Help...Timing issue

[Ahsai]

Guys, not to sound pedantic, or like a broken record, but as long as there is no voltage to the two O2 sensor, fussing with other items is not going to get the car running any better. The O2 sensors have to get power and be functional for the car to have any chance of running correctly; their operation is critical to controlling the fuel trims.

John, the OP did confirm there's voltage (0.5v) to the precat sensors (harness side) multiple times hence the challenge.

I understand that, but as the Durametric system is looking at them from the DME's perspective there still is no voltage being read, so they are effectively dead to the DME. Without the reference signal differential between the pre and post cat sensors, the system literally does not know what to do next. I would start tracing the harness from the sensors towards the DME, looking for damage, pinched wires, etc. The DME has to see voltage at both sensors to control the mixture. I'd also like to see the Durametric reproduce the pre and post cat voltage curves:

If the system is not generating the two different voltage curves, the fuel mixture is basically out of the DME's control.

Hi John, I also understand and agree with your reasoning. However, the 0.5v the OP measured at the sensor connector (harness side with sensor disconnected) has to come from the DME directly so that also implies the signal wire is intact all the way back the the DME. If that wire was shorted to ground, the OP should have seen 0v at the sensor harness.

One sure way to confirm is to back probe the signal wire of the precat sensors directly when the engine is running and all sensors connected like normal.

Edited April 6, 2014 by Ahsai

[JFP in PA]

Guys, not to sound pedantic, or like a broken record, but as long as there is no voltage to the two O2 sensor, fussing with other items is not going to get the car running any better. The O2 sensors have to get power and be functional for the car to have any chance of running correctly; their operation is critical to controlling the fuel trims.

John, the OP did confirm there's voltage (0.5v) to the precat sensors (harness side) multiple times hence the challenge.

I understand that, but as the Durametric system is looking at them from the DME's perspective there still is no voltage being read, so they are effectively dead to the DME. Without the reference signal differential between the pre and post cat sensors, the system literally does not know what to do next. I would start tracing the harness from the sensors towards the DME, looking for damage, pinched wires, etc. The DME has to see voltage at both sensors to control the mixture. I'd also like to see the Durametric reproduce the pre and post cat voltage curves:

If the system is not generating the two different voltage curves, the fuel mixture is basically out of the DME's control.

Hi John, I also understand and agree with your reasoning. However, the 0.5v the OP measured at the sensor connector (harness side with sensor disconnected) has to come from the DME directly so that also implies the signal wire is intact all the way back the the DME. If that wire was shorted to ground, the OP should have seen 0v at the sensor harness.

One sure way to confirm is to back probe the signal wire of the precat sensors directly when the engine is running and all sensors connected like normal.

What also intrigue's me is the cam position sensor code (P1531) and misfires are all on one bank, often a indication of a wiring or harness connector issue in a DIY mechanical. And if he uses the Durametric to read the before and after sensor curves, especially on Bank 1, we would see if the DME actually is seeing the sensors working in real time. If the senor is a "flat line", the DME is blind to it and the zero voltage readings are real.

[Ahsai]

^Agree

[JFP in PA]

^Agree

An additional thought I had, and the OP may have already checked this so tell me to go sit down if he already has, is to disconnect the battery, unplug the problematic sensor on bank 1 & 2, unplug the harness from the DME, and check for continuity between sensor #2 harness pin #3 and DME harness pin #46; then sensor #1 harness pin#3 to DME harness pin #46 (these should be the sensor grounds). I would likewise test sensor harness pin #4 on bank 1 to DME harness pin #19, and harness pin #4 on bank 2 to DME harness pin 18. If all those circuits are electrically continuous, we may have a bad DME, but if any are not continuous, a harness issue.

