down which contols the fuel pumps.

ZBQW wrote:

to me it sounds like you might have a dodgy hall sender in the distributor.

Would that cause the intermittent output from the ECU? The garage have had the ECU apart and checked all the connections. They seem to be OK, but the output is still dodgy.

Can you replace the hall sender or does it need an entire distributor? And how much is it likely to be?

Hall sender is available from VW as a separate part - was about £85 last time I enquired, and a complete dizzy was £125ish. Apparently GSF do the hall sender on its own for £39+VAT - though ECP and your local Bosch dealer are worth a try too!

Is there a DIY test to see if the hall sender is working? The distributer and hall sender have been changed.

Latest development: The fuel pump relay is now switched independently from the ECU. The tickover also seems to be OK. The problem now is random kangarooing. Some of the time the car feels fine, the next minute the response is a little slow, then the kangarooing starts. Any acceleration at all, even just slowly setting off from a junction, feels like alternately stamping on the accelerator and the brake! Anybody?

faecetiously: you're letting it rev too low and being too harsh with the clutch?

not as much: rev it higher mate, that'll do as a stopgap - enough momentum in the flywheel and it will smooth that rubbish out

more serious question: how long does the kangarooing last and have you any better details of when it kicks in and how it continues etc?



doing the few miles from asda to home yesterday, car essentially frozen but for the glass, it werent too happy after running gentle at 30-40 for a while (probably colder than when i started!). noticably over 2000 it was fine with anything, around and some below 2000 you needed to be a little anticpative of what was coming as there was a half seconds delay on pushing the pedal and a response occuring (and it was slightly jolty). in the mid thousands it was starting to show signs of kangarooage - boot it from the overrun and there'd be just no power, then two or three progressive jolty kicks of increasing force in the back (not too bad, but the first one caused a slight banging noise from ?suspension? a couple times - i repeated the test a lot once i noticed), before the usual torque thrust resumed.
on a "good" day it'll be perfectly well behaved pretty much all the way down to idle before starting to sulk.

odd. right now im just assuming its down to temperature.

how long does the kangarooing last and have you any better details of when it kicks in and how it continues etc?

The problem is intermittent. The first time, the car had been standing for a few days at the garage. Despite being just above freezing it started fine, tickover at 1000 revs, went to pull away - no power. It felt like I was trying to pull off in 3rd. I checked I was actually in 1st and gave it some welly. It was very sluggish. I pulled over and let the engine warm up to about 80 before trying again. This time, it pulled away but started kangarooing. I got onto some dual carriageway and revved the arse off of it and it made no difference. It took ages to get up to 60 mph, and the only time it stopped kangarooing was on overrun. It lasted for about 10 to 15 minutes, gradually kangarooing less. I left the engine running for about 5 mins waiting for my other half to get out from work then set off again with only a bit of kangarooing on hard acceleration.

Next day, car frozen, started fine, ran perfectly on way to work.
Left work, ran fine for about 5 mins @ 70mph then for about 5 mins stop/starting in town traffic. Thats when it started again - there is a slight delay before anything happens when you accelerate. Every time you touch the accelerator you get quick jolty kicks of power, both under acceleration and when trying to drive at constant speed. Again it lasted for about 10 mins before gradually returning to normal.

Today, it ran fine 30mph + stop starting in traffic.

I had problems like this, a while back.

No power, jerky and very bad acceleration, funny idle, etc.

Turned out to be a knackered HT lead, and it was only firing on 3 cylinders. The engine can run surprisingly well on 3 cylinders, but you get those symptons.

But I'm assuming you must have changed HT leads by now.