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| Joined: | 04-16-2018 |
| Location: | Santa Barbara, California USA |
| Posts: | 22 |
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Exhaust leaks absolutely can be an issue with sensitive AFR meters---small leaks can be hard to find, however. Sometimes they can be heard from under the car (on a lift) while it is running, or a telltale black streak can be seen. Sometimes you need to use a smoke machine (the type used to find intake/vacuum leaks) and pump smoke into the tailpipe to find a leak. You probably don't have one of those, so a shop would need to get involved. You could also compare your AFR gauge's readings to that of a shop's 5-gas analyzer to see if they are in the ballpark.
Regardless of AFR readings, my comment about the idle jets being lean in the transition period between idle and main jets was based on your assertion that the carbs are popping in that range, which does indicate an actual lean condition. The lean AFR readings that you posted in that RPM range bear this out. Make sure the idle jets aren't plugging up like mine were, which is quick and easy to do (can get compressed air in a can if you don't have an actual source of compressed air).
EDIT: 17.5:1 is quite lean, but won't do damage unless you are stupid enough to hammer on the engine and give it sustained periods of full load in that condition. It sounds like you are doing short test drives while monitoring AFRs, so you probably haven't hurt anything.
Last edited on 07-18-2019 04:38 am by CDA951