Sneeze, Smell, Idle- Related?
 

Im new to the forum sorry if anyone finds that fact annoying...
I need help with my Z thats driving me a little nuts.
My Z has this sneeze that wont go away,
Ive replaced my distributor rotor, spark plugs, plug wires, adjusted my spark timing and replaced my air flow meter. Nothing seems to make a difference BUT all parts were messed up in one way or another.
Ive been following specs from a haynes manual (spark gap, timing)

After driving the engine smells like charcoal and burning plastic.

My Idle is usually high (1200-1300rpm) when i adjust the throttle screw to idle around 900 and turn off the car, the next time i start it it will be at approx 400. Also during driving I will get Fluctuations of 800 to 1300.

Im at a point where i just feel like throwing parts at it blindly because they all need to be replaced anyways hahah. Does anyone know if these 3 problems could be related? Any Ideas?:017:

Current plan is to replace the horribly old looking Air Regulator, Throttle position sensor and all vacuum lines.

Welcome to Zdriver!
Maybe your cat is clogged up causing higher exhaust temps.
I had the same idle problem with my "77. It turned out to be the fast idle for the AC cycleing on off. If I remember it is a blue wire going to the tb. I just disconnected it until I can get the AC working.
It is now time for you to download the Factory Service Manual from www.carfich.com. It's free but it's cool to make a donation.

thank you for your time.. I went to the site but its telling me its under construction. :102:
I was forced to drive my Z to work today in the condition its in and found if I keep the RPMs really high when shifting and when starting in first then there is no back fire, smell is still there. Do you know if these problems are related?
Thanks again for your time and help.:023:

I just tried it and it's up. btw Tna means temporarily not available. There are many things that can cause your problems. backfiring can be caused by to much fuel. With the fsm you will be able to check everything.

It's actually "CARFICHE" :D

http://carfiche.com/

You can also download the FSM from: www.xenons30.com/reference

I would check / adjust the TPS, and check the water temp sensor (white/yellow square two prong sensor on the thermostat housing).

thnx "nismopick" good stuff....
those are 2 things I have on order. In my frusteration yesturday I went to the dealership I used to work at and ordered everything my paycheck could handle, Its a stupid desperate approach, but thats what I did and it is what it is. Thankfully the TPS and water temp sens. were on that list hahah. Thanks for the direction guys.

Ouch... you paid dealer cost? I would have ordered them from a local parts store or grab several from a local junk yard....

i got them at dealer cost not dealer resale price... used to work there. example- Intake boot AFM to Throttle body EBAY- $50, Nissan- $27

Right....

Hopefully you got the TPS for less than $40 and the water temp sensor for less than $14 (parts store prices). Like I said... I would have obtained several from the junk yard for a very small fraction of the cost, since you are replacing them as the method of trouble-shooting. I don't like to spend on unnecessary costs, but that's just me. :D

hahaha yea i saw the same "cost" quotes after i posted it.
I got better deals than my parts store and new parts bring a little ease to my mind and wallet in the future. Thanks again for your help dude! seriously.

shoot me.
 

Ive replaced-
spark plugs (new)
plug wires (new)
distributor cap (new)
distributor rotor (new)
fuel filter (new)
air flow meter (used)
boot from air filter to afm (new)
boot from afm to throttle body (new)
throttle position sensor (new)
coolant temperature sensor (new)
air regulator (new)
fuel regulator (new)
pcv hose

all this crap was in bad condition and needed to be replaced BUT my idle is now not able to be adjusted with the screw, and the intake backfire is still there. Ive owned it for 3 months and havnt really had the pleasure of driving it yet. I dont know if anyone is going to read this, I dont want to post a new thread but I am out of ideas, I noticed someone did a horrible welding job on my exhaust. (they didnt use any sort of reducer to mate the backpipe and downpipe, its like all melted metal weld) I also read "Theramz" mentioning a plugged cat. Ill take it to get fixed and see what happens.

This car is starting to be a horrible buy, because the previous owner made a complete mess out of it.... :017: but its mostly my fault for being the idiot who cant fix it right? lol.... poor pooor Z

The exhaust should be the same size as the downpipe all the way back. They may have eliminated the cat which is okay but a big gobby weld might be on the inside too, further choking it off. The blue wire I mentioned goes to that thing under the TB called the throttle chamber.
On the 280z cars the most important tools are your FSM and a multitester. If you read it carefully and step through it you will better understand how she works. Seems overwhelming at first so don't bother to much with the ECU maps for injectors. Just check all sensors.
New parts won't help if they aren't set right. Take your time and you will kill the gremlins.:fflak:

