WH Statesman miss

[AdzzeH]

Not sure if this is the right section of the forums for statesman but I couldn't find a statesman section.

I recently bought a 2002 WH statesman. The car is immaculate only issue is that it has a miss. I paid $2300 for it because of this miss, he said that it could have been a coil pack.. But its not. here is what I have done
He also said that it has a mild cam but with the miss I cant hear it. If it hasn't been re-tuned to the cam could that be causing a miss?

(It is the L67 supercharger (10psi) version)

I have replaced the:

• Coil packs
• Plugs and leads
• fuel filter
• I found a couple of vacuum hoses that weren't connected which are now reconnected
• I've ran injector cleaner through it.
• Squirted a heap of throttle body cleaner
• I put the computer into diagnostic mode and it keeps coming back with code 12

I started to think that it was just a miss because of fuel issue so I put some gas in it and the miss is still there..

My Dad is starting to think that it could have a weak exhaust valve.

The thing that gets me is every time that I replaced something the miss was almost non existent but come the next morning when its dead cold the car is running like a bucket of **** again haha.

If any of you guys have any idea please list them below cause I am out of them..

 

[AdzzeH]

I did a compression test today and cylinder 2&3 were both down on compression. Does this mean valves or something else?

 

[accentstencil]

I did a compression test today and cylinder 2&3 were both down on compression. Does this mean valves or something else?

Valves or rings. You dad was probably right with the valve theory.

 

[AdzzeH]

Ill pull them out over the weekend. if it is the valves are they a costly repair?

 

[BlackoutSteve]

How far down on compression were they? What were the results?

If valves, just get change-over heads, but be aware supercharged heads are different.
I got a fully reco-ed pair 12 months ago for $660, with hardened seats.
The seats are not hardened from factory believe it or not, but should last over 300,000.
How many Ks has the car done?

 

[AdzzeH]

The car has done 234000k's. As for the compression, both cylinder 2&3 were both around the 100psi mark.

as for the reco-ed heads should local wreckers, or is more along the lines of a performance shop.

 

[BlackoutSteve]

An engine reconditioning shop might have change overs on the shelf. Get on the phone..

Firstly. I'd perform the test again but this time squirt a little bit of oil into both of those cylinders.
Crank it over a few more times (disconnect the DFI -no ignition) and then test again.

If the readings improve, you know your previous test's poor results are the rings/bore because the oil would have helped them seal.
If the reading don't improve, then it's very likely to be valve sealing.

However, pressurizing those two cylinders (must be exactly TDC on firing stroke) with compressed air is preferred as this will allow you to hear whether it's leaking into the intake, coming through the exhaust, or into the crankcase and out of the PCV. ...or both or all three.
If you simply pressurize, the piston will head down to BDC (FAST!) and there is always a valve open at both BDCs in the 720° cycle.

These engine when healthy should easily produce 180psi.
Test ~6 revolutions, wide open throttle.