Help!! 1978 280Z barely idles

[sblake01]

So basically you solved it by correcting a problem that is seldom, if ever, heard of. I've never had a clog in a vacuum line on any car I've ever owned that I can recall. I wouldn't have suggested a clogged line because I've never experienced one. Collapsed; yes, clogged; no. The three threads from this site that you linked to had more conventional solutions. Your other problem: I don't recall your head gasket thread but were you having any other problems prior to having to replace the head gasket? What is/was the condition of the engine besides the head gasket? Is the AFM you purchased from MSA specifically a for a 78; i.e., no fuel pump contacts nor a connector pin for them? I ask that because the 78 AFM is calibrated differently than the 75-77. If your compression is okay as well as the integrity of the EFI system, i.e., no leaking injectors, proper fuel pressure, all switches, sensors, and components within spec and with proper connections, then the problem could be the AFM. It likely needs to be calibrated. That requires access to some type of exhaust gas analyzer, air/fuel wideband sensor or something of that nautre to properly calibrite it. Regardless of what others say, doing them by ear, by the 'seat of the pants' or the number of clicks doesn't really cut it.

[rickl750]

This is a long story but I’ll make it as brief as possible. I bought the car about a year ago (my first Z) and it was running great, very strong considering she had 175,000+ miles. The only issue I had was with the AFM that would act up from time to time. I placed my order with MSA over the phone and we went over everything and matched the numbers, so I’m sure it’s the right one.

Anyway, before the AFM arrived I blew the head gasket and had to replace it. This was pretty straight forward, everything went well, except when I started the engine for the first time, it ran pretty bad as expected (burning all the crap in her) but was not smoothing out. I got very concerned and took her apart to check the timing chain, sprocket and make sure I didn’t screw-up. Everything was fine, fired her up and after an hour or so she was running pretty good, a little rough but nothing to worry about. About a day later I started having issues with the idle and gray/black smoke, allot of smoke. I went thru the following:

-Checked all connections and vacuum lines (still labeled from the head gasket replacement)

-Cleaned most of the connectors (will do the rest this weekend)

-Tested the water temperature sensor

Throttle Position Switch

Auxiliary Air Regulator

Fuel injectors including the cold start not sure what the real name is (the 7th one)

-Replaced the AFM (it arrived)

Spark plugs, cap, rotor, cables and all vacuum lines.

I also checked other thing (switches, sensors) according to the EFI bible (things are bit fuzzy don’t remember everything I did during the last two weeks)

The last thing I did was to go thru every vacuum line and device that they where attached too. I either blew into the houses or created suction and inspected visually. On the large vacuum line under the intake manifold I found a lot or crud and cleared it, I also replaced the water temperature sensor (even though it tested fine) and started the car.

She ran a lot better with little smoke and it’s now drivable. She still smokes but very little and runs a little rough, meaning she is not smooth there’s a very faint put, put as you accelerate (I hope you understand what I mean).

I've tried adjusting the timing to 20 Btdc as indicated on the Chilton and Haynes manual but I can only get it to about 25 Btdc. The distributor has been turned as far as it goes. At this point I’m assuming that’s the reason why she’s not running smooth. Btw, when I removed the distributor cap I found a single bearing floating in the distributor so, at this point I'm thinking that's where my last issue lies.

Thanks,

Rick

Edited March 25, 2009 by rickl750

[sblake01]

Is that a 25 degree initial advance? Idling @ 700-800 rpm with the line from the vacuum pot blocked? If so, either something is stuck insided the distributor or it's not clocked right with the oil pump. Does the breaker plate move. Even 20 degrees is a lot. The service manual calls for 10 BTDC. That would definately cause the issue you speak of and maybe others.

[ansell]

Thats what my car used to do,i was told that the thotte switch was bad

i checked, and the only thing i had to do was adjust the switch.and

afted that the smoke was gone ....

[sblake01]

Thats what my car used to do,i was told that the thotte switch was bad

i checked, and the only thing i had to do was adjust the switch.and

afted that the smoke was gone ....

Different scenario. The throttle valve switch wouldn't be causing problems with the distibutor advance.

[rickl750]

Hi Stephen,

Ok, I removed the distributor, cleaned it up and put it back in place and I was able to set proper timing (10 BTDC). Unfortunately I broke the retaining bolt and had to extract the broken piece and re-tap. She’s running much better now and no smoke. She still has that put, put feel on initial acceleration but I’m sure I’ll figure it out eventually. I’m being patience and going over everything again. One thing I found a bearing floating around in the distributor, I’m hopping that this is not a sign of a distributor replacement in the near future.

Thanks for all your help.

Rick

[sblake01]

You can reaplace those bearings if you can find replacements. I've done that in the past but not recently. Does the advance move freely? As far as the 'putt-putt', how's your compression? Condition of valves? Just guessing at this point since there are so many things that could cause that.

[rickl750]

The advance is moving freely. Valves are good I had them checked when I had the head checked durring the head gasket replacement. I'll do a compresion test next weekend and go from there.

Thanks,

Rick