hey guys, ive spent everyday for a month fluffing about trying to make my z run right still got the same issue.

 

The motor i got it with had suspected done head gaskets. misfired at idled spluttering etc. i had another motor around and dropped that in it suprise suprise same issue with the idle. (old motor is toast now)

 

The symptoms were missing at idle and just general gutlessness.

 

I have replaced...

 

Motor and gearbox.

 

ECU, TPS, PTU, AFM/MAF, All injector plugs, idle air control yellow plug changed. water pipe sensor and plug changed.

 

Checked everything its all working does what it is supposed to for the most part.

 

It will not idle under 1500rpm if i set the tps at anything but ever so slightly off full anti clockwise, 4.45v it just laughs at me and revs high. with it turned full anti clockwise it idles just under 1000rpm but sits there going brrrrPI...PIPbbrrrIPI brrrr just missing away randomly, i tweaked CAS angle today as it did seem retarded (dont have a timing light) if i leave it for a while say 30 mins or so it will sometimes run fine at first and not miss at idle ( not cold enough to use its cold idle up) when i give it its first rev when it comes back down it misses and splutters. and starts running crappy again, sometimes i can drive it down the road before this will happen.

 

If i drop my boot from stopped the thing leaves a ploom of black smoke, and it drinks gas like mad all the time.

 

i know its alot to go through here but i really am at the end of my tether and if there was a can of gasoline around... the car would be getting a "wash" followed by a lighter.

 

I did notice when i took the plugs that were new when i put them in the old motor... and put those into the current motor, it ran absolutely perfect at first no miss at all. same thing happened initially when they went into the old motor too... i would say they were fouled but tan colour when taken from old motor and ran spot on when first put in.

 

Could this be a coilpack issue? i cant throw anymore money at it, i cannot pay somebody to fix it or even stick it on a diagnostic...

 

i have a toolbox of spanners etc a multimeter and a hammer.

 

help. :censored:

 

- - - Updated - - -

 

1991 jdm n/a auto....

and yes ive googled and scoured the internet endlessly before asking.

i've been going through this article....

 

http://www.mdsmarthome.com/z/Z%20Tech/Z%20Tech%20PDF's/Curing%20Erratic%20Idle.pdf

 

he say 0.7 ohms for the coil packs, im getting 1.3 on all of mine including spares.

 

i also notice if i turn the tps to a certain point a can hear something electrical making a buzzing noise, as far as i can tell it sounds like its coming from down by the starter motor, which is making nil sense to me.

 

really really getting sick of it...

You are trying to set a 300zx up with no timing light? and by the sounds of it no consults? and you are wondering why it sounds like a bag of bones and doesnt idle correctly?

 

Go spend some cash and get a timing light and if you cant get data scan / scan tech nissan or conzults, at least use a multi meter as you are going to need that to set the TPS.

 

adjust the timing (CAS using timing light), You cant set the idle with out setting the TPS, you need to know if your TPS is at 0.44v (volt meter), once the TPS is set using the volt meter, you should then adjust the idle.

 

the car is going to pop and and miss if all that is screwed up.

i set the tps with multimeter to 0.43 volts...

 

i just changed the idle air control unit for yet another... i set the idle to 720rpm with it unplugged and upto to temp. the moment i plug the AAC on it revs at 1700rpm, straight after changing the unit it idled perfect no missing... ive checked the water temp sensor at least 10 times, and ive swapped it, getting no reading at all across the pins on either unit when the engine isnt running but unplugging it does make the car idle faster.

 

I have no money to go and buy a timing light. zip zero nada and i need this car running so i can get to job interviews... i have adjusted cas to various positions to no avail, i would love to throw every bit of tech and thousands of dollars at it if needed. i simply have NO money.

Base idle should be set to 650 rpm with the yellow connector removed.once its set at 650 plug the yellow connector back in and the revs should pick up as the ecu takes over control of the idle speed.

 

Have you tried a different ecu?, I had an ecu fail on a V6 Calibra and that caused a lot of running problems before I tracked it down.

replaced everything, ecu ptu, fuel pump control unit etc. literally everything. hence im out of ideas.

 

i changed the water pipe temp sensor the ecu reads from as the articles i have read state it could be that failing, the car does rev higher when i unplug the unit, can these partially fail and send a bad temp reading to the ecu, i get no ohm reading at all across the pins, yet it does work.

 

just put in 27 litres of fuel, got 86km out of it. its so pig rich its ridiculous.

FIXED!!!!!

 

Cas pin was worn motor i bought must be a damn 1990...

 

Advanced the crap out of it and it pulls like mad. still has a slight idle miss and will sometimes idle at 1700rpm, which can be either tps or the water pipe temp sensor, tps is okay and set so its definately the sensor on its way out... but who cares... idling is no fun anyway ^_^