I need some ideas...

[KDMatt]

Okay folks, the Z is still running rich, and stills appears to be burning oil.

I'm going to list off some symptoms, and I would very much appreciate anyone who would like to give me some ideas. I'm finally getting to that point where I'm feeling comfortable working on my car by myself and replacing bad parts.

Here's what I'ves got for yas:

I recently discovered a discconnected PCV hose, I felt the hose, the vacuum here felt pretty weak. There was also no distinct "whistling" sound that gets spoken of often. Reconnected, better idle, 'can't tell if the exhaust is any more or less smokey though.

I replaced a cracked hose atop the valve-cover. This is the breather hose that connects back into the throttle. I have the 75/76 pre voluntary recall setup with a t-junction. The old hose, I noticed, was covered in grease and oily scum (it was shiny when I pulled it actually). This hose had a crack in it, which I temporarily sealed off with some tape before replacing.

I also seem to go through oil sporadically... I'm in the habit of checking the oil dipstick every other week. Sometimes it's still right where it's supposed to be, and sometimes it'll read that it's down by 2-quarts... strange to me.

Plugs also get fouled very quickly. After only a few hundred miles of driving they come out black on every cylinder.

I believe there is an 'over-rich' condition occuring right now. The smoke is faintly blue when the engine is cold, but dissipates as it heats up. When I juice the engine after everything is nice and warmed up, I still get traces of gray in the exhaust, which I'm told indicates a rich condition... This also has the effect of making the exhaust smell bad, which deters female passengers (bad news for me).

There's also a crack in the header in the engine bay... which only adds to bad exhaust fumes at idle in the cabin.

Also, I believe the AFM may have been tampered with at some point in the car's lifetime. I spent some time cleaning up electrical connections in the engine bay the other weekend, and everytime I'd pull one, I'd notice green corrosion from 30 years of having not been cleaned. This was not the case with the AFM connector, the connections all looked pretty clean which makes me think someone has pulled the AFM out and cleaned it up previously which also leaves room for tampering.

Is the AFM from a '77 compatible with my '76? I went to the junkyard today and it was only $9.00 to pull an AFM off of a car there so I went for it.

Any ideas people can put forward would be awesome.

[beandip]

First of all is the engine leaking Oil ? If you don't find puddles of oil under the car in the morning then it is burning oil. It sounds like that is the case from just the little you have posted here. It also sounds like the engine is running rich like you said . I cannot help with injection , sorry. If you know anyone that has a compression testing set , checking the compression is a good idea. The plugs being fowled are they wet and oily , or just black and wet with fuel ? Also when you said they are fowled , is the engine missing , or are you just pulling them to see how they look ? Gary

[KDMatt]

The engine, for the most part, is idling pretty smoothly. There isn't much of a noticeable miss, I'm just pulling the plugs and noticing them all looking pretty blacked out.

The deposits on the plugs are black, and bear a bit of an oily residue. There's only a very minimal amount of oil seapage on the floor at night, so yes, burning is the case.

Recent compression test showed (from 1 to 6)

140 140 140 140 160 150

I would really like to address my rich-mixture issue first, since I believe that will be the easier issue to resolve, not to say I'm not eager to resolve burning oil either though.

[hls30.com]

The commcon ways to enrich the micxture on the efi cars are two:

1) add a potentiometer to the temperature sensor(so you can have it report a colder temp to add more fuel) if it is there it will be the only stand alone electronic control under the hood9probably fairly near the thermostat housing), and would just have to be adjusted to back off fiel delivery.

The second way is to open up the AFM and pgysucally bend the arm of the potentiometer in it-pull the glied on cover off, and look for a bent rod. once you find it, carefully bend it straight again, and that should take care of it, by watching the samethings you are watching now, you will know if you nave a little further to bend...

Will

[KDMatt]

Hrm, I've been tinkering this week, and here's what I've discovered.

