Hi I am having problems starting my polo, turn ignition engine fires, revs for a couple of seconds then dies. Can anyone point me in the right direction? I can get it to start sometimes but not very often.
I have recently replaced the fuel filter and spark plugs but again
when I turn the ignition I can hear the fuel pump switch on, although I cannot tell if its running constantly is there a way I can check for this?
For other info
Mileage : 90k
Reg : N, 1996
Many Thanks
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mashman
Classic immobilizer symptom. First, try another ignition key; there's a chip buried in the plastic and your's may be wearing out.
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the other key was lost sometime back so would that mean get a new set from VW? many thanks for your help
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First get sombody to plug it in and confirm that the reason for the non-start is recorded as "ECU blocked" in the engine ECU's fault-memory/live-status. That code signifies that the engine has been prevented from running by the immobilizer.
If that's there; scan the immobilizer ECU's memories for "key not recognised" code[s]. If present, remove and clean the plugs on the immobilizer box with proprietory electrical contact cleaner, or replace the key-reader coil round the lock.. Only if the immob still fails to recognise the key should you get into the performance of having new keys cut and coded-in to the car.
Your best bet is to find a mobile vehicle locksmith who can come out and do all this for you.
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good post didnt know that its now logged for future...................thanks screwloose
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It sounds as the immobiliser electrical connection has bad contact. These are know problem, had happened to our N reg Polo too. There is small electronic module (immobiliser) underneath the steering wheel. You need to discoonect the connector and try some contact cleaner or WD40 on the connectors plug/socket.
This cured our problem. Give this a try before going to get a scanner etc. Hope this helps....
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There is another way to confirm this if you've got a bit of knowledge of the system.
Use a voltmeter to check if you have a switch at pin '0' of the Hall Sensor when cranking the engine. If you do have a switch all the time but both the HT spark and injector switching are both lost together after a few seconds then the problem is almost certainly a faulty immobiliser transponder or key. If you have no switch, or don't lose both HT and injector switching at the same time, or only lose one then the problem is not likely to be immobiliser. The easiest way of checking injector switching is with a noid lamp. Simply connect to an injector plug and crank the engine. If it flashes the system's working, if it doesn't it isn't. Having said that there are systems where a noid lamp will not work. This is because the ECU will sense the difference in resistance from a normal injector and shut it down. This is most commonly found in Japanese models. There's no reason however why you should have a problem with it on a VW.
The Hall Sensor has three pins. '+' which should show at least 5V with ignition on, '0' which is a switch signal to the ECU, and '-' which is earth. The ECU then sends a DC Pulse to the Ignition Module which is the centre terminal of the plug. The other two are an ignition 12V supply and earth. This DC Pulse (which can also be checked using a voltmeter) will also be lost after a few seconds if the immobilser is faulty, and the module will not switch the ignition coil, hence no spark.
Don't rule out bad connections in the fuse box, as they're not that uncommon on VWs of this age.....
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Many Thanks for all your answers, can you please descirbe to me where the small electronic module (immobiliser) is under the steering wheel? and I will check the connections
many thanks again
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If you look underneath the steering column, there should be wires that connects from the igntion key barrel to the electronic module.
If you still can't find it, post here and I will email you a picture of mine.
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great! found it cleaned connectors, car starts first time! Thanks a million to everyone that contributed to this post!
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Great to hear your problem is solved!
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