CA Smog: Diagnosing ultra rich condition

[BigKO]

A much overdo update:

I've made a bit of progress on this and I wanted to double check my findings with the experts here on Supramania.

1) I checked fuel control by monitoring the Vf signal at idle by shorting E1 and VF ports on the diagnostic block. As expected, the voltage was near zero, indicating that the ECU is pulling the maximum amount of fuel. The reading was actually 0.033 volts according to my DMM.

FYI: 0V = The maximum amount of fuel is being subtracted from the base calculations from sensors
1.25V = Some fuel is being subtracted
2.5V = No modification (A/F ratio is somewhere around 14.7:1)
3.75V (May be 3.5V) = Some fuel is being added to the base values
5V = The maximum amount of fuel is being added to the calculations

2) I checked the AFM resistance to make sure that my AFM was not bad. I recently swapped to a K&N intake for legality(which i hate to do oiling) and wanted to make sure this didn't mess up the Karman vortex meter. The resistances checked out fine for the ambient temperature that day. I don't have the exact value handy, but it was right around ~1.2k ohms for a temperature of ~78 degrees. That appears in spec: http://cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=96

3) I checked the fuel pressure according to: http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=73
Bridged FP and B+ car off: Measured 40 psi (acceptable range: [33,40] PSI... OK)
Car at idle, terminals not bridged and vaccuum removed: Measured fluctuating between 38 and 40psi (acceptable range: [33,40] PSI... OK)
Car at idle, vaccuum port reconnected: Measuring 32->36 PSI (acceptable range: [23,30] PSI... NOT OK)
Held pressure after shutdown just fine.

4) The O2 sensor was replaced (no issue before replacement....)

My question: Does the high pressure during idle indicate that I should replace the FPR?

Are there any other tests you feel should be performed?

 

[jetjock]

1) Well, if you short Vf its voltage is gonna be near zero.

2) Resistance of the AFM air temp sensor doesn't really mean much. The KS signal is more important.

3) Something is screwy with FP at idle alright. What is vacuum at the FPR?

As for further tests (after you puzzle out the FP) redo Vf correctly and check for cross counting. You can do that by either looking at Ox directly or Vf when in diag mode.

 

[BigKO]

1) Well, if you short Vf its voltage is gonna be near zero.

2) Resistance of the AFM air temp sensor doesn't really mean much. The KS signal is more important.

3) Something is screwy with FP at idle alright. What is vacuum at the FPR?

As for further tests (after you puzzle out the FP) redo Vf correctly and check for cross counting. You can do that by either looking at Ox directly or Vf when in diag mode.

1)Well... excuse my terminology. I should have stated "checked/connected" the terminals E1 and Vf on the diagnostic block using my DMM. I did not actually short them to ground, but rather placed my DMM terminals on E1 and Vf respectively, measuring 0.033 volts. I think this is the correct way of checking the Vf signal?

2)Thanks for that advice. Is this something I should be checking? I don't really expect the AFM to be an issue...

3)I haven't measured the vacuum. What should I expect at this port/ the engine in general? I'll just fire up the ol' google and get to checking, but if you have it handy I'd appreciate it. Does the 18-20 in/Hg rule of thumb apply to the 7mgte as well?

 

[BigKO]

i just took a look at this thread: http://www.supramania.com/forums/sh...e.-18-AFR-s.../page4&highlight=vacuum+measure
Looking at posts 19(yours jetjock) and post 21 I should be checking E1 and Ox instead of Vf @ idle. and looking for the following readings:
0.00 MV is lean

450 MV would be Stoich

800 MV would be rich

I'll do this.... Can you give me a bit of background knowledge as to why I can't measure Vf @ idle? Is it due to open/closed loop mode?

