Hi guys,

I came to start my G40 the other day after not running it for a while and it wouldnt start. I found that i had no spark. After performing a number of basic checks of the coil and dizzy etc i could not pin point the problem. As a last resort i decided to see if the engine would fire on my GT ECU, and it did. I then managed to lend a G40 ECU of a mate and sure enough the engine started up fine on that too.

I currently have a PSD turbo chip in my G40 ECU, so i tried changing this for the old chip i was using, however i still have no spark.

Just wondering if this problem has happened to anyone before and does anyone know if the ECU is salvigable? I have hardly any clue about the inner-curcuitry of the ECU, dont suppose there any internal fuses i could check?

Thanks

Tom

I'm pretty sure there are no internal fuses. Does the fuel pump prime (2 seconds buzzing noise from the back of the car) when you turn the ignition to on? If that's working it indicates the ECU itself is not dead (it means the processor inside is running it's program). The 'chip' is extremely unlikely to be a problem. There are various transistors inside that drive things like the fuel pump relay and the output to the coil/ignition module; it's most likely that one of those has failed. It's going to be pretty difficult to fix so your best bet is probably to find another one.

have you got the chip in the right way round? you can turn it 180 degrees and they still fit

Cheers for the quick replies guys.

As far as I'm aware the chip is in the right way round, as the engine has been running fine with the PSD chip and I've also driven it like that.

When i first turned the key i noticed that i couldnt hear the fuel pump priming. However i put this down to the fuel pump fuse becoming dislodged as i was tidying up some of the wiring.

Once this was corrected i noticed the fuel pump priming, and I've just checked it now and it is still priming. I'm not sure if its a possibilty but id be swilling to use my old GT ECU for parts to repair my G40 ECU, if somebody had enough knowledge to share with me on the subject.

As mentioned above theres a good chance i'm going to need another ECU, just dont want to right-off all my options just yet.

Cheers

bump anyone?

Sounds like the problem lies within your turbo oil feed mate, is it pissing oil out tom? yea? fuck it off and get an s13 in shares with me - otherwise you' black un's gooin' nowhere!

Your's sincerely,

Adam

Sounds like the problem lies within your turbo oil feed mate, is it pissing oil out tom? yea? fuck it off and get an s13 in shares with me - otherwise you' black un's gooin' nowhere!

Your's sincerely,

Adam

Haha piss off you noob, what do you know about oil feeds?

Yea might have to be an S13 the way I'm going!

Haha piss off you noob, what do you know about oil feeds?

Yea might have to be an S13 the way I'm going!

More than i know about low oil pressure on these crappy PY blocks lol, word on the street is that you wouldn't handle the big SX - you ask any racer, any real racer.

bump

any help would be much appreciated

Cheers for the quick replies guys.

As far as I'm aware the chip is in the right way round, as the engine has been running fine with the PSD chip and I've also driven it like that.

When i first turned the key i noticed that i couldnt hear the fuel pump priming. However i put this down to the fuel pump fuse becoming dislodged as i was tidying up some of the wiring.

Once this was corrected i noticed the fuel pump priming, and I've just checked it now and it is still priming. I'm not sure if its a possibilty but id be swilling to use my old GT ECU for parts to repair my G40 ECU, if somebody had enough knowledge to share with me on the subject.

As mentioned above theres a good chance i'm going to need another ECU, just dont want to right-off all my options just yet.

Cheers

The ECU primes the fuel pump when it is first powered up so that means the processor and 'chip' are working OK. (It also means that both relays associated with the ECU are OK) There are various drive transistors and interface chips for the sensors inside the ECU. The only things that should stop the ignition firing are a problem with the connection/interface from the hall sensor or the drive to the coil/amp. I think it would still run if any of the other sensors have problems as the ECU can detect that. The hall sensor triggers the ECU to fire the injectors and fire the ignition. To check the hall sensor is OK see if the injectors are opening when you crank the engine over - easiest to see if there is fuel in the cylinders after you've cranked it over for a while. If that works it's hopefully just the drive transistor for the coil/amp unit. You could take one out of the other ECU or you can get them from somewhere like Maplins (should be less than £1). Let me know if the injectors seem to work and I will try to work out which transistor needs changing for the coil drive and do you a picture.

