chriszzz 0 Report post Posted April 29, 2012 My old mans 540i, 2001. Was randomly running really rough a couple of days ago, mechanic did compression test said cylinders 3 and 4 have around 115 compression, the rest are 160. car has done 107kms. Guessing its going to be expensive, but what is it likely to be ? is this common for these engines? Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 29, 2012 (edited) Don't condem it yet... remove plugs, refit plugs, start and run engine, remove plugs, then do compression test with wide open throttle. If compressions are then ok...get it scanned. It's likely to be only a faulty ignition coil Edited April 29, 2012 by *Glenn* Quote Share this post Link to post Share on other sites
BM WORLD 1283 Report post Posted April 29, 2012 (edited) could also be the pcv valve?? i have done compression tests before on the v8's they normally sit around 210-220psi was the tester screwed in properly?? are the spark plugs threads damaged?? but like glenn said get it checked/scanned etc Edited April 29, 2012 by Brent HARTGE535i Quote Share this post Link to post Share on other sites
Jo Blogs 11 Report post Posted April 29, 2012 could also be the pcv valve?? i have done compression tests before on the v8's they normally sit around 210-220psi was the tester screwed in properly?? are the spark plugs threads damaged?? but like glenn said get it checked/scanned etc Dirty AFM or failing AFM or Vacuum leak can cause blocked Cats, This can be a cause of rough running, I have now had 3 M62 V8's with this issue, Quote Share this post Link to post Share on other sites
chriszzz 0 Report post Posted May 1, 2012 cheers guys. 2x coils, 1x "crank sensor". $1100 incl gst and labour and its sorted Quote Share this post Link to post Share on other sites
E30-323ti 66 Report post Posted May 1, 2012 cheers guys. 2x coils, 1x "crank sensor". $1100 incl gst and labour and its sorted So.... Does it still have low compression on 2cyls. Not sure how the above have any relationship to solving this. Or was your mechanic just doing it wrong in the first place. The M62 is like an old P76 = FAIL Quote Share this post Link to post Share on other sites
sp8s 1 Report post Posted May 2, 2012 Or was your mechanic just doing it wrong in the first place. The M62 is like an old P76 = FAILWhats wrong with the P76Beautiful old barge they were Quote Share this post Link to post Share on other sites
hotwire 352 Report post Posted May 2, 2012 Whats wrong with the P76 Beautiful old barge they were In the eye of the beholder Back on topic, if the low compression was confirmed as not a "hard" issue, then this has been a comparitively cheap fix Quote Share this post Link to post Share on other sites
