Polo engine cutting out - help needed

[Robert C]

My daughter's 1994 Polo (1.3 engine) has had an intermittent problem over the last few months.

Back in May the engine cut out on a short run from the supermarket. The mechanic was called out, arrived 20 minutes later and the car wouldn't start when they tried it. They opened the bonnet to see why, they tried to start it again and bingo it started - even though they hadn't done anything. When they took the car in to their garage to take a proper look they replaced the distributor cap.

No problems then until early September. Then on another run it cut out again whilst in the outside lane of a fast A road. This time she paid more attention to exactly what happened. When it cut out everything died - engine stopped and all the electrics died - the only thing working was the battery light on the dash. She was unable to even switch on the hazard warning lights. With the help of anoher driver she managed to get it pushed off the road by which time the electrics seemed to be working again but the car wouldn't start. After a few minutes (maybe 10 or so) she tried again and it started. Ten minutes later though the car cut out for a second time (same problem). She called the RAC who got there in 30-45 minutes. She tried to start the car and it started immediately. The RAC man followed her home expecting the car to cut out again which it did not. We then took the car to my mechanic who checked the car over thoroughly and said that he could find nothing wrong with it. He recommended that we disable the immobiliser which had been fitted when we bought the car as he had had cases where this had been causing cars to cut out. We did this (and the immobiliser was removed from the car completely) and the car seemed to be OK.

Now two days ago (mid October) the car cut out again. The sequence was everything went off (except the battery indicator), then the electrics came back after about 10-20 seconds. The car would not start at that point but when she re-tried starting it a minute or two later it started. She took it back to her garage who checked it over again. Confirmed that they could find nothing wrong whatsoever mechanically and suggested it must be something electrical.

The only other thing to note is the car has occasionally had a situation where whilst driving along it seems to lose a little power and then, almost immediately back to full power. This may be related. The most recent check confirmed that there were no problems with the fuel line.
As the fault is very intermittent I am concerned about taking it to an electrician as they are unlikely to be able to replicate the fault whilst testing it. So my question is: anyone had similar problems and, if so, what was the ultimate cause? Any other ideas as to the likely fault? I would just like to point the electrician in the right direction of possible faults.

I have posted this on another forum too but I am worried about my daughter's safety as nothing seems to predict this fault occurring - no warnings, nothing.

Thanks,
Rob

[Crasher]

Which Polo is this, one of the last of the old shape or the first of the new 6N type? You can tell this from the chassis number which goes wvwzzz and then 80 or 6N. Initially I would say it is the distributor hall sender (for either of these models) as these often fail and will cause the car to cut and refuse to start but start again later when they have cooled down. What throws a spanner in the works is the loss of electrics although it can’t have completely failed as the ignition light is on. If it is a 6N, then the symptoms suggest to me the ignition switch BUT if that failed (which is very common on the 6N) the battery light may not come on. I think I would start with the switch and then the distributor. The distributor is best sourced directly from a VW dealer and they cost under £100 and come with a two year warranty. These have to be set up with a timing light and with the cars ECU in Basic Settings so diagnostic equipment is necessary. On that note, both possible versions of the Polo have reasonable diagnostics so a fault code read would be a good idea.

[Robert C]

Thanks Crasher for the ideas. It's an 80 not a 6N.

[Crasher]

More than likely it will be the distributor but have a code read done first. The type 80 uses the earlier plugs known as 2x2 so whoever reads the codes will need the appropriate adapter cable. The plugs are supposed to be attached to the side of the glove box under the dash to the right of the bonnet pull and both plugs are usually yellow but may be black and white.

[Robert C]

Thanks - will let you know how we get on

Rob

[Robert C]

According to the electrician there was a loose wire in the ignition which probably came loose when hot and going over a bump or something. As it cooled down it would settle again and work again.

Thanks for the help - fingers crossed he's fixed it.

Rob

[Robert C]

Oh no - the problem is back.

Having "fixed" the loose wire in the ignition the car she took it on a couple of four hours drives with no problems. Unfortunately it then suffered a catastophic failure belching out exhaust and overheating. This resulted in the cylinder head gasket having to be replaced.