Cheers for the quick replies guys.

As far as I'm aware the chip is in the right way round, as the engine has been running fine with the PSD chip and I've also driven it like that.

When i first turned the key i noticed that i couldnt hear the fuel pump priming. However i put this down to the fuel pump fuse becoming dislodged as i was tidying up some of the wiring.

Once this was corrected i noticed the fuel pump priming, and I've just checked it now and it is still priming. I'm not sure if its a possibilty but id be swilling to use my old GT ECU for parts to repair my G40 ECU, if somebody had enough knowledge to share with me on the subject.

As mentioned above theres a good chance i'm going to need another ECU, just dont want to right-off all my options just yet.

Cheers

The ECU primes the fuel pump when it is first powered up so that means the processor and 'chip' are working OK. (It also means that both relays associated with the ECU are OK) There are various drive transistors and interface chips for the sensors inside the ECU. The only things that should stop the ignition firing are a problem with the connection/interface from the hall sensor or the drive to the coil/amp. I think it would still run if any of the other sensors have problems as the ECU can detect that. The hall sensor triggers the ECU to fire the injectors and fire the ignition. To check the hall sensor is OK see if the injectors are opening when you crank the engine over - easiest to see if there is fuel in the cylinders after you've cranked it over for a while. If that works it's hopefully just the drive transistor for the coil/amp unit. You could take one out of the other ECU or you can get them from somewhere like Maplins (should be less than £1). Let me know if the injectors seem to work and I will try to work out which transistor needs changing for the coil drive and do you a picture.

Cheers mate. Well I'm pretty sure the injectors are firing as i can smell fuel after cranking it over with the faulty ECU. Like i said I've tried my mates G40 ECU and it runs sound on that so theres no problem with the hall sensor. Like you said it looks like theres a faulty ignition drive/ transistor within the ECU.

If you could get me a picture up pointing me in the right direction of where this is within the ECU and how to go about changing it that would be great.

Cheers again

Cheers for the quick replies guys.

As far as I'm aware the chip is in the right way round, as the engine has been running fine with the PSD chip and I've also driven it like that.

When i first turned the key i noticed that i couldnt hear the fuel pump priming. However i put this down to the fuel pump fuse becoming dislodged as i was tidying up some of the wiring.

Once this was corrected i noticed the fuel pump priming, and I've just checked it now and it is still priming. I'm not sure if its a possibilty but id be swilling to use my old GT ECU for parts to repair my G40 ECU, if somebody had enough knowledge to share with me on the subject.

As mentioned above theres a good chance i'm going to need another ECU, just dont want to right-off all my options just yet.

Cheers

The ECU primes the fuel pump when it is first powered up so that means the processor and 'chip' are working OK. (It also means that both relays associated with the ECU are OK) There are various drive transistors and interface chips for the sensors inside the ECU. The only things that should stop the ignition firing are a problem with the connection/interface from the hall sensor or the drive to the coil/amp. I think it would still run if any of the other sensors have problems as the ECU can detect that. The hall sensor triggers the ECU to fire the injectors and fire the ignition. To check the hall sensor is OK see if the injectors are opening when you crank the engine over - easiest to see if there is fuel in the cylinders after you've cranked it over for a while. If that works it's hopefully just the drive transistor for the coil/amp unit. You could take one out of the other ECU or you can get them from somewhere like Maplins (should be less than £1). Let me know if the injectors seem to work and I will try to work out which transistor needs changing for the coil drive and do you a picture.

Cheers mate. Well I'm pretty sure the injectors are firing as i can smell fuel after cranking it over with the faulty ECU. Like i said I've tried my mates G40 ECU and it runs sound on that so theres no problem with the hall sensor. Like you said it looks like theres a faulty ignition drive/ transistor within the ECU.

If you could get me a picture up pointing me in the right direction of where this is within the ECU and how to go about changing it that would be great.

Cheers again

I will dig out my spare G40 ECU (runs but causes misfires!) and trace the coil drive transistor. I will hopefully sort it sometime over the weekend.

Cheers for the quick replies guys.

