Help!! 1978 280Z barely idles

[rickl750]

Hi Guys,

I’m back with more problems. On the last episode I had finished replacing my head gasket and after a few issues (rough idle, gray smoke, etc) she started running fine. Now a few days later I’m having issues again, she’s running rough, can’t really idle on her own, gray smoke out of the tail pipe. So far I’ve checked the wires, plugs, vacuum lines and try adjusting the timing, since I don’t have a timing light I’ve simply tried moving the distributor just a little to see if it improves (I’m picking up a timing light tonight). I’ve done a lot of searches and tried what was suggested without luck. I’m not sure what else to do at this point, any suggestions would be greatly appreciated.

Btw, I have a 1978 280Z 2+2 L28 stock with automatic transmission. One more thing as part of my troubleshooting I replaced the air flow meter (I had just purchased one from Motor Sports)

Rick :mad:

[racebird1]

You must check your fuel pressure first at the intake somewhere after the fuel filterand you need at least 36 psi to even begin to run properly. next make sure there are no NO! cracks or leaks in the boot from the air flow meeter to the throttle body Then the next question is what does it need done to keep it running and what is that giving the engine more air less air more fuel less fuel. Then just about everything that sends information to the computer need tested. It sounds like you have some sort of a intermitent problem. Good luck

[rickl750]

Racebird1,

Thanks for your suggestions, I’ll try to check the fuel pressure in the next couple of days. I need to by a pressure gauge and try to get home while there’s still some daylight. As for the air flow meter it’s new and the boot has no cracks or holes. But your right I need to find out what’s missing to make her run right, more or less fuel/air etc.

Thanks again, I’ll post my results after I get a chance to try your suggestions.

Rick

[racebird1]

Something may be giving the computer the wrong signal so it might not be getting the right air to fuel mixture so if you can determine what is off then you might be able to determine what could be sending bad info. Has this car been running good up to now or are you trying to get it going after it's been sitting for awhile. Has the timing been played with. Make sure there isn't somewhere else air could be getting sucked into the intake manifold such as a vaccum line. Check for water in the distributor.

[rickl750]

The car has been running great for over a year until the head gasket blew. It sat for about a month until I had time to do the work. After the gasket was replaced it ran good, like it used to for about a day and then this happened. It starts right away but it's rough and after a minute or so, it has problems idling on her own and it starts to smoke.

[sblake01]

How's the adjustment/condition of your throttle valve switch?

[rickl750]

Sblake01,

I have not checked it. I found one of your threads on testing the throttle valve switch and will do it on Friday (I took the day off to hopefully take care of this).

http://www.classiczcars.com/forums/showthread.php?t=27642&highlight=throttle+valve+switch

Thanks,

Rick

Edited March 18, 2009 by rickl750

[racebird1]

Another thing to check mainly because you were in the engine just make sure nothing happened to the timing chain. Just make sure it still has the tension on it at that it is still timed.

[rickl750]

Hi Guys,

The timing is fine so is the throttle valve switch as far as I can tell, I don't have a volt meter so I tested it manually as indicated on the atlanticZ website http://www.atlanticz.ca/zclub/techtips/tps/index.html

Having said that I found something curious, when I start the engine it takes about 15sec before she starts smoking and idleling rough. I took the clamp of the boot between the air flow meter and the throttle body and started the engine, just as it started to run rough I separated the boot from the air flow meter to allow additional air in and the engine smooth out the smoke almost completely disappeared.

I checked the connector and it is fine. The air flow meter is new and I just replaced it because the old one would act up once in a while. At this point I've done the same test with the old and new air flow meter with the same results.

So I'm assuming that there's an issue with air flow, but I'm not to sure how to proceed. Any help would be appreciated.

Thanks,

Rick

Edited March 20, 2009 by rickl750

[rickl750]

Ok, I've replaced every vacuum line and still having the same issue. Any suggestions?

Thanks,

Rick

[rickl750]

Ok, she's now running fairly well. I found a clog in one of the vacuum connections and I replaced the water tempature sensor. She is still moking, not as much as before never the less still smoking. I've adjusted the timming without much improvement. Anyone have any suggestions?

Thanks,

[rickl750]

Well, I guess I'm on my own! Thank you all for your assistance.

For those of you that might stumble on this thread, here are some links that I used to partially resolve my issue.

http://www.atlanticz.ca/zclub/techtips/EFI&fuel.htm

http://www.atlanticz.ca/zclub/techtips/efisystem/280zfuelinjectionbook.pdf

http://www.atlanticz.ca/zclub/techtips/tps/index.html

http://www.classiczcars.com/forums/showthread.php?t=31702&highlight=idle

http://www.classiczcars.com/forums/showthread.php?t=31531&highlight=idle

http://www.classiczcars.com/forums/showthread.php?t=30868&highlight=idle

Edited March 24, 2009 by rickl750