just bought a "new" 300zx 2+2 and the only problem im having so far is cold starts.

has anyone had trouble starting their car in the cold? My car turns over in the cold then i have to stop then re-start it again. it starts fine warm.

 

hi! welcome! i had the same exact problem. what year is your z? early z32's had pcv valve issues. maybe that could be the problem. check your aac valve and your iacv-regulator. thats wat i did. i took off the hoses that connected from the aac thru iacv-regulator and i sprayed the inside of the hoses and the regulator with wd40 and magically it fixed the problem. i bought a regulator and all hoses just in case but that fixed my cold starts and now it starts and runs like a dream. also try cleaning your throttle bodies, check ecu codes, vaccum leaks, timimg, coolant temp sensor, dampner. there are write ups on here to check for ecu codes manualy. hope this helps :-)

 

"i took off the hoses that connected from the aac thru iacv-regulator"

eh? wheres that located? and will the engine throw a code on the dash like check engine for me to diagnose a code or do i have to look anyways. yes its an early z 90'.

 

early zs had a problem with the valves, not pcvs

the iacv is located in the back drivers side of the engine. right behind the plenum. next to it is the aru. ohm test the connectors for the two to see if they are working correctly. you can take them off and apart and clean them

this link should help you with those two parts
http://home.swipnet.se/e-solutions/IdleTech.html

heres a writeup on how to check the ecu for codes
http://www.ttzd.com/tech/diagnostictech.html

 

these things dealing with the iacv and aac seem to be dealing with idle problems, which i dont have. wasnt sure that this would help cold starts....also i know the car is fuel injected so would giving it a little gas at startup be bad for the car? it seems to work.

 

the air regulator could be causing that. its purpose is to raise the idle when the engine is cold, so if its not working youre engine might not idle high enough to stay on.

it was just a guess.

can you smell gas/ are there any leaks?
you can check your coolant temp sensor, fuel filter(replace), TPS

 

yea it runs strong, fine and everything. when it starts i dont smell gas as of now....maybe battery?? couldnt hurt to replace anyways right? i mean i dont know when it was replaced--atleast it didnt say on the maint. schedule.

 

uhh i'm no expert or anything but i dont think the smell of gas has anything to do with a battery. the smell of gas can be a vacum leak somewhere. the air regulator controls the idle when the car is cold. i cleaned the regulator and hoses and it started excellent. when i used to turn it on in the mornings, the car would not start. i had to keep the foot on pedal to make it stay on. then idle would fluctuate from 500-100 or turn off. so i cleaned throttle bodies, cleaned air filters, check maf, and cleaned regulator and hoses. now car starts and idle when cold is about 1500 then as it warms up down to 800-900. that may be your problem. i took it to nissan and they wanted to charge me $250 just to check connections between ecu and aav. so you can take it to your nearest nissan dealer or u can do it urself. if i could do it, so can u.

 

so from which parts to which parts did you clean exactly?

 

ok. i cleaned the whole entire idle system. in b300z's first reply on here, he posted a link ( 1st link ) of the 2 valves that include the iacv-regulator, and aac valve. now, the hoses that connect to each other are the ones i cleaned. i also cleaned both valves by disconecting the hoses, then spraying the inside of the valves AND the hoses. or you can take both valves off which are kinda tricky but can be done. next i took off both throttle hoses and cleaned both throttle bodies. its best to have someone keep the car on while u do this; the car will not run for long. on open throttle, clean the inside with throttle cleaner. follow the instructions on that link that b300z posted and you will be fine. i followed that exact same procedure and now my car idles great. also check the connectors of both valves. they may be a corroded and need to be cleaned. makes for a good little project for the weekend. lol. yes the regulator may be ur problem. its job is to raise idle while car warms, then shuts off. then aac takes over after that.

 

It's best to clean the throttle bodies with the engine off. To thoroughly clean the TB's, you need to open the throttle all the way. Thottle body cleaner by itself won't cut through the buld up....you need to use a tooth brush.

 

well it turns out that its not cold starts but actually seems to be when my car sits for more than 30 min after its been driven that it doesnt want to start within first few cranks. it starts fine at cold, or even if its warm and been driving withing 5-20 min.

 

have u done ohm tests on the connectors? i just finished today putting on my regulator and it does feel much much better, like new. it started to do it again, wat u said about not wanting to turn on after u start it the first time when its cold. what exactly have u done to pinpoint the problem?

 

Same problem here with my '91 2+2. First couple of times I turn the key, the engine won't start. Third time or so it starts and runs fine.
If you've found what's the problem, please, let me know. Thank you!

 

You should try all of the suggestions listed above. Any one of them, or all of them can solve your problem. 1 problem can have many different causes. One of the joys of these cars is that 1 symptom can have many different possible cures.

 

now, boyZ--when you start yer car, are you turning on the key for a little short time to prime yer fuel system before you start----not long--just a slight hestiation on the way to ignition?????? if not---try it. before you spend too much more money, find out if you need to. my AE was doing that---i had to do as i wrote, and i had to let the car run for 30 minutes after i change batteries or disconnect battery..drive it to the store--around the block..w/e........nice turbo.........

 

yes my car cranks twice then starts on the third one any time after sitting for 1-4 hours but starts fine before sitting an hour or after 4...say for the night or if it sits for half an hour. not sure what the deal with that is.

 

Yes, I do that every time, on every fuel injected engine I own (my Ducati is a lazy horse itself ). I am starting to think it is the fuel pump that does not provide enough fuel pressure when the engine has been sitting for a while. Does it make any sense? Thx!!

 

mine still has been doing the non-start game on first crank while warm....anyone else have any solutions or know of anything that is causing this? boyz?

 

Have you tried all of the suggestions already given?

Is anyone going for fuel temperature sensor on this one as a far outside shot? I don't think I've ever heard of one failing though.

 

fuel pump. haven't had a problem yet since i replaced it. not to say that it couldn't be a number of other possible problems.