i am back for more sage wisdom, and maybe some criticism as well...i can take it...so, today i pulled the ecu out to check. the fsm i downloaded was for an 86, as at the time, there was no 85 available. it and one of the links i was sent to showed the ecu was under the seat, but its in the kickpanel on the passenger side, as one of you guys told me it would be. my chiltons doesnt even talk about it. i noticed the face that has the potentiometer and slot with lights has been ground or sanded clean. no labels of anykind. i saw two lights inside the slot, one clear, one red. as instructed, i turned the key to on, the clear light comes on, then i turn clockwise and wait...the light goes off as soon as i move the screwdriver. after ten seconds or more, i turn it back counter clockwise, and the light comes on, but just stays on. no flashing here or on the dash. i replaced the positive battery clamp about a week ago, or maybe twenty five starts. is there a step i am missing? has it not been started enough times to generate codes? the battery was only disconnected for twenty minutes. as always, thanks for the input!

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85 300zx n/a with leaky t tops

Please read the 85 FSM for a description of how to run the ECU codes. Follow it step by step.

right as usual, red. however, as i mention, there was no 85 on the list of available fsm's. now i cant seem to find where i found that much. is it zbums website or somewhere you might be able to steer me? the instructions i downloaded, didnt mention anything about running it first, just said to turn the key on, and turn the screw right, wait, then turn back and read codes. turns out the clear is actually green, and due to my red/green color blindness it looked clear. thanks again.

i found xenon z31 website, and it shows that 84-86 are the same procedure, and also mentions lights flashing back and forth between red and green. all i see is steady green on. i am continuing to research while i wait for the sun to go down so i can see the light better. it looks like the red is dark, but i will make sure. any guess why the green is on steady? the zenon page also says to depress the gas pedal three times, and shift thru the gears. i am assuming, possible wrongly, that those are for automatic trans. thanks a third time!

and another thing...zbums website adds to the instructions that the exact location of the potentiometer is important to mark, as it will not function properly otherwise. mine was fully counter clockwise. a few more minutes and it will less sunny, and i can see the lights better...

[xenonz31.com] EF+EC section page 44.

You are lucky I gave you this much.



Edited 1 time(s). Last edit was 2009:06:23:17:04:27.

i am truly blessed! thanks for going that extra mile, red! turns out thats the site i downloaded the 86 fsm from. at the time, the 85 wasnt on the list. i downloaded the 85 just now, and when i scroll down on the table of contents, it says the same thing. that its for the 86. i will follow the instructions to the letter. just wanted you to know. i have studied that page so many times, i could almost recite it from memory. well, maybe a few years ago i could have!

success!
following the fsm instructions i got a 23 and 31 flashed at me, instructed to push gas pedal down and back once, and the 23 disappeared. next instructed to start the engine. should have had a 14 and or 31, but only 44 appeared. the book says this means no problems.

what about that question about where to leave the potentiometer set when done? i left it as i found it, all the way counter clockwise.

my sympton is a random mixture change that happens at the exact same time, as the engine temp comes up. during this temp band, the engine sounds louder, like an exhaust leak,and lacks power unless i really step on it. then after warmed a bit more, it returns to normal mix, and runs and drives great. if i disconnect the battery, the symptom goes away...for a few starts, then reappears...

i was sure i would get a code for a sensor or afm, etc.

disappointed and glad at the same time.

how is your cyl head temp sensor? It will make the car run whacky after startup. If it hasn't been replaced might as well on a car that old. Two z31 of mine replacing the chts made a world of difference. Also check the wiring as it runs over the engine and then down to the chts. there is an oval connector atop the engine that I just cut off and soldered the leads. the connector for the chts is same as the fuel injectors. there is a procedure on the web if you search on how to replace. Don't overtighten. It only needs to contact the metal of the cyl head snug is plenty.

The CHTS can be tested via the FSM directions using a DVOM.
Do not worry about the potenio setting on the ECU.

excellent input, again thanks! will check asap.