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During the process of initial registration last year, I was referred to some smog techs to diagnose my egregious emissions measurements. As their report said, the high HC can be linked to the low compression values they got. Ideally, I would've been more involved in the process (confirmed they performed the non-rotary test correctly or get it tested with the proper tools), but I didn't think my simple smog trip would go that direction.
I've got a few questions:
1) How sound is the connection between HC and compression? High HC readings seem to be caused by other factors judging by previous threads.
2) What do you guys think about the compression numbers they gave me? Cause for concern (spec psi hot, 78psi after 15 minutes engine off)?
3) Signs point to a rebuild in my future if everything stated can be confidently trusted. However, the context of my car seems a little different from past rebuild threads. The PO got the 12A factory rebuilt in 2005, and it's only been something like 26k miles. I'd imagine a factory rebuild is of quality workmanship, and the mileage just seems so low for there to be issues. Any chance this is all a freak coincidence caused by a gunked-up engine (seems like the PO left it sitting for long periods at at time) and an incorrect compression test? Don't want to bite the bullet on a rebuild unless I really have to.
Start by fixing your exhaust leaks. The report indicates that you have several, both before and after the catalysts. Any fresh air getting I to the exhaust before the cats will throw off the readings, because it's introducing oxygen before it's supposed to, i.e., the injection pumps air into the cats so that the platinum core can be superheated and burn out the remaining exhaust residue gases. After the cat leaks also cause problems in that fresh air is introduced which will throw off readings prior to the tailpipe sniffer.
A set of exhaust gaskets is far cheaper than a fresh rebuild, which - I don't know how someone would have gotten a 'factory' rebuild for an old 12a from Mazda in 2005. Did he take it to Japan and drop it off at their door? Seems unlikely it was factory...
I was unaware exhaust leaks had that profound of an effect, thanks. Fortunately, I've since gotten my car smogged. As for the nature of the rebuild, I'll take your word for it. It was written down as factory in the original invoice the shop had given the PO, but yeah, I guess 2005 does seem a little silly. Makes me wonder what they even meant by that then.
I don't know how someone would have gotten a 'factory' rebuild for an old 12a from Mazda in 2005. Did he take it to Japan and drop it off at their door? Seems unlikely it was factory...
05-10-23, 05:41 PM
