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Discussion Starter · #1 ·
I have a 2000 Taurus 3.0 Vulcan. The car blew a head gasket last summer, didn't really overheat much before i caught it. I replaced both head gaskets and the front head just to be sure. The car ran great since. Then I was driving on the freeway on cruise control at 80mph and everything was fine then all of a sudden the car lost power and started to slow. It started to downshift into passing gear so i knew something was wrong, when i put my foot on the gas it was floored by the cruise control. I pulled off and the motor was missing and the light was on. I drove it home and checked the codes and it had p0302 and p0305 misfire. i cleared the codes and restarted it and now p0302 went away and only p0305 remained. i pulled the plug for cyl 5 and it was bridged with something, so i cleaned it and put it back in and now i still have a slight misfire. i tried switching plugs and wires, checked the coil, replaced the fuel filter and injector. i did a compression test and it showed a low cylinder. cyl 4 110psi, cyl 5 60 psi, cyl 6 110psi. my question is the car ran great up until that point, what could've happened just driving on the freeway to lose power and make a skip. its just a slight misfire at idle but still runs great. light keeps coming on cyl 5 misfire. I have to get it smog tested, will it pass?
 

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All those compression #s seem low.... even 110 is way too low. Did you do the test with the throttle at WOT? Was the engine recently run (i.e., sat for 4 days before the test)? Was the starter cranking the engine at a decent RPM?

The 50 on #5 is horrible. No wonder you have a miss showing on that cyl.

When you did the HG, did you have the heads milled flat? Head bolts properly torqued?

A leakdown test would help narrow down the low compression numbers.
 

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Discussion Starter · #5 ·
throttle was wide open, engine was warm, cranking full RPM's. Head Gasket was done a while ago. It was blown on cylinder #5. No water in oil just water into combustion chamber. I did not mill head I replaced with a rebuilt head. New head bolts all torqued properly. Car was running great up until that point when i lost power on the freeway. I don't know if this is related but I've noticed when i pull out the pcv valve from the valve cover the engine stalls out, also if i remove the oil filler cap while the engine is running it stalls out like a vacuum leak.
 

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HA YOU KILLED IT! But seriously, what head gaskets did you use? Were they the correct thickness? Installed upside down? Right bore? MILLIONS of questions..need answers...and yes, things will be fine for a little bit and then **** the bed in situations like this. More things to check would be for a valve stuck open, broken spring, or maybe even a valve is out of adjustment. As far as the pcv, an engine in good order will stall with the pcv just pulled while running...it has nothing to do with your problem...
 
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