Help...Timing issue

[Ahsai]

This is getting more interesting. I found this odd though -> "But with the ignition still on I got NO voltage down the two heater wires from the car harness." You disconnected the O2 sensor when making measurements, right? One of the heater wires supplies +ve from the same circuit as the coils/injectors, etc when the other wire is the GROUND supplied by the DME. So one of the wires should have ~12v...Since your car starts so obviously the coils/injectors are getting power but yet the O2 heaters do not?

Also when you tested for voltage from the sensor, you used a very low V settting (e.g., DC 2V full scale), right? The voltage produced from an O2 sensor is small at < 1v.

[JFP in PA]

Latest update.

Cleaned MAF just in case.

Checked bank 1 and bank 2 pre cat. wires from the cars harness to O2 sensor connection. When I turn the ignition switch on (did not start motor) I get a full 0.50 V down the harnesses signal wire (from the car). But with the ignition still on I got NO voltage down the two heater wires from the car harness.

Next I pulled the O2 sensor off the car and put a ohm meter on the heater leads of the O2 sensor...I got continuity so I assume the heater element is good.

I then applied heat to the tip of the O2 sensor and hooked up my volt meter to tell if I could detect any voltage change in the sensor....I got NO voltage and no change.

I cleaned the throttle body before I reinstalled the motor.

I have NOT cleaned the idle stabilizer...that will be my next task after your suggestion...thanks for making it !

The 0.00v O2 sensor readings are constant @ -0.01 and 0.00

Thanks again for every ones help and keep the suggestions coming.

Your lack of voltage to the O2 sensor's has got to be the crux of the sensor problem; no sensor, good or bad, works without the correct voltage to it. It is sounding more like an electrical issue upstream from the sensors.

[Ahsai]

Agree with John.

[Reebuck1]

OK, more info:

I cleaned the MAF, throttle body and idle control valve (idle control valve was really dirty).

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.

Same proceedure Bank 1 o2 sensor connector (with the o2 sensor disconnected) I placed the volt meter (set at 12V) on the two heater leads (black-wire and red/white-wire) hoping to get 12 volts but I got no reading (0).

Am I right in assuming the Bank 1 signal circuit is good but the heater circuit is bad coming from the car to the connector??

I removed the Pre-cat. Bank 1 o2 sensor from the car and used my Ohm meter to verify the I had a good heater circuit on the o2 sensor. It appeared good!

The o2 sensor was covered with a heavy gray dust. I am guessing from running so rich.

I heated the tip of the o2 sensor with propane torch with my volt meter hooked to the sending circuit and got NO VOLTAGE even when the o2 sensor tip heated red ...no movement at all.

Where up stream should I now look? The cable runs into the back of the fire wall with no connections I can get at. Is there a connection under the back seat I can access?

Is there a reason the two pre cat. sensors would go at the same time?

Sorry to keep bugging you folks about this but it is driving me crazy. There has to be a simple correction. Thanks again !!

[Ahsai]

Ok, this is getting more interesting.

I assume you meant "0.5v" and not "0.05v" for the O2 signal. If that's true, you are correct that the problem (at least) is at the power supply to the heaters. All the wires you measured are the correct wires. Gray dust on sensor is normal.

1. Check fuse C2 (30A). The power flow is: 12v power->C2->injection/ignition relay ->line "b"->BS21/1->black wire of the O2 sensor heaters black (see the diagram below). In case you blew the fuse while you were measuring. The relay and the fuse are not shown.

2. Turn the key to the last position before cranking like you did when testing

3. Measure the red/white heater wire (connect the black meter probe to a ground point such as the rear lid latch) and you should see ~2v. This is the ground supplied by the DME but it's never 0.00v. If it is, you have a wire break between the heater and the DME.

4. Measure the black heater wire (connect the black meter probe to a ground point) and you should see ~12v. If not, the only connection point between it and the injection/ignition relay is the BS21/1 bridge point located at the rear relay behind the rear seats below the carpet. check the voltage there.

In position 6 here. Here I'm assuming your injection relay is good (position 2) since this relay also supplies power to the ignition coils and your car starts find. Depending on what you find, we may need to revisit the relay.

5. Repeat steps 2 to 4 for the postcat sensors (yes postcat) and you should get similar readings. That will help us diagnose it further.

6. Measure the resistance of the heaters. They should be ~10Ohm

Let me know what you find and good luck.