I was just looking at the "throttle chamber" in the FSM. Maybe the sensor for that air system is bad. I remember hearing an audible click when it would idle up or down so I assumed it was AC cycle related. My car is waiting for paint so I can't check it now. I know that after I disconnected it she ran good with no idle changes.Let us know what you find out. Some people come hear, get what they want and go away.

thanks
 

thank you for your help man! yea I went through the FSM and kind of did get overwhelmed you are correct. I put the TPS on without any adjustments, might have a problem around that. also I just took a picture of the exhaust so you can get a laugh-
Attachment 19929

also got some pics of the engine bay shot from drivers side
Attachment 19930

I cracked the top of the charcoal canister so I am missing one vacuum line, the line went from the canister to the top of the dashpot. I cracked it off yesturday before the picture was taken but the problems existed before that. Also! there are wires jumped together, I bought it with a missing fuel relay? I honestly dont know what belongs there next to the battery.

Okay, that jogged my memory. In the manual, EC section it mentions the BCDD valve. Inside the TB there is a hole about 10mm dia. Plug it from the inside. No more fast idle. The charcoal can doesn't matter as long as the line to the engine is not open. I fixed my canister by drilling out the broken one and inserting a short tube and epoxied it in place.
The 2 red wires coming out near the battery are + and - to the ECU. They hook up directly to the battery. Looks like the one to the green jumper is +.
I would stop throwing new parts until I corrected the shit thats for free.

the green wire is a horrendous kill switch going to the fuel pump, and you are correct it is + ... Im curious to know what the arched wires are about a foot in front of the battery (towards bumper) something belongs there and I dont know what it is.
Also the fast idle is no longer happening. It is now the opposite- idle starts high, first cold start of the morning, then all day and every run thereafter it is barely hanging on, around 400 -500 RPM Idle and the intake backfire thrives in that condition it occurs on low rpm to acceleration and the lower the rpm the more intense the backfire becomes and the idle adjusting screw will not allow higher rpm... loosening does nothing tightening will make it stall out.

Heres another thing, on lunch I went out to disconnect the wire under the throttle body like you told me, ran the car, still the same. after engine was warmed up I randomly put a drop of water on the exhaust manifold, so im playing with boiling water drops while thinking about complete other things and put a drop between the two injectors shown in the picture. no boil on that port which pulled my thinking in another direction. Attachment 19927
so im not getting the same temperatures out of this port as I am every other one. Injector looks like its in pretty bad shape (the rail is a mess also)

I understand I should probably shut up and follow the charts on the FSM but i keep jumping to these other possibilities and become convinced it must be this or that hahah. Sorry if this is annoying.

p.s. distributor valve seems to be stuck also loll
Attachment 19928

Makes me wonder if your injectors or clogged/leaking...

E gad what a mess!. Get a 9 volt battery and some jumper leads. Check each injector including the cold start by pulling the plug and touching the terminals with the +and - from the 9 volt. You should hear them click on and off. No click = no good.
Remove the distributor and spray the guts with PB blaster or Sea Foam penetrant. You should be able to move the breaker plate with your fingers and it should return freely. If not it is probably junk. If OK then use a vacuum gun to test the diaphram, these usually go bad.
Disconnect the cold start valve to see if the backfiring stops, it could be staying or stuck on.
Backfiring in the exhaust means unburned fuel and or late timing.
2 crossed plug wires will run just a little rough but backfire ocasionally even at idle. Recheck your plug wires and firing order.
Check your Thermotime switch per the fsm ohm test.
Spend your money on tools not unnecessary parts.

beautiful. Thanks theramz! I will continue diagnostics tonight or tomorrow after work and keep you posted. Im sure this will be a useful lesson to another newbie one day. Although I did get frusterated and threw parts at the car, they were all definitely needed. And you are correct, I could use a timing light lol, all my tools are mostly suspension related.

update:
Unplugged cold start injector, seemed to help for a 5 mile drive but started its backfiring and dying out again. Just to clarify its backfire in the INTAKE not exhaust.
going through other forums i stumbled upon this picture
http://farm5.static.flickr.com/4058/...b18c3c8b04.jpg

Its some guys float mechanism, my gas gauge does not work so im guessing mine looks similar. Im going to drop the tank and buy a timing light, as well as follow the FSM tune up procedures and first off all the suggestions given on this thread

I will update after all the inspections are done, the forums help has been greatttttly appreciated and i will keep u guys informed.

before i start
 

before i start dropping the tank-
I dont think datsun would manufacture a fuel rail and sell every z like this... mine is not normal right? it just seems like an unnecessary mess.. Also in the red and yellow box... what belongs there?


