Auq cupra wont fire up help please.

[Green1788]

So last week at mod nats i took car to get was after jet washing car it refused to start so i left if 30mins went back and started then drove back to stoneleigh parked car up for the night.
Following morning i started car up it struggled then fired up whoever there was no throttle response and was running lumpy it then sucked last fuel from lines and shut down.
Since then the fuel pump is not priming and car not starting its turning over just no start.
I had fuel pump out and tested all good relays fueses are all good.
Then had guy plug into obd reader and there is no signal going to my ecm this is where i am stomped as have no idea what to do next.
I have been on the look for wiring diagrams to check all my wires make sure none broke but not had any luck with the diagrams.
I would really appreciate someones help or knowledge thank you.
Mk1 cupra 180bhp 2003

 

[mty12345]

Hi mate, are you 100% sure about the fuel pump relay and the ecm relay? What did he mean by no signal to the ECM? No power? If so was there a fault code?

 

[Green1788]

Yes all relays where checked working perfect.
Cant get any code because there is no signal.


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[mty12345]

Have you checked the big metal fuses on top of the battery as well? (middle one is fuel pump from memory) Also are you 100% sure about fuses 10,29,34,43 as they are all ECU related? If so then it could be a dead ecm, but is unlikely IMO. Much more likely is a lack of power getting to it for whatever reason.... wiring, corrosion etc. If you definitely have no connection to the ECU (but you can connnect to other modules) then the next step would be to have a look at the ECU itself and check that water ingress hasn't corroded the connectors. Also check that the ground point for the ECU is ok and that you have 12volts going to the 12v pin on the connector (if you can find the right pin-out.....be careful you don't short the wrong pin to ground etc too) If you have power and ground, then it must be the ECU itself at fault.

The only thing that puzzles me is the fact that in your first post, the way you described it starting and then dying sounded much more like a lack of fuel pressure than no power to the ECU. I guess it could have been the ecu dying, but it seems strange. With that in mind, it's sometimes possible for a relay to show as ok when checked with a multimeter, but carbon build up on the contacts inside the relay itself, can mean that it's unable to flow enough current to prime the pump or energise whatever circuit it is connected too. If all you have is someone elses word that there is no signal to the ECU, then i would double check that for yourself before you spend countless hours chasing a problem with your ECU, that could well be just dirty contacts on a relay or a fuse that looks visualy ok but has a hairline crack etc . Hope that's some help towards finding the issue.

 

[Green1788]

Hi thank you for the advice.
The car has now got a dead battery which was brand new last month would a bad earth aid in draining my battery?
I will get new relay and fuses and check it all over as like u say im taking someone elses word its fine.
Thank you again

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[mty12345]

You're welcome mate and i expect the flat battery is just from turning it over without starting. Starter motors draw so much current that the battery will go flat in a fairly short amount of time, even if it's brand new.

 

[Green1788]

Hi bud just an update on the car i have had it running again i took ecu out last night and kept in house today i plugged all back up the car fired up but every 10secs the idle would drop and eml and epc light flashed on then back off. It then died out i took key out and gove 10secs or so put key back in soon as turned ignition on 409 relay was clicking and the throttle body was flabing. So took 409 relay out checked place back in still clicking but car started with same idle issue so held rev at 2k and after a minute or to it started to idle normal and since is now starting and running fine im gonna replace the relay for piece of mind but the throttle body im guessing was resetting self from being unplugged.


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[mty12345]

Glad to hear you got it sorted. That is the trouble with relays, they can check out as ok then fail under load or just randomly. It's worth noting that the fuel pump relay is used to run multiple items, when you next scan the car you'll probably find about 11 fault codes related to it not latching.

 

[Green1788]

I havent replaced yet as waiting on it being delivered.
On starting car its now running 5sec then epc ling and eml both flash and drop revs any idea on what might be.


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[Andrewwright]

I havent replaced yet as waiting on it being delivered.
On starting car its now running 5sec then epc ling and eml both flash and drop revs any idea on what might be.


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Unplug maf and test

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[Green1788]

I have unpluged maf and coils everything i could think of.
Today i finally got a code from the car which is p2101 has anyone seen this before?

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[Andrewwright]

I have unpluged maf and coils everything i could think of.
Today i finally got a code from the car which is p2101 has anyone seen this before?

