Dear All I am new to this forum but find it very interesting and helpful. I am now hoping someone out there can help me in my hour of need! Ok, so a little background history for you. The car wouldn't start and because of over fueling and I was told it was a faulty ECU by Bosch. Got a new ECU, then they said it was the injectors staying on and flooding the engine, I changed the injectors, tested them yesterday, all 4 prime the engine for 2 seconds and then stop, then if I turn the key again to start the engine they have a good cone like spray and stay on, is that correct or should it be intermediate sprays of fuel? I have a spark but one thing I have come across is that the blue temp sender has no reading when I use my vault meter and the plug adapter neither. So I am now thinking, if I change the blue temp sender and the plug (as looks like its a bit contaminated with coolant) i'm thinking this should solve my over fueling problem and start!??? Can anyone give me some advice on the above and what the next stage is once I get the new blue temp sender? I read somewhere that you are supposed to put the engine past 3000rpm 3 times and this resets the ECU? So any pointers help and should I reset the car up by hand and then bosch to map the ECU or fine tune it? Thanking you in advance for your time and help......
Has there been any work done on the gearbox or clutch just before this trouble has arisen? What you describe sounds depressingly common. There's an earth lead that goes onto the gearbox, which gets disconnected during e.g. a clutch change. Then it doesn't get put back. Return currents from the starter motor then flow in 'bad' ways back to the battery, including via the ECU, which fries it causing the injectors to be on 'full-time, full-bore' which is bad. Hope I'm wrong!
Mines over fuelling too at the mo so if I find out what's causing it I'll let you know, about to swap out jets and blue temp sender.
when i first got mine the blue temp sensor was gone and all it did was make it misfire and cough quite a lot but with it disconnected the car ran okish at least until i could buy a new sensor.
ok, thanks for your replies, keep me posted on any updates and more ideas you may have to help me. I have more time maybe tomorrow to try and fire her up and see if she starts, I'll keep you updated on my progress or should I say lack of progress!!!
if the pump runs continuously when the key is turned 1 click then the ecu is blown, if it primes then stops then this usually means its ok. to start with i would look over the wiring carefully, then replace the blue temp sender if its the original or a pattern part. 1st check would be the box earth as above, next i would look at the brown and brown/white wires to the side of the head. the ecu earths here so make sure the ring terminals are clean and the wires are undamaged. revin the engine over 3k 3 times puts tghe ecu into setup mode, it wont work unless the blue sender is also unplugged. this allows you to change the idle and co settings but it wont reset the ecu or anything. worth looking at the ignition timing too, this is all in my digifant tuning guide
thanks John. The pump primes for 2 seconds then stops, so hopefully that is ok. The blue temp sender is in the post to me and in the meantime I am checking all the wiring very carefully as you suggest. I'll double check earths aswell. Thanks for your guides and the clarification on the engine rev 3 times etc etc, very useful. I'll report back with the outcome next week.....fingers crossed for a positive result just to keep the Mrs happy!!
Ok, so I have cleaned up all the earths and put her back together again and she starts, but she starts with issues which I hope you can help me with. I haven’t received my new blue temperature sender yet so she is starting and running roughly. She also has a new ECU in there which was set up and mapped for a different Golf GTI 8v. My main question is, she will only start without the injection fuel rail plugged in, if I plug that in before I start it she won’t start. If she’s ticking over and I plug the fuel rail connector in she dies. Can anyone tell me the reason for this? What’s my next step now? I am hoping my blue temp sender arrives this week, get that fitted and perform the rev 3 times over 3k to put the ECU into set up mode. Then what? Can anyone tell me the future please!!
are you sure its starting with the fuel rail unplugged? because when the fuel rail is disconnected no fuel at all should be getting thru the injectors. that would suggest fuel is getting in some other way pics?
oh, and you dont need the blue sender to perform any of the setup procedures, as they should all be done with it disconnected anyway
Ok, tried her again today after reading your posts and I see what is happening. When the fuel rail is plugged in via the switch it won't start as it floods the engine, then I disconnect the switch and turn her over and she fires, she idles for a few seconds then dies, so she must be burning and surving on the fuel in the engine from the previous over fueling when the switch was connected. I have tried getting her started and then connecting the fuel rail switch and then she just dies. This is the problem I had originally and Bosch told me the fuel rail needed replacing, which I did, with all the injectors and fuel regulator, now it looks like I am back to square one! So, its over fueling, could this be a fuel pump problem? A fuel filter? Even though when I changed the injectors and rail I tested them and they primed for 2 seconds and stopped and then the injectors all flowed with a nice cone spray. So now I am alittle confused on where to go from here? Any thoughts are most welcome!
right that makes more sense. it sounds like the new ecu is blown as well, is it still open circuiting the injectors? what you need to do now is go over the battery wiring very carefully to stop it happenign again. the battery -ve is the most important factor here, you must ensure the -ve lead to battery has a good clean connection to the gearbox/block. the best way to do it is to fit the late mk2/mk3 rear gearbox/engine mounting bolt which has a stud on the end where you can run your main gearbox earth lead. I'm not sure if this bolt will fit your van though! but if you can find some similar way to do it then you're sorted. one thing i have suggested in the past is to run a good chunky battery earth direct to one of the main starter motor mounting bolts
Thanks again for the responses, again much help for a novice like myself. This however has happened before with the over fueling problem, infact this is where it all stems from! The garage I took it to sorted around the problem (not fixing it) telling me they fixed it ......however, this would only last for so long, a few months and then the over fueling and starting problems began again. This is why I took it to Bosch and they told me it was the ECU, so I got a new one and then they tell me its the injectors so I replace all them and now still the same problem of over fueling. This is why I am here asking people in the know and understand the frustration of a none working vag!! John, I ask you a question to expand my knowledge, if the ECU is open circuit upon the injectors how did the garage fix that to trick the ECU? is that possible? Is there a work around? So, anyone fancy a working holiday on my car in Valencia!!!haha
I still have the similar overfuelling issue at the mo and I'm going down the injector route, will swap them over the weekend hopefully and repaort back. Also got a blue temp sender to try. Just worried that I have an ecu prob too....
Test the resistance of the blue sensor engine coolant sensor against temperature. let us now what you find.
cant think of any way to fix an open circuit ecu without changing it for a new one! unless they opened it up and fixed the damage