[Reebuck1]

Re-did voltage checks on Bank 1 results below: (ground used was rear deck lid latch)

RD/WT...... heater wire to.... ground.......12 volts

BK.............heater wire to ground...........12 volts

Pre. Cat. Bank 1

BL/RD..........................to ground.........0.6 volts

YW/WT........................to ground.........0 volts

BL/RD....................to YW/WT.............0 volts *****

Post Cat. Bank1

BL/RD.........................to ground.......0.7 volts

BK/WT .......................to ground........0 volts

BL/RD.........................to BK/WT.......0 volts *****

Car now has two new pre cat. sensors but acts the same.

I checked sensor wires back to DME and got continuity on the pin wires you asked me to check.

Cleared all fault codes and ran motor at different speeds for 15-20 minutes and ran "short test" but got NO FAULT CODES. Car still has idle problem.

One thing I had not looked at before is the G 40 Tiptronic file and found one fault code listed.......22 P1770 Load signal

I pulled the following "Actual Values" while the motor was running and only list those that changed from yesterday.

today yesterday

Hot film MAF 1.26 1.28

IATS 68.3 69.8

ECTS 86.3 72.8

Spec. air mass 15 17

Exhaust temp after cat. conv. 212 c 58c

Oil Temp. 85.5c 72.8

Rough-running threshold 11.3 8.5

Rough running 4.0 0

FYI.....................thanks, Bob

[Ahsai]

^Agree

An additional thought I had, and the OP may have already checked this so tell me to go sit down if he already has, is to disconnect the battery, unplug the problematic sensor on bank 1 & 2, unplug the harness from the DME, and check for continuity between sensor #2 harness pin #3 and DME harness pin #46; then sensor #1 harness pin#3 to DME harness pin #46 (these should be the sensor grounds). I would likewise test sensor harness pin #4 on bank 1 to DME harness pin #19, and harness pin #4 on bank 2 to DME harness pin 18. If all those circuits are electrically continuous, we may have a bad DME, but if any are not continuous, a harness issue.

Hi John, those tests have not been requested yet and I agree those are good tests.

So far, the continuity between the DME and precat sensor are only confirmed for the heater circuits to the precat sensors. Regarding sensor signal pin #4 and ground pin #3, Bob measured between pin #3 and pin #4 and got 0.5v on both precat sensors hence it was assumed that the DME's signal reaches the sensor connectors. I agree though it would be good to also perform the tests you proposed to positively confirm it.

[Reebuck1]

JFP, Just saw your note and I will re-check the pin continuity in the morning. Thanks for the suggestion !!

[Ahsai]

Re-did voltage checks on Bank 1 results below: (ground used was rear deck lid latch)

RD/WT...... heater wire to.... ground.......12 volts

BK.............heater wire to ground...........12 volts

Pre. Cat. Bank 1

BL/RD..........................to ground.........0.6 volts

YW/WT........................to ground.........0 volts

BL/RD....................to YW/WT.............0 volts *****

Post Cat. Bank1

BL/RD.........................to ground.......0.7 volts

BK/WT .......................to ground........0 volts

BL/RD.........................to BK/WT.......0 volts *****

Car now has two new pre cat. sensors but acts the same.

I checked sensor wires back to DME and got continuity on the pin wires you asked me to check.

Cleared all fault codes and ran motor at different speeds for 15-20 minutes and ran "short test" but got NO FAULT CODES. Car still has idle problem.

One thing I had not looked at before is the G 40 Tiptronic file and found one fault code listed.......22 P1770 Load signal

I pulled the following "Actual Values" while the motor was running and only list those that changed from yesterday.

today yesterday

Hot film MAF 1.26 1.28

IATS 68.3 69.8

ECTS 86.3 72.8

Spec. air mass 15 17

Exhaust temp after cat. conv. 212 c 58c

Oil Temp. 85.5c 72.8

Rough-running threshold 11.3 8.5

Rough running 4.0 0

FYI.....................thanks, Bob

Bob, please look at John's suggested tests carefully. They are testing the signal and signal ground wires (pin #3 and pin #4 on the precat sensors) continuity between the sensor harness connector and the DME. The continuity tests you posted before were the HEATER circuits between the sensor connectors and the DME, which were intact.

