Believe I am having an electrical problem not sure

[John Monteith]

86 Mazda 626 2.0l non-turbo manual tranny.

history: late November ’12 to December ’12 my car started to run very rough. Talked to a few people and they told me to do the Dollar test. Turns out I had a burnt valve. Parked car until income tax comes in to fix it. Took it to the shop in February ’13 the mechanic contacted me told me the head was warp and there was no water in the radiator. I thought it was weird cause I did check it early in Novemeber ’12. He shaved the head replace all the valves plus seats. Got my car back up had to take it back the same day as one of the injectors started to leak fuel bad. Really bad. Got it back next day everything is okay dokay until.

Issue: I was trying to go to another town and get tires for my car cause they really need it. drove only about 15 miles and the car start to jerk. The tachometer was jumping alot so I pulled over and stop and the engine stalled. Waited about 5 mins and the car stared up and ran for a few mins but started to jerk again. I manage to drive it home. I knew the ignition switch need to be replace cause the wipers and the a/c would randomly cut off. Wiggle the key they would come back on. After replacing the switch I tried once again to go to the tire store but once again it did the same as above. So I figure bad gas since the car sat up for a few months. Drain the tank and cleaned it, boy it needed it. Replace the Fuel filter and strainer. Fill it with gas with no ethnol and took it for a ride again. Still acted up. After messing it for a few days I notice when the a/c is on plus other things such as lights, wipers and such it would do the jerking thing faster but with them off it would take them longer to do it.

I have check my altenator, have new battery, replace spark plugs with some ngk copper ones, check the ohms of the coil wire, have new coil and new parts in the distributor(did that before the burnt valve)

Now the reason why I think it is electrical is cause I was checking other parts out under the hood and on the air bypass solenoid valve there are 3 sets of wires a: is for the a/c b: is for high altitude and hot idle compensations and c: is for p/s and high altitude compensation. When I checked set A: by what my Haynes manual tells me the voltage is suppose to be the same as the batter but it is reading 10 volts instead of 12. So I assume I am have a short some where just not sure where as everything looks good.

All this happens when the car is warm. I do have a video demonstrating what it is doing. In the video where you will here my redneck voice my idle has always been kinda high around 1200 rpms with a/c off when a/c is on it jumps up to 1500 rpms. Just fyi. Oh and I am at my wits end on this one.

I also found something similar to my situation on the forums but did not see a solution to it.
Any help would be appreciated.

In case video does not show up.

[video]http://www.youtube.com/watch?v=j7T6M2cYV_Q[/video]

Topic

[Jim]

i would look at the charging system again. How did you check the alternator? Make sure battery cables are clean and tight. is the alternator putting out at least 13v at all times? even when the accessories are on?

[John Monteith]

I used a multimeter. I test the lead going to battery while the car is off it gave me 12+v and I stuck it to the other connection wires to make sure there is no voltage bleed through to them. Then I started the car checked voltage while everything is on and the wire going to batter was 14+v and the lead to the ignition is 14+v and the lead that goes to the cluster(alternator light) was 13+v.

Atleast that is what my Haynes manual told me how to test it.

[Jim]

i would stay at the battery terminals. one lead on positive one on negative. look what the voltage is when the car starts that surging.

[John Monteith]

I just did it and it is reading a 1 volt less than what it says at the alternator. I also did the ground test like Eric had in his video and it appears I have a ground issue. Unfortunately mother nature is not going to allow me to work on my car today. So it may be a few days before I post any results after fixing it.

[college man]

Have you looked at the IAC or checked for vacuum leaks?

[Trent “Teddy” Martin]

It sounds like you may have a bad/arcing ground causing the to jerk. Another case I’ve come across was a slim line crack in the radiator only visible under heavy load spraying out onto the dizzy causing it to misfire making the car jerk.(You said no coolant in the radiator. Had to go somewhere )

[John Monteith]

Well after looking at it again this afternoon, silly me need to remember how to read a multimeter. After re-looking at my the ground is .01v, the alternator is running 14+v at the battery and around 13.4 to 13.6 with everything on. Now I watch the voltage when the car died and really did not see it drop until after the car shut itself off.

As for the iac I am kinda confused as to which is which as for the parts houses they are saying one or the other. In the shop manual they have air control valve and air bypass solenoid valve. My car was the first year Mazda had fuel injection and neither part is cheap.

Oh I forgot to mention I have the Shop manual for my car too with wiring diagrams.

[Author]

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