As far as I'm aware the chip is in the right way round, as the engine has been running fine with the PSD chip and I've also driven it like that.

When i first turned the key i noticed that i couldnt hear the fuel pump priming. However i put this down to the fuel pump fuse becoming dislodged as i was tidying up some of the wiring.

Once this was corrected i noticed the fuel pump priming, and I've just checked it now and it is still priming. I'm not sure if its a possibilty but id be swilling to use my old GT ECU for parts to repair my G40 ECU, if somebody had enough knowledge to share with me on the subject.

As mentioned above theres a good chance i'm going to need another ECU, just dont want to right-off all my options just yet.

Cheers

The ECU primes the fuel pump when it is first powered up so that means the processor and 'chip' are working OK. (It also means that both relays associated with the ECU are OK) There are various drive transistors and interface chips for the sensors inside the ECU. The only things that should stop the ignition firing are a problem with the connection/interface from the hall sensor or the drive to the coil/amp. I think it would still run if any of the other sensors have problems as the ECU can detect that. The hall sensor triggers the ECU to fire the injectors and fire the ignition. To check the hall sensor is OK see if the injectors are opening when you crank the engine over - easiest to see if there is fuel in the cylinders after you've cranked it over for a while. If that works it's hopefully just the drive transistor for the coil/amp unit. You could take one out of the other ECU or you can get them from somewhere like Maplins (should be less than £1). Let me know if the injectors seem to work and I will try to work out which transistor needs changing for the coil drive and do you a picture.

Cheers mate. Well I'm pretty sure the injectors are firing as i can smell fuel after cranking it over with the faulty ECU. Like i said I've tried my mates G40 ECU and it runs sound on that so theres no problem with the hall sensor. Like you said it looks like theres a faulty ignition drive/ transistor within the ECU.

If you could get me a picture up pointing me in the right direction of where this is within the ECU and how to go about changing it that would be great.

Cheers again

I will dig out my spare G40 ECU (runs but causes misfires!) and trace the coil drive transistor. I will hopefully sort it sometime over the weekend.

Cheers mate, much appreciated!

The transistor to change is marked TC1 on the circuit board (it's a D shaped black thing with 3 wires). The transistor type is BC337. They are 17p from maplins electronics (www.maplin.co.uk - they have quite a few high street shops) or your other ECU will probably have the same parts in. When working on it you will need a fine soldering iron (you can damage transistors by overheating them) and I would put the ECU on a sheet of aluminium kitchen foil to avoid damage from static. It may be easiest to cut the existing transistor off and solder the new one onto the wire legs. Make a note of the orientation of the transistor before you remove it - the new one must go the same way round.

I can't guarantee it's going to fix your problem, but it's worth a try.

I'm having trouble attaching a picture - the transistor is below the rubber air pipe just before it attaches to the pressure sensor. It's marked TC1 just next to it.

I'm still having trouble with the picture - if you can't work out what to change from my description PM me your email and I wil send it.

just testing file uploads!

should work now.

Got a little update on this if anyones interested (been out to Ibiza, hence the delay). As suggested above i changed the transistor at TC1 on the circuit board and it works fine!

Absoultely top advice mate, much appreciated. Best 17p I've ever spent.

Got a little update on this if anyones interested (been out to Ibiza, hence the delay). As suggested above i changed the transistor at TC1 on the circuit board and it works fine!

Absoultely top advice mate, much appreciated. Best 17p I've ever spent.

Glad it worked!

Nick

17p ? Cant argue with that! Better than £80+ for a new ECU!

Exactly. I've got a chap at work to solder the transistor properly on the board for me this week so they'll be no chance of it vibrating loose.

would this faulty transistor cause the fault memory to show a map sender fault?

I am having a similar problem, my g40 runs but misfires its arse off and i have checked all the usual stuff that could cause it. i put a volkswagen fault reader on it and it showed map sender- implausible signal. i erased the fault to see if it was sporadic but it reappeared.

You said that this transitor was just before it attatches to the pressure sender- would this be the cause of the map sender not reading.

i have been looking for a replacment ecu and am having a lot of trouble finding one ( for an affordable amount) 17p sound a lot better to solve the problem.