2000 polo 1.9 sdi non-start

[tweedman]

Hello and thanks for taking the time to read this.I am trying to help out a friend who has a non starting polo sdi (engine code AQM).Approx 12months ago this same problem occured with the first symptons showing as power surging and engine cutting out with the glow plug warning light blinking.After various attempts at locating the problem the fuel filter was changed and this seemed to cure the fault.I was very sceptical that this was indeed the fault but it cured it for approx 12 months.The same problem has risen again and a change of filter has not cured it,suprise suprise.Glow plug light blinking when ignition is on and when trying to tow start various buzzers and warning lights come on including glow plug and oil light.I have checked the fuel shutoff solenoid for operation and checked for fuel at the injectors which there is.I realise that getting a fault code would be the ideal solution at the mo but just asking you all here if the fault rings any bells.

Regards Tweedman

[Crasher]

Give it a light shot of Easy Start and see if it runs but only spray a tiny amount at a time.

[tweedman]

Give it a light shot of Easy Start and see if it runs but only spray a tiny amount at a time.

Hi Crasher,
I am not at the vehicle at the mo but i would think it probarly would start for a sec or two with easy start but would this tell me anything?
I would have thought that with fuel at the injectors then it should start, but there must be something electronic in the pump stopping it.

[Crasher]

It is about the only test I can think of without a fault code read and then if that says nothing, pegging the engine to check the pump timing. I have had quite a few VEP (separate injection pump) engines jump a pump sprocket tooth for no apparent reason, often not long after a belt change. For the two that it happened to me with, we traced it to the make of belt we were using, a very large German electrical manufacturer beginning with B. Now we only use genuine VAG belt kits but I still see this on cars we have not done belts on.

[tweedman]

It is about the only test I can think of without a fault code read and then if that says nothing, pegging the engine to check the pump timing. I have had quite a few VEP (separate injection pump) engines jump a pump sprocket tooth for no apparent reason, often not long after a belt change. For the two that it happened to me with, we traced it to the make of belt we were using, a very large German electrical manufacturer beginning with B. Now we only use genuine VAG belt kits but I still see this on cars we have not done belts on.

I will check the timing the next chance i get but even if the pump timing was out i wouldnt have thought this would cause the glow plug light to flash with just the ignition switched on.For approx two weeks before this the car would sometimes surge but shortly after would return to normal so this is making me think that the pump timing should be ok,i may be proved wrong.Thanks for all the help thus far.

[Crasher]

A fault code read is a good step to take first.

[tweedman]

Hi,My friend had his car in the garage today and was told that he needed a new engine control unit costing around £700.Would anybody know if this a common thing to go wrong as hes scared of buying this and it not fixing the problem.Thanks

[Crasher]

No it is not common at all, I replace about 1 or 2 engine ECU’s a year out of the hundreds of cars I work on. Blaming the ECU is the retort of someone who does not know what they are doing, ECU failure is probably the least common component failure I see. What is the issue, car, year, engine code and any fault codes reported?

[tweedman]

No it is not common at all, I replace about 1 or 2 engine ECU’s a year out of the hundreds of cars I work on. Blaming the ECU is the retort of someone who does not know what they are doing, ECU failure is probably the least common component failure I see. What is the issue, car, year, engine code and any fault codes reported?


Hi ,All the details are above on my original post.No fault code was given to him.

[speed12]

Sorry to dive in and change the subject

But Just out of curiousity,

How does your freind find the 1.9sdi?

Has it been economical and until now fairly reliable?

Or would he recommend the 1.4tdi instead? I only ask as i am on the look out for a nice little polo for the work run.

[tweedman]

Sorry to dive in and change the subject

But Just out of curiousity,

How does your freind find the 1.9sdi?

Has it been economical and until now fairly reliable?

Or would he recommend the 1.4tdi instead? I only ask as i am on the look out for a nice little polo for the work run.

Car has been 100% reliable up util now.Very good on fuel he says.

[Crasher]

Tweedman, there is no way I would recommend an ECU without a specific fault code. Does the car start at all?

1.4 TDI every time, sweet little engine, the 1.9 SDI is horrid!

[tony_pennell]

Hi Tweedman,

See my post today re similar problems on my 2001 Polo SDI. Hopefully some kind guy will solve both our problems at the same timer!

tony_pennell.

[Crasher]

I hope he did, 3 years ago...

[tony_pennell]

Sorry, new to forums and didn't notice the date of that post. Do you have any clues on my problem ? If I knew which ecu pins to check, I could do a proper continuity check on the wires to the needle lift sensor - from your comments, it seems you have great knowledge of such things!

Tony.

[Crasher]

What is your engine code?

[tony_pennell]

Thanks Crasher. Don't know where to find the engine code, but I recall when buying parts they looked it up and said its AQ* or A*Q (* is another letter). Certainly got a Q in it! It's a 2001 SDI with Reg: Y287 FBR, so I suspect you have the means to find it from that.

