Mazda 626 hesitates under load

hesitation

#1

I have a 1993 Mazda 626 ES with a 2.5 L V6. It has 170,000 miles. Recently it started hesitating and missing when driving up hills. I’ve changed the spark plugs, spark plug wires and ignition coil. Still hesitates. Any ideas what to check next?


#2

Since you have worked the ignition system already, which is a common area of trouble for the symtoms you mention, check to see if there is a dirty fuel filter or weak fuel pump causing this trouble.


#3

I second the cat’s response.


#4

Get a spray bottle with plain water. At night or in subdued light, start the engine. Carefully spray the water lightly around the distributor cap, plug wires, etc. and watch for signs of electrical leakage (arcing, sparks, purple glow, etc.). Might very well find a cracked distributor cap. Hmm, not sure what kind of ignition the 626 has, but you get the drift.


#5

Well I changed the fuel filter and it still has the same problem. Any other ideas?


#6

… check for evap and vaccume leaks, also egr & pvc …
can you pull up any codes ? … I have a '98 pro. with the 1.8 and have problems too …

geo m


#7

I gave it a try. By the time I was done the engine was dripping. But no sparks, glows, etc. that I could find. The engine kept idling fine.


#8

I replaced the PCV valve 'cause it was broken not that I thought it would fix this problem. Haven’t checked egr. I guess I’ll have to educate myself on how to check it.


#9

One other mystery: The check engine light was on a while ago prior to this problem. When I had it checked they couldn’t retrieve any codes. It seemed like there was an incompatibility between their reader and the Mazda computer. The plug fit the socket but the wires didn’t seem to match-up. Is there a Mazda specific reader. I hope not…


#10

Since you replaced the fuel filter I would now have the fuel pressure checked while doing a live run in a area that is giving you problems. The fuel pump may need to be replaced.

There may be a manual method to retrive the codes but I’m not sure how to do that with your model. Some cars have you make a connection in order to run the error codes.


#11

Here is a link to a good site that shows how to get the codes for a 91 Mazda truck. This may apply to your vehicle also.

http://www.troublecodes.net/mazda/91MZDpup.shtml


#12

One more thought along these lines. Look inside the distributor cap for carbon tracking or the little carbon button in the center of the cap might be missing. Look at the rotor also. Again, not sure what exactly your 626 uses in the ignition area, but HTH.


#13

I decided to take it to a shop to see if they could figure it out. They believe the catalytic converter core is melted. They diagnosed it by separating the converter from the exhaust pipes and looked inside. So I believe them that this is a problem. Is this a result of another problem? Will it solve my hesitation problem or am I just throwing money to solve a problem that was created by a problem that hasn’t been fixed yet? Or by replacing the plugs, wires, etc. that I did fix the problem that created the catalytic converter problem?


#14

First, u have a car with 170 000 miles !!
has the o2 sensor(s) been replaced?
is the cat as old as the car?
what and how did the shop check / test drive, ect?
what led u to repace the coil?
all basic tune up has been done? all filters ect?
yes, that year is mazda specific code reader
geo m


#15

"First, u have a car with 170 000 miles !! " Yes it only has 170,000 miles.

"has the o2 sensor(s) been replaced? " No but maybe that’s next. But at $200+ it would be nice to not replace it.

"is the cat as old as the car? " It was until it just got replaced.

"what and how did the shop check / test drive, ect? " I drove it with one of the mechnics in the car. I described how I was pushing on the gas but the car wasn’t going faster.

"what led u to repace the coil? " My repair manual had electrical resistance tests that i performed. The tests results were out of spec. However when I installed the new coil I got the same results. I don’t have confidence in my meter…

"all basic tune up has been done? all filters ect? " Yes. Most fluids and all filters have been replaced in the last six months.

I’ll pick-up the car tomorrow and let you know if the problem is solved.


#16

Changing the catalytic converter fixed the problem. Or perhaps all the mainetance I did along with the converter fixed it. In any case it runs quite well now.