Have a 2008 mini cooper r52 with 162733 miles on it. This has been an ongoing problem. The missing got really bad a couple of weeks ago. So I decided to change the plugs, wires and coil pack. Ran fine for about a 20 mile test run right after install. Went to check it out this morning and about 2 minutes after starting it stumbles a bit and the cel comes on. P0302. I did do a compression test a couple of weeks ago and cylinders 1,3, and 4 had 200psi. Cylinder 2.....145psi. I have also check valve springs, none broke or loose. The check gas cap light comes on all the time also. I have an autoenginuity on the way, maybe can do some extensive testing when that gets here. I am needing suggestions on what to look for or check. Sorry for the looooong post. Sent from my SM-N960U using Tapatalk
That’s a big split on cylinder 2. Have you checked fuel pressure? Could be a pump at tome for a new filter. I changed mine at around 100k and it was black.
Yes it’s in the tank. You can get to it by taking out the bottom part of the back seat. There is an access panel it’s under that panel. I don’t know if that’s it but given the miles if you have never changed the filter it is probably time to do it. The fuel pump could be going bad that is why I think you should check the pressure. But the big concern is that you have a P0302 misfire on cylinder 2 and that is the one down on compression. You could do another compression test and on cylinder 2 put a little oil down the cylinder and see pf the compression comes up. If it does you have bad rings, if not you may have a bad valve. Do it first without the oil to confirm your first reading. here’s a link to the fuel filter. https://www.detroittuned.com/mini-cooper-fuel-filter-g1/
Here's the results of the wet/dry compression test. Dry. Wet 1. 190. 1. 210 2. 175. 2. 210 3. 195. 3. 200 4. 190. 4. 200 Sent from my SM-N960U using Tapatalk
This dry test shows cylinders within ten percent of each other which is suppose to show the compression is good. Your original dry test showed #2 cylinder had a real problem but it indicated a much better dry compression result this time. I’m only a shade tree mechanic at best but I have to wonder which test numbers really represent your engine ?
I think the difference is the engine was cold on the first dry test. If those numbers are within spec, would a bad injector cause a miss. And the miss is not all the time. Just random and at lower rpms. May need to switch the #2 injectors and see if the miss moves with it. Sent from my SM-N960U using Tapatalk
Ok. Swapped #2 injector with #1. Went on a 25 mile round trip. Well the misfire code did not come back.......buuut it did throw an p1125, p1126 and p0326. What the heck? I did replace the throttle body last year. So I may be looking at the wiring harness? Haven't went any further. Waiting on my scan tool to arrive. Sent from my SM-N960U using Tapatalk
I believe that P1125 and P1126 are for the Throttle body position sensor and P0326 is knock sensor. Could you have disconnected some wiring when working on the engine and not have gotten them reconnected well or jostled the wiring and you were not aware of it or the connections need to be cleaned or sensors are bad and need replaced. So you can check out the wiring connections and if’n that doesn’t help then you’ll be able to give your new scanner a workout. Good luck.
If you don’t already have this link, this is all the codes. https://www.motoringalliance.com/articles/1st-generation-mini-ecu-codes-chart.48/ You may have already said but what grade gas are you running and is it from a top tear supplier? Long shot but bad gas. Have you cleaned your throttle body lately? You said you just replaced it last year so I doubt it’s dirty, unless you have a K&M type air filter and have over oiled it. I’m with @00Mini check all your connections. Also check all your ground wires.
Yes will go over my connections and check the wiring. We only use premium or non-ethanol. I did put about 5 gallons in it from a local mom and pop store just before the test drive. Sent from my SM-N960U using Tapatalk
I went through a long hellish process a year ago to solve a cylinder 2 misfire on my '04 MCS... very very long story but it ended up being worn camshaft lobes. Replaced with a used cam from Allmag and misfire solved. Other issues persist, I've been dormant in here for a long time but it's probably time I started a new thread...
I was just reading your thread. I was thinking i am going to have to end up pulling the head. Sent from my SM-N960U using Tapatalk