Just picked up a 280 zx turbo yesterday and I'm having some trouble with it. The body and interior are in excellent condition, so overall I'm very happy with it. Now I just need to figure out the engine woes.

It starts up ok, but will run really rough. I can only give it a little bit of gas at a time, definitely not enough to drive it anywhere other than maybe moving it from one parking spot to another. However, there's a senson on the engine next to the battery that if I unplug it after it's already running will allow me to drive it. I made it 200+ miles last night with the sensor unplugged. The guy I bought it from said that he had just replaced that sensor and I think he said it was a coolant sensor, but I wouldn't put any money on that.

The car has been sitting for at least two months, possibly much longer...we put brand new spark plugs in last night, it ran a bit better after that. I'm planning on putting new wires, new fuel filter and a new distributor on it as well as some fuel treatment. It had 3/4 tank when I got it, I drove about 85 miles and then filled it up with 93 octane.

That's all I can think of as far as the obvious stuff, but I was wondering if anyone else had any issues with this particular sensor or if possibly something else could be causing this. The guy said he hooked up a scanner to the car and the error code pointed to the sensor.

Also, is there a particular repair manual that is better than others for this car?


Thanks in advance for any and all ideas!

 

Sounds like the cylinder head temp sensor which sends signal to ecu for when engine is warm and thus alters the fuel quantity to lean it out. You can download an 82 FSM from the web on one of the forums do a google. performance nissan sells one on cd and if you do a web search or e bay you can maybe find one for sale. haynes or chilton are better than nothing. There are two units on the front of the engine if I remember right one of them for the gage unit and the other is cylinder head temp sensor. Do a search I might be thinking of 300zx motor. The 280 sensor may be on the right side about the middle of the engine.

 

What part of the country you in? probably guys in your area can help if we knew about where you were located.

 

Thanks for the info, I'll check into that. Google is my friend...

I'm located in Columbus Ohio btw.

 

PM this guy: BlackzxT He had the same problem you are having. The car would only run with the CHTS disconnected. The car is supposed to stall with that sensor disconnected. I'm pretty sure he got it figured out, but I can't remember what the problem was. Shoot him a PM and he might be able to help you out...thats if he doesnt see this thread and give you a response here.

And here's a link to an '82 FSM: http://carfiche.com/manuals020/cars/82_datsun_280zx.zip
Its availability changes every hour so if its not available when you click the link, then try again at the top of the next hour (if you try at 6:55 and its not available, try again at 7:00)

 

people have been known to slip a resistor into that circuit to simulate the chts. If that has been done search along the wiring from the chts for something that might look spliced in. PO did that to friend z31 had a hell of a time finding it. PO disguised it well or shady mechanic.

 

Thanks for all the suggestions and links so far. Did a lot of reading...lot of things to check but in the end it will be worth it. I used to have the same car only it was a 5 speed without the back seats. Can't wait to get this one running right.

I'll post a picture of the sensor I'm talking about tomorrow sometime just to make sure we're talkin about the same one. I also found something on the other side of the engine (sensor possibly) that also looks brand spankin new. It's fairly close to the firewall. I only spotted it because it has a brand new purple wire on it.

Anyhow, I've compiled a pretty decent list of stuff to check after reading thru a couple threads on here. Now I have to find a manual that will tell me where all the stuff is. Went to two different parts stores today, but neither of them had it. I'm gonna try a bigger parts store tomorrow and if they don't have it I'll order it. I'm mechanically inclined (somewhat), but I don't know that much about engines other than the basics. I did read thru the turbo sticky, but I'm not sure if I learned something or if it just confused the h*** out of me.

Thanks again for any and all suggestions. I appreciate it greatly. Once I get it running well enough to get it out of my garage I'll post up some pics. She's a beauty.

 

Well, no progress as of yet. I changed the fuel filter last night, that was the only part I wanted that the parts store had in stock. I was able to finally download that service manual. TYVM for the link! I'm going to see if I can follow the troubleshooting directions this weekend hopefully.

One question tho, while the car is running if I put my hand on the hose coming out of the fuel filter, I feel a pulsing. Is this normal?

 

Alright, one more question. I decided to take out the computer tonight. First trouble sign was that there was only one bolt of the two that are supposed to be there holding it in. No biggie, but there was a green plug that was plugged into absolutely nothing.

Anyone know what this is or where it's supposed to go, or more importantly could this be causing the engine to run rough?

Here's a pic of it:

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If you're talking about the connector with the Green wire and Black wire, then it doesnt get used.

I believe it has something to do with hooking up the ECCS analyzer, but I could be mistaken on tha part. 100% positive though that the car doesnt use that plug.

 

I think that is the wire to the O2 sensor it in the glove comparment or under that area at 30000 miles it will triger the light on the dash then you just disconnect it and replace the sensor every 30000 miles or so.

 

Darn...I mean good I guess. I was hoping I stumbled across the problem.

One more question, in the shop manual it has a picture of the plug where you do a bunch of tests to different pins with the ohm meter. I thought that was on the computer that is inside the drivers side, but the plugs look different than the pictures in the manual, plus there are different numbers of pins.

Is the thing I'm supposed to be testing somewhere under the hood?

I should probably just let someone who specializes in these cars fix it, but I'm not quite ready for that yet. I like a challenge.

 

Make sure the tests in the manual are reffering to the turbo model. The non-turbo used a different ECU and a different pin layout for the connector. It just used one long connector instead of the smaller seperate connectors for the turbo ECU.

