palmer765s

hey guys got a 84 z31 AE 5 speed turbo and recently starting having some problems with it was out one night with a few friends drifting and decided to let the car idle and cool the turbo it just shut off wont start on its own got it jump started and it was in limp mode so i had it towed home and knowing nissan MAFs i went and got anohter one from a buddies parts car swapped them out and still nothing so then i started thinking it was fuel cause it would iudle on its own but had to start it on starting fluid but if you touched the throttle it wanted to choke out so i put a 255 pump in it got a new fpr and removed the filter to put a guage there just as a temp test still getting nothjing so then i thought the alt went bad and fried the ecu cause it was charging at diffrent rates either 11 or 15V so put a new alt on it and borrowed a buddies ecu from another turbo z its still not starting on its own i have 3 mafs for it 2 ecus and all new fuel system minus the injectors (DSM 450cc injectors are on the way) but as of today with the borrowed ecu in i can start it with the maf unplugged and it will go into limp mode of course but once i plug it in the car dies i did do the maf test with the back on the pins and all the readings are lower then when the fsm says could it be i have a bad maf ground or wires some where ? oh and it is also constantly blowing the main bat fuse in the bay. some one give me some advice
i saw some where where some one said their speed sensor caused this could that be it ? im just so tired of throwing parts at it and nothing changing

rogerz

try doing some diagnostics instead of throwing parts at it. I see no numbers indicating that you know your fuel pressure, vacuum or timing specs.
here is the first thing to correct:
Get your battery load tested. Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen. Usually on a rainy night around Oh Dark Thirty.

Clean the connectors for the maf or afm, ecu and tps. Deoxit by CAIG is probably the best connector cleaner on the market. spray with CorrosionX after cleaning and before putting together this will help prevent any further corrosion. DON'T USE DIELECTRIC GREASE.

rogerz

if you get it running try sitting in the car in neutral and rev the engine. if you can get to 4500 or 5000 rpm (with maf installed). If it revs quite likely it is the speed sensor. purple wire pin 26 if memory hasn't failed.

palmer765s

The only way it will stay running is with the maf unplugged if I plug it in while the car is running it will die

rogerz

get your fuel pressure. check your ignition timing. check for vacuum leaks. check your air intake system. when things get weird on a z31 look first to the battery and cables and gounding.