88 300zx turbo ss cold start issues

[s0m3th1ngAZ]

alrighty ive had moby d!ck taken to 2 different mechanics (nissan dealer and my family's tech) and neither of them have been able to fix the problem.

basically cold starts are a *****. it takes several cranks (on average) to get the pistons firing and it happens gradually. once it does fire it may or may not hold rpm and stay in warm-up mode. sometimes it pegs at 2 grand and does the normal thing and fall back to around 800rpm, others its fluctuates like a pendulum. cold weather doesnt seem to affect it, in fact it's easier to start in the morning than when i come home after class/work where its been sitting in the sun. once everything is gravy and i put the engine under load, i can hear piston slap (or some metal parts banging up against other metal parts, but thats the way i would describe it) this goes away in about a minute.now, the techs that have worked on it gave me conflicting opinions. the nistechs said the afm was malfunctioning, however the other one said it was in perfect order( even tried a new afm and it didnt have an effect) after $300 worth of diagnostics, my family tech ruled out several things. he replaced the air auxiliary control valve/switch, secondary injectors, the idle up sensor/switch, fixed a wiring problem involving home depot spl, a vacuum leak, and gave it an engine treatment. none of this to any avail. it still does the same thing every time i let it sit for a couple hours. however it does run allot nicer:P

oh, it runs perfectly after being warmed up.

so any other ideas you guys can throw at me? im tired of spending money and not having **** fixed.

[NISTECH]

head temp sensor has a bad connection. Easy check with an ohm meter. Near the front timing cover coming up from by the Tstat is a short sub harness. There is a black rectangulat 2 pin connector between your fuel pressure regulator and the #1 plug wire. Disconnect that connector and place your ohm meter leads on the terminals in the connector with the subharness that goes down. There should be an ohms reading there, if not you have an open circuit between the other end of the subharnesses connector and the headtemp sensor likely due to corrosion. Now if you do get a reading very gently pull on the subharness and see if you loose your reading with the movement, if so you still have the problem. The proper repair is to replace the subharness and head temp sensor. However just as a test you can unplug the subharness on the connector clean both the sensor terminals and the connector terminals.[ its a yellow connector BTW] tighten the pins a bit with a scribe by slightly bending the split ends oof the connector terminal toward the center of the terminal opening.

Note it is an absoulute ***** to get to that yellow connector. You need to remove the a/c idler pulley braket to gain access.

[s0m3th1ngAZ]

yup, they both checked that out too, passed with flying colors.

[s13sr20chris]

i would start off by giving her the basic. check fuel pressure, ign timing, idle speed, tps adjustment, etc.

however, if you are looking to replace some stuff i would go ahead and put a temp sensor and pigtail in her.

i love those pigtails. any time i replace a temp sensor that will plug into that pigtail, i just cut it off and splice her on in there.

[NISTECH]

Yea we do the same out here. Dont matter the model we use that subharness and snip off the end of it. Z32 is the most popular use.