 

[3p141592654]

This is a repost, but seems like it is needed here:

The Vf1 output has three different types of Vf output.
• O2 Sensor Feedback Mode
• Diagnostic Mode
• Learned Value Mode

1. Oxygen Sensor Feedback Mode.

* T1 and E1 Connected (In the diagnostic block.)
* Engine Running at 2500 rpm

Result of Ox sensor signal processing:
5v=Rich
or
0v=Lean or Open loop condition
_______________

2. Diagnostic Mode

*T and E1 connected
*Engine off

Results of Diagnosis:
5v=Normal, No trouble codes stored.
or
0v=TCCS Trouble code stored. View the 'Check Engine' Light, It will blink codes.

________________
3. Learned Value Mode

*T and E1 not connected
*Any operating conditions, RPM's, or speed.

The Vf line feeds five stepped voltage values of 0,1.25, 2.5, 3.75, 5.0 volts

Meaning: Result of Air-Fuel ratio voltage feedback

Learned Value: It is a fuel injection correction coefficient which tailors the standard fuel injection duration to minor differences between engines due to manufacturing tolerances, wear, and minor mixtures disturbances like small vacuum leaks.

Note:
• Discard Vf reading when engine is open loop It will be fixed on 0V (cold, WOT, etc.)

 

[jetjock]

Thank you Jon. That was indeed needed. To clarify a bit in order to output an emulated O2 signal on Vf the idle contact must open (IDL high). That would be the case @ 2500 rpm. IDL being low (contact closed) would result in mode 2. Put simply IDL status is what switches between the two modes, engine running or not.

 

[BigKO]

This is a repost, but seems like it is needed here:

The Vf1 output has three different types of Vf output.
• O2 Sensor Feedback Mode
• Diagnostic Mode
• Learned Value Mode

1. Oxygen Sensor Feedback Mode.

* T1 and E1 Connected (In the diagnostic block.)
* Engine Running at 2500 rpm

Result of Ox sensor signal processing:
5v=Rich
or
0v=Lean or Open loop condition
_______________

2. Diagnostic Mode

*T and E1 connected
*Engine off

Results of Diagnosis:
5v=Normal, No trouble codes stored.
or
0v=TCCS Trouble code stored. View the 'Check Engine' Light, It will blink codes.

________________
3. Learned Value Mode

*T and E1 not connected
*Any operating conditions, RPM's, or speed.

The Vf line feeds five stepped voltage values of 0,1.25, 2.5, 3.75, 5.0 volts

Meaning: Result of Air-Fuel ratio voltage feedback

Learned Value: It is a fuel injection correction coefficient which tailors the standard fuel injection duration to minor differences between engines due to manufacturing tolerances, wear, and minor mixtures disturbances like small vacuum leaks.

Note:
• Discard Vf reading when engine is open loop It will be fixed on 0V (cold, WOT, etc.)

Thank you for the wonderful resource, it directly addresses my questions.

Based on this new information, it appears that I was attempting(poorly) to check the learned value of Vf. Did I accomplish this by checking Vf, and E1 previously? how would I go about measuring Vf if I did not....

In addition to checking the vacuum at the FPR, I now plan to check the voltage in Mode 1 by having someone hold the motor at 2500RPM while I connect T and E1.

For mode 2, I expect the voltage to be 5V as I have no codes stored. I'll reaffirm this by checking the voltage anyway.

If there's anything I've missed, please let me know.

 

[3p141592654]

Just remember that in mode 3 0V can indicate an open loop condition due to an issue with fuel control. You need to verify O2 cross counting using either mode 1 or by directly measuring O2 sensor voltage.

 

[BigKO]

Just remember that in mode 3 0V can indicate an open loop condition due to an issue with fuel control. You need to verify O2 cross counting using either mode 1 or by directly measuring O2 sensor voltage.

"I now plan to check the voltage in Mode 1 by having someone hold the motor at 2500RPM while I connect T and E1. "

That's the plan. Thanks for the help. I've been out of town a lot for work lately, so it's slow going, but I'll post back as soon as I've done the test.