My daughter picked up the car from the garage after the cylinder head gasket was replaced and drove home. The next day she drove to the shop (only about 5 mins away), went shopping for about 30 mins and then started driving home. About two minutes into the drive she was stopped at a traffic light when the engine cut out. This time the electrics did not die and she was able to restart the car immediately. She thought that maybe she had stalled so didn't worry about it. Next, as she came off a roundabout and headed uphill the car suffered its other problem - it lost power very quickly, almost going to stop then shot forward again as the power returned. This all happened in a very short timespan, only a second or two. However, about two minutes later she was just slowing down at another junction when the engine cut out again. Again the electrics were OK but this time the car would not re-start - she described it as the classic sound of a car trying to start but failing to do so. A friendly motorist helped push the car out of the way of other traffic. Then, after about ten minutes, just as she was ringing the RAC, she tried again and bingo it started.

She took it into the garage who took yet another look at it and decided the only thing that could be wrong was a worn rotor arm which they have replaced.

I have advised her to ask the garage about whether they had carried out the diagnostics suggested in previous replies and what they thought about replacing the distributor. In the meantime I thought I would check on this forum whether previous advice still held. I am particularly interested in whether the momentary loss of power could be related and could be caused by a failed distributor hall sender. Also, am I right in thinking that a failed distributor hall sender could sometimes run fine (e.g. a couple of four hour drives) and then cause the engine to cut out a couple of times in close succession?

All advice very gratefully received as this is becoming expensive...

Thanks,
Rob

[Crasher]

It does sound like hall sender failure as I said previously and these change how they misbehave according to temperature. Assuming the car is a 1.3 CL and not a GT, it will have the engine code NZ so the distributor will be 030 905 205 S which is now 030 905 237FX and from VW these cost £230 exchange. The hall sender is available as a repair kit under the VW part number 030 998 065 for about £146 from VW but is also available from Bosch under their number 1 237 011 076 and from a number of other companies such as Bremi and Facet. It is quite a fiddly job to install this repair kit.

[Robert C]

Thanks - that gives me some confidence. Will an ECU read say that there is a Hall Sender problem?

[Crasher]

Possibly and definitely if the code read is carried out with the ignition on and the engine not running so the read should always be done with the engine running if possible. The ECU on those can be a little blind to a faulty G40 sender (its component name) and often it ends up being an educated guess to change it. What is the engine code?

[Robert C]

Don't know about the engine code - will have to ask my daughter to find out.

However, some more news... she got the car back from the garage with the relpaced rotor arm. he had taken it on a couple of short runs and had no problems. She therefoer decided to take it on a longer run and see what happened. After about half an hour it stopped but this time it was more a gradual loss of power than the moer sudden stops she has had in the past. Also she reminded me that recently when it has been stopping there is a judder just as it is stopping.

I have also been doing some searching for similar faults and it is amazing how many VWs seem to get this problem. I'm a bit concerned at the cost of the replacement hall sender so wondered if any of these suggestions are worth exploring with the garage:

Fuel pump (someone with a 1998 1.3 Polo)

Throttle housing (P reg 1.4 Polo)

"carb icing" (apparebntly a problem on Polos - suggests that need to check the warm air pipe between the exhaust manifold and air filter, it may be damaged or missing and Check the vacuum operated flap inside the air filter to ensure that it moves to allow warm air intake (engine running!))

Ignition amp

Ignition coil (is this the same thing as the ignition amp?)

Fuel pump relay

And a guy with a 92 passat who said: wiring harness for the distributor, coolant sensor, and warm-up/idle control. This harness is below and to the passenger side of the ignition coil. All of the harness tape had been rubbed off and the wires were resting against a metal coolant flow pipe, (I believe its for the heater). The insulation of a red wire with a black stripe had been rubbed through and the wire was shorting to ground on the metal pipe.

And finally, something to do with the differential pressure regulator (another Passat)


Any thoughts as to whether it is worth exploring these first?

[Crasher]

Fuel pump, £170 to £180 depending on the engine code and I have very rarely had to replace one since the car was launched eighteen years ago. A blocked fuel filter is possible. The lift pump in the tank (£40 genuine) is a possibility, they often fail and can damage the main system pump but if this is the case, the main pump whines quite loudly.

Throttle body issues will not stop the car when driving and the type 80 1.3 Polo does not have a motorised throttle body on the NZ of 3F engines, only on the single point AAV. A fault code read would point out a throttle body steeper motor issue on an AAV.

