Failed CO emissions - all controls removed - where to start?

[siteunseen]

1 hour ago, SteveJ said:

It's the "Batman angle" of the photo that's fooling you.

I'd never heard about the Batman Angle so you know I googled it. 

https://en.wikipedia.org/wiki/Dutch_angle

"Dutch angles were used extensively in the satirical 1960s Batman TV series (and its 1966 film spin-off) in which each villain had his or her own angle, as they were "crooked".

Edited October 6, 2019 by siteunseen

[Dave WM]

5 hours ago, thetwood said:

OK. A few questions that I know are basic for you guys, but the electrical systems and testing electronics is all new to me.

1) Is there somewhere in the FSM that shows the ECU and which pin is which? I've been looking through and either am not finding it or just don't know how to read it correctly...

2) With the temperature sensor disconnected, should I get an ohms reading by testing the two pins in the sensor?

3) The pins in all of these sensors are corroded. What's the best thing to use to clean?

1) The ECU is located on the driver side kick panel under the hood pull. Before doing anything, make sure the key is off and the battery disconnected. remove the panel, the 36 pin connector has a retainer that must be pressed and then it will hinge off the ECU.all test are done on the connector NEVER the ECU, so after removing the 36 pin connector you will need to find the pins per the diagrams in the FSM, check the one for the temp sensor.

 

2&3) Yes with the temp sensor disconnected as shown in the pic you should be able to get a reading off the pins. they are corroded so it may be unreliable but non the less prob with the points and see what you can get. You will ultimately want to clean that up, I use a paint gun spiral brush and some contact cleaner applied to the pins and scrubbed. There is a good chance the sensor will not be correct as it lives is a very harsh environment (water corrosion lack of proper antifreeze, age...) But its always best to test and record. I check new parts as well, just to be sure before installing them.

 

as far as testing, the FSM has two test modes,

1) resistance and continuity (all done with the key off and the battery disconnected). multimeter in the ohms or continuity setting.

2) Voltage test, done with the battery connected and the key at either ON or Start depending on what is being tested. multimeter in the DC voltage setting.

What you want to avoid is connecting the ECU to the 36 pin connector with the power on. This is why I like to have both the Key off and the battery disconnected, much less likely to accidentally connect with power on if both are done.

 

 

 

 

Edited October 6, 2019 by Dave WM

[thetwood]

OK. I have to apologize to everyone. I thought I had printed the entire FSM. Apparently not, and I missed the section I really needed to be looking at. Let me study a bit so I'm better informed with my questions...

I couldn't get any reading from the temperature sensor at all, but it is pretty corroded. I'll try some more and will clean.

[siteunseen]

On my car there's a male on the temp gauge sensor female on the wire and it would plug onto here...

[Dave WM]

45 minutes ago, thetwood said:

OK. I have to apologize to everyone. I thought I had printed the entire FSM. Apparently not, and I missed the section I really needed to be looking at. Let me study a bit so I'm better informed with my questions...

I couldn't get any reading from the temperature sensor at all, but it is pretty corroded. I'll try some more and will clean.

there is a pretty good chance it will just be open, and need to be replaced. I suspect it will be bad even after cleaning the pins.

In the mean time check the 36 pin connector, still wondering about what that plug that is currently attached to the thermotime swich is doing. Again with the battery disconnected you can check the resistance for the temp sensor at the 36 pin connector. IF its open try shorting the two leads of the black plug with white wires (after removing it from the thermotime swich) and get another resistance reading, should be 0 ohms (or very low) at the 36 pin connecter IF that is indeed the plug that goes to the temp sensor. The idea is to check the wiring so we know exactly what we are dealing with. IF that connector is indeed the one that goes back to the 36 pin connector temp sensor, then your best bet will be to just get a new one, test it, and if good install.

[240260280]

Your car will foul the plugs quickly if the water temp sensor is not connected and everything else is nominal.  The computer will think you are in Antarctica and flood the cylinders with gas.

Some pictures here showing how the temp sensor wiring goes back to the harness: http://atlanticz.ca/zclub/techtips/tempsensorpot/index.html

This will help you better understand the Z's EFI system. It is not that difficult: http://atlanticz.ca/zclub/techtips/efisystem/overview.html

[Zed Head]

This book is easier for testing, it shows the connector in a drawing with the pins labeled.  It has all of the years up to 1981.

