GolfGTIforum.co.uk
Model specific boards => Golf mk3 => Topic started by: 8vgti on 24 February 2007, 18:15
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Where is the ECU hidden in the car - is it under the bonnet or somewhere inside the car?
Cheers
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its under the plastic where the wipers are.
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thanks for that Carl. If I have a faulty ECU, what would I need to get a replacement from a breakers....do the codes just have to match from the one in my car to the one I get and would it simply be plug and play?
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You can't do that matey.
The in-built VAG engine immobiliser is coded to your key and another ECU will refuse to start the car cos the key would be unrecognised. You would have to get the ECU re-coded by a dealership to match your key or take all locks and the ignition barrel and smart-key to go wi the replacement ECU from the breakers.
No scrapyard ecu swaps wi vw im afraid :cool:
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oh dear I hadnt thought of that :cry: Lets hope its not the ECU then....will have to wait for the stealership to do their diagnostic check as my local garage could not identify the cause of the the non-start/poor running problem (thats why its now at the dealer). The fault codes that were coming up were for parts that my motor doesnt even have, so it looked like the ecu was scrambled.
Any idea how much it would cost to have an ECU re-coded to match my key??? :undecided:
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Dont know mate but someone here will soon post the amount.
I just had a thought. You could get the key to go with the ecu from the breaker (they might insist you take the ignition barrel too) but dont change it - get another key made where they can do vw keys (wi a code reader like mister minit keycutting or summat) and get them to cut a copy if your own key but wi the second key's transponder code. Then throw the one from the breakers in a drawer and hey presto - ecu swap! Only the new key will start the car but the original will still open the doors anyway - they will have the same blade but different transponder codes!
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A new ECU with key will cost £200 - £250.
Recode a second hand ECU to your car/key £80 inc p+p. I was quoted that about 3 years ago when I had my problems.
8vgti - mate before you get your fault codes checked again, change the ECU relay! A faulty relay doesnt show up in a fault codes check.
Also disconnect the battery for 15 mins. This will do a reset and should delete all the other faults. Or stop them showing up again.
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Cheers for the responses.
Could I get the an ecu and key from the breakers and then just swap the chip from within the key with mine?
Len - I have tried everything mate and the ecu relay was the first thing I tried as I have had that problem before (see the early post on the huge post about golfs cutting out and oil light flashing!!!).
The story is....car was running fine, left it for 4 days and then when I came to use it, it just wouldnt start. It turns over, has plenty of spark and fuel is cutting through. Changed leads and dizzy cap as I have never done them, and tried all the usual relays. Took it to local garage and no faults came up on diagnostic. They had it for a week and tried various things and managed to get it running. Then when they were driving it was running really rough and you could only build up speed very gradually or it would die if put under any load. They turned it off and now all it does it turn over.
So I thought the only option to at least get a diagnosis and get the car back on the road (buses and trains arent good!!) would be to take it to the stealers. They cant look at it until tomorrow so will wait and see. MAy not be ecu I am just investigating options in case it is.
Len - where did you look at getting the ecu for £80??
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That was to reprogramme.
They had already done a full check on mine that cost me £55. And found nothing wrong with it!
Bear in mind that this was 3 years ago and they may not do that service any longer!
www.aptelectronics.com
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Further thoughts - if you are getting spark at the plugs and fuel my guess its not the ECU.
More likely timing. Or perhaps a sensor. Dunno if Golfs are the same but I had similar on my 405 Mi16 - turned out to be the water temp sensor.
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Also for ECU related issues in the Deals & Discounts section there is a place offering 5% discount on testing.
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Well VW have managed to get my car running and supposedly all they have done is to change the ecu relay.....unbelievably annoying as this is the first thing I tried before resorting to the garage as that has gone before. Whats the chance of buying a new faulty relay?????
The previous garage tried everything with no luck so will find out tomorrow if this works...if it does it is the most expensive relay ever.
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Well I spent nearly £300 before finding out it was the relay! How much did you spend?
Any other advance on 300?
:laugh:
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so far Len the cost has been £150 (£100 for the garage and 50 for dizzy cap, leads) and the £8 for what might be a faulty relay! VW have phoned this morning and the car starts but they havent driven it which was what happened last time and it played up.
If it is the relay I will well p*ssed off as that was the first thing I changed....oh well at least it will be running. I reckon the bill from VW will be at least £150, so I may come close to your 300!!!
will keep you posted
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Not heard of a faulty ECU relay preventing the car starting before so yea let us know.
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Well I spent nearly £300 before finding out it was the relay! How much did you spend?
Any other advance on 300?
:laugh:
Thanks to everyone on here when mine played up it only cost me the ECU temp relay :grin:
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Len, several years ago I had an itermittitent problem where the car would cut out and then eventually the car just wouldnt start, it would just turn over - the cure for this was to replace the ecu relay so it is similar syptoms this time - just that the ecu relay made no difference this time when i replaced it.
still no word from VW so I think that the test drive showed up the problem
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Hall sender, relay 30 ???
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Hall sender, relay 30 ???
changed it but made no difference.
Well got car back from VW and it was the fuel pump relay......which I had bought and tried before taking it to the garage so not happy that it could be a faulty one I bought :angry: :angry:
Grand total for two garages to sort the problem £272.00, plus the £40 I spent on leads and dizzy cap :cry:
Going to try the relay I bought again at the weekend to check that it is faulty and is not just an intermittent fault elsewhere that may have cured itself temporarily. Not totally sorted cos now if you take the car over 5000 rpm it feels like it has hit the rev limiter....will have a search on here cos I remember a similar thread a while ago. Why is it these costs occur just as you are looking to sell your motor??
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8v, if its hitting the limiter at 5000rpm its very likely its the timing belt thats out. Could be other things but in most threads this is the cause.
The same thing happened on mine. Timing was out, running lumpy and revving to 5000. After adjusting all has been fine.
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Well if it is the timing out then the VW garage should have found that!
But first disconnect the battery for 15 mins, totally both terminals. This is an ECU reset and sometimes it goes into "safe" mode.
If it still wont rev past 5000 then its timing! And then go back to the VW garage and complain!
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I only thought that from reading previous threads on here (altho also mentions dizzy and sensors). will try it tonight and see if that works. Cheers for replies
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I agree with len, the ecu is providing fuel and spark so if the timing belt slipped during start-up, or the hall sensor has a broken wire thats intermittent or is just dodgy, that could be the problem tho its strange no dtc's were thrown up. Jeez most mk3's throw a camshaft speed sensor error 000515 just cause you scan wi the engine not running. Did you see the output on vag-com, i.e. is the ecu communicating all the right info everywhere else?
check the cambelt timing. I had an audi 80 which the belt slipped on, musta happened during start up as it fired up ok and was warming up in the driveway, then it cut out and wouldnt restart. In desperation after weeks of tinkering, i decided to check this as i had done everything else. It was three or four teeth out and the tensioner was seized. I think it had heated the belt in that first few minutes and caused it to soften, stretch and jump. I sorted it, new belt etc and away it went like nothing had happened!
Remember that if you clean the TB or remove it or the accelerator cable then you must do a TB alignment with vag-com, its very easy to do. That can stop the car starting if not done.
Maybe the dizzy has slipped round or the wee carbon brush in the cap may be cracked or sticking - that causes similar problems to yours.
Or you dropped your key in a puddle and the chip is dead.....