Cold Start/idle Issues.

[CaptainP 2]

This is a fairly common topic and I've looked through the search a fair bit but I seem to have a strange problem with cold starting and general running. When I first start the car, the revs are fairly low (about 900) and I need to keep it revving for a while before she settles down. The revs then increase to about 1100 where she ticks over fine but runs a little rough, hesitant and heavy on fuel. This seems totally alien as on my old GTI when starting revs would be up at around 1600 before the SAD closed over and the revs dropped down to about 1000.

 

So far I've tested the SAD on a battery and it closes over after about 4 minutes. I've then put it back on the car and checked by undoing the pipe that go's into the front (by the plug) and the SAD has closed, so I beleive the wiring is ok. I have also replaced the ECU sensor, ignition amp, distributor cap, rotor arm, plugs & leads. I have a spare AFM which I'll be changing over this week but it's a weird one, the only thing I thought of (but haven't checked yet) is the pipes that lead off from the SAD are clear and not blocked with crud.

 

Any other things that I could try/adjust? Timing possibly?

 

Thanks.

[RINRIN 1]

Just be sure of the SAD wires, by using a multimeter. I had the same problem and that is solved with a ground cable to SAD

[Tom Fenton 1,542]

Remove the throttle body and thoroughly clean out all the drillings, then try and set it up again.

[CaptainP 2]

Cheers Tom, yeah I have done this, still the same though.

 

RinRin, if I plug my test leads & bulb into the SAD connector loom should it light up?. I take it after a certain amount of time the bulb will go out (when the cars up to temp)? As I'm now suspecting it could be a loom/plug problem as when I originally tested the SAD in place I thought the hole was closing over but now I'm not so sure. It definitely works when I connect it straight to a 12V source to it though so it's not the SAD at fault.

[CaptainP 2]

Well this has beaten me, good voltage coming through the SAD plug on my multimeter. I thought I would remove any abnormal bits like the K&N air filter system and put everything back to standard incase I was getting an airleak etc (probably best setup anyway). Started the car up & still the bloody same, 800rpm rising to about 1100 when warm. What a puzzler, just gonna drive it like it is now I think, not much more I can swap over to diagnose.