I have a '94 DX pro and I'm having some problems with misfiring and bogging down. It's an automatic with 91k miles. Only routine maintenance has been performed (oil, filters, brakes, and such) and I don't think we have done anything else major on the engine sinse we bought it at 24k miles.

Problem 1) When in neutral with a cold engine start, when I try to rev up the engine it misfires or something so bad that it can't get past about 3k rpm for a while and the whole car shakes. After the engine gets warmer this problem slowly goes away.

Problem 2) When accelerating there doesn't seem to be any power until the RPM's get up above 3k or 4k. This happens all the time even if the engine is warmed up.

This is my wife's car and I rarely drive it but now it's going to be my car (she gets the Jeep Grand once our twins are born) so I decided to do some work on the pro. I changed the plugs to platinum +4's and noticed the problem for the first time after this but it may have been happening before I changed the plugs, as I hadn't been driving it.

Any ideas on what may be causing this and what I should check. I have Zero mechanical knowledge (changing plugs and doing oil changes is the extent of my abilities) so keep that in mind. However, I am capable of learning.

I also have some magnecore plug wires, and a cone filter/adapter setup on the way. Should I install those before trying anything else?

As for the plugs I put in, they all seemed to be properly seated but is there any way I can double check this? When I installed them I just unscrewed the old and screwed in the new ones right from the box. Did I miss any steps? I can check the part number on the plugs I put in if needed.

UnderDaHill

 

I might have done a 60k service. I just can't remember. If not I'll get it in for service this week (less the stuff I've already done).

Thanks for the replies. I'll let you know how it all turns out and thanks for the quick replies.

UnderDaHill

 

put ngk back in,+4 suck i see it all the time mazda likes denso or ngk

 

Thanks for the info about the +4's. I'll go ahead and swap out the wires first before I take them out. No reason to toss them out until I confirm that they are the cause of the problem.

UnderDaHill

 

According to Tri-Point Engineering, the problem isn't the wires, but rather the boots that fit into the head. Sitting down there in the head, they get pretty hot. The plastic gets brittle and cracks, and the spark leaks out to the side of the walls. Over about 3k rpms, cylinder events are happening fast enough that this is less of a problem.

Course, the first time it happened, the local Mazda dealer wanted to replace both the computer and the TPS: to the tune of $1100. What a F-in rip-off. (I took it to Tri-point instead and they diagnosed the problem and replaced the wires for about $80, IIRC.