Leon mk1 auq bad cold start

[Dan K]

Hi can anyone help me in really stuck now. Basically when I start the car every morning and after work it starts really rough like its fuel starved. If I rev it hard it nearly sorts it out but then goes to do it again then stabilisers itself. It lasts about 10 to 2 seconds. If I don't rev it then it is like its choking and trying to cut out.

Once this has finished the car drives perfect

No codes are detected. I have tried a new genuine temp coolant sensor unplugged and cleaned maf. No difference. I cleaned throttle body and it didn't do it for about a week and then it's stared doing it again. Check coil packs all seem ok no brown on the bottom. Had a quick look at hoses all seems ok but without smoke test I suppose you never really no.

I have replaced all the rivets on the secondary air pump about year and half ago.

Any input would be great I'm really stuck now I haven't got vag com either

 

[Alexis27]

Fuel filter?

 

[Dan K]

The fuel filter was replaced on the last service. Could this still be the fault.

 

[Alexis27]

Shouldn't be an issue of it was replaced

 

[Dan K]

I'm just stuck now Everytime I search on the web it always brings back all the thinks I've done or tried and now I don't no where to look.

 

[betogt]

I replaced the MAF and all problems were gone

 

[Dan K]

I unplugged the maf but didn't make any difference on start up.

 

[DrewCole]

Just as a test, pull the 100 Relay which is under cover in the engine bay towards the bulk head, this is for the SAI.

Mine ran rough at cold start and I thought it was the SAI playing up, so by removing the relay it prevented the SAI from switching, which has thrown up the EML on the dash but it's nothing major. The engine runs perfect on cold start now.

So I will either remove or replace the SAI pump.

I had replaced the rivets on the pump previously but the actual pump itself is faulty.

 

[Dan K]

Worth a try definitely. Is the relay fuse in the fuse compartment in the engine compartment fuse box. Also couldn't I just un plug the electrical connector that connects to the sai. I am decatted.

 

[spudboy6]

I had similar fault recently and turned out to be my fuel pump it's self , changed it and been fine since

 

[Dan K]

Hi have a cupra r fuel pump at home. Are they easy to install and will it need vag com or anything once installed.

 

[spudboy6]

Under the rear right seat , three screws to get cover off ,
Unplug pump , tap plastic locking ring round to release pump,
Swap pump then reverse to rebuild ,

No vag com needed and Cupra r pump straight fit

 

[Dan K]

Wouldn't a failing fuel pump throw up a eml light

 

[spudboy6]

It would throw a low pressure fault eventually but only once it had failed completely and by then it's too late your stranded ,

 

[Dan K]

Ok will try the sai fuse and put the fuel pump on then see How I get on. Car only covered 77000 miles is this common for fuel pump. Car is tuned to around 230bhp with standard pump so maybe pump working harder than it should. Also will any fuel leak out the pipes once disconnected. Also I have changed injectors to cupra r injectors a while ago could a leaky injector cause this problem then once car fired up its flooded slightly with fuel then it burns it off and then drives normal.

 

[spudboy6]

Was your map adjusted for R injectors ?
Also you need a 4bar R pump ideally to run the bigger injectors , you've probably overworked your pump ,
Release fuel cap to relieve pressure but won't loose much when changing pump , when you take pump out tank it will be full off petrol so let it drain in to the tank and have a rag ready ,

 

[Dan K]

Yes the injectors were mapped in correctly. I was told by them the 4 bar pump would be better for the bigger injectors. I got the pump but never swapped it. Ok will give the sai fuse a try and change the fuel pump. Will do it as soon as I get chance. Thanks for the posts hope this solves my issue as its doing my head in now