The thermotime switch has about 50-60 ohms, I think, so would fool the ECU, maybe enough to let it keep running if the sensor switch was connected there.

 

[thetwood]

Know it's been a while, but between traveling and a nasty cold, I wasn't much feeling like being in the cold garage... But do have some testing results now.

Went through the ohms testing guide in section EF of the service manual along with the same in the EFI manual. Thanks to everyone who pointed me in the right direction there.

1) The second of the three Air Flow Meter tests (terminals 7 and 8 ) had no continuity or reading. 6/8 and 8/9 both had good readings (182 and 103).

2) Water Temperature Sensor (13) had no continuity. After tracing wires, I found a bullet connector in the engine bay that led to this terminal, so looks like it's not hooked up at all.

3) Air Regulator (34) had no continuity. Traced it to an empty harness connector. Don't think this car even has this anymore.

4) Thermotime switch (21) had no continuity. Traced to an empty harness connector and another bullet connector. Knew this wasn't hooked up, but shouldn't need it either with no cold start...

5) The Yellow wire that was hooked up to the Thermotime seems to trace back to the aftermarket fan on the radiator, and also runs the temp gauge in the dash. I'm guessing this should instead hook up to the temp gauge sensor.

6) I cleaned the contacts in the Water Temperature Sensor and still get no ohms/continuity at all. I do get readings on the Thermotime switch, which is why I'm guessing they had something plugged into it (even if it made no sense...).

 

So, here's where I was planning to start (but would love input): Get a new Water Temperature Sensor and new temp sensor plug, hook up to the bullet connector wire (and ground that goes with it) and put it all together.

Not sure about the missing the the AFM with terminals 7 and 8...

[Zed Head]

47 minutes ago, thetwood said:

2) Water Temperature Sensor (13) had no continuity. After tracing wires, I found a bullet connector in the engine bay that led to this terminal, so looks like it's not hooked up at all.

6) I cleaned the contacts in the Water Temperature Sensor and still get no ohms/continuity at all. I do get readings on the Thermotime switch, which is why I'm guessing they had something plugged into it (even if it made no sense...).

So, here's where I was planning to start (but would love input): Get a new Water Temperature Sensor and new temp sensor plug, hook up to the bullet connector wire (and ground that goes with it) and put it all together.

There are two bullet connectors in the harness between the sensor itself and the ECU.  Trace the wires back from the sensor.  Measure resistance at the sensor itself.  Can't tell if you did that.  If your wires aren't right a new sensor won't make a difference.

If the engine starts and runs with no coolant sensor reading then you probably have a bunch of "resetting" ahead of you.  Other stuff has probably been messed with, most likely the AFM, or maybe there's a big vacuum leak somewhere..  The coolant temperature sensor is one of the most important sensors in the system.

[thetwood]

41 minutes ago, Zed Head said:

There are two bullet connectors in the harness between the sensor itself and the ECU.  Trace the wires back from the sensor.  Measure resistance at the sensor itself.  Can't tell if you did that.  If your wires aren't right a new sensor won't make a difference.

If the engine starts and runs with no coolant sensor reading then you probably have a bunch of "resetting" ahead of you.  Other stuff has probably been messed with, most likely the AFM, or maybe there's a big vacuum leak somewhere..  The coolant temperature sensor is one of the most important sensors in the system.

The bullet connectors are not hooked up to anything. They're just hanging empty in the engine bay. I traced from the bullet connectors to the ECU, but there's nothing going to the temp sensors from the bullet connectors. The only thing hooked to any of the three temp sensors was the Thermotime, but I traced that to the aftermarket cooling fan and not to the ECU. 

[Zed Head]

There's a small mini-harness that's missing.  Get a fuel injector plug (it fits the coolant temperature sensor) and some wire and some bullet connectors and make your own.  You need that circuit.  Older BMWs and Volvos and Saabs use the EV1 type connector, if you want to make a quick wrecking yard trip.  Or there's the internet.

https://www.amazon.com/Fuel-Injector-Connector-Type-Pigtail/dp/B01M0GCLZP

[Dave WM]

Maybe a close up pic of the harness as is would be in order. See what you are working with.

Edited October 26, 2019 by Dave WM