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Polo 9N 2004 1.4 FSI AXU engine trouble.
Hello everyone!
First of all, sorry for posting this in English. I'm not from Germany and unfortunately English is the only international language I know.
I'm having some trouble with my 2004 VW POLO 1.4 FSI (engine code AXU) and i'm hoping someone here might be able to help me.
The car refuses to start most of the time (90%) at the first key and it takes several tries for it to actually start. Sometimes it starts wonderfully, sometimes i have to spend 10 minutes trying to start it in order for it to start.
When it does start, the idle fluctuates. Not a lot... But enough to make the whole car shake like the engine is beginning to stall. It never actually stalls but the RPM dips from around 700 RPM to around 600 RPM, then it goes back up and then it dips again and so on and so on. If i'm actually driving it, the engine works normally.
Here is a short video of the starting trouble i am getting:
https://www.youtube.com/watch?v=zvGXiIICGrM
The ECU doesn't have any errors whatsoever and i've taken the car to several mechanics and neither of them couldn't identify what was actually wrong with the car. Each of them gave a best guess that the next mechanic i went to, in hopes for a more definitive answer, quickly dismissed.
Until now i've heard the following possibilities.
- Something electric, like a cable snapped in the harness (but that would not allow the car to start at all)
- Injectors (but that would make the engine run erratically when driven)
- Fuel pump (But i can hear it work every time i put the key in and if it were the fuel pump, the car would also not start at all)
- Fuel injection high pressure pump (Again, the car would either not start at all or the engine would stutter and stall while driving)
- Timing chain (2 different mechanics checked out the chain and confirmed it was okay)
- Cam shaft issues
- Throttle body needed cleaning (done that, still no improvement)
- EGR valve (also cleaned, no improvement)
- Catalytic converter (replaced)
I have already invested a lot more money in this, than i have actually spent on buying the car...
Can someone please help me with some advice? I can't sell it in this condition and i'm also afraid to take it out for a drive, fearing that i will have to leave it somewhere in the middle of the street if it dies completely.
Thank you all in advance!
I'm really looking forward to any type of advice you may have on this.
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11 Antworten
First try a new Temperature Sensor. The Right amount of gasolene is calculated on the temperature values wich is very Important especially when Starting the Engine. The temperature Sensors are responsible for a lot of Faults in the VW Concern. I will send you a link for the Right Sensor this afternoon wich is only 5 €.
If the ECU dosen't drop any Errors whatsoever we have to think "Whats normal for the Car that it wouldn't start?"
And if thats the case we could erase the Fuel Pressure and Air, that left is a spark. Do you have a spark when cranking the engine without it running? You know what i mean, when the error appears.
Zitat:
@larry100 schrieb am 16. August 2020 um 11:07:27 Uhr:
First try a new Temperature Sensor. The Right amount of gasolene is calculated on the temperature values wich is very Important especially when Starting the Engine. The temperature Sensors are responsible for a lot of Faults in the VW Concern. I will send you a link for the Right Sensor this afternoon wich is only 5 €.
That is something i didn't try yet. But it's worth taking a look! Thank you!
Zitat:
@BlackY092 schrieb am 16. August 2020 um 11:07:33 Uhr:
If the ECU dosen't drop any Errors whatsoever we have to think "Whats normal for the Car that it wouldn't start?"
And if thats the case we could erase the Fuel Pressure and Air, that left is a spark. Do you have a spark when cranking the engine without it running? You know what i mean, when the error appears.
I forgot to mention that i replaced the spark plugs recently. Still no improvement. But thank you for the suggestion!
Zitat:
@AdrianF88 schrieb am 16. August 2020 um 11:15:24 Uhr:
Zitat:
@BlackY092 schrieb am 16. August 2020 um 11:07:33 Uhr:
If the ECU dosen't drop any Errors whatsoever we have to think "Whats normal for the Car that it wouldn't start?"
And if thats the case we could erase the Fuel Pressure and Air, that left is a spark. Do you have a spark when cranking the engine without it running? You know what i mean, when the error appears.
I forgot to mention that i replaced the spark plugs recently. Still no improvement. But thank you for the suggestion!
Im not talking about the spark plugs, i'm talking about if you get a spark at all. Take one spark plug out and put it into the ignition coil and see if you get a spark at all.
Zitat:
@BlackY092 schrieb am 16. August 2020 um 11:43:05 Uhr:
Zitat:
@AdrianF88 schrieb am 16. August 2020 um 11:15:24 Uhr:
I forgot to mention that i replaced the spark plugs recently. Still no improvement. But thank you for the suggestion!
Im not talking about the spark plugs, i'm talking about if you get a spark at all. Take one spark plug out and put it into the ignition coil and see if you get a spark at all.
I understand now. Thank you! I'll have the shop take a look at this. But if i didn't have spark, wouldn't i get cylinders misfiring? The car drives perfectly once it gets going.
Sorry, but most of in your mind simple logical argumentations are not convincing because the car's electronic and the possible inside faults are much more various.
And think about the ignition coils as well.
The reason behind erratic idle could be a leak in air intake and/or exhaust.
Zitat:
- Fuel pump (But i can hear it work every time i put the key in and if it were the fuel pump, the car would also not start at all)
- Fuel injection high pressure pump (Again, the car would either not start at all or the engine would stutter and stall while driving)
What about checking the holding pressure (back pressure valve) of the fuel pump inside the fuel tank?
If it's faulty it would take a while until the pressure is back only for the first engine start.
Zitat:
@Talker1111 schrieb am 16. August 2020 um 13:16:47 Uhr:
Sorry, but most of in your mind simple logical argumentations are not convincing because the car's electronic and the possible inside faults are much more various.
And think about the ignition coils as well.
The reason behind erratic idle could be a leak in air intake and/or exhaust.
Zitat:
@Talker1111 schrieb am 16. August 2020 um 13:16:47 Uhr:
Zitat:
- Fuel pump (But i can hear it work every time i put the key in and if it were the fuel pump, the car would also not start at all)
- Fuel injection high pressure pump (Again, the car would either not start at all or the engine would stutter and stall while driving)
What about checking the holding pressure (back pressure valve) of the fuel pump inside the fuel tank?
If it's faulty it would take a while until the pressure is back only for the first engine start.
Thank you so much for the suggestion! You are actually the second person to suggest a problem with the fuel pressure! The other person suggested it could be a leak in the fuel rail or a leaky injector. But at least now i have two people pointing me to fuel pressure! At least i know the general way in which to tell the shop to look! Thank you again!
Zitat:
@larry100 schrieb am 16. August 2020 um 13:17:06 Uhr:
https://m.motointegrator.de/.../...-kuhlmitteltemperatur-autlog-as2004
Thank you! I'll try to buy one and replace it myself. See if that helps.
@AdrianF88
It is a long time ago, but were you able to solve the problem? Was it the temperature sensor causing the trouble?