Hey all.

So I had my S4 turbo running a month or so ago and it was idling average and climbing a little every few seconds. I shut it off due to a fuel leak and discovered there was a vacuum line not plugged in which I presume caused the funny idle.

I was missing airbleed sockets in the LIM (causing the fuel leak) so I managed to find a full S5 intake for less than the price of one socket.

So I now have a S5 lower and upper with a S4 throttle body.

I connected it all up the same as before but now its running pretty bad. It idled at about 800 but the motor was shuddering quite a lot and just didn't seem to want to fire properly. I let it run for a minute or so and then gave it a very gentle touch on the peddle get it to 1500rpm. It climbed all right but was still pretty shaky. I had to ease the pedal off otherwise it would drop and stall. I didn't feel comfortable revving it while its like this so I shut if off and here I am.

I have removed emissions and done the throttle body mod. I realise that the throttle body mod will cause it to be a little awkward on start up but I feel that there is something else at play here. Last time when I only had the vac line missing and it was leaking fuel it seemed to idle pretty strong but slightly irregular.

I probably won't have access to it till next week but if I can get some idea of what to look for it would be really appreciated.

TPS was correct when tested before last startup. It should have about 5-10L of fuel, I could hear the fuel pump (which was surprisingly loud).

I have some crappy videos that if I get a chance will upload.

 

You probably already checked this but I'll mention it anyway. Have you tried adjusting the idle screw(s)?

 

Haha I actually forgot about that! That may bring the idle up but it still felt very hesitant.

I can't remember if I adjusted the CAS before or after last time. It was REALLY out before I did.

Wouldn't be something to do with air in the fuel lines would it? Seeing has I had the secondary rails off. IIRC I can release the air by opening the fuel cap or something.

 

I don't think air would be a problem because it's a return type fuel system. You should adjust the idle and stab the CAS. Maybe double check for vacuum leaks by spraying carb cleaner around the connections and see if it stumbles.

 

I'll check for vac leaks, check the CAS, adjust the idle screw and double check my grounding as per Aaron's guide.