TOPIC: Mini update

Haven’t gotten the grove installed yet on my 2011 Mini Cooper JCW. I am told I have the first mini this was ever done to! Well unless someone beats me to it! But we gotta problem. I was waiting to install it until I figure out why it missfires under boost. Well, now it has lost compression on cylinder 3. So last night I put the compression gauge on it. Dumped some oil in it and checked again. It was higher. So that means its the rings that are leaking. I think what happened is washdown from incomplete combustion that was caused by weak coils. My spark plugs kept breaking and I found that was because of an incorrect torque spec from alldata. They were being put too tight. So now I need to figure out if it needs a rebuild or a new engine. I poured some oil in the cylinder and left it set. Kinda doubt that’ll do anything but we’ll see. Needs a turbo as well. So I have no idea when I’ll get the groove put on it!

a dose or two of Ron's Pure Snake Oil should help with leaky rings, Vernon...and it's on SALE right now...
Then I'd Groove it to help figure out if your washdown theory is correct (what if it's just a bad injector overdelivering fuel on THAT cylinder?)

I put new injectors in it. I bought the car wrecked and fixed it up. The previous owner didn’t take good care of it. I do have some snake oil but I don’t think that’s going to work in this case. Reading up on how it works I don’t see how it’ll work here. This isn’t anything that’s worn. The compression was perfectly fine when I got it. Just running it around hard trying to find the cause of the missfire I think is what did it. I currently have it sitting with oil in the cylinder to see if that affects anything

Back before Ron made Snake Oil, he recommended a product that had similar results.
For engines with problem cylinders like this, it was recommended to add some of that product directly to the problem cylinder through the spark plug hole, exactly like it seems you have done with oil, replace the spark plug, and run the engine.
Ron has several examples of that product working very well to fix the compression issue, and very quickly - its getting a high concentration of the good stuff right close to the source of the problem. I see no reason why his improved version wouldn't have similar (or better!) results.

Should I shut that cylinder down when I run it with it in? Shutting down by unplugging the injector

I’m not sure. On an engine with more cylinders I am tempted to say no, but with only 4...
Maybe Tracy can give you a better answer (I’ll try to get his attention), unless Ron sees this and chimes in. In the meantime, pop over to the Snake Oil site and poke around - the answer could be sitting there for everyone to find!

Good news, Vernon: Tracy replied via email to me, so I'll copy/paste that here:

"Here's what I recommend Vernon to do. Almost the same as a regular compression test.

First, pull the fuse for the fuel pump. Remove the wiring plug for the injector on the affected cylinder. Pull the spark plug on the affected cylinder. Block open the throttle plate. Rotate the engine w/ the starter to get the piston in the affected cylinder down to BTC or close to bottom in the bore. Then squirt in SO thru spark plug hole, trying to hit the cylinder bore wall and avoid the piston top. Probably use a 10 CC syringe of SO, just use part in first application. After adding the SO, check w/ a light to see results. A borescope would be ideal to look, if available.
The SO, needs to be on the bore wall to work, easier if it's a V engine, harder if a vertical 4 cylinder. If the SO lands on the piston top, maybe squirt in a small amount of oil to rinse the SO over onto the piston edge/bore wall. When it's known that the SO is on bore wall/edge of the piston, THEN use starter to roate engine thru several rotations to spread the SO on bore walls/rings. Repeat 'till the SO has all been applied to the bore walls. IF the starter rotates the engine fast, then use it in short bursts to avoid spraying the SO out thru the spark plug hole.

Thinking about it, I think after all the SO has been added, I'd reinstall the spark plug to keep the SO from being sprayed out of the spark plug hole. THEN use starter to rotate the engine to spread the SO around the bore. If I saw that some of the SO had got on the piston top, I'd squirt in some oil to help rinse it to the edge of the piston, and wait a bit to give it time to get to edge of the piston. Plus if I added oil, I would draw it up into the syringe and use that to get as much SO out of the syringe as possible.

Obviously, once all the SO had been added and I knew it had spread over the bore wall, then put it all back together and start it, expecting some smoke for a minute or two. And, if I had to use oil to rinse the SO to the piston edge I'd try to use just enough to do that without over-doing it.

Tracy"

I'm guessing You'll have some thoughts about how to apply a fairly even "bead" of the Snake oil to the circumference of the piston, where it meets the block wall, especially if you have a borescope to take a peek inside while you're doing that...maybe an extension to the nozzle of the syringe, using a small diameter hose? Heck, if you're going to go that far, I would do all 4 of the cylinders that especially if I had a way of seeing what I was doing. It might take time and effort, but directly applying it to one of the main surfaces we want treated probably makes it take hold that much better and likely faster than waiting for the hBN to circulate through the whole oil system.

Vernon, Ron may want to chime in here.
If I remember correctly Ron had a similar problem engine where 2 cylinders had 30-60lbs compression and he figured the engine needed a complete opening and parts replacement. Tracy knew of a product that does wonders to engines with this kind of problem and was touting it here on this site for a while but there was a similar product one can purchase here in the states called RVS. Somehow Ron heard about this and called Justin who sold it and asked if his RVS added to the oil would fix a problem so severe. Justin stated that since it was such a severe case that Ron would have to apply this in a similar fashion to what Greg is suggesting, directly to the problem cylinders. So if my memory serves me correctly, Ron applied it as directed straight to the cylinder, put the plugs back in and ran for an hour. Then did another compression test and found both cylinders were now around 150lbs each.
Needless to say Ron was ecstatic and posted of his success here. His exuberance is what prompted me to try the product also many years ago.
Ron could fill in the details of what actually happened and if this would apply to your situation.

Cool. I will give that a go. I do have some SO from when I got the throttle body. I definitely will have to use oil with it due to the unique design of the pistons. Is there a difference on doing this with a warm or cold engine?

RVS, Cerma, Xado...all similar variations of Snake Oil, with active ingredient making the triboceramic coating hexagonal Boron Nitrate (hBN).
Ron's done his homework on this stuff, including that compression remedy kman mentioned, and come up with a higher concentration/better brew of the stuff.

as to trying it on a warm or cold engine...well, if it has aluminum heads, I'd be sure to do the initial treatment of the problem cylinder on a cold engine, since you're pulling and replacing a plug. for an engine treatment, I think you'd want to add it to a warm engine, but read the instructions that came with it.

Do I need to let it “soak”? Or just put it in and and turn it over couple times and fire it up?

I would think that simply following the procedure Tracy outlined would be best, rather than letting it drip down past the rings. get it applied to where it needs to be, and let normal pressures and movements distribute it when you do fire it up. it would likely help to have whatever of the dose is left after application to the piston in the rest of the oil supply. but you did say the previous owner didnt take the best care of it - maybe a flush before will help remove whatever crud is in oil channels/passages before treating the cylinder/piston? Fresh oil in the car will definitely be ideal moving forward, but if there are metal particulates from the suspected damaged rings in the oil, that should assist the hBN with bonding to appropriate surfaces. And again, what do the instructions that came with the Snake Oil say? Maybe there are better, clearer ones on the Snake Oil website that can help answer this.