AMC Eagle

[MadMan]

Originally Posted by MIPS

Edited: Wait no, there's one last variable. An exhaust leak can cause a lean condition. Right now the entire length from the manifold to the back is a bit of a disaster or clamps, welds and whistling. It might be advisable to fix that first before proceeding.

Only an exhaust leak up to, and only a little bit past the O2 sensor can cause the sensor to *read* lean. However, I will say that even a pinhole leak can throw off the O2 sensor reading, especially close to it. Also, that any significant exhaust leak will kill the engine power, strange as that sounds, you would normally think a leak would create less backpressure to hinder the engine, but it's kinda the other way around. A big enough leak will create a blockage with its own air currents.

Also, an analog meter might be better for reading the oscillating O2 sensor output, but obviously yours is quite a bit off. But there's also that thing where DVOMs don't necessarily read oscillating DC voltage that well.

Also also, I feel like I suggested replacing the O2 sensor before, but I can't be fucked to go back and look :P

Also also also, nobody ever replaces O2 sensors on pre-OBDII cars, because there's really no way that the driver would be informed of its failure.

[MIPS]

I blew up the gas tank.

The EVAP system has been gradually repaired as when I got the car it didn't work at all and on Saturday I finally replaced the gas cap and the system pressurized normally again.
However in the past at some point after it had failed the tank had developed leaks and was patched with putty and now that everything was under pressure again it promptly began weeping fuel out around the patches. Tank rebuild is $450, but a new OEM tank is $155 plus shipping. Guess what I'm doing.

[MadMan]

Originally Posted by MIPS

Tank rebuild is $450, but a new OEM tank is $155 plus shipping. Guess what I'm doing.

I wouldn't trust a 'rebuild' anyway. It's literally gonna be some drunk bastard taking a mig welder to it.

Here's the thing though (I mean obviously you need a new tank anyway, but) the tank really shouldn't BE under pressure. It should either be vented to atmosphere or under a slight vacuum. Granted, I'm not familiar with the evap system on that particular car - or older cars in general - but a pressurized gas tank is like a bomb, I can't really think of any practical reason for it to be under pressure at any point in time.

[MIPS]

EVAP system on the eagle allows the tank to pressurize and forces vapor through a steel line to the charcoal canister up front. From there it's burned whenever ported vacuum is present (opens the purge valve during acceleration).
Well I guess with the tank out I can verify the vent line isn't restricted. I did check it before when I rebuilt the rollover check valve.

[dishdude]

You wanted something unique and you got it. A K-car would have been so boring in comparison.

[MIPS]

I think at this point a Reliant would of been more...reliable by this point?

[MadMan]

It's possible you bent the float arm. Really weird symptom, anyhow, cuz generally, there is no more resistance... uh, travel? than it can have... if that makes any sense.

[MIPS]

It turned out the plastic grommet in the sender assembly is cracked. It must of gotten nudged.



The good news is that even though it split the pickup is still snug enough to be nudged back and then recalibrated (with a few frustrating misadjustments before getting it perfect), so I've been happily running with a happy tank and sender for the remainder of the summer.
In the meantime the headliner was dropped to begin with reupholstry, the console was reinstalled and the prewiring began for all the funky accessories.
The final thing that was performed before summer officially ended was to adjust the mixture screws. The carb rebuild left a lean running condition and we verified that all adjustments are still matching to the Carter spec, so now that we know the engine, exhaust, electrical, intake and the carburetor are in good order we can perform the adjustment and not need to worry about external variables.
The problem is that AMC's own documentation does not describe how to do the adjustment on an electronic feedback carburetor. In fact, it's as if the half a page of mixture screw adjustment procedures are not intended specifically for this car at all...
The internet is awash with different ways to do it (by vacuum, by ear....these people are crazy), but me and my mechanic determined the easiest way was:

-Turn the computer on while telling it the engine is cold. This centers the stepper motor and the metering pins. We don't want them trying to correct the mix while adjusting or you will be stuck rubberbanding your adjustments, so sticking them in the middle means we can make the adjustment and not have to bias too lean or rich to compensate.
-Turn the computer off and unplug the stepper motor
-Attach tachometer
-Start the car and let it come up to temp.
-Set the curb idle to spec
-Perform the mixture adjustment, as per spec. You will need two screwdrivers with marks drawn on them to ensure you are turning both screws at the same time and to the same positions.
-Complete adjustment by turning off engine, removing tachometer and reconnecting the stepper motor. It will re-initialize the next time you turn the car on
-Verify adjustment by installing plastic air cleaner cover (the how-to is in the book but it's basically a piece of plexiglass over the top of the air cleaner), starting the car, letting the car enter closed loop and ensure the metering pins oscillate back and fourth within their range
-Optional: Probe the signal wire for the O2 sensor and attach either a Digital Multimeter or an oscilloscope. If the mixture adjustment is correct the voltage should swing between 0.8 and 0.1v with no prolonged time on either end of the waveform (due to still running still too lean or too rich)
The great thing about the electronic feedback is that precise mixture screw adjustment isn't necessary. Just get it in the ballpark and it will do the rest.

So everything under the hood is now done after a year of work, it's getting 24 highway and 17 city in 2WD and the interior is coming together. Next year is gonna be all about suspension and bushings and it badly needs all of that.

[MadMan]

Originally Posted by MIPS

it's getting 24 highway and 17 city in 2WD

Impressive!

[MIPS]

The coolant switch failed again. I noticed as the mercury dropped the car would stall at a rolling stop or idling at a light.

I ended up purchasing one of the official AMC testers for the feedback systems. It's nothing special other than it reduces an hour or two of testing down to about a minute. I really don't need it but I couldn't resist the bragging rights.



It immediately hung up waiting for the car to warm up. I waited until the engine was clearly hot enough to open the thermostat and then checked the CTS from the diagnostic port. It was open and forcing the car to stay open-loop. When I went to disconnect the harness to test at the switch itself it separated into two pieces.
When I rebuilt it back in June I used JB Weld. While it should be able to handle the heat of a wet manifold it was now a brown color and crumbled. I reached out to a connection and bought another one that was used, but supposedly good from a junked rust bucket. Unfortunately it to seems to have an internal corrosion issue. I'll swap them out for now and rebuild the rebuilt one again but use a high temperature rated epoxy.

[Titan1a]

Urethane bushings?

[MadMan]

Neat!

But hey, there's something very important that you may not know yet: CONNECT THE BATT LEADS FIRST!

[Electronic M]

Ya know it would be funny if your thread got more traffic than the eagles nest because your doing a better job than them...

[MIPS]

I did the writeup on rebuilding this exact switch there, only to discover you can't see it unless you are a registered member, so it won't get cached and indexed by Google.
Videokarma, thank you for the most part for not hiding chunks of your forum behind a registration wall.

[Electronic M]

Originally Posted by MIPS

I did the writeup on rebuilding this exact switch there, only to discover you can't see it unless you are a registered member, so it won't get cached and indexed by Google.
Videokarma, thank you for the most part for not hiding chunks of your forum behind a registration wall.

You mean they actually let a non-flat earther in....Wow!