Attachment 19840

Backfiring through the AFM is like fecebad. I think the dizzy not giving advance has been solved by advancing the timing to far. You really shouldn't drive it like that. Repair or replace the dizzy first. Check the cold start valve by removing it from the manifold and crank the engine (coil disconnected). It should squirt when you crank the engine. Next, do the same with it unplugged, it shouldn't squirt. The wires you have noted are fusible links. They should have plastic covers on them. Not that important. The fuel rail looks stock, it's just be tweaked around by a po/ gremlin.
Be patient and careful so you don't ruin something. We can get you through this, wax on, wax off.

I don't remember if you stated the year of your car but here is my '77 in progress. There are some slight differences. I'm guessing yours is a '76. You can make it better and dependable. The only thing new on mine is the thermosat, water temp sensor and thermotime sensor. The engine is a complete rebuilt so I had the advantage of it being on an engine stand.

update
 

out of money and out of work.

I checked the cold start injector it doesn't squirt at all

The car was built in april of 1977, its a 5 speed, I took a video of the engine bay and rpm gauge while it is running, Im trying to post it now.

here is a video of me trying to keep the car at 3000 RPM... I am uploading another video of the back fire which is going to take a while....
http://s756.photobucket.com/albums/x...=LazyZblah.mp4

[IMG]http://i756.photobucket.com/albums/x..._LazyZblah.jpg[/IMG]

It sounds like either the AFM or TPS to me sense it sounds to be running pretty smoothly.

it doesn't idle smoothly at all... im trying to get the other video uploaded its being difficult.. It has a horrible low idle and intake backfire... once i get it past the low rpm acceleration it seems to run fine. the only way i have been able to drive it (the small amount i have) is by keeping the rpms high at the take off and revving it up in between shifts.. watch the new video when i finally get it up here.. I already replaced both tps and afm when i got frustrated a couple weeks ago and just started throwing parts at it. Thanks! ill get it posted soon



... By the way- It WILL rev past 2,800 and this is not a video of the idle. I have just found that if i try to hold around 2,800 i get this strange fluctuation. I want to fix this as well as all the other problems but am hoping it is related to the intake backfire/rough idle and will kick start somebody's memory or whatever. thank you!

here is video of the engine idle and a quick over view of the engine.
it starts by showing the horrible exhaust weld, which is probably plugged, then it goes over the engine.
at 00:28 it shows a hose that has a plug in it.
at 00:43 it shows random wiring that goes no where.
00:55 stupid kill switch someone put on the car (positive to fuel pump)
01:20 you can hear the sneeze
01:38 " " "
01:42 I adjust the idle screw and nothing happens


http://s756.photobucket.com/albums/x...kebackfire.mp4

http://i756.photobucket.com/albums/x...kebackfire.jpg

It's definitly not firing on all 6. The timing is way to far advanced, firing when the an intake valve is open. That screw is for air mixture not rpm. You could have a dead cyclinder. Pull all the plugs and do a compression test. Use your thumb over the spark plug hole and have someone crank it over. You should have a healty pfft on each one. Those wires go to something behind that plate, probably a bypassed relay.

The hose in this pic^^ used to go to the AC

compression test was normal, i unplugged the injectorrs and they all clicked with a 9 volt except the cold start... i need to buy a timing light and have someone re-weld that exhaust to get rid of any back pressure, pull the distributor and possibly replace it, WD40 did not fix anything and it seems to be moving freely.

the wires under the dash are all a mess also.

Another budget test is to rotate the dizzy plate clockwise and hold you finger over the vacuum inlet it should hold position until you let go. If not it's ng.

Or just suck on the hose and if you get air its no good as well. Either or lol

Not running on all 6
 

Hey Friend,
Sounds like you are running on about 4 cylinders (maybe less!). Thanks for the video, that is so helpful! The exhaust weld is doing very little to cause all of this, if you really wonder, remove the muffler and the back flow problem should be about right. The rest of the work and new parts are probably not helping fix this problem, but they are not a bad investment at all. Don't loose any sleep over buying a few hundred dollars worth of important parts. In today's terms we are only talking about a single car payment on a newer Altima!

I have spent hours as of the last few months on my two Z's and had some very similar problems! It had a very simple solution too! You have checked the injectors with a battery, but they need power from the car to work. As with mine, I am guessing that the fuel injector harnesses are shot. On my car they could be cleaned and bent and made to work, but they had to be wiggled and jiggled to get them to contact. I bought a new set of them off of Ebay for about $15 shipped and the car is running well again. I bought an extra one and replaced the harness on the Head Temp Sensor as well. Before you do this, a simple test is just listening with a screwdriver on your ear and then placed on each injector while the car is running. Tick, tick, tick, check until you hear a different sound from one of them and start there.

