Losing spark intermittently stumped

[239am]

So I just purchased a 91 240sx. I drove it for a few days and everything was a ok. Then driving home from work one night when I was getting off the highway the RPMs dropped for a second and everything was ok again. I got home and in the morning tested the battery and alternator and everything was ok. Then I went to auto zone to get a dist cap and rotor and on the way home when I stopped at the mini mart it died. After 15-20 mins it restarted and took me home. I changed the cap and rotor and still it stalls after a while and then restarts after letting it cool down. I checked the coil, I checked fuses the first day. I am going to change the ignition realy and the transistor tomorrow when I can go to the junkyard. I tried searching everywhere if anyone has any Ideas Id love to hear them. My car is a ka24de w auto. I have a chilton guide too I searched through also.

[zachattack_5491]

Grab yourself an FSM (Factory Service Manual). I don't have a link, but a google search should work. It's at least a million times better than the Chilton. Check the usual suspects I guess, fuel and spark. I don't really know what else to tell you from that description.

If it is a temperature related issue it could be the temperature sensor but I doubt it would make your car impossible to start.

Test fuel pressure and pump
Test injectors
Test for spark on all cylinders

If it's really hot where you live, I guess it's possible that you're experiencing vapor lock. If it does it again, take off the gas cap and see if it starts.

[239am]

Its not a fuel issue. I also forgot to say that the car has spark until this happens when it stalls. I tested for spark when it last wouldnt start and had nothing. I pushed it out of the way and then right before I was about to leave it it started again and was ok on the way home.

[zachattack_5491]

Oh, I saw that you put losing spark in the title... but I didn't know if that was a random guess at the problem. That certainly narrows it down.

You're sure the coil is good? There's another plug on there for something in the ignition system, I can't remember what it is but test that too. Find a friend with a spare coil and toss it on there.

[239am]

I have tried another coil I also forgot to mention that. When I tested the spark I checked it @ the wires first nothing so I moved back to the coil and nothing there either because I was thinking CAS, but it seems to be before that so thats why tomorrow I will try a relay and transistor maybe they act up when hot hopefully that will get it. I can guarantee tho that when I do find the problem I will post my results. I find threads in car forums everywhere with a google search that have similar questions and everyone tries to help, but the author never says what helped they just stop posting when they figure it out I guess.

[239am]

update. So far I have tried ign. relay, fuel filter, coil, dist. cap& rotor, plugs. Its definitely getting fuel. I got ecu codes 11&21 so I am going to try a distributor as soon as I can find one.

[zachattack_5491]

Thanks for keeping us updated. It sucks finding unsolved threads on the internet with your EXACT problem.

Make sure you check the wiring. Wiring issues are often the cause of weird intermittent problems like this.

[239am]

It was the distributor. So if anyone is having codes 11 and 21 come up together its likely the distributor. it took forever to find a used one or else new its $350

[roy23pim]

ive been having the same problem but on my 95 240sx.. it just turns off on me while driving.. til finally a couple of days ago it just didnt want to start.. it would just crank.. so i tried wiggling the wires on the distributor connection and it would turn on again but only for a couple of minutes.. i bought another connection and rewired the connection.. and nothing no spark at all.. i did make the mistake of having the battery connected while i was cutting and rewiring.. the connection im talking about is the one with 6 wires on the distributor.. maybe i got some of the wires mixed up.. anyways i got another harness and ecu.. which im gonna install tomorrow.. if it still doesnt start would i need to check the relays?

[RushRacing]

well im no expert so please dont flame me if im wron but ignition contol modules can do this. When they warm up after running they will breakdown. Im pretty sure the module on the ka is in the distributer. You can get your old one tested at autozone for free. When you replaced the distributor did you keep the old ignition module?