EFI relay unplugged

[rcb280z]

That's funny! Blue, I looked at EF-32 of my 77 FSM and am not really understanding what pin 49 is. I see other wires running into the same place as 49. Is this a common ground area for these wires? Ok I see it now! I pulled my wiring schematics that I had blown up several years ago so I could read them. Looks like 49 runs to one of the FI fusible links on the battery. But I'm still not sure if this is a connector or what. So do I check it the same way? What should I be looking for at pin 49? Thanks

Edited January 27, 2012 by rcb280z
left out important info

[240260280z]

I did a 2nd look and Pin 49 goes to ground so you should use a pin associated with gnd

Pin 13 is the return from the temp sensor.

[rcb280z]

Ok Blue, I got 2.96 at pin 13 and 0.00 at 49. That is good correct?

[240260280z]

Water Temp. Sensor

Ok, that shows you get 2.96kΩ at the sensor and at the ECU so your sensor and wiring are OK.

One more test you can do for completeness is to bring the motor up to temperature then measure the resistance of the sensor.

AAR

Ok the Water temp sensor and wiring seems ok, and for the moment assume the ECU connector and ECU are working fine so let's look at the AAR.

Take a quick look here: http://atlanticz.ca/zclub/techtips/aar/index.html

Here is how to check:

- Ensure your motor is cold.

- Pull the hoses off each side of the AAR

- Look through the AAR, you should be able to see through it.

- Reconnect the hoses

- Start the car then use pliers or vice grips or fingers to immediately squeeze one of the hoses feeding the AAR

- When the hose is squeezed,the RPM's should drop.

- Release the squeezing

- Run the car for 10min

- Again use pliers or vice grips or fingers to immediately squeeze one of the hoses feeding the AAR

- When the hose is squeezed,the RPM's should NOT drop.

- Turn off car

- Pull the hoses again

- Look through the AAR, you should not be able to see through it

I also thought of a couple of new things to check that can make your idle inconsistent:

- BCDD not working properly

- Throttle Valve not closing properly (weak return spring or carbon)

btw What is your idle rpm when your car is warmed up and you blip the pedal a few times?

[rcb280z]

OK, AAR is new and I did those test's a couple of months ago but, I am going to do it again because I understand the process of elimination we are doing. The idle fluctuates between 850 and 950 depending on how it's driven. but, after cold start and 10 minutes of warm up it idles around 850. If I blip the throttle it drops below 850 but comes right back to 850. BCDD seams to be working as I drive the car. Holds a high idle until the car almost comes to a stop. I will check to see if throttle is completely closing while engine is not running and if there is carbon build up. Update on what I did to the Z a couple years ago: Replaced injector connectors, WTS, Thermotime, AAR, TPS, and all those connectors, all vacuum lines and AFM to throttle body boot, the emission's hose from the valve cover and PCV and hose. Cleaned egr valve, intake including throttle body. Oh, and she has a new Catalytic converter. Did all this because I had to get it ready for California smog. We moved back here about 3 years ago. On a side note the Z passed with cleaner numbers than our 05 Altima did! I was pretty proud of that. Don't know if this helps or makes things tougher. When I get back home tomorrow I will perform those test's outlined above and get those results posted. Thanks Blue.

[240260280z]

No problem. If all the parts are new,refreshed or cleaned then this is becoming more of a mystery. Lets try to methodically go through it. AAR is next based on what you noticed in post #12 above as the aar is supposed to hold a high idle when cold then it gradually reduces the idle. The Fuel/Air mixture should still be controlled by the AFM and temp sensors as the AAR is not an air leak.

FYI some AAR's got gunked up because of the hose routing from the valve cover top.A change was done in '77 to reduce this:

As you can see, the original routing is on the left and the modified is on the right. Gummy vented gases from the valve cover no longer got routed through the AAR after the mod. On some cars the T junction behind the AAR was capped but on others, the T was removed and a small metal pipe with rubber adapter was routed from the back of the AAR to the front boot hose. Like this:

Your problem may even be something weird like the AFM flapper sticking. Let's findout

Edited January 28, 2012 by Blue

[Zed Head]

What about the TPS not making its throttle closed contact? No idle enrichment "increment" (Blue's attached diagram in Post #16, #2). It's been the culprit for rich running on the full enrichment end, I wonder how much fuel would be missing if it didn't make contact on the idle end.

[rcb280z]

OK, the pic with the yellow plug wires is how mine is set up. I will also double check TPS. When I checked last it was making contact at idle position. Blue, I'm going to give you another update that I just thought about while I was working on my brothers car. On start up (over night) she fires almost right away (cold start works). Idles at about 850 like the AAR is not working. But, if I raise the throttle to about 1500 for about 30 seconds and let it go it actually only drops to about 1300 and thats when the AAR is working. As if the AAR requires that help to get it working. But if I don't raise the throttle it never gets to that 1300 rpm and idles rough like not enough or too much fuel. not sure if this helped or made it more complicated.

[Zed Head]

The valve in the AAR is a disc that slides perpendicular to the air flow. So there's really no reason for it to be affected by throttle opening, intake vacuum or RPM. What you think is the AAR working is probably something else.

What happens if you press the throttle closed after you get it to hold at 1300? If it goes back down that would be a sign of a sticking throttle, maybe some gunk on the throttle body plate.

The BCDD uses engine vacuum to open a passage to allow more air past the throttle body. So it could be affected by intake vacuum. You might have a problem internal to the BCDD (maybe a stuck solenoid since that is what is supposed to be activated by an amplified signal from the speedometer), causing the diaphragm to stick, letting air past the throttle body. Take the vacuum line off of the BCDD and see if that affects anything. That will remove the vacuum that opens the valve, I believe. I'm not 100% clear on the BCDD operation, but that might tell you something.

[rcb280z]

Zed Head, Sorry I didn't make myself clear. When the AAR is working, as the engine is warming, the rpm's drop slowly down to set idle speed of 850. i have to initiate the higher idle for some reason by manually raising it. If I don't the engine sounds and looks like it is bogging down. It doesn't just jump to higher idle right away after starting it. I have to help it get there. The thing that confuses me more is after it sits a couple hours while I have been trouble shooting it and I start it up it goes to the higher idle right away. If it did this every morning after sitting over night everything would be good. Should I remove the vacuum line you are speaking of before I do a cold start? I think that is what I am reading in your post. Thanks.

[240260280z]

Please run through the checks in post #28.

If the AAR is working, and it is cold enough, your idle should be ~ 1200 to 1400 rpm as soon as you start.

The pressing on the pedal bit seems strange... that indicates possibly a sticking throttle valve, weak return spring, slop in the linkage from the accelerator pedal to the throttle valve, binding in the linkage from the accelerator pedal to the throttle valve, or a malfunctioning dash pot. Possibly even the BCDD.

[rcb280z]

OK Blue, I will run those and post tomorrow afternoon as soon as I get back home. Thank you.