So I have had a complete engine rebuild at a cost of £4500. I decided to keep the car no matter what so just went for the build on the proviso I could get all valve clearances checked and were within recommended tolerances.I have changed all coolant hoses for brand new, changed both water pumps, radiator, thermostat, spark plugs and all lambda sensors as thought it best to do once engine was in bits and access made it easy.

I was told the timing chain was "stretched" whatever that actually means and all chains guides etc have been renewed.

Now I am getting misfires across all cylinders see attached. I had a mechanic tell me its air leaks front and back of the engine.

From the symptoms of misfires and lean mixture I’m suspecting air leaks between inlet valves and throttle butterfly.

Spraying brake cleaner fluid towards the inlet manifold under the supercharger at the front of the engine causes an instant Missfire and rich mixture - this would suggest an air leak on the inlet manifold gaskets or injector seals.(this was not present before engine work under taken)

There is also a potential air leak on the vacuum connection for the brake servo connection on the throttle body housing - probably just the internal ‘O’ ring on the push fit connector - again spraying brake cleaner fluid on this location causes Missfire and rich mixture.

Would these issues potentially cause misifires across all cylinders??? Range Rover Vogue SE 2007 L322 4.2 Supercharged 121k. Engine rebuilt @ 120666 Miles

Yes. Sounds like your engine builder has done a poor job. I would bounce it straight back at them without touching it. 05 L322 4.2SC
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If unmetered air is getting into the engine then it could all sorts of strange goings on I guess.

I'd be getting it smoke tested to properly identify any leaks and then sending it straight back to the engine builder. If you start messing with it then they could well try and wriggle out of any warranty on their work.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

So I sent the car back to the rebuilders and they then gave me the car back still with air leaks, misfires and shorter clearances between the tappet and the cam shaft lobes.

How after a rebuild would you get even shorter clearances further out of tolerance. I don't understand how that could happen. Unless I'm missing something here. Air leaks have been remedied by replacing the reused gaskets they had used for some crazy reason.

So in short here are the pre and post rebuild valve clearance measurements taken on Bank 1 only. If anyone has any theories as to how this could happen I would appreciate any feedback on this.

[b]Pre Rebuild Valve Clearances
Bank 1 Offside
Pre Rebuild Clearance Under Recommended Min. Clearance of 0.18-0.22 INLET
Pre Rebuild Clearance "Under Recommended Min. Clearance of 0.23-0.27 Exhaust
Cyl 7 Back
Inlet A 0.178 Exhaust A 0.205
Inlet B 0.178 Exhaust B 0.205
Cyl 5
Inlet A 0.178 Exhaust A 0.205
Inlet B 0.178 Exhaust B 0.205
Cyl 3
Inlet A 0.127 Exhaust A 0.205
Inlet B 0.127 Exhaust B 0.205
Cyl 1 Front
Inlet A 0.127 Exhaust A 0.127
Inlet B 0.178 Exhaust B 0.178

[b]Post Rebuild Valve Clearances
Bank 1 Offside
Recommended Min. Clearance of 0.18-0.22 Inlet
Recommended Min. Clearance of 0.23-0.27 Exhaust
Cyl 7 Back
Inlet A 0.1 Exhaust A 0.127
Inlet B 0.127 Exhaust B 0.152
Cyl 5
Inlet A 0.1 Exhaust A 0.205
Inlet B 0.127 Exhaust B 0.205
Cyl 3
Inlet A 0.127 Exhaust A 0.178
Inlet B 0.127 Exhaust B 0.178
Cyl 1 Front
Inlet A 0.1 Exhaust A 0.1
Inlet B 0.152 Exhaust B 0.152

NB - If value 0.1 means the 0.127 fila gauge wouldnt go in!!![/u] Range Rover Vogue SE 2007 L322 4.2 Supercharged 121k. Engine rebuilt @ 120666 Miles