mvpz

I have my 1986 z31 which is a weekend driver. I started it last month and took it for a drive and it ran great so i parked it in the garage till today. I went today to start it but no luck. The fuel pump primes and I turn the key it fires and stails and wont stay running. I unplugged the MAF sensor the car starts and idles great and runs up to 2000 rims . I plugged the sensor back in and again the car will not start. Is this a clear cut case the MAF sensor is bad or could there be something else in that circuit that can cause such a problem

THANKS IN ADVANCE

NismoPick

MAF.

Also check ecu codes.

rogerz

if you would really like answers that would help you and avoid flames give the following info when you post: year of car, n/a or turbo engine, stick or slushbox. Most of us can tell by the year what model you have ie 85T is a turbo z31. Z cars come in many flavors and they are all different. example 84,85,86 Z31's pretty comparable. there were changes in 87,88,89. in addition 300ZX can refer to two completly different cars the Z31 and the Z32. No mindreaders here the more info you can post the more likely you get a cogent useful answer

next download the fsm from xenon. if it is a turbo car they have a speed sensor integral to the speedometer which if it goes out sort of looks like the maf is gone because the car won't accelerate thinking it is already going 142mph and cuts off fuel so you get around 2K rpm. drove me crazy for a couple days til I figured that out. test the maf with a vom per the manual procedure. They are really a fairly simple device and unless someone stuck a screwdriver in there to clean it up they last. I wouldn't put much faith is reading the codes. might have been okay back in the age of dinosaurs when all you had to do was buy a new part but that has past. Check your fuel pressure. check your spark, check your vacuum. pull the Otwo sensor connector see if that makes things work. outside chance it is the chts. read the manual get some data. If you can find a z31 in the junkyard any maf will do no matter the year nor turbo vs n/a

mvpz

My car is a 1986 non turbo automatic
I'm getting two codes 23 and 31

rogerz

do you have the fsm it will tell you what the codes mean 31 is Air condition so not your problem. 23 TPS again not probably your problem. I've never seen one affect the car altho others will argue differently. As I said codes usually more of a hindrance than any help. Tps easily adjusted but I sincerly doubt it will solve anything. check your fuel pressure hearing something that you think is the fuel pump means nothing. Check the vacuum. check the ignition timing. a cheap pressure gage for fuel and some fittings. a cheap vac gage and some hose for vacuum. You need some data other than i think i hear it running. pretty much puts you in the "I tried nothing and it still doesn't work" category. however if you think the maf is bad just spend the bucks throwing money and parts at it may eventually get you there

mvpz

Hey Roger Good advice
One question when I disconnected the MAF the car runs great up to 2,000 rpm wouldn't that lean towards these items being good ?
The car ran perfect before parking it a month ago. With the info I have given should I feel confident in making the investment in a MAF ? Or is there a sure fire way to be sure
thanks again

rogerz

The sure fire way is do what I suggested. But like I said you want to throw money and parts at the thing with no data - GO FOR IT.
Not the best way to get things right in my opinion but hey if you get lucky go buy a lotto ticket.

mvpz

I finally had the chance to sit down with my maf sensor and take some readings
Between the pins for the conection on the MAf
Here are the results. They seem to be inline with these numbers

Ohm readings across all the terminals.
A-B : 663 / 609 / 580.
B-C : 72 / 73 / 72
C-D : .9 / .9 / .9
D-E : 1.68k / 1.75k / 1.74k
E-F : 11.1k / 11.1k / 11.1k

MY READINGS ARE AS FOLLOWS
A-B 554
B-C 72
C-D.2
D-E 1.71k
E-F 11.0k
With these results is it safe to think my sensor is ok ?

rogerz

Do they meet specs in the fsm? if you are in the Seattle area we have three z31 to pick apart all with a maf. I found a blue 86 that matches mine and found a number of plastic interior parts in excellent condition. Feel lucky enough to go to the casino tonite

mvpz

The specs im comparing mine to are posted on the xenonz31web site and are in line with those numbers. Should i feel confident mine is good and be looking for another issue ?

mvpz

Had alittle time today so I unplugged O2 sensor and all symptoms are the same
Runs with MAF unplugged no start with it plugged in

rogerz

a maf is electrically about as complicated as a light bulb. did you blow air through it to verify the ohms are changing? I used a hair dryer to test mine.

look at ef&ec 55 in the fsm I don't know what is posted on xenon but the fsm is the bible on this stuff. there are a bunch of tests there. I''d do em all

if someone stuck a screw driver in there and busted the sensing element then she no workee. READ THE FSM. or if you know any computer guys ask them what RTFM means