Edited March 28, 2014 by Ahsai

[Reebuck1]

_{Ahsai...Thanks you for the great info. Here is the results after following your direction:}

_{I did mean 0.5V...sorry I used to many 0s.}

_{Checked fuse C2...fuse was good}

_{On Bank 1}

_{Pre cat. Measured RD/WT heater wire to ground........ NO VOLTAGE 0.00v}

_{Pre Cat. Measured BK heater wire to ground.....Got 11.77v}

_{Post cat. Measured RD/BK heater wire to ground.......NO VOLTAGE 0.00}

_{Post cat. Measured BK heater wire to ground.....Got 11.77v}

_{I measured Bank 2 and got the same results}

_{Some further back ground. When I dropped the motor and trans (automatic) I failed to completely disconnect the wiring harness to the auto trans and pulled about 12" to 15" of wiring}

_{from the center tunnel before I noticed it. The wiring was all still tape wrapped and I saw no breaks outside the car so I assumed it was still good to go. Any chance that I popped lose some sort of O2 connecter under the back seat, if there is one there? Maybe that is were the trouble could be.}

_{Again thank you very much for your help !!!!}

[Ahsai]

Ok, looks like you get the 12v power to the heaters on all the 4 sensors but their grounds being at 0.00v are questionable.

Combined with your previous measrement that you also see 0.0v between the RD/WT and BK heater wires, I suspect the heater ground wires are FLOATING and disconnected from the DME.

Check this first: measure BK again to make sure you get ~12v on BK, then immediately measure between the RD/WT and BK again and see if you get ~12v. If not, the RD/WT wire is floaing.

There are no connectors in the back seat for the O2 sensors. Their ground wires connect directly to the DME. Refer to the diagram above, the precat heater ground wires of both sensors are joined at junction "31", which then connects directly to pin 30 of the DME (not shown in the diagram). Similarly the postcat heater ground wires are joined at junction "32", which connects directly to pin 1 of the DME.

The next steps will be more involved...Can you:

1) Disconnect the battery -ve terminal

2) Disconnect the DME from its socket

3) Check for continuity between pin 30 (RD/WT) of the DME socket and the RD/WT heater wire of the precat sensors?

4) Check for continuity between pin 1 (RD/BK) of the DME socket and the RD/BK heater wire of the postcat sensors?

DME 5.2.2 pinout info here.

Since you pulled on the wire harness, I guess it's possible some wires got disconnected at the DME socket end although hard to imagine since the wires are all taped in a bundle...

Good luck.

Edited March 28, 2014 by Ahsai

[Reebuck1]

Ahsai,

Double checked BK to ground and got 12v. Double checked RD/WT to ground..0v Checked RD/WT to BK with meter and got 0v.

When I disconnect the battery do I just disconnect the + terminal or should I do both + and - ?

The car is a Cab. C2 so..... I think the DME is on the right side once the top is up (remove cables and pull back window up) DME under the carpet. When I disconnect the plug from the DME I am hoping the plug pins will be marked so I can find pin #1 and pin #30. Does that sound correct?

Or are you talking about removing the two large connector plugs in the engine bay (one with blue paint spots and one with white paint spots) and check the pins at that point? I know

the pins on the large connectors are marked and I am guessing they come directly from the DME?

[Ahsai]

Ahsai,

Double checked BK to ground and got 12v. Double checked RD/WT to ground..0v Checked RD/WT to BK with meter and got 0v.

When I disconnect the battery do I just disconnect the + terminal or should I do both + and - ?

The car is a Cab. C2 so..... I think the DME is on the right side once the top is up (remove cables and pull back window up) DME under the carpet. When I disconnect the plug from the DME I am hoping the plug pins will be marked so I can find pin #1 and pin #30. Does that sound correct?

Or are you talking about removing the two large connector plugs in the engine bay (one with blue paint spots and one with white paint spots) and check the pins at that point? I know

the pins on the large connectors are marked and I am guessing they come directly from the DME?

That's good. Looks like we're zooming in for two floating ground wires (still hard to imagine how this happened but that's what the measurement told us for now).

Disconnect just the negative battery terminal is good enough.

The DME pinout info is here.

I think the DME location may be a bit diff on the cab. I'm not sure. Will update this if I have more info on it.

No, I'm not talking about the two round connectors. The O2 sensor wiring don't go through those round connectors at all since the sensors are on the cats and not on the engine itself like the cam sensors, coolant sensor, etc.

