I'm About Done With The %**&ing Efi

[mjr45]

Thanks Blue, prayers are always always appreciated and I believe truly do work.

Mike

[Zed Head]

 I'll try cleaning the wiper and test it again and see what happens.

People have been known to loosen the screws that hold the board in place and shift it so that the wiper rides in a different spot.

 

From what I've seen though, and my own experience with one AFM that ran lean, there's not much you can do to fix them once they start crapping out.  I've never heard of a an AFM that went bad on the rich side though, usually they go lean.

 

Have you confirmed that the mechanical advance in the distributor is working?  Connect the light and rev it up.  Also, not clear why you don't just connect the vacuum advance like it's supposed to be.  There is no benefit to leaving it disconnected.

 

And the fuel pressure dropping to zero is not right.  You can test the pump versus the regulator versus the injectors/CSV by pinching the lines shut, one at a time then obth, and running the fuel pump.  If the fuel hose is new enough to survive a pinch without splitting.

[mjr45]

Zed, yes the mechanical advance is working, but the vacuum diaphragm on the dizzy is shot, thats why its disconnected and from what I've read it doesn't matter that much and may lead to a vacuum leak. On the fuel side of things, I've clamped the line from the fuel filter to the rail with a pressure gauge in place (permanently attached between the filter and the rail) and pressure dropped slowly, so I replaced the check valve in the pump as well as the O rings with no real change in pressure drop. I also tried clamping from the rail to the filter after the gauge and the drop was a little faster which leads me to believe the problem lies somewhere in the rail, as I said I believe there is a microscopic hole in the rail by the #1 injector, the rail was actually bent and had a break in it where the nipple to the injector is and when straightened, a hole was there whichI had brazed by a guy who does it for a living which is not to say it might not have a hole or it could be the FPR is bad which is new but who knows. There is no obvious fuel leak (no gas squirting out) but the dried brown goo which keeps appearing on the heat shield makes me wonder. If there is a tiny drop in fuel pressure when running would that make the ECU deliver more fuel and thus run rich? I haven't tried checking pressure when running, basically didn't want to run, lines up to the widnshield and leave the hood up and go for a drive. Thanks.

Mike

Edited March 21, 2015 by mjr45

[Zed Head]

If you've removed the fuel lines from a pressurized rail you know that there's quite a bit of fuel that comes out before pressure drops.  The hoses and the filter expand slightly under pressure and hold some volume.  If that pinhole was the source you'd smell a lot of gas.  Actually, the car probably would have caught on fire by now.

 

FPR's tend to leak down.  You can clamp the return line to test that.  Still unlikely, but injectors and CSV's can leak.  Those would cause richness.

 

You're kind of at the point where you just have to spend extra time being extra thorough on each component, with good accurate measurements.  That's how the FSM procedures end up also, from quick measurements of continuity in the front of the chapter, to measuring actual numbers in the middle. 

 

On the numbers and details topic - are there part numbers on the injectors?  And where did you get them, new?  eBay, CL new may not be the same as parts store new.

 

Details are the key, "slowly", "new", "working", etc., doesn't tell the story.  eg, mechanical advance "works".  2 degrees or 20 degrees?  The more detail you can add the clearer the picture becomes.

[FastWoman]

One common problem with these Z distributors is a sticking breaker plate.  Does yours move freely?  Pull off the distributor cap and rotor, and try giving the thing a twist.  You should feel no binding.  If your breaker plate is stuck, then your mechanical advance might not work correctly, hence difficulty running at higher RPMs.  That could also account for incomplete combustion, hence all the carbon you're seeing.

 

Blue, the zig-zags in the potentiometer tracings lead to a voltage ladder that insures the linearity of the scale, probably preventing drift as the tracings wear.

[Zed Head]

I have to say that I can't look at a potentiometer diagram and figure out what should happen.  But I do notice that the air temperature circuit seems to be in series with the AFM circuit.  

 

I wonder if a broken air temperature sensor, either opening the AFM circuit, or shorted, removing the 2500 ohms of resistance, would cause everything to go rich?

 

Where's superlen?

 

Air temp would be resistance on 27-6.

 

2nd edit - I'm going to say that a broken air temp. sensor goes very rich, since higher resistance = lower temperatures.

Edited March 21, 2015 by Zed Head

[240260280z]

I measured 6 to be at or near ground so the resistor array and the temp sensor seem to be in series from the diagram but are not.

[mjr45]

OK folks, here are the test results I got today:

 

Timing w/o vacuum - 15°, mechanical advance approx.21-22°

CTS - 3110 ohms @ approx 60°, I don't have a thermometer that goes below 100°

AFM - measured @ the ECU connector

           pin # 6 & 8 - 198.6 ohms, should be around 180

           pin # 7 & 8 - 179.6 ohms

           pin # 8 & 9 - 112.4 ohm, should be around 100

           Air Temp Sensor - 2530 ohms @ 61° F

           Fuel pump relay circuit - 63.6 ohms ( measured on 200 scale on my meter)

           Air regulator and fuel pump circuit - 43.4 ohms (200 scale)

           Fuel pressure - 36-37PSI @ idle w/o vacuum, 30-32PSI @ idle with vacuum

           TPS - checked OK @ no throttle, at full throttle checked out as NG, smae result after trying minor adjustments, so

           maybe this is the culprit.

 

Fastwoman, the mechanical advance in the dizzy works, turns easily and I checked to make sure the weights move easily.

 

Zed, I think I may have figured out the brown goo on the heat shield since I agree that if it was fuel it woulda caught fire before now. I think it was coolant leaking from that two wire gizmo(don't remember what its called) that had something to do with advance of the dizzy on the older 280 dizzy which I had disconnected after trying to repair it. I got the injectors off of Ebay from a TX company and don't recall the name and can't see any numbers on them.

 

Here is a pic of the wiper in my AFM, hope you see the tracks from the wiper arms and the worn off spots on the carbon trace. I gently cleaned the wiper arm contacts and very minutely bent them to make a little firmer contact with the trace.

Edited March 22, 2015 by mjr45

[Captain Obvious]

I'm traveling so my resources are very spotty, but I can tell you that pin 6 Is a ground line. It's an analog ground for the sensor, so yes, those two parts ARE in series, but not in the usual sense.

Yes, if the temp sensor in the AFM has gone open circuit, you will run rich.

[mjr45]

So are you saying that because the 6&8 pin reading could be a bad air temp sensor even if the air temp check was OK(2530 ohms @ 61° was about right by the Bible)?

[240260280z]

AFM and temp sensor measurements are fine!

[mjr45]

It looks to me that the TPS maybe is to blame, if the WOT is not being seen by the ECU that it would be running at the idle mixture setting all the time which would make it run rich. Correct?

Edited March 22, 2015 by mjr45