What about the Durametric reading of the postcat sensors? Do they read 0.00v as well?

I did a test for you since my car is waiting for some new cats, I have all my O2 sensors unplugged. I turned the key to the last position before cranking (key ON engine OFF) and used Durametric to read the O2 voltage. Durematric reported 0.46v on all 4 O2 sensors (sensors are not present at all), which is the bias voltage supplied by the DME. Perhaps you can unplug all your sensors and repeat this test to see what Durametric reports? Will give us one more data point.

Edited April 7, 2014 by Ahsai

[Reebuck1]

Ahsai, Thanks, Absolutely will happy to do it....... I'll try anything short of suicide to get this solved. First thing in morning I will take care of it.

I guess I bring my Durametric up just as if the care were running and go to "Actual Values" tab and look at the O2 voltage to get the information

you need??

Again thank you for all the help !! Bob

[Ahsai]

Ahsai, Thanks, Absolutely will happy to do it....... I'll try anything short of suicide to get this solved. First thing in morning I will take care of it.

I guess I bring my Durametric up just as if the care were running and go to "Actual Values" tab and look at the O2 voltage to get the information

you need??

Again thank you for all the help !! Bob

Bob, yes that's all you need to do. Durametric connects, runs and retrieve sensor values when key is in the last position before cranking even when engine is not running. It will give you the correct readings of air temp sensor, coolant sensor, etc. It should also report the ~0.45v bias signal the DME sends out to all four o2 sensors as the actual values of voltage of precat and postcat sensors REGARDLESS if the sensors are connected or not. You can repeat the measurements with all 4 sensors disconnected.

If Durametric still reads 0.00v with sensors disconnected, you can use your voltmeter to check the actual voltage of the O2 sensor harness signal pin.

[Reebuck1]

Here are the results of my continuity tests:

I unplug the problematic sensor on bank 1 & 2, unplug the harness from the DME, and check for continuity between sensor #2 harness pin #3 (BK/RD)and DME harness pin #46;

NO continuity

I took the DME plug case off so I could see the wires underneath but I have yet to find the BK/RD wire to DME pin 46....still looking!

If I plugged one of the sensors back into the harness I then have continuity between DME pins 3,4,5,22,23,24,30,31,32,33,34,49,50 and 51 ....BUT NOT DME pin 46

I then tested sensor harness pin #4 on bank 1 (BK/WT) to DME harness pin #19, and harness pin #4 on bank 2 (WT/BK) to DME harness pin 18.

I am going to now see if I can get the Durametric data requested....Be back in a while.

[Reebuck1]

Here is the data from the Durameteric .44 volts with sensors plugged in AND with sensors unplugged.

O2 sensor voltage ahead of cat. conv..........................0.44 V

O2 sensor voltage ahead of cat. c. bank2...................0.44 V

SAME READING BOTH WAYS !

Did you receive my info from tracing all the wires ?? If not I'll resend it. Thanks again, Bob

O2 sensor voltage ahead of cat. conv O2 sensor voltage ahead of cat. c.

10:58:59.7661528 0.44 0.44 10:59:00.6459317 0.44 0.44 10:59:01.5162280 0.44 0.44 10:59:02.3864437 0.44 0.44 10:59:03.2564061 0.44 0.44 10:59:04.1569588 0.44 0.44 10:59:05.0564867 0.44 0.44 10:59:05.9668498 0.44 0.44 10:59:06.8362710 0.44 0.44 10:59:07.7163602 0.44 0.44 10:59:08.6164072 0.44 0.44 10:59:09.5370516 0.44 0.44 10:59:10.4371053 0.44 0.44 10:59:11.3267299 0.44 0.44 10:59:12.2067827 0.44 0.44 10:59:13.0860933 0.44 0.44 10:59:13.9855119 0.44 0.44 10:59:14.9255642 0.44 0.44

[Reebuck1]

I did not state that I DID get continuity when checking DME pin #18 and #19 when I followed your instructions.....BUT NOT pin #46

[Ahsai]

Well, pin #46 (blue/red) is the sensor ground to all 4 sensors proided by the DME so if it's missing, got to be the smoking gun!

