Car shutting off and on randomly while driving

[psulja]

This is on my manual NB1, mods are an SRI and a Racingbeat muffler.

Okay, so this problem started in the middle of winter. The first time it happened I did a hard pull from a dig, as I shifted into second the car lost all power for a quick second, turning off and on quickly jerking me back and forth, I put the clutch in and just coasted and it seemed to be fine. Then I did another pull a few days later and it did it again.

After that the problem went away for a while until I took a road trip to OH where it happened a bit more frequently during hard driving in some twisties chasing XCLR8TN. The roads were a little bumpy but not too bad. When we lined up to do a pull this happened in first, second, and third.

Again, after that the problem stopped for a while other than a few times here and there until this week, today probably being the worst. I was driving in traffic leading up to an expressway where the speed changes from 80kph to 100kph so I downshifted to 3rd and was going to accelerate up to about 115kph, but with about half throttle the car just didn't want to co-operate. It shut on and off probably over 10 times in that short stretch to the point that I almost pulled over because it was so bad.

So a quick overview; when accelerating a little harder the car loses all power, radio shuts off, gauges all drop to 0 for a quick second, then the car turns back on and everything seems normal. Whenever it does this it obviously starts jerking around as if I was jabbing the throttle or kicking the clutch in and out.

It also happens over some bigger bumps or when I go over railway crossings at regular speeds (50-60kph).

I checked for codes but it's still just the one for my intake mani/egr (the 99-00 NB issue).

Any ideas what this could be? I can't do one specific thing to replicate it and it doesn't happen everytime I do a pull, just spontaneously whenever it feels like it lol

[WASABI]

Perhaps a wire short? YellowYata had something similar....

http://mazdaroadster.net/showthread....CPS-failure%29

[wannafbody]

Check the battery ground to the power frame

[psulja]

I'll have to check the wiring. Today the car completely died on me so I had to pull over. A couple of friends suggested a short somewhere going to the alternator if the car is losing all power. I tried checking the wires while pulled over, after moving a couple to try and get a better look I tried to turn it back on and it started right away so I think it might be somewhere around there but can't be too sure.

I'll check the battery ground like suggested.

When i got the car started again the battery light came on for a bit and then went away as well.

[—kung fu jesus—]

It might also be a relay starting to go or with a bad lead.

[WASABI]

Psulja, did you read YellowYata's thread? His issue was a wire that had worn through from touching the water pump belt, and would sometimes short out when the exposed wire was jostled and hit the metal of the pulley. Check it out.

[psulja]

I haven't had a chance to read that thread yet, but I did notice that after i played with the wires yesterday it didn't happen until after I hit a bigger bump today so I think it might definitely be a short somewhere, just have to find the time to see where it might be.

I took a couple videos of the problem and will see if I can post one of them up tonight or tomorrow.

[— YellowYata —]

Was, thanks for the recommendation but I doubt this problem is related to the crank sensor wiring grounding on a pulley. That wouldn't cause the kind of electrical problems described. I think it's something else like an electrical connection that's barely hanging on i.e. battery ground, a ground on the motor, connector under the dash and so on.

[psulja]

[— YellowYata —]

If not for the radio cutting out, I would suggest checking the plugs and wires first. This is happening only on acceleration, yes?

[psulja]

No, it does it while cruising sometimes as well; it just so happened I was in the city getting stuck at lights for the videos.

[— YellowYata —]

Ah. Have you done anything electrical lately? Run wires? Install a radio? Just want to get that out of the way. Last, have you considered your ignition switch? Sometimes people with ten pounds of junk dangling off their keychain can ruin the ignition switch.

[psulja]

Nothing new Has been done as far as electrical goes.

For the ignition switch, I haven't considered that but both my key chain and the po's were always very small/light. It's just the key for the car and a tiny adjustable wrench, no other keys.

[WASABI]

Was, thanks for the recommendation but I doubt this problem is related to the crank sensor wiring grounding on a pulley. That wouldn't cause the kind of electrical problems described. I think it's something else like an electrical connection that's barely hanging on i.e. battery ground, a ground on the motor, connector under the dash and so on.

No problem, I was merely suggesting some out of the box thinking, as to the cause. This is a Canadian car, driven in the winter, so I am beginning to think loose/corroded connection.

[— YellowYata —]

In post #7 you said you "played with the wires" and that the problem seemed to go away for a little while. What wires? Spark plug wires? Also you said the instruments all go to zero but judging from the jumpy video, the only thing I see going to zero is the tach which is normal if it's reporting sudden loss in RPM. The other gauges, of course, wouldn't jump to zero anyway and the ODO seems to retain power so it's not a sstem-wide electrical outtage.

Given that the radio cuts out, I think it's something related to the ignition switch. Perhaps it's the switch itself or the wiring to it. If it weren't for that detail about the radio, then my suspicions would be plugs, wires or cam sensor.

That's all I can think up so far but I certainly wouldn't rule out checking your battery terminals, chassis grounds, electrical connectors, vacuum hoses and for anything else that would be worth looking into.