Hi.

I really hope someone can help. I have a 1988 polo 1.4cl auto that keeps stalling while driving. I have replaced the throttle body and put a new battery on. If I take my foot off the accelerator it sometimes comes back to life....if not I slip it into neutral and use the key. It also doesn't get up to temperature staying below 70° and drops when I put the heater on. Not sure if the two are connected. Its only done 39,000 miles and it's a nice little car when it runs properly. 

Thanks in advance.

The temperature not exceeding 70 when it should be near 90 is very likely to be the thermostat (if there's enough coolant/antifreeze in the system).

Is the heater also slow to warm the car if on from the start?

 

Thermostats and o-ring are around £10 and fairly easy to change. 

I'd advise new coolant too if you don't know car's history.

 

I don't think there was a 1.4 engine fitted in 1988 (which may be UK F or G registration) only 1.0 or 1.3.

So I'm not sure about stalling. A warm inlet manifold (heated by coolant) would help economy.

Is the crinkly warm air hose from exhaust manifold in good condition?

 

If it was a petrol carburettor engine not throttle body I would have some more suggestions.

didnt make an auto in 88 or mk2f either....confirm what car you have ?

If EFI intermittent stalling is likely to be ignition system related, crank of cam sensor. Depending on the sophistication of the ECU when sensors are unplugged that will often kill the engine so worth checking the plugs and pins are tight. 

On 28/01/2022 at 07:43, steveo3002 said:

didnt make an auto in 88 or mk2f either....confirm what car you have ?

Sorry its a 98....typo

On 28/01/2022 at 07:43, steveo3002 said:

didnt make an auto in 88 or mk2f either....confirm what car you have ?

It's a 98....sorry typo

Definitely expect this is a crank sensor. Had this on a 2000 lupo years ago. 

Ah that makes sense then, so you have a MK4 on this forum not a MK2F 

 

Do you know what engine code you have ? it's on the logbook the engine serial number should begin with 3 letters that's the code. as this well tell us if you have a crank sensor as mentioned above or just the cam sensor in the distributor and these are known for going bad especially when warm the engine cuts out then is difficult to restart until it cools down 

 

When you replaced the throttle body did you do the VCDS alignment procedure ? as this will affect how it drives, the low water temp is almost certainly the thermostat not closing properly again a very common fault when you replace it check the cover there is a bridging piece that the thermostat pushes against and they are prone to breaklng also only replace the thermostat with a genuine VW one not one from ECP/GSF as the quality is questionable at best   

Hi...thanks for your help.

Engine number is APQ017038

I was told to just bolt on the throttle body so no didn't do the procedure you mentioned. It's only done 39000 miles...when I first put the throttle body on it went without fault now its stalls about 6 or 8 times on the 20 min drive to work. I'm a bike 🏍  person normally so not a great knowledge of cars.

OK the APQ only has the cam sensor in the distributor no crankshaft sensor, so that's a possibility, a scan for any stored fault codes might highlight this 

 

The throttle body adaption method can be overcome by driving the car for about 20/30 mins using varying throttle loads, it's easier to do this on a manual rather than auto as the gearbox will keep trying to change gears to match the throttle input, so I would probably rule that out as a cause, on the drivers side end of the inlet manifold is the inlet air temp sensor and manifold absolute pressure sensor and this combined unit can suffer with oil contamination so might pay to remove it 2 torx screws and spray clean it with some carb cleaner, don't use a brush or anything similar as it's quite a delicate item.

Very helpful thank you i will get on with that today and let you know how it turns out. The car has been to two so called mechanics that couldn't find the problem. Cheers 🍻 

On 30/01/2022 at 00:15, nige8021 said:

OK the APQ only has the cam sensor in the distributor no crankshaft sensor, so that's a possibility, a scan for any stored fault codes might highlight this 

 

The throttle body adaption method can be overcome by driving the car for about 20/30 mins using varying throttle loads, it's easier to do this on a manual rather than auto as the gearbox will keep trying to change gears to match the throttle input, so I would probably rule that out as a cause, on the drivers side end of the inlet manifold is the inlet air temp sensor and manifold absolute pressure sensor and this combined unit can suffer with oil contamination so might pay to remove it 2 torx screws and spray clean it with some carb cleaner, don't use a brush or anything similar as it's quite a delicate item.