I can hear John laughing :)

Where did it go though?

The Durametric readings seem to make sense also.

I still have problems recociliing this latest discovery with the measurement you took in your post #29 where you said you got 0.05v for which I asked you if it was 0.5v and you said yes.

"Looking only at Bank 1....I turned on the car ignition (did not engage the starter) and with my volt meter (set at 2.5V) attached to the car side of the connector ( black/white-wire and blue/red) to the O2 sensor cable running from the car...I got 0.05 volt steady. I turned the key off and the voltage disappeared."

Anyway, you gotta find that #46 ble/red wire first :)

[JFP in PA]

I did not state that I DID get continuity when checking DME pin #18 and #19 when I followed your instructions.....BUT NOT pin #46

If your continuity checks did not get continuity between sensor #2 harness pin #3 and DME harness pin #46; then sensor #1 harness pin#3 to DME harness pin #46 (these should be the sensor grounds), your O2 sensors have no ground circuit going back to the DME, which is why the DME is having problems seeing them.

[JFP in PA]

Well, pin #46 (blue/red) is the sensor ground to all 4 sensors proided by the DME so if it's missing, got to be the smoking gun!

I can hear John laughing :)

Not really, just quietly smiling when progress is finally made....... :thumbup:

[Ahsai]

Well, pin #46 (blue/red) is the sensor ground to all 4 sensors proided by the DME so if it's missing, got to be the smoking gun!

I can hear John laughing :)

Not really, just quietly smiling when progress is finally made....... :thumbup:

Thanks for your clear mind :notworthy: bringing us back on the right track. That's why you're a pro and we're not.

Edited April 7, 2014 by Ahsai

[Ahsai]

Thinking more about it, there's one way that can make all the measurements consistent...your blue/red wire is disconnected from the DME harness side (hence you can't find it there) AND it's shorted to ground somewhere so you got 0.5v signal measured before between pins #3 and #4 on the harness side.

[Reebuck1]

Don't smile yet guys!!! I was using the wrong wire (BK/RD) when checking continuity to DME pin# 46. It should have been the BL/RD wire. So using John instructions

and the correct BL/RD wire at sensor pin #3 I DID GET continuity back to DME pin# 46.

My Durametric does not show after cat. voltage so I measured the after cat. signal wires YE/WT and BK/WT to ground and got a 0.4 volts. So I believe I am getting this .4 volt signal on pre and post cat. wires??

I looked really hard for a small BK/RD wire under the DME pin # 46. It was not there. That is when I realized I was chasing the wrong wire.

I am sure DME pin# 46 has a BL/RD wire going to it and that is what I saw at the harness connection. I believe my DME pin# 46 continuity check should have been with

sensor harness pin #3 ??

John comment " If your continuity checks did not get continuity between sensor #2 harness pin #3 and DME harness pin #46; then sensor #1 harness pin#3 to DME harness pin #46 (these should be the sensor grounds), your O2 sensors have no ground circuit going back to the DME, which is why the DME is having problems seeing them." If John's "sensor #1" is the pre cat. sensor and "sensor #2" is the post cat. sensor...THEN I GOT GOOD CONTINUITY on those lines (BL/RD) back to DME pin # 46.

This means I have continuity to DME pin #46 after running John test with the correct BL/RD wire. I also have continuity per instruction with DME pin # 18, #19.

Ahsia, I see your question in post # 64. I also do not understand it.

Went back to car and working with Bank1 only I disconnected pre and post cat. sensor from their harnesses. Put volt meter on wires running to DME and got the following:

pre cat. bank1 pin #3 (RD/BL) TO pin #4(YE/WT)........................... 0.2 volts

pin #3 (RD/BL) TO Ground..................................... 0.7 volts

pin #4 (YE/WT) TO Ground..................................... 0.4 volts

post cat. bank 1 pin #3 (RD/BL) TO pin #4(BK/WT).......................... 0.2 volts

pin #3 (RD/BL) TO Ground...................................... 0.7 volts

pin #4 (BK/WT) TO Ground...................................... 0.4 volts

I am guessing I would get same results on Bank 2 side.

