got the CODE p0308 ( Cylinder 8 misfire) , took it to FORD because i have Powertrain warranty for 30 more days.. the code reset its self x2 ,i took it in they ****ed me around trying to sell me a full tune as repair as i was at 87000km, they were convinced that it was extra carbon on the plug as a cause , i had to talk them into just replacing 1 plug and see what happens, he said his OBD read s no compression changes in computer that it was a tune problem , i told them to replace the plug and i was going to get a full compression test done at a local shop. my initial diagnosis fee wasn't warranty covered btw. Then "some how" he drives it again and says he needs to do more investigating , i tell him "do what you want I'm not paying for anymore time". He comes back to me saying he finds low compression and they have to apply to Warranty dept to fix, no other details . FYI my service advisor is clue less and i am more than not impressed that the information train from mechanic to me. thats where i stand now. waiting for approval.
My questions are : Once approved ( i don't see why it wouldn't be) what repair am I in for? my mechanical know how stops at basic tune ups and you tube repairs. What can i get done to the engine to maximize a warranted repair while the cylinder is being repaired? any thoughts? I was thinking gaskets , plugs , seals all stuff i can get done that won't require my paying additional labour.

 

First off OBD2 has no way of knowing compression, or lack there of.


If you do indeed have no compression, it could be something mechanical in the cylinder head (bent valve, stuck last adjuster etc)
It could also be something more serious deeper in the engjne like a hole in the piston



If the claim goes through under warranty you shouldn't owe for that first hour of diagnosis

 

If they seem low compression would they have done all cylinders to compare or would they just do the affected ? Would it be in my best Intrest to have them do the rest of them incase others are not up to spec?

 

I would think a good technician would automatically want to check compression on all cylinders before tearing down to find any issues

 

turns out i have a burned valve, ant idea what may be the cause of this?

 

Ford just called me they stated they are replacing my engine, anybody have any tips or important questions to ask about it before hand?

 

Wow! 30 days before the warranty expired! I don't know if you are lucky it happened when it did or unlucky it happened at all.

 

so i got a New Block not a remanufactured they said. Pulled it out of the shop and 200 km down the highway, light comes on and flashed while I'm trying to accelerate to highway speed. ran code reader and it says p0300 and shows random cylinder misfire for numerous cylinders , any ideas why or what this might be with a new block. i was having problems with them trying to grease me for a tune up before they found my block was done , but now ? any idea what tests are acceptable now? i feel as if the old misfire was caused by the old valves being shot now it may be a problem with reinstallation. thoughts? what tests should i have to pony up cash for?

 

Did they do new plugs or just move them over from the old engine?

 

OEM plugs in OEM block , also noticed last minute oil leak after shutoff only a few mils but every time , service guy today said since code is not symptomatic they might just test and reset . Never ending story .

 

you are wrong! If you have a quality scan tool you can run a relative compression test to see which cylinders are low on compression. Any quality technician knows about this. The regular backyard mechanic obviously would not know about this.

 

That's not a "relative compression test" - it's a "cylinder balance test". It doesn't measure compression.

This thread is 5 years old.

 

I enjoy watching mechanic videos and in several I watched the test was called a relative compression test?