I swapped in the AFM from the 77, this made no difference. I'm beginning to feel that a faulty/messed-with AFM is not my problem.

I did however notice an exposed, corroded green wire coming off of the coolant temperature switch. Hrm... Maybe the coolant temperature switch and/or sensor are not functioning properly? Does anyone have a test procedure for these things buried away?

Other Thoughts?

[sakijo]

Burning oil usually caused by worn valve seals and guides. Mine were bad, but only blew smoke when engine was hot and I gassed it.

[KDMatt]

Well, I finally bit the bullet and decided to toy with the AFM spring tension today (even after cleaning out a very corroded temp sensor connection, which didn't make a difference).

I rotated the gear about 8 teeth CW to try to lean things out. Smoking seems like it has been reduced a bit, but is still, very much, there.

Also, I'm noticing little specs of liquid spewing out the exhaust too. 'Can't tell if it's just condensation (it IS getting below 60/50 here at night now), or if it's fuel or oil or what. All I know is that it's blackish and relatively thin.

Any other EFI junkies wanna fire some ideas at me? I'm hoping to clear this up a lot before changing spark plugs again (and subsequently heading off to school in the next couple of days)... It's getting annoying to change plugs every two months... It's getting the point now where it's getting tougher to start, and that's how I know my plugs are about toast.

[jfairladyz]

I believe there is an 'over-rich' condition occuring right now. The smoke is faintly blue when the engine is cold, but dissipates as it heats up. When I juice the engine after everything is nice and warmed up, I still get traces of gray in the exhaust, which I'm told indicates a rich condition... This also has the effect of making the exhaust smell bad, which deters female passengers (bad news for me).

I know this was suggested earlier but I'm gonna have to go with the valve stem seals as well on this one. Strong blue smoke on start up that fades as the motor warms is usually a tell-tell sign of this. As is the oil consumption.

Try running a heavy weight motor oil to see if this remedies the smoking. That is of course only a bandaid if it helps.

[hls30.com]

Black smoke-too rich

blue smoke valve guides-or oil control rings-use a timed compression test to figure out which.

How many miles have you put on the car in the last week or so(and since you have owned it). If it is less than 100, straighten out the carbs and start driving. A car that has been sitting can leak oil bast the seals and take a while to burn it all off.

I routinely put thin high detergent oil in my cars(those with "sticky" oil) when I get them-that usually means they burn a good bit of oil until the second or third oil change, and they have less chance of popping out a valve retainer and creating a problem worse than blue stinky exhaust. Check the condition of your current oil.

Will

[KDMatt]

Hrm... Well I'm overdue for an oil change, and I've noticed that my oil is, sorta thin I guess. I mean, it's not ridiculously thin... It's still just as thick as the oil I keep pouring in there (Castrol High-Mileage formula).

Maybe I should try some 20w in there for a while? ... Come October this car is going to be stored... and naturally, I plan to run it every now and again just to keep things from settling too much, but I have to know, is a heavier grade of oil more or less likely to make the engine seize from inactivity?

EDIT: Is it also possible that the "High-Mileage" formula has a lot of detergents in it and is really thin because of that? ... I mean I'm no oil expert, but this 10w I keep putting in there seems a lot thinner than I remember most normal 10w oil being.

[zeiss150]

I don't know much about FI but have you cleaned the fuel injectors? check the connections to the injectors too. If that Z is still in the junk yard pull the computer and swap them out ... its a long shot but maybe something is wacky with the computer? I use castrol 30 weight, seems to work great ... but I have a fresh rebuild.

Good luck, Matt-

P.S. pull the temp sensor from the thermostat housing and clean or replace that and all the connections

[KDMatt]

Clean connections on:

All six injectors

cold-start

aux. air regulator

thermotime switch

temp sensor

throttle pos. sensor

afm connectors

... and that's all I can remember doing ATM.

Also, seems like a lot less smoking now that I've dialed the AFM lean... which makes sense I suppose.