tech9

Posted on another few forums, with no a lot of luck.

Hey, i'm a little new to z's, but i bought a 1977 280z and were trying to get it running. At first it wouldn't start at all, and a little replacing of fuel line, cleaning out the tank, fuel filters, etc. we got it running and idling perfect. Very little smoke

The problem is when you actually give it gas, sometimes at cold start it will rev up almost perfect and its actually drivable for about 2 minutes, then it just loses power. There is smoke coming out the exhaust, and we made sure its not water, but we haven't ruled out fuel or oil. We tested all the electronics and they seem good.

It will produce a smokescreen at high rpms (if you can get it there - 1500+) but will have little smoke at idle. The smoke smells a little like gas, but a lot like fuel.

The plugs have oil on them, and were still trying to determine where its coming from, it has good compression, so i'm thinking the head. But is this why there is such a performance decrease?

I'm going to try and find a junkyard head and try that one out, could there be an electronic problem?

Thanks for the help.

NismoPick

Welcome to ZDriver!

What color is the exhaust smoke?

white = burning coolant
black = running too rich
blue = burning oil

Running rough is prolly a mis-tuned AFM, CHTS, air regulator, or wiring prob.

tech9

We ruled out coolant (level is fine, coolant is clean, oil is clean).

It is defiantly burning oil (has to be from the valves), but there is also a gas smell, so im sure its too rich. I have no idea how to fix the richness problem, as this older injection is new to me. I tested the sensors as the service manual suggested, but i'm thinking something is wrong with one of the sensors causing this.

snwbrderphat540

sounds rich, whats the compression at? if its good shouldnt really be oil on teh plugs and i think your just mistaken oil for fuel. and yes what color is the smoke? p/s welcome to Zdriver

tech9

Thanks for the welcome!

The smoke "looks" white, but its hard to tell sometimes. My friend was standing in it, and was saying its kinda grey like fuel.

The compression of ALL the cyls were around 120, none were +- more then 10%. The top and lower end of the motor sound almost perfect idling, and it starts right away, etc.

I will post a video later.

tech9

Click here to watch 280z-exhaust-idle

Click here to watch 280z-rev-up

You can't hear it well, but you can tell its leaning / riching the engine so it ends up losing rpms.

NismoPick

I'd say that's blue smoke...

PS... please get rid of those cheap *** "autolites" and get NGK's (well... maybe once the engine isn't spitting up so bad).

snwbrderphat540

agreed ^^^^ thats blue (oil) smoke. and those number 120 are a little low. mine were all at 180 or 190. did you check them properly? give them a few cranks with not spark to any of them and holding the gas at WOT. and yeah NGK is the way to go. your car actually acts like my dads, compression around 130 i think it was and blue smoke... if you hold a piece of cardboard/plastic being the exhaust and rev it up a few times see if it accumulates oil on it. but thats what it seems to be. his car runs fine though, doesnt seem very vast for a full exhaust header and cam though so we are re-building the motor sometime soon. hone it and re-wring it.

tech9

I don't think the oil is the cause of the running problems though, do you think?

I think there might be something wrong with the electronics.
I would rather fix that first before we go into the motor.

Thanks for the help!

snwbrderphat540

well if the motor is only 120 psi it shouldnt show to many running odd signs but could be the cause of your smoke. also you say its wehn the car gets hot, now you need to think of teh static and dynamic compression on the cylinders. could be alot lower once the car heats up, started happening with my Z32 till eventually it ran like crap all the time. however thats just a possibility. electronics isnt going to make the car burn oil though either, and since it doesnt seem to be blowing black smoke (rich state) then it might not be any of the obvious problems like the CHTS. but could still be the AFM.

but who knows, your plugs look like crap, so i would get teh NGK plugs (and order them its cheaper then going to like autozone for them) and tehn you said you cleaned teh external fuel system. maybe get some good clean premium gas, do a full tune up (good new plugs, new cap rotor and wires) and tehm run seafoam half a tank of fuel half a bottle of seafoam and run the other half through your vacumme lines. it'll clean stuff up, you could also run carb cleaner through some vacume lines preferebly infront of the throttle body. and also drive the car hard. its all it took to get my car to run good. but make sure all your fluids are changed.

tech9

Well the main problem is that those plugs are new, brand new, the smoke really don't worry me yet, i'm waiting till I can actually get the car running.

Right now the car don't have enough power to get down the driveway and back up. Power is the issue right now, it just wont rev up correctly. I read the EFI bible, and did all the tests and still cant find the issue.

I have cleaned every connection, and tested almost everything. It seems like its not getting enough fuel. I'm still leaning twards the hard gasket. I'm going to pull the head just to check. The coolant has a little foam in it, but oil was clean, I just want to make sure.

snwbrderphat540

hmmmm.... you could always get a coolant tester that will let you know if your getting any fuel etc. in it from a blown head gasket, pulling a head isnt exactly a walk in teh park. lol. and by the look of the oil on those plugs that could be another reason its running bad they are so caked in crap. clean them off with starting fluid/brake parts cleaner and such.