Thanks, Bob

[Ahsai]

A few points:

1) So to summarize you get continuity between the DME and the sensor harness side for both sensor signal (pin #18, 19) and sensor ground (pin #46).

2) Durametric should also show postcast voltage as well...have you looked lower down the list in actual values?

3) From my wiring diagram, I got the following colors. Your last set of results seem to be from bank2 and not bank1? (although it may not matter which bank). Not sure why you got 0.2v between pin#3 and pin#4 now when you got 0.5v before...

pin4 for precat bank1 is black/white

pin4 for postcat bank1 is black/yellow

pin4 for precat bank2 is black/white

pin 4 for postcat bank2 is white/yellow

4) Can you select only the 4 precat and postcat voltages in Durametric (and not any other acutal values) and plot them during engine warm up? We may see the precat sensor reading turn from 0.45v initially then to 0.00v later. If that's the case, give the gas a few revs and see if the sensors will report something non-zero. I start to think the 0.00v reading of the O2 sensors are real due to a massive air leak.

[Reebuck1]

Sorry, I was under the impression Bank 1 was the driver side of the car and Bank 2 the passenger side of the car. If I am incorrect that is why my reference to Bank 1 was incorrect.

The 0.2v was not steady and only for split seconds.....could be my meter.

I only have pre. cat. voltages available on my version of Durametric (6.3.2.5) for my DME 5.2.2. I can only give you the pre cat. numbers. I sent Durametric a request for a program on the post cat. data.

I am in agreement on your wire colors the bank issue I mentioned above.

You were correct on the voltage values. Turned key on but not started car....got 0.44 volts . Start car volts stay at 0.4 volt for a short period then drop off quickly to 0.0 volts. Rev the gas up

and the voltage picks back up then drops off again. When you rev gas both banks changed but not together or equally. On high revs ups I could get up to 0.71 volts for short periods but most often below 0.20 volts.

[Reebuck1]

Just pulled up my error code log on our last run and get the two codes:

P1602....Supply voltage open circuit.

P0102....Mass air flow sensor short circuit/ open circuit

Thought you like to know

Thanks, Bob

[Ahsai]

Excellent! Back to some sanity finally. When you rev the engine, it makes the mixture go RICH instantaneously hence O2 sensor reading spike up temporarily only to be overcome by the abundent O2 in the exhaust stream (to much O2->0.00v reading). The fact that you can get 0.7v also means the sensors have good range.

So.....is it possible that you have reversed the bank1 and bank2 sensors?? i.e., bank1 sensor plugged into bank2 and vice versa. Indeed, bank1 is on the left and bank2 is on the right. I really hope it's that simple.

Now your MAF sensor, are you sure the connector is fully seated? Also, you used MAF sensor specific spray when you cleaned it, right?

Both P1602 and 0102 point to MAF shorted or disconnected.

[Ahsai]

A few more ideas. I still suspect air leak after the MAF:

- After you drive around the block, what are your FRA and TRA values now?

- Disconnect your MAF completely and see if that helps idling

- Check oil filler tube for leak (oil cap should have some slight vacuum)

- Reconnect MAF and pinch this AOS hose circled in green (be careful not to damage it though) and see if idling improves. You can even monitor the misfire counts in Duametric acutal values in real time.

[Reebuck1]

Ahsai, Thanks, I'll get to what you suggest tonight.

I think that the cause for the two error codes in post 72 above came from when you asked me to get the pre cat. Duramtric voltage without starting the car.

I had the air cleaner and MAF out of the car so I could take the manual voltage readings. Otherwise I don't think we would have seen any code.

I replaced everything before getting the last voltage readings you requested.

I'll clear everything before I try your above suggestions and see if we get any more error codes.

Thanks, Bob