99 626 throttle body issue
 

Im sick of chasing this so ill try to make it short.

99 mazda 626 2.0
bought from junkyard, had idling issues. Temp fixed by adjusting throttle cable.

Recently had a light fender bender, I rear ended someone just hard enough to feel it, but not enough to leave even a scuff. Car kept running, soon started to pour smoke out, got it to work, it died, wouldnt start back up again.

Threw the scanner on it, got a p1602 immobilizer code.
got it to run at WOT, and ONLY at WOT, at no more than 1000rpm. Stalls out if I let off the gas. Found that the throttle body is BLOWING air out, rather than sucking it in.

I can not figure this out for the life of me. I feel like a piss poor excise for a mechanic right now.

Wierd, can't see how it could be related to a collision that left no damage.Unless you had a converter ready to crumble, then it might jar it enough to clog up the exhaust. Generally if compression is blowing out the TB instead of sucking it in i would assume a hole in a piston/valves stuck open or a completely clogged converter. If the smoke is blue i would lean toward a piston/ring/valve/timing problem. If the smoke is black i would lean toward a converter/injector/timing/control problem. Either way i would start with a wet/dry compression test. You could remove the upstream o2 sensors to bypass the converters for a few seconds to eliminate that possibility. I would likely do that before running the compression test.

Well luckily I have the shop at my disposal. So im thinking maybe cut the pipe before the cat, see if it stays running. If it does, assume clogged cat?

Im not worried about exhaust repairs, this seems to be the simplest caveman friendly diag method at this time.

Does it have a pre-converter? Like one under the exhaust manifold. Maybe part of the manifold? Dunno what country your in but US models generally do. The o2 sensor just unscrews and done.

Yes it does have a precat. Ill pull the o2 before it tomorrow and see if it at least idles.


Side note, since this is a $400 junkyard winterbeater.
happen to know if a universal cat works as a precat? Never seen it done before, and im not spending big money on this car.