Bizzare Revving Problem
 

Hi all, newbie here!

I've got an '03 S40 1.9d that I've just serviced, replaced the clutch and turbo on. Ran great before stripping it all apart.


Started the car, ran up to temp fine but won't rev past 1200 in neutral. From the other posts I've read, checked the MAF but that all seems okay.

What's weird is that, if revved as soon as the car is started (when warm), it'll rev freely and without issue, I can hear the turbo spooling up etc.

I've tried priming the fuel system and bleeding the air out of it but that hasn't really changed much.

I obviously had to disconnect the battery so I'm wondering if that may have caused some of these problems? The car is undriveable as is, it's just not making any power.

Any pointers would be very much appreciated!

Thanks

James

I pretty much doubt that the battery being disconnected would cause the problem. The 1.9D it's not like the GDI, that needs to relearn how to run.

Check that all the vacuum lines are connected properly in the right place and are secured. Also check that the N75 turbo boost valve is plugged in properly.

You could also disconnect the MAF and see if the engine Reva properly.

Let us know how you get on

Sadly I've been through all those and they seem to be where they should. Did the MAF thing and it made no difference - Like I said it ran perfectly before doing the clutch.

So I managed to get it on the road: start up and always hold above 1500 rpm and it runs a treat, pulls strongly with the turbo kicking in when it should. The instance it hits idle though, it has no power and won't rev. Killing the engine and restarting it does solve this though (again, avoiding idle).

I'm a bit stumped really, it feels like an ECU thing? The fact it runs great until hitting idle. Obviously could be wrong...

Thanks for the help so far!

I am not ruling out the ECU, but I have never heard of a similar problem being caused by the ECU.

I am trying to backtrack what would need removing from your car when replacing the clutch.

The crankshaft position sensor would have been disconnected, EGR connector, dump valve connector at the back of the inlet manifold, MAP and MAF sensors. Have you made sure that all of them are undamaged and plugged in properly?

Try looking at the egr. It might be getting stuck open...
Have you cleaned it? They are terrible on these engines and clog really bad...

Solved!

After unplugging sensors one by one, removing the boost solenoid freed the engine up.

Turned out that the grub screw that limits the wastegate actuator travel was too far out, some how this was causing the problems...

Wound it in until the engine ran sweet, now all sorted!

Brilliant. Glad you got it sorted