Rs4 b8 cold start issues

[Harry76]

Hi all,

I’ve had my RS4 a couple of months now and it has been all good aside from last night I drove for around half hour, parked up for a couple of hours and then when I tried to start the car, it cranked, engined seemed like it was about to start but then shut off immediately like it didn’t have enough fuel. After a few more failed restarts it then spluttered to life eventually.

Driving afterwards was fine (engine all good) and restarts when engine warm all fine/immediate (even after restarting when car sat for half hour or so had no problems). However, left it for a few hours and then experienced same issue, cranked but it felt like engine didn’t quite have enough fuel to start up (so after a couple of failed attempts I dabbed the accelerator after pressing the start button and hey presto she fired up).

Any thoughts on what the issue could be ? Doing some research leads me to believe it could be either coolant temp sensor (not giving enough fuel on cold start) or perhaps cam position sensor ?

Any help/advice would be appreciated (will get it booked in but don’t want a spend a small fortune on diagnostics if it can be pinpointed relatively quickly)

Thanks

Harry

[AndyBrad]

i would get yourself an odbeleven plugin and then you can see what your dealing with

[Harry76]

Thanks - obd11 reader says fuel trim bank 1 and bank 2 too rich, no other faults. Does that shed any more light on what could be causing it ? Quick google search does state that faulty coolant temp could cause this ..

Not sure if coincidence or not but I’ve just put battery on ctek trickle charger and haven’t had any issues starting the car whilst it has been connected - could it just need a new battery ?

[Jools]

Does your CETEK have a battery crank check option?
Have you checked the battery voltage (CETEK disconnected) before starting and while running?

If the ODBII says fuel trim rich, have you looked at the O2 lamba sensors?

[Harry76]

Thanks - no will check battery whilst ctek not connected (don’t think it has ability to check whilst cranking ). Have booked it into garage on Monday , will let you know what they say in case helpful to anyone else

[AndyBrad]

I noticed that i got the odd error after having the car on charge. Cleared it and all good.

fuel trim could be lots of things. sensor, injectors, maf etc etc

but is the battery ok if your keeping it on charge as if its lot it will throw all sorts of errors that may or may not exist

[Harry76]

Thanks - fuel pressure seems to be holding ok so thankfully not the fuel pumps and various sensors also seemed ok. However, battery doesn’t seem to be holding charge that well, so will change as that may be the issue