# 85 300z Code 23 where to start?



## JETComputers (Oct 11, 2004)

I have gotten an 85 300z N/A that had been sitting for about two years. I dropped a battery in it and after cranking for a few seconds it actually started. The problem is that it starts easy but when you give it fuel it stumbles really bad but sometimes it takes off like a rocket. I have checked all vacuum lines gave a full tuneup fuel filter all that good stuff but with the same problem.. Now on to the computer. I read some posts here to get the info for pulling the codes out of the computer. Problem number 1: when I took the computer out I marked where the test selector was but when I went to turn it, it was already turned fully counter-clockwise. I don't know if this would be part of the problem. Anyhow it shows a code 23 and 31. From what I have read 31 is supposed to be there.. From what I read code 23 is for the idle switch circuit but I don't know where to start checking to fix this problem... Any info and help is greatly appreciated.
Justin.


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## 0341TODD (Nov 15, 2003)

The idle switch circuit should be the throttle switch, I dont know that it would give you that kind of problem if it was going bad though-- actually- it might now that I think about it.

I had a problem where I was getting too much fuel on start up when the car was hot. It kept fouling my plugs and I had all kinds of problems. Then I took my s-afc out of my other car and hooked it up in my Z and that took care of the problem b/c I could decrease the fuel at idle. 

Check your fuel pressure regulator also- maybe it has gone bad- that could cause you some problems with fuel also.

What exactly is it doing? just stumbling on idle? does it feel like one or two plugs arent firing?


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## JETComputers (Oct 11, 2004)

*stumbles only under throttle*

It idles just a pretty as you please nice and smooth but when you give it throttle either in or out of gear it stumbles like its missing and or not getting enough fuel. Its kinda like its under a very heavy load it will increase RPMs slowly but by no means steady. Once you get the RPMs up high you can back off the gas and stab it again and it picks back up alot better but still not like it should. But sometimes it'll do just fine. If you press the gas slowly and I mean very slowly it will increase the RPMs with no hesitation. I'll check the fuel pressure. Do these cars have schrader valves to check fuel pressure?
Thanks for any and all help
Justin


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## Zen31ZR (Mar 24, 2004)

Idle switch circuit:closed throttle switch. I beleive it's integral on the TPS. Look around on the TB and see if anything else is there besides the TPS.


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