Hi. I didn't get round to looking at the car this weekend. As you probably guessed I'm not mechanically minded at all.....do I replace just the sensor in the distributor or the whole lot.

I've looked online for one but there seems to be two or three different types.  Can you help me out please 🙏 

You can replace just the sensor but it does require a bit of mechanical knowledge to strip down the distributor, the correct part number for a complete distributor are Bosch 0 905 202 AB Marelli 0 905 202 AE or factory refurbed 030905 237 GX

 

https://volkswagen.7zap.com/en/rdw/polo+derby+vento-ind/po/1998-158/9/905-905030/

On 30/01/2022 at 00:15, nige8021 said:

OK the APQ only has the cam sensor in the distributor no crankshaft sensor, so that's a possibility, a scan for any stored fault codes might highlight this 

 

The throttle body adaption method can be overcome by driving the car for about 20/30 mins using varying throttle loads, it's easier to do this on a manual rather than auto as the gearbox will keep trying to change gears to match the throttle input, so I would probably rule that out as a cause, on the drivers side end of the inlet manifold is the inlet air temp sensor and manifold absolute pressure sensor and this combined unit can suffer with oil contamination so might pay to remove it 2 torx screws and spray clean it with some carb cleaner, don't use a brush or anything similar as it's quite a delicate item.

Thanks again for all your help.

I have fitted a new distributor, replaced the throttle body, cleaned the sensor you mentioned, new air filter and oil change. The car is running 90% better; however, and this is the bizarre twist to the tale. It still stalls but only after turning right quite sharply, ie roundabout or twisty country roads, I just take my foot off the gas and it kicks back into life....apart from twice where I have had to whack it in neutral and use the key.

I really can't think what it is.....I'm flummoxed.

Thanks in anticipation 👍

The fuel lines run down the right hand side of the car, so it could be getting fuel starved, maybe a lift pump starting to die. What's the fuel filter looking like?

5 minutes ago, Yeti said:

The fuel lines run down the right hand side of the car, so it could be getting fuel starved, maybe a lift pump starting to die. What's the fuel filter looking like?

Thanks for replying.

Fuel filter was my next thing to change going to do it at the weekend...can the fuel lines be blown through?

I haven't been under a 6n in years, so I can't remember. I'm not sure if they're moulded on, or if there's a rubber joiner on the ends. I think they're like a 2f with an accumulator, filter and pump behind the o/s/r wheel, so I suppose the other thing could be if the accumulator's damaged or full of crap. The fact it's doing it on right turns makes me think it's something along those lines. 

14 minutes ago, Yeti said:

I haven't been under a 6n in years, so I can't remember. I'm not sure if they're moulded on, or if there's a rubber joiner on the ends. I think they're like a 2f with an accumulator, filter and pump behind the o/s/r wheel, so I suppose the other thing could be if the accumulator's damaged or full of crap. The fact it's doing it on right turns makes me think it's something along those lines. 

That's  a great help thanks, I thought I was imagining things but I tested my theory on the way home tonight and it stalled just after turning right. I'll get on to it at the weekend and post my finding... thanks again for your help Yeti 👍👌

does it stop dead or fade away ?

i would expect a fuel problem to fade away slightly rather than go off like a switch..and if had ran dry then a little more than normal cranking to restart it

 

you could run the engine and push n pull on all the wiring see if it dies 

Hi thanks for your reply.

It fades and doesn't always cut out completely. If I take foot off the gas it kicks into life again. It seems to happen more when tank is less than a quarter full.

ah yes then i would agree to look at the fueling system