Dead Mazda 626


#1

I have a 1991 Mazda 626 that I use for a commuter. Yesterday morning, I turned the key and got a huge “bang”. I don’t know if it was under the hood or exhaust, but everyone within a 1/2 mile radius ducked for cover.



The engine will start, but it dies as soon as the electronics throttle it back to idle. I can get it to run, but only at full throttle. The check engine light is off. Any suggestions?


#2

Inspect the plastic air supply tube that connects the air filter housing to the intake manifold. It should be air tight. Look for splits, loose connections, etc. Weak motor mounts are quite deleterous to the tube.

1/2 mile… Quiet neighborhood.


#3

Determine the source of the “bang,” and you will probably find the culprit.


#4

I looked over the engine very carefully except for that particular connection. I’ll look it over today.

1/2 mile - rural neighborhood.


#5

I’ve been looking, but I haven’t seen anything obvious, and it won’t make loud noises again. I assume this was an exhaust backfire, but I’m not sure. Oh well, time to either keep looking or put the beast out to pasture.


#6

Check the fuel filter and see if it is clogged. It sounds to me there is a lack of fuel getting to the engine. Possibily a weak fuel pump also.


#7

Had something like that happen to me, and it was a clogged catalytic converter. Once replaced, it ran fine. I didn’t know how to verify that, so I had to have a mechanic look at it.


#8

The fuel filter is relatively new, and so is the catalytic converter. I had to replace it when I bought the junker because it wasn’t there (substance abusers around here like to “liberate” them to sell the metals inside).

I’ve done a little more tinkering and discovered that if I pull the electrical connector from the “Air Flow Meter” which is attached to the air filter assemply, the engine will start and idle. It will not, of course, allow me to give it throttle. As soon as I reattach the connector, the engine shuts down. Am I correct in thinking the air flow meter might be kaput?


#9

It sounds like you have a large vacuum leak due to what appears to be an intake explosion.
A large vac. leak will cause a refusal to run at idle and mid range.
About all I can suggest is go over the entire intake tract for a cracked intake manifold, blown off or split wide open vacuum hose, etc.
Try pinching off the large vacuum hose to the brake booster on the offchance that an explosion could have ruptured the booster and see what happens.


#10

Noticed while pondering this that you have posted more info. It still sounds like an intake explosion although the vacuum leak may be a non-issue now.

I believe this car uses a vane (or flap) type air meter similar to the old VW air cools.
Even if an intake backfire occurred on those cars (much less an explosion) the result was usually that the vane in the air meter would be blown out and the car would barely run if at all.

I would suggest removing the intake boot and looking in there with a flashlight or either remove the air meter for inspection.
If the vane still appears to be in its proper location then gently use a small screwdriver and try pressing on the vane. The vane should move freely when pressed and return to its closed position.

Hope that helps.


#11

Thanks for all the info…I’ll pull the air meter tomorrow and check it.


#12

Well Gollee,
sounds like a timing belt problem to me !