Gene in NC
09-16-2009, 09:43 PM
B-12 Chemtool jumps mileage on '89 525m. Never seen more than 24+mpg, even on way to coast with a 325' elevation drop from Raleigh, NC.
Ratty looking plugs and strange intermittent cyclic chugging until full temp plus 2-4 miles, led to B12 try. Prev experience with similar products like Techron and even the limited availability super stuff BG 44K, did not show much improvement.
Followed B-12 instruction of one can to 16g. Difference was 120 mi round trip at 70-75 mph. First 25m around 23.5 mpg then noticed avg improving. Reset and avg around 26 mpg and growing for next 10 mi. Reset again and mpg improved to nearly 27 at end of 120 mi run.
Interesting that there was no "chugging" from cold start at beginning all the way to 120 mi end of trip.
Return trip mpg grew to 29.8 for the last 50 mi. Maybe this is common for '89 525m, but it surprised me.
However, on return, 1/4 tank fuel level, the chugging that had been limited to cold start, first few miles, came on at 75 mph and persisted, intermittently, for about 20 miles. Off I85 to avoid traffic jam, we added about 8 gal of Exxon 93 and drove next 15 mi at 45-50 to avoid I85 traffic problem. No chugging.
Filled up with Conoco 93 and ran the 50 mi above with only a couple of very minor chugs. Next day the chugging was back with a vengance.
Sorry to be so long, but
1) problem is a real PITA with no solution in sight, and
2) Effect of running injector, etc. cleaner in fully hot engine for extended time, 240 mi here, may be a worthwhile report.
Ratty looking plugs and strange intermittent cyclic chugging until full temp plus 2-4 miles, led to B12 try. Prev experience with similar products like Techron and even the limited availability super stuff BG 44K, did not show much improvement.
Followed B-12 instruction of one can to 16g. Difference was 120 mi round trip at 70-75 mph. First 25m around 23.5 mpg then noticed avg improving. Reset and avg around 26 mpg and growing for next 10 mi. Reset again and mpg improved to nearly 27 at end of 120 mi run.
Interesting that there was no "chugging" from cold start at beginning all the way to 120 mi end of trip.
Return trip mpg grew to 29.8 for the last 50 mi. Maybe this is common for '89 525m, but it surprised me.
However, on return, 1/4 tank fuel level, the chugging that had been limited to cold start, first few miles, came on at 75 mph and persisted, intermittently, for about 20 miles. Off I85 to avoid traffic jam, we added about 8 gal of Exxon 93 and drove next 15 mi at 45-50 to avoid I85 traffic problem. No chugging.
Filled up with Conoco 93 and ran the 50 mi above with only a couple of very minor chugs. Next day the chugging was back with a vengance.
Sorry to be so long, but
1) problem is a real PITA with no solution in sight, and
2) Effect of running injector, etc. cleaner in fully hot engine for extended time, 240 mi here, may be a worthwhile report.