Hi,i bought a 300zx z31 86 na 4 days ago,it barley ran when i bought it and the water pump was out and it ran really rough with a very light tick in the passenger side head.So i changed the water pump, timing belt, tensioner, spark plugs,oil change. it ran alright but it just dident seem to pull very hard so i decided to throw a distributor i had sitting around on and when i tryed starting it it wouldn't start it would just back fire,so i put the old one back on. still the same thing and messed with it for a while and it starts now but runs really bad and back fires out of the intake i have changed the angle and it still does it but when i turn it all the was toward the rear of the car it runs the best.please any thots of what it is?

 

Do a general tune up. Replace the spark plugs, spark plug wires, distributor rotor and cap. Change the drive belts, clean the MAF and throttle body. Buy a timing light and set the timing properly (if you haven't already). Check the vacuum and the fuel pressure. Change the fuel filter and air filter. Lastly, change all of your vacuum lines. If they are original its about time. Buy high performance silicone vacuum lines. (thumper300zx.com) has diagrams and measurements for this. Get the vacuum lines from (hiperformancestore.com). Use NGK plugs and wires if possible, if not use Bosch.

This general tune up works like magic. If you are still having problems after you have done all of this, then your z will be more easily diagnosed. Lastly, don't cheap out on anything. I will come back to haunt you. I have an 86 na too.

 

If it is backfiring out the intake, you did something wrong. Did you put the distributor on right? spark plug wires on right? Something is screwing up the timing

 

Was planning on doing a full tune up, but I dont want to throw much more money at it.with out know its needed.andd I believe I put the distributer on rwrong.ever time I take it back out it changes for the worse. We have been messing with it and cant seem to get it to tune right, I believe it is the distributor. How do I tune this dam thing cant find much info on it

 

I have to agree with the above posts. A top to bottom tune up is the only way to start up with your 'new' 86 Z. I have 2 of 'em now, one w/ turbo. One I have driven since June '86 when it had 6 miles on the odometer.

You can't expect your Z - perfect as it was in 1986 - to run just like new 27 years later. You don't know what junk parts were put in and what lousy work was done on it over the last 27 years. Your car is most likely showing the result of years of poor mechanical work and either cheap or dead parts - and bad adjustment work after that.

If you like the car enough, start from the beginning and tune it right. Any Z31 will reward you by running well when you have covered everything. If you have to cheap out now and still need to end up with a winner, you bought the wrong car. Try Accord or Civic.

I found out over the years that Z31 distributors are not interchangeable. For some reason, the final angle-per-tooth varies from unit to unit in 85-86-87. I solved my distrib problem by running through 4 of them when I did a motor swap (85n/a into 86na/). Three of them would not provide the angle required no matter how adjusted. It was either over or under.

So somebody may have switched your orig distrib and it's just the wrong one. Gotta try others.

At this point in their history, Z31s are not for impatient types. They are gorgeous to drive and perfect to look at - but they need some expert attention now and then. They don't take to one-night stands. If you treat them like that, they are insulted. They get even by saying "No way, dude. Walk home." :-)

 

will set the timing tomorrow,| Repair Guides | Engine Electrical | Distributor | AutoZone.com

 

was planning on doing a full tune up,in till this happened, so since i had no use able info on this i found this | Repair Guides | Engine Electrical | Distributor | AutoZone.com
i followed the instructions and i dont thinks i got it right,cuz its still barley running and jumps up and down and wont idle.

 

okay so i figured the distributor out,and now the car sounds great but as soon as the rpms get new 2000 is stumbles driving it or not. tomorrow im going to go buy vac lines and spark plugs wires.any idea on why tho?

 

2000RPM, The air flow meter, aka MAF? Limp home mode?

 

I pulled the codes from the ecu and got a 12, 23, 31 i think the 12 is my maf and i think 23 is my tps .But i do not know what 31 is?i put nkg plugs and wires in,and ordered some vac lines.

 

Try cleaning the MAF before you go buy one and see if that satisfies the code. If not get a new MAF. Sounds like it needs to be changed though. They run in price anywhere from $150 to $200. The tps is on the side of the throttle body and is simple to change. They sell them for $45 on amazon or autopartswarehouse.com. The the "answer key" for the ECU codes is in the Haynes book, on the ECU itself, or just try looking them up online.

Tip for the future: Call your prefered auto parts store for the part you need before you show up. The z's are so old a lot of times they don't have the parts in stock. Also, make sure you get a good idea of what the part looks like too.

 

I found a maf locally from a buddy waiting on him to bring it over,i cleaned it but no luck not that dirty ether really,and on the tps trying to find one closer so i dont have to wait 2 weeks to get it in the mail,btw can i use a tps from a manual not turbo? i know the auto had a extra plug for the tranny but wasn't sure if i could just leave that unplugged?why i was asking is cuz i have one from my old z

 

okay...so i got a new maf and took my old tps (off a 1986 na manual)And both 12 and 23 are gone but it still drops at throttle. 31??????

 

Ok if code 23 disappeared then I wouldn't worry about the tps.

Code 31 is ECU, A/C switch, power steering switch, and fan switch. ECU seems to be the prominent problem when this code is displayed though.

 

another fourm said 31 was ( 31=ECU input signal is beyond normal range) do you think it would ecu or wiring harness?

 

I'm not sure how you would go about checking the harness, but beyond normal range could just mean the ECU is bad. Most of the info about code 31 mentioned a bad ECU. I don't think you will find out otherwise until you replace it. Hey if a new ECU doesn't fix it, then just return it and you won't lose your money.

 

well the maf light came back on.okay so i figured i would try and hunt down the problem clean all the connectors and wiggled all the connecters,then the car seemed to fix its self and ran great for a few hours and then when i went to start it again the problem came back?this is the second time its fixed its self and came right back.idk what it is any more?

 

Do you have a test light? A test light will tell you if power it getting through to the MAF. A test light is cheap to buy and easy to use and can save you from doing a lot of unnecessary work. Use the test light to check the O2 sensor too.

Search the interent for all the possible problems for poor engine runnability and make a list. Go through each item on the list and check them thoroughly. If the item checks out ok eliminate it from the list. This is how I fixed my Z.

 

will do in a couples days when it quits snowing,and whats sad is im in myrtle beach sc.lol

 

i believe i figured it out i believe i have a small head gasket leak,i believe it is trapping air in the coolant and causing the car to freak if i bleed the air out it will run past 2k rpms.is this possible?how can i figure out if it is for sure a head gasket?

 

btw.what is a decent head gasket? and other then head bolts and a full upper gasket set is there any thing else i will need?and what kinda bit do i need for the heads,hex?

 

You can check for a blown head gasket with a compression gauge. The gauge should come with a guide that tells you what the different readings are. A vacuum gauge is a great way to find out how your engine is doing, but first get a compression gauge and run a compressing check.

As for the head gasket, just order an OEM one. As far as I know there isn't a "performance" head gasket. You still search around for one though.

 

Not sure what size the hex head is, but if you have a decent tool kit you should be good.

 

Very well put. It's most definitely not for someone with out patience