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Weird 280zx problem... can't figure it out??


Phenomenon

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Ok so i have an 81 280zx with the inline 2.8L non-turbo engine and 5 speed trans.

 

Issue 1: Takes 3-4 tries to start the engine.

 

Issue 2: Temp gauge not working.

 

Issue 3: Once the car is finally running and up to temp it begins to "buck" and burn a ton of black smoke (obviosly rich), it will continue to do this till i shut it off and let it cool down for while then its fine till it heats up to normal again.

 

I have no idea if these issues are related but i can't drive the car for more then 5-10 mins before it starts acting up again.

 

Can someone please help me? I miss driving my car.

 

Gordon

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replace the temp sensor so that the gage works but not related to anything else. replace chts may help the black smoke issue (these are two different units don't confuse them. one has two pins the other only one. download the fsm from xenon so you can look things up before coming here as you will likely get flamed big time with a post such as the one above. often times from me but I am feeling charitable tonight after three glasses of wine. hard starting get your battery load tested at a reliable battery shop usually FREE (and the charging system while at it). check your battery cables for loose and/or corroded terminals. If some jerk put those one size fit all clamp on terminals get some new for real cables those things are a problem waiting to die while you are out driving to Kamloops but still 100 miles to go. Ground cable should go to a bolt about a foot below the battery and thence to the starter. Grounding through the tranny bolts is not a reliable ground and zx are not liking low voltage for running their electronics. My hard start problem disappeared when my starter died and I replaced it. figure it was either not spinning the engine fast enough or pulling enough amps out of the syatem to bolix the electronics. now it starts if you look hard at the key. if you are around vacouver they have a z club there with some very knowledgeable folks you should make contact with them or see if there isa club in your area. If you want to drive south you can look our club up in Seattle.

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Not sure i worded that right the first time...

 

By hard starting i meant you have to crank it over at least 3-4 seperate times to get it to stay running. (start, die, start, die, etc till it stays running).

 

No idea what a "chts" is... can you clarify?

 

This problem just started recently.... it ONLY stumbles/farts/burns black/pees me off once its at operating temperature.

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Sounds like your "matchbox" is getting heatsoaked. I had the same problem a few years ago with a nonturbo and changing out the ignition box on the side of the distributor cured it.

 

 

"download the fsm from xenon so you can look things up before coming here as you will likely get flamed big time with a post such as the one above."

 

 

This site has rules about spoon-feeding info on common problems and fixes...

zcar.com is a great site for maintenance and repair type questions.

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step one READ THE MANUAL. having it under your pillow at night will not help. use google to do a web search or the search feature on this website. You might want to get a basic book on how automotive engines work. without at least a limited working knowledge of how a fourstroke cycle internal combustion engine with spark ignition works you are not going to be able to understand the advice you are given. lots of things on forums get abbreviated because they are used all the time. when one like chts pops up search on that you'll probably find what you are looking for.

 

Cylinder Head Temp Sensor. feeds a signal to the ECU telling it to lean down because the engine is hot.

 

Don't know why bluez would think that an ignition problem would produce black smoke but hey everyone has an opinion. i'd say you have to solve your fuel delivery problems and have good vacuum for a start. with the engine idling pull the oil filler cap on top the engine. if she runs worse that is good. If evrything stays the same you most likely have some vacuum leaks to repair. If the attachment feature works there will be a pic of a cheap homemade fuel presssure check device. It goes in between the fuel filter (which if you haven't changed you might as well) and the piping atop the engine which feeds the injectors. fuel pressure should be around thirty psi at idle and to up to 36 when you gun it.

 

Don't neglect what I said about battery maintenance. Most people kinda ignore it but it is the heart of the electrical system and if not in top conditiion will cause weird problems. I had that heartache with a Brand New Battery so ASSUMED that was not my problem and kept working on other things to cure my troubles. Finally had eliminated a lot of stuff with a lot of work. Took it to the shop for a load test. It was marginal and they replaced it with a new one. All the weird stuff stopped happening.

 

And that is your last freebie next one will be flamed

post-1378-076070900 1281025739_thumb.jpg

Edited by roger.svoboda
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This morning I read this post to fast. Should have waited untill my 2nd cup of coffee...

 

I thought the engine was running fine untill warmed up then would cut off and not start till cooled down. Thats why I called out ignition heatsoak.

 

Anyway, it sounds like you need to start with the basics, poor or coroded EFI electrical connections, vac leaks, ect. Go to this site http://www.xenons130.com/ and download the Factory Service Manual, (not some Chilton's or Haynes manual) and use it to properly test all the components of your fuel injection system.

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I'm not new to engines by any means... just new to datsuns/nissans. I just dropped a vortec 350 into my 95 Safari minivan just because i can. 100% custom wiring by me.

 

I did do as you said and had the battery tested... 100% also had the alt checked... also 100%.

Pop the oil cap off and the idle drops so vac is all good... going to put a meter on it anyhow tonight.

 

I'm thinking the CHTS is likely the culprit as you suggested... now i just have to "try" and find a new one... no one has parts for this car here... not even a listing.

 

Fuel pump, filter and all rubber hoses have been replaced already so they "should" be fine.

 

 

Worst case scenario i have a chevy 350 here and a turbo 350 trans that i can drop in the car... then i know for sure what i'm doing as i built the engine myself.

 

Thanks, Gordon

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I was thinking after i clean the terminals and give them a pinch to make them a bit tighter i'd put dielectric grease on them to keep the crap out.

 

The product you mentioned... can't find it anywhere here. (hick town alberta, canada) lol

 

You can get Deoxit at Guitar Center... http://www.guitarcenter.com/Default.aspx?source=4WWRWXGT

Edited by NewZed
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Ok so i have done as everyone said to do....

 

Fuel pressure is A-ok

Vacuum is A-ok

Sensors test A-ok

 

I did however figure out this ONLY happens after running the engine wide open...

 

I took a vid so you guys can hear what its doing.

 

"sometimes" just shutting it off and restarting it fixes it but usually it has to cool down for an hour and then its fine again until you run it WOT.

 

Any ideas?

 

http://www.youtube.com/watch?v=POM4mAKVpUg

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If you have cleaned all the connectors especialy the chts,tps and afm one thing you can check is action of the afm flapper door. Take the boot off in front of the afm and push the flapper all the way threw it's range off motion. Does it move forward smoothly and return to closed position on it's own? If it feels sticky in action at all or creeks like an old door hinge hit it with some WD40 and work it out.

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Checked everything... even the afm door/flapper thing.

 

The only thing i can think is that "maybe" the fpr is randomly getting stuck thus allowing full fuel pressure to the injectors all the time.

 

I would guess that that would make the car run like crap.

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