Cesar, pay attention to the weather and the heat inside your car. Remember that both your ECU and your ignition module are INSIDE the cabin of the car, just inside the kick panels. So if your car has been baking in the sun, both of these components will be starting out a bit on the hot side when you start your car. If the weather is a bit more fair, and if your car has been sitting in the shade, your IM and ECU will be less heat-stressed. I don't know whether that would coincide with when your engine messes up, but it's something to watch.

These intermittent problems are the worst! I hope whatever the problem is, that it just FAILS for you, so that you can track it down.

Just an update: car hasn't been acting up, since I isolate the MAF unit from the ground rod (MAF has no bracket) , i dont know if that was the problem.

Like you said FastWoman... this intermittent problems are the worst so far..

Thanks

Cesar,

Download the Factory Service Manual (FSM) AND the Fuel Injection Bible (under downloads on this site). Three things, I would check the Thermotime sensor, the Airflow Meter (AFM) and the Throttle Position Switch (TPS) to make sure that they are functioning and set properly. S30 series Z's with Fuel Injection were not equipped with MAF sensors -only AFM.

Read the Fuel Injection Bible and begin checking you system out. Use the FSM to further check the condition of your Z.

It could also be a faulty temp sensor in the fuel injection. ECU thinks the car is cold when its warm. There should be two, an engine temp sensor and an air temp sensor. An electrical supply can sell you real freeze spray. The upside down air isn't bad, but freeze spray is the real thing.

I will go out pn a limb and doubt its the thermotime switch, it operates for 8 seconds at startup to turn on the cold start injector. Pull the plug off it or the cold start injector when hot and behaving badly, no change eliminates it as a possible problem.

Edited June 15, 201113 yr by jaltman

Cesar,

Download the Factory Service Manual (FSM) AND the Fuel Injection Bible (under downloads on this site). Three things, I would check the Thermotime sensor, the Airflow Meter (AFM) and the Throttle Position Switch (TPS) to make sure that they are functioning and set properly. S30 series Z's with Fuel Injection were not equipped with MAF sensors -only AFM.

Read the Fuel Injection Bible and begin checking you system out. Use the FSM to further check the condition of your Z.

Andrew thanks for the advice

It could also be a faulty temp sensor in the fuel injection. ECU thinks the car is cold when its warm. There should be two, an engine temp sensor and an air temp sensor. An electrical supply can sell you real freeze spray. The upside down air isn't bad, but freeze spray is the real thing.

I will go out pn a limb and doubt its the thermotime switch, it operates for 8 seconds at startup to turn on the cold start injector. Pull the plug off it or the cold start injector when hot and behaving badly, no change eliminates it as a possible problem.

Jaltman thanks for the advice.

THANKS EVERYBODY!!

You are giving me a lot of points to check that MOST LIKELY I would have missed on my own.

I'll be updating...

THANK AGAIN

It could also be a faulty temp sensor in the fuel injection. ECU thinks the car is cold when its warm. There should be two, an engine temp sensor and an air temp sensor. An electrical supply can sell you real freeze spray. The upside down air isn't bad, but freeze spray is the real thing.

I will go out pn a limb and doubt its the thermotime switch, it operates for 8 seconds at startup to turn on the cold start injector. Pull the plug off it or the cold start injector when hot and behaving badly, no change eliminates it as a possible problem.

Agreed..

Yeah, not likely the thermotime, if only because the problem presents itself in a warm engine after the engine has been running fine for a while. However, you can't automatically eliminate the cold start valve just by unplugging it. Sometimes these things jam open a bit and dribble/spray fuel even when they shouldn't. Hook up a fuel pressure gauge, and see how fast your fuel pressure drops off after you've shut off the engine. If everything is tight, your pressure should hold for hours, or even days. If not, it will peter away fairly quickly. That said, your cold start valve isn't going to suddenly open when the engine is warm.

Whatever your problem is, it would appear to be electrical, and it might even be your electrically connectors. After suffering decades of harsh use, the electrical connectors under our hoods are usually pretty crusty and crumbly. Try cleaning up all your connections with DeOxit (best) or some other contact cleaner. You might also need some very fine (e.g. 600 grit) sandpaper to polish contacts and/or a tiny screwdriver to scrape corrosion. If the plastic body crumbles on one of your two-conductor connectors, you can buy new off of Ebay. Just do a search for "injector connector 280Z." There's some seller ("forest," as I recall) who sells some pretty good kits. I'd frankly replace all my connectors if I were you. Old connectors are trouble.