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YACT: Jittery Acceleration problem

43st

43st

Diamond Member
Symptoms
1. When it rains my acceleration gets jittery (has happened, to some degree, ever since I got the car... it was never much of an issue)

2. Just got back from a long road trip (using AC the entire time) and now my acceleration is very jittery (all the time, even without AC on).
- engine is fine at idle.
- engine is mostly fine above 3000 rpm.

3. Engine started running fine yesterday afternoon but when I turned on the AC it became horrible again (even when I turned the AC back off!?!) Today the car is still very jittery when accelerating.

4. Car is a 93 Mazda 626 w/ manual transmission and 138k miles.


Speculation
1. Air conditioner compressor is dying and it's effecting the engine.
2. Distributor/Spark plug wires are bad (Don't know how to test this!?!?)
3. I don't think it's a bad fuel pump because that feels a bit different (ok acceleration, poorer at higher rpm, shouldn't be effected by AC)

Can any of you guys help me? 😕
 
That's a classic wet wire/distributor symptom. Your car probably has a distrubutor. If you take the distributor cap off, you'll probably find moisture under there. You'll probably also find that the gasket that's supposed to seal it up is either hard/cracked/disintegrating, or missing altogether.

If the gasket is fine, and it's dry under the cap, then your plug wires are most likely to blame, and they should probably be replaced. The better wires will come with a small packet of silicone grease (called di-electric grease) to form a waterproof seal between the boots and the plugs/cap. Use it. Just put a small bead of the stuff on the inside of each boot, in a complete circle, and it will spread out evenly when you connect the wires. Don't over-do it, or it'll spread on to the contacts, and act as an insulator.

You can also use some of this grease on the ditsributor cap gasket.
 
I replaced the spark plug wires 3 years ago along with the cap and rotor. One of the old spark plug wires fell out of the mounting boot. It certainly drives in a similar fashion as it did when that happened. The cap and rotor are totally clean and dry currently.

About the O2 sensor comments... Do you guys have anyway that I can test this? An OEM sensor is pretty expensive and no doubt the good 'ol NYC mechnic will nail me with a good 30%-50% mark up.
 
93, 94 and 95 626s and MX6s have a long running problem with the spark plug wires. They rot fairly quick. Did you replace them with Mazda parts? If so, the same thing is probably happening.

Try changing the spark plug wires again.
 
I'll get new spark plug wires this evening. The last wires I got were from Advanced Autoparts I think, they're certainly not OEM.
 
Update...

I installed new spark plug wires last night and that did the trick. The #1 wire on the left had a broken core so I was only firing on three cylinders.

Thanks for all the advice guys.
 
Originally posted by: spidey07
O2 sensor?
Click to expand...
SOB !!!!! I had a similar acceleration problem thread that went 2-3 pages and nobody said it was O2 sensor. We were about ready to junk the car because we thought it was a tranny problem... had a thread on that and another thread on a possible trade in. 3 threads later, one last ditch effort to save the car for ourselves was to replace the O2 sensor (costing us another $100) and that fixed the problem.

Bastards!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 😉
 
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