Carb icing would be possible if it had a carburettor but it is fuel injection of either single point or multi point but we still have no idea which engine code is in the car so cannot identify the system.

The ignition amp is built into the coil and is not separately replaceable. These are prone to failure but normally die and that is it, no go!

Fuel pump relay, possible but unlikely. Again, the engine code would be extremely helpful.

The Passat is a completely different car apart from it having an engine and funnily enough, the exact same coil.

Differential pressure regulator! It does not have KE-Motroinc electro mechanical injection; it is electronic injection of either the Digifant or Mono Motronic variety. Again, if we knew the engine code it would make life easier.

I am sorry but I can’t help feeling you are clutching at straws here, the car has the same concept as most infernal combustion engines built in the last 120 years, citing every possible reason a car could cut out could make this post very long.

The cars engine code and a fault code read would be most enlightening! If you PM me the cars reg I will tell you what it is! Until then I am out of here…

[pkyp]

Hi Crasher,
I have a 1997 1.0L polo, which exhibits a similar problem.
Can be driven for hours no issue, then when I stall it, or sometimes try and start it after it has been driven, it fails to start.

The battery is good:fuel tank is full.

Sounds like there is no fuel getting to the engine,

Your point about the engine cooling down and the car restarting is almost the exact issue I see. After about 30 - 45 minutes, suddenly the car will start.

Can you advise me if this is the hall sender you mentioned eariler?
Thanks
PK>

[Crasher]

Possibly but your Polo is a 6N not a type 80 and has quite good diagnostics so I would get it fault code read first.

[Free_rhyme]

I had the same problem with my MK3 POLO. I ended up having to change the speed sensor (£400). Works fine now. Apart from the constant flashing from my dodgy temperature sensor, and ABS light on constantly. :S

[arjunf]

hi guys - i have a polo 1.6 cl auto. similar problems. first of all while driving it just cut out and stopped. i tried starting and the engine turned fine but didnt start. RAC worked out the engine coil had failed. had that replaced and it started fine BUT now there is the loss of power at different speeds cold or hot. While driving sometimes it seems it wants to change gear but then just loses power and slows down. IT DOESnt GO OFF so i can slow it down and then press down on thegas to speed up again. Not sure what this is..... my mechanic had a look but hasnt been able to work it out yet as its intermittent....

any other ideas?

arjun

[Crasher]

You need a fault code read on the engine and gearbox computers.

[arjunf]

hi thanks for getting back to me. the mechanic put on the diagnostic computer to the car and there was only one code that came up - it says "00609 - ignition coil short to ground 1" and thats it. the ignition has been replaced already by RAC (twice) so this one is only a few days old. is there anything else that would cause this fault ?

thanks
arjun

[Crasher]

If that code keeps coming back there is a problem. What is the cars year and engine type code (e.g. AEE)?

[arjunf]

car is a 1997 1.6 CL AUTO

ENGINE CODE : AEE 156687

[Crasher]

00609 Ignition output 1 Open circuit/short to earth

1) Wiring open circuit in earth wire
2) Wiring has short to earth


If this code keeps coming back with a new coil, you have a wiring fault which could be in the wire between the body and the engine or a poor connection where the coil picks up its earth.

[arjunf]

hi - thanks - i will get this checked but wil this be the cause of the car slowing down ?

[Crasher]

If the coil receives a poor earth, the spark will be poor so therefore will the engines power output.

[arjunf]

hi - my mechanic ckecked all the leads and couldnt find any prob with earth but he connected a new cable from battery to engine coil and all code cleared and never came back so i thought the prob had gone.........BUT as i was driving earlier it started jerking again as if it was about to lose power again..... so looks like something else is causing this....

any ideas?

[Crasher]

Fault code read and start from there.

[arjunf]

sorry i dont understand last message

[Crasher]

The first step would be to have a fault code read done and see what is stored. If it is the same code as before then that needs pursuing deeper and if there is another code, have that looked into. If there are no codes it is a fault outside of the ECU’s abilities to detect it and that helps as there are only certain things that can be.

[arjunf]

well once the new earth lead was attached the code was gone and never came back. so i am gonna drive it over the weekend as it did judder earlier and then see if any codes are back....

if not what do u think it would be?

[Crasher]

I will reserve judgement until I know the results of a code read.

