Mazda Repair: Stalls when put in gear, vacuum leaks, vacuum leak

Question
Recently bought my son a 91 Mazda 626 with a automatic transmission. Car runs great, starts fine, but when put in gear, it stalls instantly. Restarts fine. If you increase the RPMs as putting in gear, and work the gas and brake like a clutch, it is ok. We have looked for Vacuum leaks, and checked all the plugs, wires and dist.
Thank-you in advance for your help.
Best Regards
Joe

Answer
Sounds like it is in need of a few things.
I would suspect that it has a locked converter and may need a new solenoid. Also, it may have a sticking idle air control and leaking injector seals that are causing a vacuum leak that is almost impossible to find without using carb cleaner to locate it. If you use the carb cleaner method I suggest having a fire extinguisher handy just in case, but carb cleaner with the use of the red straw that comes with most cans can offer a economical method of finding leaks without tearing your hair out trying to distinguish hissing from the myriad of other noises in an engine bay when using the hose method.
Also check ignition timing to ensure that it meets factory specs. The timing specs are listed on the emissions tag under the hood.


A diagnostic scan and a hydraulic pressure test will confirm or debunk the possibility of a locked converter. If the converter is locked and the solenoid is burned up a transmission flush will also be in order to ensure the condition will not reoccur. Most service shops will have the required equipment to do a transmission flush.

Regards,


John