my problem started out as an exhaust leak between the manifold and pipe flange(just after the first O2 sensor). The idle was similar to that caused by a vacuum leak, wether the engine was hot or cold. Over time the idle got worse to the point of stalling, and when driving, even with my foot holding the accelerator steady, I could feel the engine surging up and down. The codes at the time were 12,51 and 55. The van finally quit staying running unless I held the throttle open, however would continuously surge heavily doing so. So I fixed the the exhaust first. Then the catalytic convertor started glowing(brightly) after about 4-5 minutes of trying to keep the van running(which still wouldn't stay running on its own and still surged fiercely. So I used a salt water mix in a spray bottle while someone else kept the engine running with the cat removed and the exhaust manifold open to atmosphere, and found the misfire caused by my coil pack and wires failing(plugs are new). Now, I checked the codes again in the PCM... only code was 27... and 55 but who cares :) I haven't had a chance to check the injectors yet to pinpoint which one's) are failing. could it not also be the PCM failing. Just wondering what you think... obviously multiple problems... but I am not very good with anything that is not OBD2 :) Thank you for your time.
Hi Brad, I would be inclined to check the resistance of each of the injectors to find one or more that are off-value (usually the injector has a resistance of about 1 ohm. Ideally you will find the cause of the lean operation via that approach. Let me know if that is not helpful. Please "rate" my answer (see below). Thanks, Roland