The injectors may all be working. But you still have "dead" cylinders. Check the wires, check the plugs for cracks, check the distributor cap for cracks/dead spots. If all of that is ok and you still have a problem... If a cylinder is locked up, sometimes pulling the plug wire on and off a couple times while idling will get her back in action. You have checked compression and that is good, so you really don't have much to worry about there. Maybe you should pull of the valve cover and adjust the valves (or at least check them). Any manual will give you instructions or you can find them online. It is really easy, and satisfying when you get them done and correct.

I also put some Seafoam in the oil to clean the valves, you may want to do the same. Finally, the car will need the plugs pulled and cleaned almost every time you work on the EFI. They gum up or get fuel fouled. Sometimes you will have everything else correct and it still will be "off" and you will start pulling more wires, etc. and it will just be fouled plugs from the last time you tried.

I'm not a betting man, but I would put money on the injectors or harnesses being the problem. Give it a go and let me know. I have some more ideas, but lets start there for now.

update
 

the Z has been parked since my last post..
I've been both frustrated and busy looking for work since i hooked the injectors to the 9 volt. to the injectors.
I just ran the car a second ago. (It fired up better than it has ever started before) I listened to all the injectors with a screwdriver and the one new injector (previous owner installed) is the only one which does not make a clicking noise. All of the harnesses look pretty new for every injector, but at least im getting this narrowed down.
I have not yet done any valve adjusting. Im just writing this small update because this forum is very important to me and if im not writing i feel guilty.
Once again thank you so much for the help. I am planning some tear down time and electrical testing hopefully this weekend!

the wiring to injector that made no noise tested out okay. I pulled the injector and cranked the engine with the distributor disconnected and no fuel came out. I noticed the 1st injector is leaking bad, PO had the hose clamped and when I took it off I found the hose is badly cracked. the 2nd and 3rd are seeping and the 4th is silent when I listen to it...
to sum it up I do not approve of the visual condition of any of the injectors.
Does any one know where I can get a set of well rebuilt injectors? I want to just replace all of them. The more new parts I have on the engine the happier I am, Im also afraid of replacing one and watching another go out and then another and so on.
Thanks for the help!

pictures
 

Attachment 19760

injector #1 above


Attachment 19761

injector #3 above


Attachment 19762

injector #4 above. This is the new injector that makes no noise when the car is running

NOTE: I have the metal clips off in the pictures they are normally on the car when it was running funny.

Here is the best deal I've seen yet. Go to ebay and search "datsun 280z fuel injectors" This guy also has all the hardware so maybe you can make a deal with him. After you start breating again maybe you want to take your 9 volt and search the junkyard.

pulled the injectors today.
Here is a picture of the new one I have been talking about that the P.O had installed, pictured next to the older cracked one...

The newest one that was installed is about 1/4" shorter this is not a problem right?

:icon_axe:
<a href="http://s756.photobucket.com/albums/xx209/BenZ513/?action=view&current=injectordifference.jpg" target="_blank"><img src="http://i756.photobucket.com/albums/xx209/BenZ513/injectordifference.jpg" border="0" alt="Photobucket"></a>
:icon_axe:

The black pintel cap is missing, the reach is short and the shape tells me it' s from a different car. The injectors are color coded for volumn. I think yours are supposed to be green.

man i need to do some more research... you are saving my @$$ "theramz".
the 2 new ones i bought are green, (picture came out a little blue) im going to let it sit till i can afford all 6, take off the rest of the rail, and replace every hose and seal. should be all paid for in about 3 weeks?

<a href="http://s756.photobucket.com/albums/xx209/BenZ513/?action=view&current=newinj.jpg" target="_blank"><img src="http://i756.photobucket.com/albums/xx209/BenZ513/newinj.jpg" border="0" alt="Photobucket"></a>

Lazy Z have you tried to check the timing chain on it? I'm having similar problems and have done a whole bunch of changes to it but the motor stumbles. Im thinking about checking the timing chain? Think is a good idea?

not running well at all
 

I have much this same problem. How do you know which plug to put on what fuel injector? They are not marked in any way.

Does anybody know how to identify which plug goes to what fuel injector/ They are not marked.

How do you know which plug goes where on the fuel injectors of an 85 300ZX?

77 Z backfiring or choking
 

Order a new thermotime switch from Nissan. It is located in the thermosrat housing and it's brown in color. That controls the cold start valve. If it's not functioning correctly it will send a signal even when the car is already warmed up and the cold start valve will dribble excess fuel and cause some of the problems you're having. Good luck with it.