I have a 1998 626 and the rmp tend to shake alittle when the car is stoped in drive or reverse and jerks aliitle. It was real bad and the car used to misfire due to spark wires but with new ones in it still shakes a liitle.If any one knows the problem it would be appreited if u can help me out.
Thanks,

 

Is it rough like still missing or just vibration felt inside car?
If still missfiring a few things that are a little common.

#1Were the spark plugs also replaced with the new plug wires? If not then check the spark plugs for carbon tracking down the outside of the ceramic insulator. Often times a failing plug wire will get black carbon track line down the inside of the boot and this track will also get burned into the ceramic allowing spark to ground out to the cylinder head.
#2 make sure the fuel pressure regulator diaphram is not ruptured and vacuum line is not drawing raw fuel directly into the intake manifold.
#3 Vacuum leak from intake manifold gasket no uncommon on 98-01 4 cyl 626 either. Make sure to carefully check on the underside of the #1 and #4 intake runners as this was the area most common to rupture.
#4 EGR valve sticking open. This will cause problem most commonly after some sustained steady driving and then coming up to a stop. Diagnose this one by simply unplugging the electrical connector when idle is good and driving around for a while. If valve is never allowed to open it cannot stick that way.

All four of the above were somewhat common on 98-01 4 cyl 626 so might be a good starting point.
If is not missfiring but just vibrating then check motor mount for being weak. 4 cyl always did vibrate a bit that you could never make go away. Only cure for some of the vibration is the V6

 

i already changed the plugs so their good, and how do i check if the fuel pressure regulator diaphram isbeing ruptured. The vacume line had some oil on the end of the pvc and the splinter. And where is the egr valvelocated. Also the car is only vibrating and not misfireing. If i leave the car alone the vibration gets worse and the car feels like its about to turn off.
Thanks,

 

i have a 98 626 also and i had the problem with the shaking and i solved it i started putting the expensive gas and after a few full tanks in went away
(If you have a V6 it requires the expensive gas the highest as per my machanic said)

 

i have a 4 cyl. so will your idea still work?

 

This problem started after i had got my transmission gasket replaced, from there my mass air sensor went bad which ireplaced and since then its been shaking when ever i leave it sitting there for a while. Also starting up the car in the morning is problem too, not to big but it doesnt start on the first try with remote starter like it used to beforethe transmission job.

 

i did a few things on my mazda 626 to fix the shaking it had. i had the spark plugs replaced, and the spark plug wires. the other thing i did was had my fuel injectors cleaned out. i cant remember why this was suggested for me to do, but i had it done. that stuff you put in with the gas does not work to eliminate the shaking nor does it really clean out the injectors (my personal opinion). i went to this kwik car lube place and had it done $69.99. they did a combustion chamber cleaner, cleaned the intake manifold and added a fuel treatment.

this maybe the cheapest things to first. let me know if you have any more questions. ive dealt with alot concerning this dang car.

 

Thanks for the help and are you talking about that "zoom" thing where they clean your valves and everything?

 

i think what they did was somehow blow all the gunk out.. something like that. it really did the trick b/c my car didnt shake badly anymore after it was all cleaned out.