Another EFI problem

[jonathanrussell]

Fine Stephen...whatever techicalities you like...I suggest that the original poster focuses on these three components. It is my suggestion based on my experience with the car and I stand by it.

[turbo 260]

So far everyone has you looking at fuel. maybe it's on the spark side. i've seen Nissan distributers cut out when they get hot (roughly 15-20 minutes after start up0 die, then run again after they cool off. Try this, get an extra spark plug, new or used, and next time the car dies pull a plug wire, plug it to the extra plug and ground it by the strut bolts. Try cranking the car and see if you are getting spark. At worst this will eliminate the dizzy as the culprit. Speaking of plugs, have you checked them to see if the car is running rich when it dies? To much fuel will kill the car, but it will usually smoke black smoke first.

Jim

[EdMo]

Yes, I have also checked the plugs as well, only a month old they did seem a little more carbonized as running rich. Now the engine itself has only about 600 miles and the rings should have already set, but these are the same plugs during the breakin. So I went ahead and replaced them with some plugs that I had previously used during the first start up. The problem remained the same.

Do want to say quickly thanks for everyones input .... I've got alot to check, unfortunately most is on weekends because of work.

I did speak with Mike Mcginnis from Bonzai Motorworks this afternoon, mainly because I was ordering the subharness connectors for the sensors. I have replaced the Thermo sensor, sending unit sensor but did not replace the cold start because I did not see it in catalogue when ordering other sensors. So I am also getting the cold start sensor as well, but probably will not get here till next week. Mike also had alot of information, some as other posts earlier, but he highly suggested I do this as well. He also recommended to change the Fuel Pressure Regulator everytime you change the fuel pump. Its the original regulator so I'm sure it would be a good idea to replace as well. I've got to much $$ invested to quabble over a few more bucks.

[DatsunZsRule]

Fine Stephen...whatever techicalities you like...I suggest that the original poster focuses on these three components. It is my suggestion based on my experience with the car and I stand by it.

Not to start an argument here, but Stephen's response to how those E.F.I. components work on a stock 280Z IS correct wheather you want to believe it or not :classic:

Anyway back to the original posters questions-

"Do you know whether the cold start sensor is the same as the FI temp sensor and where I might be able to find the mating connectors?"

No such thing as a Cold Start Sensor or F.I. temp sensor. I'll try to clear things up here for you. There are only 2 main temperature sensors in the 280Z Bosch L Jetronic system. One for coolant temp. and the other is for air temp. The Water Temp. Sensor is located at the Tstat housing and the air temp sensor is located in the A.F.M. (Air Flow Meter)

Stephen has already explained how these function in his post above so no need for me to repeat it.

As for the connectors- are you looking for a injector connector for the Cold Start Valve? If so, Courtesy Nissan has them www.courtesyparts.com

"Also, after warm up you can here the fuel pump humming (this is the second pump acting the same) and can smell gas, so it almost seems like its choking itself."

If your smelling gas then check for leaks. perform a fuel pressure test if you have the equipment to do so. If not then at the very least do a visual check. For the pump, does this noise happen with a full tank? Reason I ask is because they will make more noise when the fuel in the tank gets lower. Also what brand of fuel pump did you install? Aftermarket or Factory?

[EdMo]

The sensors I was referring to, are located at the thermostat housing, which Mike mentioned were the Thermo Time Sensor and the Wather temp sending unit and the other that I had not replaced was the water temp sensor. At the Z Clinic here in Austin, these bullett connectors and sensor were there main concern and they explained as cold start sensor and FI temp sensors. Though he did mention they adjusted the AFM, but not sure what adjustments were made. But before and after this the problem is the same, so anything they did...did not help or make a difference. I have checked for fuel leaks all around, but do not see any.

[turbo 260]

You know, I really don't see it being a sensor. The only one really effected by time/ temperature is the head temp. We need to know what's going on when it dies. Try the spark plug test for spark. see if you can get a noid light ( I believe that advance auto sells them for about $12) and test for injectors firing. A fuel pressure gauge will help make sure the pump,regulator and filters are all OK. Those three tests will really help to narrow down the possible causes. I'll still guess it's spark, but that's just a guess. To bad you weren't closer to Tampa, I have both types of factory EFI analyzers.

Jim

[EdMo]

Hot dang it...call me stupid, but what I have replaced is the water temp sensor, the water temp sending unit and have not replaced the Thermotime sensor or the Cold start valve.

I wish I were closer to Tampa.

[DatsunZsRule]

I too have all the equipment but I'm in MN. My Z is still in winter storage So I'm unable to lend a hand as well since your in Texas but anyway, I hope you aren't just replacing things because you think they are bad or the cause of the problem. You'll take yourself to the poor house doing that.

[TomoHawk]

Did you check the programming on the engine computer? Sometimes it'll get oout of balance and you need to go inside an press the reset button to get it back to the default settings, so it doesn't shut off the fuel pump when the coolant gets too hot.

Well, you can't do any of that :cheeky:, because the ECU ( Engine Control Unit) is about as dumb as a transistor radio. It just takes inputs from the coolant temp sensor, the air temp sensor, AFM resistor, etc. and generates pulses to turn the injectors on. It's not anything like a computer or a brain, and if you ever get any work on it by a 'modern-trained' mechanic, you'll know better if he tells you that you need a new engine computer, or you can reprogram ( 'rechip') the engine computer for performance.

Remember the L28 engine is of the old-school design, which relies more on the mechanicals to get power. the ECU is there to make sure it gets the fuel it needs for the temperature, RPM, and airflow.

You would do well to get yourself a copy of the '280Z EFI bible.' It has diagnosis charts and procedures. Also atlanticz.ca has several tech sections which describe how you can test sensors and other stuff.

thxZ

[sblake01]

One of the main problems with these systems is the lack of understanding of them. And it gets spread around enough to where people end up throwing parts at a problem until it's fixed. I prefer not to take that route. jonathanrussell, you can respond to what I say with a surly attitude; that's your call. My cars run. I don't come here for advice as I've worked on these cars for over 30 years. I'm not trying to prove anything. I would just like to see correct information. You do it your way, I'll do it mine. I would also like to see him get his problem corrected without seeing terms like 'brain' or 'tricking' the system. Call what I said 'techicalities' if you wish but that's how the system works.

[jonathanrussell]

Not to start an argument here, but Stephen's response to how those E.F.I. components work on a stock 280Z IS correct wheather you want to believe it or not :classic:

I don't recall questioning Stephen's response or indicating that I don't believe it. I am though tired of him picking at my terminology when i am merely trying to point the poster in a direction that seems to make sense to me. Car runs good when cold. Car warms up and immediately falls apart. In my experience...and I have experienced something similar...it is the thermotime sensor, water temp sensor, or cold start VALVE.

[sblake01]

You will note by my statement which was

Check each of the mentioned components as per the FSM. There is a test procedure for each one as well as the rest of the components in Section EF

that you and I are on the same page. I just think it's important to use the correct terminology especially when responding to someone who, at least by the content of his post is not as experienced with the system and it's troubleshooting as you or I or many others on this site. I won't say anything else along those lines here since it seems to bother you so much.