Lambda problem?

[delorean82]

Thank you for the tip on using the diagnostic plug to get a reading from. That worked great. FV tested out at 44.3. Replaced the o2 sensor and started the car, reading was 44.2 until it warmed up and then it went to 10. Seemed to run really smooth at 10, when I could hear the FV kick in the meter went 44 and ran rough. Then back to 10 after FV kicked off. Seems to me the car is running rich and needs to be adjusted up to get a consistent 44 or so before the FV kicks in. I'm I in understanding the correctly? It gets kinda to wrap your head around sometimes.

[Bitsyncmaster]

Thank you for the tip on using the diagnostic plug to get a reading from. That worked great. FV tested out at 44.3. Replaced the o2 sensor and started the car, reading was 44.2 until it warmed up and then it went to 10. Seemed to run really smooth at 10, when I could hear the FV kick in the meter went 44 and ran rough. Then back to 10 after FV kicked off. Seems to me the car is running rich and needs to be adjusted up to get a consistent 44 or so before the FV kicks in. I'm I in understanding the correctly? It gets kinda to wrap your head around sometimes.

You looking to adjust it to read about 30 to 35 degrees (average) after it is warmed up.

[delorean82]

Ok so I was able to get the car dialed in to 44 - 32.
But still getting the hot cat only near the muffler end of it, then the car just died. Wouldn't restart.

Does this sound like when I finally get it dialed in the cat was on it's way out and fianally went plugging the exhaust and casting the car to run poorly?

[Bitsyncmaster]

Ok so I was able to get the car dialed in to 44 - 32.
But still getting the hot cat only near the muffler end of it, then the car just died. Wouldn't restart.

Does this sound like when I finally get it dialed in the cat was on it's way out and fianally went plugging the exhaust and casting the car to run poorly?

My guess would be yes, your cat is plugged. You really need to pull it and look inside to know for sure. The honeycomb will melt when it gets that hot.

It's also very hard to set the mixture with a plugged cat. It will be changing every few minutes.

[delorean82]

That's what I thought, thanks for all the help. The car was Also sputtering like it was backfiring but wasn't . Tells me that it was just backed up with back pressure

[delorean82]

Ok so I took a break from this problem to read the book closely and found that I had actually mixed up number 3 with number 1 plug wires.

So car runs better, no hot cat. But now I have a new problem I still can't dial the fuel in with the dwell meter and I have a high idell. Rpm is about 900 to 950 when it used to be 750 consistently. I checked for vacuum leaks and only find a slight one at the w pipe where the o rings are but I replaced those.

As for the fuel I closed the mixture screw all the way, full lean, then opened it up until I got a decent fuel injector spray. Still cannot get the dwell meter to get off 84. It fluctuates between 84.3 and 84.7. When I push the WOT switch it goes down to 53.4.

Any ideas?

[DMCMW Dave]

Ok so I took a break from this problem to read the book closely and found that I had actually mixed up number 3 with number 1 plug wires.

So car runs better, no hot cat. But now I have a new problem I still can't dial the fuel in with the dwell meter and I have a high idell. Rpm is about 900 to 950 when it used to be 750 consistently. I checked for vacuum leaks and only find a slight one at the w pipe where the o rings are but I replaced those.

As for the fuel I closed the mixture screw all the way, full lean, then opened it up until I got a decent fuel injector spray. Still cannot get the dwell meter to get off 84. It fluctuates between 84.3 and 84.7. When I push the WOT switch it goes down to 53.4.

Any ideas?

You're still apparently running way too lean. What happens if you keep going richer? Does the idle speed up more or does the car sputter and slow down?

If you richen and now the idle is way too high, but it otherwise seems to run OK, you are compensating a vacuum leak. If you try and accerate but the car backfires or lacks power, you are more likely dealing with unmetered air leaks.

Your WOT switch test proves the ECU is working. You could do the service manual battery/ground O2 sensor test to verify that the ECU is working completely. Disconnecting the O2 sensor should get you to 45 degrees all the time, if that's not the case you are chasing other issues.

Common issues:
Unmetered Air Leaks (usually can be adjusted to idle OK but will lean misfire on acceleration and CO setting will seem erratic/lazy):
Idle Air pipe aka "the pipe of agony" not inserted all the way in;
Torn rubber gasket between the air metering assembly and the throttle;
Missing o-ring under the fuel distributor

Vacuum Leaks:
Disconnected brake booster or auto trans modulator hose;
Missing intake O-rings.

Sneak Air Path (internal air leak):
Stuck idle motor or disconnected idle thermistor (usually more like 2000 RPM idle)
Stuck/bad decel valve springs
Idle stop screws too far in
Brass idle screws open

[Bitsyncmaster]

I agree with Dave S. Your way to lean because the lambda is trying to make the mixture richer.

You idle speed just may be your curb idle is set to high. When the plugs were wrong it kept the idle speed down into the idle ECU control range. Make sure your three bypass screws are fully seated and then back out the lower screw on the idle arm.

[bluscreen]

Agree. Here's an easy test. Yank the RPM relay and jumper the brown wire to the yellow/red wire. Key does not need to be on. The RPM relay will start buzzing at 50% (45 deg). You can now test your circuit and meter to your hearts content without running the engine and melting things. When you have the meter working and reading 45 (55 if/when you hit the full throttle microswitch) then you can go back to troubleshooting the engine.

FYI - there is a series of simple tests given in the manual that are really handy to verify the electronics. (page D:04:05, paragraph 5). This seems mysterious to most but is works well.

If you disconnect the O2 sensor and GROUND the connector on the car (not the sensor) the dwell meter should read 87 degrees. You will hear the FV change pitch as it moves. If you put a 1.5V flashlight battery + on the car connection and ground the neg of the battery to the frame, you'll see the dwell swing to 20 deg. With the O2 sensor disconnected (or connected with the engine off) it should read 45 all the time.

I'm thinking my Actron meter may be dead. I'm troubleshooting an open loop issue and when I try the above test (car off, RPM relay wires jumpered) I hear the FV buzzing, but connecting the meter to an engine ground (or any ground) and onto the bottom-right diagnostic pin (or disconnecting that and using the orange wire directly) yields no output when the meter is set for Dwell. When set for RPM it shows 2-ish on the bottom 8-cyl scale, and when setting to volts it shows 5-ish. In fact, with the car running (and warmed up but still clearly in an open loop) the dwell setting still shows nothing. When running the RPM setting I think moves the needle over to a steady 10 if I recall correctly. Any wisdom for this? Is a new meter in my future?

(Brand new Bosch O2 sensor and confirmed continuity for it to the lambda ECU and also that it is grounding)

[Bitsyncmaster]

I'm thinking my Actron meter may be dead. I'm troubleshooting an open loop issue and when I try the above test (car off, RPM relay wires jumpered) I hear the FV buzzing, but connecting the meter to an engine ground (or any ground) and onto the bottom-right diagnostic pin (or disconnecting that and using the orange wire directly) yields no output when the meter is set for Dwell. When set for RPM it shows 2-ish on the bottom 8-cyl scale, and when setting to volts it shows 5-ish. In fact, with the car running (and warmed up but still clearly in an open loop) the dwell setting still shows nothing. When running the RPM setting I think moves the needle over to a steady 10 if I recall correctly. Any wisdom for this? Is a new meter in my future?

(Brand new Bosch O2 sensor and confirmed continuity for it to the lambda ECU and also that it is grounding)

The orange wire is the FV signal through a 1 kohm resistor. Try your meter on the three pin bulkhead connector red/ brown wire but my bet is your meter is NG.