If this is the connector you're seeing in your manual:

then thats the non-turbo ECU

 

Yup that's the one in the manual. Ok well that explains a lot. Guess I need to search for a turbo manual then. Does a chilton or haynes manual have these same tests or do you have to have a service manual to get that indepth?



Thanks a bunch! This forum has saved me hours of standing around scratching my head and swearing so far.

 

If you downloaded the service manual I linked you to then yes, there is a turbo section in there. The turbos EFI is reffered to as ECCS. So go into the fuel and emissions control chapter and scan down to the ECCS diagnostics areas. You'll have to do some searching though because a good chunk of the manual involves using an ECCS analyser (which you probably wont be able to find). But all the information to manaully test is in there. You just have to read until you find it

A Haynes is a good reference to keep on hand though. If I were you I'd head out and pick one of those up. It has a more "home mechanic" vibe to it.

 

Yup, that's the manual I've been looking at. I've been reading it on the PC, which is kinda cumbersome with all the scrolling...I was able to print out EFEC chapter of it today at work, so I'll have another try at it tonight and see how many more questions I come up with.

Thanks again!

 

Well I definitely have made some type of progress with her. I put the computer back in it and cleaned all the plugs like I've seen suggested, and I took her out for a drive around the block a few times. For the first time I was able to put the pedal to the floor repeatedly and not have it stumble at all. I didn't get much boost, the needle looked like it was at maybe 1 or 1.5 pounds of boost, but that's definitely progress.

I still had to run it without the CHTS plugged in. I pulled that out as soon as I started it. It still stumbles a little bit when I'm slowing down, but tonight everytime I put the pedal to the floor it reacted.

Before I drove it home this weekend the guy I bought it from fiddled with the screw under the AFM cover for awhile to get it to idle decent. Maybe now that some other stuff is working better that screw needs adjusted again? Either way I'm definitely makin some progress here.

Big thanks for all suggestions I've received!

 

That screw adjusts the air/fuel mixture at idle. It wont have very much affect on part throttle, and it will have no affect at WOT.

 

Well a small update.

I finally got around to doing the component testing per the manual. The only thing that was a little off was the AFM. The manual said it should be around 280 ohms or slightly higher and mine is reading 200. I also pulled out a couple plugs (brand new plugs) and they are dark as heck. From the looks of pictures with plug diagnosis, this means that it is running rich??

AFM a safe bet here? Kind of an expensive guess if that's not really it...

 

you can lean the AFM out by adjusting the spring tension. As long as you take it in small safe steps its a safe procedure. An air/fuel ratio gauge would help you out here.

 

Is the spring inside of the little black box part of the AFM, as in I won't have to pull the entire thing out of the car to get to it? I'm not seeing much in the manual on that part as far as the theory of how it works exactly. Do I want to tighten the spring to lean it out, or loosen the spring?


As usual, thank you very much for your amazingly prompt replies!

 

This sounds like part of the problem I was having. Only my Turbo ran really odd at cold start and better at warm. The previous owner had replaced the CHTS with a brand new CHTS from BlackDragon and he also called it a coolant temp sensor. Now when I compared it up with the CHTS from my 2+2 they were similar, but there was a difference. I didn't start seeing results until I swapped the CHTS out for the one from my 2+2. I even took both of the sensors out and tested them in water and was getting different readings from them. I'm wondering if what you order from Black Dragon is a water temp sensor and they just happened to be very similar to the point that they fit? It just seems odd that the previous owner replaced it, and the previous owner of my car replaced it.

Another possibility is your timing. My timing was set correctly then even being set correctly the car started running worse and worse then at times would run better, it seems like it turned out to be a combo of the Ignition Module or Ignition Coil causing drastic differences with the timing.

 

Mine has a lot of new looking parts on it. I have the CHTS that was originally in it, it reads WAY off of the specs in the book. The one that is in it now reads what appears to be correct, only the car runs like crap if it's hooked up. The distributor, plugs and wires all look new, as does the ignition coil. I'm guessing the previous owner already went thru the same stuff I'm doing, but gave up. I bought all that stuff (except ignition coil), but I'm going to get this sucker running right no matter what it costs me.


I bought a timing gun yesterday but couldn't find the marks on the car. I think I found them in the book today and understand where to look now, so I'm going to try to check the timing again tonight. If it's still bad I'm going to fiddle with the AFM and try to figure out the spring fairlady mentioned. If it's still bad I'll probably replace the AFM and if it's still bad after that I'll have to break down and pay a shop to fix it.

Just a shame that it's so nice out today and this beauty has to sit in the garage. Great day to take the t-tops off.

 

^ Use some white out or something similar and mark the timing notch on the crank pulley. That will make it easier to see where your timing is at with the timing light. You also may need to clean up the timing mark tab on the right/front side of the engine cover, just above the crank pulley. If it's been a while since someones checked the timing then it probably has a lot of dirt and crap caked up on it.

 

you sound like you're in the same boat as me, determined to get the car running great no matter what. I'm getting there, all I have left is my exhaust leak. Then I plan to swap in my T-5 tranny, and get some minor rust repair and a paint job. Then all that's left is interior which really isn't in that bad of shape.

Do as j said, and get some whiteout. Once you've got the notch on the pulley and the timing plate marked everything else is really easy. Notches on the timing plate go 2 degreese per notch. Top notch is 0 and the bottom notch is 30. I've been told to set timing with the TPS disconnected. I did that and that worked for awhile, but once I replaced my Ignition Module I had to set it with TPS connected before it worked right.