Hey all, this is my first post. I have a 78 280 mostly all stock. Since I have gotten it I have put on all new plugs, wires, k&n filter, fuel filter ,oil filter, temp sensor, thermotime switch, rotor, cap, fuel lines, one new injector, electrical connectors to all engine sensors, new temp/thermotime harness, and battery. Since I replaced the harness I have been having trouble with my starting. The car will start, but it can take a while if cold, and then if I touch the gas peddal it will choke up and stall. If I just let it sit untill it hits 120 degrees it is fine. So it sounds like I have a bad temp sensor right. Except I know it is new. I also did all the multimeter tests that the manual says to do. Now the temp sendor is comming up NG as well as the air regulator and the air flow meter. I know the air regulator is working cause I get a good cold idle and warm idle. I also took off the air flow meter and tested it according to the book and it was fine. The temp sensor tests fine when I perform the insulation test and the resistance test. So my conclusion is that I have bad wiring somewhere. Does that sound right? Is there something that I am missing to check? And if I am right than what could have happened to make all those things come up bad in my multimeter checks? All I did was replace the temp/therm bundle and now this happens. I think that my car thinks it is at a warm temp when it is not cause there is a problem communicating between the sensor and the brain.
So so I have to replace the entire bundle or is there a easy way of testing out the wires individually for a break or grounding problem?
I hope someone can be of some help cause this has me stumped. And thanks for reading all of this I know it was long.


Killer

 

isnt this a common problem w/ all z cars? mine is a 10 - 15 minute warmup before i try to take off anywhere first time of the day.

 

but why does it have to be. Can't we fix it? This stinks

Killer

 

I have the same problem with my Z but it is much harder to start after I have been driving it a while and then when it cools off for a couple minutes its harder then hell to start. I wasnt even sure it was going to start.

 

I was thinking it may have something to do with the distributor timing. At least in my car. But you other guys may need to get your thermotime switch or cold start valve checked.

 

I think the L series engine is not to good when it is cold- it is very tempremental. But It usually takes my car approx two minutes to stop missing and backfiring etc, and after about six minutes it will idle wothout stalling... It does stall when i touch the pedal though...

Alan, Australia

 

Yes the Z cars have been known to not work so well when they are cold, and the early Z's had a tendency to overheat. Another thing I live in El Paso, TX where we have about 300 days of sun. So I really don't have a problem with it. But when winter comes I notice it takes awhile to start. during summer time I can crank the car with one start but when it gets cold (cold here is about 50 degrees and that is during a real cold winter) my car starts in about 3 cranks. I also replaced the cold start valve last week. My was leaking gasoline. But once the cars are warm they run like hell. Another thing the guy with the 81ZX, I think I have the same problem like yours. the problem I think happens to be with IC unit. another thing with the Z is that they have a tendecy to vapor lock. So it will be a little bit hard to start when they are hot.

"It can't rain all the time"

 

Hmm...

Try pinching off the fuel return line and/or disconnecting the vacuum line going to the fuel pressure regulator...

By doing this, we will be causing it to run a little bit richer...if it runs better with the line pinched or the vacuum line disconnected, then we can access that the problem is that you are running lean when cold.

My '77 280Z has had the cold start injector bypassed and it runs fine when it's cold after the first 6 or 7 seconds or so, so I don't *think* that it is common with every Z out there...even if the ECT is new, the ECU may not be reading it properly due to a wiring problem, or something to that effect. It could also be that the ECT itself is bad...

Let me know if it changes anything...

Bill
92 GSX
77 280Z

 

Thanks, you so far have the best answer out of anyone. My mechanics think it is running lean too. What we think is that when I changed some of the parts and wires it changed the readings that the computer was seeing. So I will adjust my afm and get my valves done at the same time soon. I'll post if that fixes it.
Thanks

Killer

 

LOL Skully, I can respect that.

Bill
92 GSX
77 280Z