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I have recently obtained a 1.1 single point inj mk3. It starts first time and will then run for a couple of days without problem. It will then stall and refuse to start. Leave it a few hours and it starts again.
Has new dizzy, rotor and fuel filter. It has no fault codes stored on the ECU. I have checked every thing I can think off. Anybody got any ideas. This is a lovely little car but its driving me mad.

when you say new dizzy, do you mean youve replaced the distributor itself or the cap? Sounds to me like classic symptoms of a dodgy hall sender on the distributor. (new distributor or new hall sender time)

my mk2 did this for a while, stopped the car, it stalled and then wouldn't start for bout 30 mins, when i had a check under the bonnet there was no fuel in the fuel filter, i had a check of all the hoses and things and then fuel just rushed through into the filter, did it when i moved the air box...probably not the same thing but just thought i'd let you know just in case

Gareth_GT_Hatch wrote:when you say new dizzy, do you mean youve replaced the distributor itself or the cap? Sounds to me like classic symptoms of a dodgy hall sender on the distributor. (new distributor or new hall sender time)

changed the lot used new cap and rotor but used dizzy from scappy. I thought it was hall sensor. Maybe the replacement one was also faulty. I may try a new one.
Thanks

Mk2Adam wrote:my mk2 did this for a while, stopped the car, it stalled and then wouldn't start for bout 30 mins, when i had a check under the bonnet there was no fuel in the fuel filter, i had a check of all the hoses and things and then fuel just rushed through into the filter, did it when i moved the air box...probably not the same thing but just thought i'd let you know just in case

Thanks fuel lines are clear

Try whacking a new coil on it and see if that helps.

Unlike a lot of people on forums. I don't tend to buy parts without diagnosing a problem.

Is the warm air hose on, intact, and the exhaust shroud corrosion free (standard culprit for carb icing)?
How's your service history?
When you say it won't start, guessing that it's still turning over ok?
What's the weather like when it does it? Cold? Misty?
What's your spark plug condion?
Are you getting a good spark?

omicron wrote:Unlike a lot of people on forums. I don't tend to buy parts without diagnosing a problem.

Is the warm air hose on, intact, and the exhaust shroud corrosion free (standard culprit for carb icing)?
How's your service history?
When you say it won't start, guessing that it's still turning over ok?
What's the weather like when it does it? Cold? Misty?
What's your spark plug condion?
Are you getting a good spark?

thanks It is a sp injector and I know the hedghog is working. It usually cuts out when warm but not always. It turns over fine. I am leaning towards coil or hall sensor but don't understand why it is fine again after a couple of hours. It has no spark but the trouble with inj systems is that one sensor can stop the whole thing. I'll change the coil next time it stops and see if that starts it again.

Hedgehog? Got me on that one?

I thought the 1.05's were all hamster driven?

Tell me how you diagnose problems without changing or replacing parts ?

Certainly, you can test certain electrical values, but not everyone knows these or has the equipment / knowledge to check.

As we are discussing an injection car, carb icing doesn't come into the equation.

No spark and cutting out sounds like classic hall sender failure.

Hardhitter - It's not a GT/G40, therefore it's single-point. Talk me through how that works in an environment that is totally immune from carb-icing? How do I diagnose without swapping parts out. In a basic engine like a polo, with my eyes, ears and a consideration of the facts. Oh, and with my lifelong loathing of spending money I don't have to. How do you diagnose things?

The SPI have a coolant warmed inlet manifold, with an electric pre-heater that looks like a hedgehog. I've never seen or heard of carb icing symptoms on an injection car, and I ran the original AAV SPI engine in my Polo for a few winters without the warm air feed with no problems.

I'm with Dan on the changing parts to diagnose - the Bosch Monomotronic might not be the most complex of systems, but swapping out parts is by far the easiest method.

Anyway, the problems described sound either like classic hall sender failure (which I presumed we could eliminate as the dizzy had been replaced) or the coil breaking down. The Polo coils aren't that reliable, and can start to work very intermittantly - my brother's GT had exactly the same symptoms you're describing, and sometimes went for months without the problem re-occuring. Then it slowly got worse and wouldn't run at all - stuck a scrapyard coil on and it was fine.

If you find it is the coil then I'd ultimately get a new item in the end, it'll be money well spent in terms of the fuel economy returns.

amstrange1 wrote:The SPI have a coolant warmed inlet manifold, with an electric pre-heater that looks like a hedgehog. I've never seen or heard of carb icing symptoms on an injection car, and I ran the original AAV SPI engine in my Polo for a few winters without the warm air feed with no problems.

I'm with Dan on the changing parts to diagnose - the Bosch Monomotronic might not be the most complex of systems, but swapping out parts is by far the easiest method.

Anyway, the problems described sound either like classic hall sender failure (which I presumed we could eliminate as the dizzy had been replaced) or the coil breaking down. The Polo coils aren't that reliable, and can start to work very intermittantly - my brother's GT had exactly the same symptoms you're describing, and sometimes went for months without the problem re-occuring. Then it slowly got worse and wouldn't run at all - stuck a scrapyard coil on and it was fine.

If you find it is the coil then I'd ultimately get a new item in the end, it'll be money well spent in terms of the fuel economy returns.

Thanks for all the help. Haynes do a manual on engine management and it tells you how to get the fault codes and what they mean. It was very usefull but did not solve the problem. I am going to fit a brand new hall sender and coil and pray that it does the job. Will post if it works.

Thanks for all the help Brand new dizzy cured the problem so it must have been hall sender

as a quick aside, there's an added benefit to the hedgehog - it traps the nuts what secure the airbox to the throttle body, should you be clumsy enough to drop one down there. (or, you could say, it acts a secondary, coarse air filter, should your usual one be perforated)

found a super shiny (polished from a year or more of 95 ron & rushing air) 10mm nut staring up at me when i dismantled the inlet manifold doing the engine over - without the hedgepig i'd not only have crap-all luck with cold starts, but would have been looking at a much more severely knackered engine a lot earlier.