I had another thread, but wanted a better tittle


2006 mini (base) 89,000 miles has been misfiring on cylinder 2 for a while. (5 months is what I think they told me)

Replaced distributer, wires and plugs. Still missing.

I just swapped cylinder 1 and 2 injectors this morning, still missing on cylinder 2.

Ran a dry compression test.

1: 170
2: 115 <---------AHHHHH!
3: 178
4: 180


I have never done a wet compression test, so I didn't feel comfortable dumping oil in there and trying it.

So, any guesses? Bad valve seal or spring? Bad piston ring? It really drives 'ok'. Little low on power and little missy at idle.

I think they don't want to take it in to a real shop and drop big money on it, so I may be learning my way around the tiny engine bay. Saabs were my thing, now this might be.

Input?

TIA.

Also, how the heck does this happen at 89k? My poor beaten on saab b204 "stage 3+" td04 turbo has 190k on it and only had to do a head gasket 150k.

 

The wet test will tell you if it is the rings or the valves. Then do a cylinder leak down test.

 

If it has been misfiring for a long time you may want to look at pitting on the cam, which is allowing the valve to not seat properly. Our 2006 head was not milled flat and as a result created a misfire which pitted the cam and made it so much worse. It was eventually diagnosed and finally fixed at around 40,000 miles.

 

Was the fix a new head in that case?

or just a new cam?

 

You don't need to do more tests, unfortunately: you're going to have to do some exploratory surgery to find your problem. You'd be lucky if it were your cam. With that amount of compression loss, you should look closely at your valves and piston rings.

 

The owner of the car is thinking that they don't want to do an overhaul as once we dive into I we may as well do the timing, water pump, ect.


They are thinking about trading it in or selling it as is. What would a trade in value or private party be on an 06 non turbo with 89k and a non running engine?

I assume a shop would quote 1500+ to pull the head and do a possible ring/valve job.

 

it sounds like its a valve. I dont think its the rings. Bad rings usually means smoke in tail pipes because oil is seeping thru. The compression is considerably lower so the valve is either not closing all the way, possibly chipped or bent valve. If you have bad rings compression wont drop that low. or at lease shouldnt drop that low unless the rings are missing completely. but i could be wrong

also i think you might loose less money if you fix the car rather than sell it with a bad motor. If you fix it at an independent shop it should cost 1000-1500 for a valve job. If you can find a head online for $300-400, then pay an installation of $500. that would save you a bit. I just sold my head with 40k miles for $400 2 weeks ago. I am sure you can find a good used one.