We've been trying to track down a misfire on a 1996 Mazda MX-6 with a KL engine (V6). All easily accessible vacuum hoses have been replaced (we will do the last 2 tomorrow), and vacuum leaks around gaskets have been exhaustively searched for. The misfire occurs only when pulling with full throttle from below 2000 rpms. Generally a 3rd/4th gear pull from about 35mph.
There are four o2 sensors, one of which has been replaced with a new bosch wideband sensor. All of the sensors are reading sort of wonky (mostly reading rich). The replaced sensor reads zero'd out most of the time, although tonight it would peg upto 1.245V and stay there for a bit, then go back to zero'd out (with occasional bouts of reading within spec).
It throws o2 sensor codes somewhat regularly (for all of them), but it's hard to believe all the o2 sensors are bad (so we've been thinking it's got to be a vacuum leak, but cannot find it). It will also rarely throw a multiple cylinder misfire code, and then also very rarely, an EGR boost sensor code.
We've been fiddling with this car for a week now, with plenty of KL forum searches and are getting frustrated. Any help would be greatly appreciated. Thank you in advance.
*Edit: Also the timing has been set. TPS has been adjusted.
