New to the forum need some help on a 89 zx !!!!

A home for 1983–1989 300ZX owners!
89-300zx
Posts: 2
Joined: Wed Dec 11, 2013 1:33 pm
Car: 1989 300 zx non turbo

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i have a 300 zx 89 non turbo. i have blown 2 Ptu sensors and not sure why. of course car wont start because of this! it trys a few times and then it kills the ptu i have looked all around and cant find anything not plugged in or a short nothing. anyone have any questions or can give me a next step


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sx moneypit
Posts: 9378
Joined: Wed Aug 26, 2009 2:54 am
Car: 2010 370Z
1986 Toyota MR2
Location: Memphis,Tn.

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Moved this to the Z31 forum.

Welcome to NICO!

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evildky
Posts: 14713
Joined: Sat Jan 31, 2004 9:23 pm
Car: 71 240ZT, 87 300ZXN/A-T, 06 350Z GT, Tundra TRD RW
Location: Louisville, KY
Contact:

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Just to be clear that we are talking about the same thing. The PTU (Power Transistor Unit) aka the ignitor, aka coil driver is not a sensor of any kind, it receives the signal from the ecu and changes it to the proper signal to fire the coil (as transistors do) and absorbing the heat and surge associated with firing a coil, when it craps out, you get no spark, sound about right?
These are a common point of failure as these cars age, I'd have a good look at my engine and chassis grounds, IIRC there is a chassis ground near the drivers headlight on the frame rail. If everything looks good I'd upgrade to the pathfinder unit http://z31performance.com/forum/basic-r ... istor-unit

89-300zx
Posts: 2
Joined: Wed Dec 11, 2013 1:33 pm
Car: 1989 300 zx non turbo

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Was told it was a sensor but yes the power transistor unit. i will have to try the upgrade but i was trying to find out why it would just keep blowing them so maybe i can get it back on the road before the upgrade any ideas what causes them to keep blowing? i didnt see any non connected ground wires by the head light

G-E
Posts: 129
Joined: Thu Aug 09, 2012 1:28 pm
Car: 1. 1987 300zx Turbo-swap, SF interior, koni rallisport springs/struts, msa swaybars
2. 1997 Sebring coupe
3. 1987 300zx 2+2 becoming a caged racecar with RB swap...

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Possibly a bad coil causing feedback? Bad alternator creating voltage spikes?

When was the last time you did an ignition tune up btw?

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evildky
Posts: 14713
Joined: Sat Jan 31, 2004 9:23 pm
Car: 71 240ZT, 87 300ZXN/A-T, 06 350Z GT, Tundra TRD RW
Location: Louisville, KY
Contact:

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you said it keeps crapping out, how many have you gone through? were any of them new? or were they all 25 years old? When I suggested a bad ground I wasn't talking about a broken wire I was suggesting a corroded ground, I megasquirted my z31 so I no longer have the stock harness but I recall there being a chassis ground on the frame rail near the drivers headlight I'd suggest you locate any and all engine grounds, check the crimp connector for corrosion or broken wires maybe even pull them off and scuff the mating surface of the ring terminal and the part of the body they bond to.

ALRUI
Posts: 8
Joined: Thu Jun 17, 2021 6:23 am
Car: 1987 Nissan 300ZX

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Hi Folks, Tried doing the PRW-2 "upgrade" on the 87 300ZX with no success. Can someone with a spare PRW-2 please verify for my that the center ground terminal is supposed to be grounded to the PRW-2 case (metal back side &/or brass insert for screw? My son just picked one up at the local salvage yard and before installing I was probing around and none of the 3 pins is grounded to the case which seems incorrect. Please advise. 

Thanks!
​​​​​​​ALR

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VStar650CL
Technical Expert
Posts: 8289
Joined: Thu Nov 12, 2020 1:25 pm
Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

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This is pretty descript:

http://www.xenonzcar.com/z31/prw2.html

Your '87 should already have a 3-pin PTU, so if you have or need the external block ground to the black wire on the center pin, I'm not sure why. Maybe your harness is earlier? In either case, yes, the center position on the PRW-2 needs ground.

ALRUI
Posts: 8
Joined: Thu Jun 17, 2021 6:23 am
Car: 1987 Nissan 300ZX

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Thanks, thats the upgrade we did, my concern isn't the "how to" portion just that the particular unit he got doesn't have a case ground to the center nor any of the other pins for that matter. The original transistor is grounded to the bracket. I'm thinking the unit he got was defective.
ALR

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VStar650CL
Technical Expert
Posts: 8289
Joined: Thu Nov 12, 2020 1:25 pm
Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

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On an '87 that wire should be grounding through the harness, so ohm the center pin on the car side of the connector to ground. If it's open or high resistance then that's the problem.

ALRUI
Posts: 8
Joined: Thu Jun 17, 2021 6:23 am
Car: 1987 Nissan 300ZX

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The vehicle side has a good ground. He went around and cleaned a bunch of the grounds as the car has been sitting for years & that one in particular since he has the no spark condition was checked for continuity.
ALR


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