Tony.

[Crasher]

It is a 6K Polo so basically it is not really a Polo, it is a Seat Cordoba and it has an AQM engine. Can you describe the problem again for me and have you had a fault code read carried out?

[tony_pennell]

Thanks Crasher, (http://www.vwaudiforum.co.uk/forum/showthread.php?130047-2001-Polo-SDI-start-run-problems-%28138-000-miles-on-clock%29&highlight=polo+starting)

The history and symptoms are detailed in my original post ( 2001 Polo SDI start/run problems (138 000 miles on clock) . I had an error code readout done (but didn't get a printout - I don't have the kit myself). The only code showing was 'needle lift sensor SC or OC to B+' (intermittent). This was cleared and immediately returned. I was advised to check continuity of wires and resistance of sensor with results listed in the post. "If all wires OK but snsor not, get a new injector/sensor. Oh, and change the crankshaft speed sensor, too, that sometimes helps with starting". At that point I sent my post. Have been offered S/H sensor + injector for £56 (1 month warranty) or £96 (3 month's warranty). I can pick up the other sensor tomorrow, if necessary. (http://www.vwaudiforum.co.uk/forum/showthread.php?130047-2001-Polo-SDI-start-run-problems-%28138-000-miles-on-clock%29&highlight=polo+starting)



Tony.

[Crasher]

You could have various fault codes; it would help to know which one it is.

17653 (P1245) Needle lift sender -G80. Short to earth

17654 (P1246) Needle lift sender -G80. Implausible signal

17655 (P1247) Needle lift sender -G80. Open circuit/short to positive

00542 Needle lift sender -G80 Input open/Open circuit/short to positive/Short to earth/Implausible signal

A new injector is part number 028 130 203 E £249.48 inc. VAT, I priced one up from Bosch direct and it worked out only a few pounds cheaper.

Checking needle lift sender

The needle lift sender signal is used to determine the Commencement Of Injection (COI). If it fails, the commencement of injection switches to open loop control according to engine speed and engine load. During normal operation the COI is controlled by a closed-loop function according to engine speed, engine load and temperature.

Testing

Disconnect 2-pin connector for needle lift sender (G80)

Measure resistance between connector contacts. Specification: 80Ω to 120Ω

If the specification is not obtained, replace No. 3 cylinder injector.

If the specified impedance is measure check the wiring between test box and connector for open circuit G80 harness plug pin 1 to ECU socket point 62 and G80 pin 2 to ECU socket point 55, the resistance should be no more than 1.5Ω. Also check wires for short to one another, to vehicle earth and to battery positive.

[tony_pennell]

Thanks Crasher,

The fault code was P1247 - SC or OC to B+. Your test procedure sounds like sense. I have a feeling one wire IS earthed. Will check tomorrow now I know which ecu pins I should be looking at.

Tony.

[tony_pennell]

Hi again Crasher,

I have checked everything as instructed. Resistance of sensor 90 ohms, Wiring resistance to ecu from plug - both less than 0.5 ohms. no shorting to each other, to earth or to positive.

I had to take the ecu out to identuify the pin numbers for checking (disconnected battery for 20 mins beforehand). It looked a mess, so I took it to pieces. Full of water/verdigris - not surprising, the 'hermetically' aluminium case has a ventilation hole to let the moisture in! Doh! Cleaned it off, dried it, and replaced a tiny 10 k resistor that had come adrift - ends corroded off. Re-sealed it (and sealed the ventilation hole!)

She started straight up and runs, but still has the same problem. Sometimes OK for half an hour, but sometimes reverts to limp mode, although it will (usually) go again normally if you switch off and restart it with the accelerator pressed. Ticks over at about 1000 rpm (is that normal?) The heater warning light is still flashing - I will get the error codes cleared and re-read this afternoon.

Any thoughts? Alas, it's looking increasingly like a replacement ecu rather than the No 3 injector?? Should I ask for any specific tests with the code reader?

Tony.

[Crasher]

Yes, you do need a replacement ECU but remember they are not plug and play.

[tony_pennell]

Hi Crasher,

Thanks for your cheerful news!

Codes read today were the old needle lift sensor fault and a (new) throttle sensor fault. Unfortunately they didn't do as I asked and record the actual code numbers.

Before I go mad on a new ecu (it must be coded to the car, I know) I will try one more thing: my garage man said that, since the coil on the needle lift sensor is apparently OK, it must be the needle sticking (IFthe fault is actually in the injector, rather than the ecu). He suggests I take the injector apart and simply clean it. I've done this many times with other 'ordinary' injectors to good effect. He said the only time you HAVE to replace the whole thing is if the sensor coil goes OC or SC, as it's not available as a separate part. Worth a try anyway!

Not sure about the throttle code bit. Had a similar problem on my Astra a year ago - and that WAS the ecu and cost me about £200! Hmmm.

I'll keep you informed.

Tony.