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throttle body. Wiring or maybe just knackered or maybe just a simple reset may help. If I was you I would disconnect the battery completely for 20 mins, switch the ignition on when the battery is out just to sap that last bit of power in the cable's...once the 20 mins is up, stick the battery back in and wait for throttle body to do it's thing (it will make noise as it's moving around setting itself,leave the car alone till it's done!) Then test. . May not be a full reset but basically the same thing will happen, if nothing happens then your throttle body or wiring if faulty. Does the throttle work at all?

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[Green1788]

While the throttle is resetting do i need ignition on?
Thank you for replying


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[Andrewwright]

While the throttle is resetting do i need ignition on?
Thank you for replying


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After the 20 mins is up, connect the battery, the noise will start, keys in or not if I recall right. Maybe wrong, may have to put the ignition on to get the noise to start but do not start the car and do not touch the throttle peddle. If the noise doesn't happen disconnect the battery and try again. Mine did it once but the battery was disconnected for hrs but I've read it only takes 20 mins for it to do a (reset).

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[Andrewwright]

It's worth a try and free to do yourself, may help cleaning the throttle body but you can't move the insides around at all by hand. Also the wiring is ok? Again may just be back luck and need a new one, cheap as chips second hand and piss easy to fit.

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[Green1788]

It's worth a try and free to do yourself, may help cleaning the throttle body but you can't move the insides around at all by hand. Also the wiring is ok? Again may just be back luck and need a new one, cheap as chips second hand and piss easy to fit.

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Yea easy to fit as long hS have vagcom.


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[Green1788]

After the 20 mins is up, connect the battery, the noise will start, keys in or not if I recall right. Maybe wrong, may have to put the ignition on to get the noise to start but do not start the car and do not touch the throttle peddle. If the noise doesn't happen disconnect the battery and try again. Mine did it once but the battery was disconnected for hrs but I've read it only takes 20 mins for it to do a (reset).

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Ok i will give this a bash tomorrow and will let know how i get on thank you so much for the replys


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[Andrewwright]

Ok i will give this a bash tomorrow and will let know how i get on thank you so much for the replys


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Worth a try mate. Give it a go, see if it ticks over alright, if it does take it for a slow drive max 40mph and when close to home give it a boot, see if it goes back to driving like crap, if it does it will need a proper alignment with vagcom. Failing all that and the alignment doesn't work, wiring and replacement is next step.

Also with the MAF, easy way to tell if it's broken, have the car running and unplug it...if there is no change in the engine sound/running the MAF is broken/needs replacing...if the engine sounds like it's about to die the and returns to normal once plugged back in the MAF if fine.

 

[mty12345]

Have you got the new 409 relay in now?
For the engine not to even run then there must be some serious issue with the EPC system as it will usually still run but just be limited to 2000rpm. Are you sure that you haven't accidentally pulled the connector off of the throttle pedal when removing the relay panel? Same with the electrical connection to the throttle body itself, is the plug secure?

I would get somebody with VCDS to scan it for you before you start replacing parts. p2101 is a generic code, the 5 digit VAG code would almost certainly tell you exacty what the problem is, as like andrew says it could be wiring or something else.

These are complicated cars and if you plan to keep it long term, then a copy of VCDS will save you countless headaches, and probably pay for itself within a couple of years too.

 

[Green1788]

Have you got the new 409 relay in now?
For the engine not to even run then there must be some serious issue with the EPC system as it will usually still run but just be limited to 2000rpm. Are you sure that you haven't accidentally pulled the connector off of the throttle pedal when removing the relay panel? Same with the electrical connection to the throttle body itself, is the plug secure?

I would get somebody with VCDS to scan it for you before you start replacing parts. p2101 is a generic code, the 5 digit VAG code would almost certainly tell you exacty what the problem is, as like andrew says it could be wiring or something else.

These are complicated cars and if you plan to keep it long term, then a copy of VCDS will save you countless headaches, and probably pay for itself within a couple of years too.

Hi bud yes new relay is changed. The csr does run just doesnt run right every 5 to 10secs the epc and eml flash up causing revs to drop by at least 500rpm.
Where would i get a copy of the vcds do you need a lap top with it also? Thanks again for replys

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