[arjunf]

hi - crazy day - loss of power occured 4 times today .. once at 50 mph.... nearly resulting in an accident but anyway......... had the car checked again and this is the code :

00519 Manifold Absolute Pressure Sensor G71 - not a plausible signal. error occurs intermitently.

hope that makes sense to you.

thanks

[Crasher]

00519 Intake manifold pipe pressure sender -G71 Implausible signal

Possible causes

1) Loose contact
2) G71 defective

[arjunf]

where is it so that i can check ? if connection are ok i presume its faulty..how much do they cost for my car

[Crasher]

The G71 MAP sensor is on the right of the inlet manifold (quite tight to get at) and is referred to by VW as a “Thrust sensor” as it also contains the Inlet Air Temperature sensor. The part number is 036 906 051 but I can’t tell you the price form home.

[arjunf]

hi - had a new sensor fitted today - cost me 52 pounds from europarts.... the mechanic fitted it in two mins (just under the carb....)

driven the car today at various speeds upto 80 and so far it seems ok but i guess i will see what happens over the next few days and let you know.

appreciate all your advice.

arjun :biglaugh:

[Crasher]

It isn’t a carb, the AEE has multipoint fuel injection. I am pleased a new sensor has helped so far as they don’t often fail.

[arjunf]

hi - my car doesnt have fuel injection it has a carburettor

[Crasher]

The AEE engine has multipoint fuel injection. No Polo 6N ever had a carburettor. If it had a carburettor it would not have a Manifold Absolute Pressure sensor.

[arjunf]

so why does mine have a carb and a map sensor.... i can send u a pic if u want :confused:

[Crasher]

Post a pic if you like and I will show you what you think is a carb is actually a throttle body.

[arjunf]

ok shall i post it here or email it to u ?

[arjunf]

hi - :aargh4: the problem is back........... so now what shall i do....

do i have to get it checked all over again ?:aargh4:

[Crasher]

Without wishing to be rude about your mechanic, I think you should get it to someone who is more familiar with VW.

[arjunf]

:biglaugh:
well hes is a bit of an expert - used by many .... but not sure what to do now...i will takeit to him again but wondering whether i just get an electrician to look at it?

any recommendations from u ... whats next - i got new coil , new map sensor.....

it does it when accelerating and usually over 30mph and 4000rpm and when is about to change gear...

[Crasher]

Well I always seem repetitive over this but a code read first and act on what comes up. It is no use approaching it any other way as it is simply the easiest way.

[arjunf]

well so far the codes havent ben correct / helpful o could the main computer sensor thing whatever its calld be faulty ?:1zhelp:

[Crasher]

The codes aren’t always direct to the fault, they often require interpretation. “Barking at codes” as I call it often results in a waste of money. Post any codes that are stored.

[arjunf]

hi there again. the error code was same as above - MAP sensor - but help is at hand. some from VW who is an technical / electricians expert is coming on saturday to look at it - i spoke toi him and he seems to know what the prob is .... so i will keep u informed.

:D

[arjunf]

hi me again - ok i finally got the vw guy to check it ..... and guess what its the throttle body ( i think u mentioned this as a possibility) and i got this confused with the carb - its a single point injection...... anyway he reset the codes and programed the throttle body to understand max and min opening levels but it still lost power - so he said the throttle body is failing..... so thats what i need to get changed and i am gonna try and find out prices today - any tips ? when i get it changed do i have to reprogram or reset any codes?

[Crasher]

No it is not single point; the AEE engine has four injectors so it is multipoint injection. What fault code(s) did he get/clear?

[arjunf]

he had - BASIC SETTINGS NOT PERFORMED - reset that - and as mentioned he set the throttle to tell it what the settings should be - but the prob still occured so he said that it needed changing

[Crasher]

Did the same code come back?

[arjunf]

i have not had the code checked again but i am gonna get a throttle body for thirty pounds - then see what happens...

[arjunf]

hi again

i found this site selling new throttle bodies for around 80 pounds

http://www.anchorcarparts.com/proddetail.asp?prod=030133064f&cat=49

what u reckon

[Crasher]

Give them a go.

[arjunf]

hiya - just thought id let you know - the throttle body worked !!:biglaugh::biglaugh:

since i had it fitted i hav not had the problem.

thanks