Edited March 28, 2014 by Ahsai

[Ahsai]

Ok, found it for you http://www.renntech.org/forums/topic/33878-dme-location-for-a-99-996-cabrio/?p=179604

[Reebuck1]

Looks like there are two silver boxes .....question is which is the DME?? Both have 88 pin connectors.

OK got it................ the was the box on right. A little slow but at least I'm steady.

Got continuity between pin 30 (RD/WT) at the DME plug and socket (RD/WT) heater wire of pre-Cat. sensor.

Got continuity between pin 1 (RD/WT) at the DME plug and socket (RD/BK) heater wire of the pre-Cat. sensor.

What now? Your thoughts?

[Ahsai]

Ok, I think the next step is to install two new precat sensors and see if that cures those O2 sensor codes. The 0v measurement between the heater wires may be fooling us as the ground is provided by a transistor in the DME and perhaps it won't supply ground when the sensors are not installed. On mine (DME 7), I got around 10v between the heater wires.

Now at least we know for sure the sensors got positive power to the heater and also signal from the DME. Also the wires are intact. Only DME and sensors are left and I would bet on bad sensors.

Edited March 29, 2014 by Ahsai

[Reebuck1]

Thanks so much Ahsai for all the help !!

I have two sensors on the way and expect to get them first part of next week. I'll let you know as soon as they are in.

Thanks again !!

[Ahsai]

You're welcome and do let us know.

Good job testing as much as you can and not just throw parts at it.

[Reebuck1]

Got o2 sensors yesterday and put them in the car.

Results were same as before............. bad idle (Low Speed) above 2000 RPM runs great.

Some stats:

ECTS ECTS Ignition timing TRA Bank1 TRA Bank2 FRA Bank1 FRA Bank2 O2 sensor V. O2 sensor V.

ahead of cat. 1 ahead of cat.2

0.98 0.98 0.37 0.37 0.37 0.98 0.98 0.00 0.00

I am lost.................not despairing yet but lost.

Can't believe the DME would be bad if it was working before I started all this.

Any thoughts

[Loren]

Please clear all fault codes - start the engine let it idle, drive it around the block - then re-read any fault codes (including pending codes) you have and report them here.

[Ahsai]

+1 on Loren's suggestion. With new precat O2 sensors, even if the heaters are not working, once the sensors are warmed up enough by the exhaust gas, their voltage should start to swing between 0.2 to 0.8 approx once per second at idle. The heaters are just there to warm up the sensors faster and get the car to optimal a/f ratio faster.

[JFP in PA]

My thought process keeps taking me back to this being a wiring problem ahead of the sensor rather than the sensors themselves. Below is the Porsche diagnostics process for both P0130 and 0150 (it is from the Boxster OBD II manual, but should be exactly the same on this car). If the problems persist, I suggest starting over from the beginning as we are obviously missing something:

[Ahsai]

My thought process keeps taking me back to this being a wiring problem ahead of the sensor rather than the sensors themselves. Below is the Porsche diagnostics process for both P0130 and 0150 (it is from the Boxster OBD II manual, but should be exactly the same on this car). If the problems persist, I suggest starting over from the beginning as we are obviously missing something:

What's puzzling is he performed all the tests under "Check Oxygen sensor" and varified that ~0.5v between pins 3 and 4 on ALL 4 O2 sensors so the DME signal is getting to the sensors. However, I agree that 0.0v reading from Durametric also means signaling wire shorted to ground since the DME outputs 0.45v on that signal wire (pin 18, 19) with respect to the ground pin 46. Basically inconsistent measuements that cannot be reconciled.

Perhaps he has an intermittent problem where the fault comes and goes at different times when measurements were taken.

[Reebuck1]

Ok folks finally able to get back to car.

Followed Loren instructions

Received following Fault Codes:

P1319....Misfire emission-relevant

P1313....Cylinder 1 misfire emissions-relevant

P1314....Cylinder 2 misfire emissions-relevant

P1315....Cylinder 3 misfire emissions-relevant

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

P1531....Camshaft adjustment bank 1

Also saw the following Alarm 132 fault codes:

49....K lead not present 1 occurance counter

23....W lead not present 8 occurance counter

42...Wrong key or wrong transponder pill not present 15 occurance counter

I am also providing all the read outs from my "Engine Module ME5.2.2 at idle after my around block run:

RPM 720

Load Signal 1.30

Air mass 14.25 to 16.25 jumping

Speed 0

Voltage 13.45

IATS 69.8

ECTS 72.8

Throttle plate angle 0

Ignition timing 3.8 to 9.8 jumping

Spec. air mass 16 to 17

Spec. air adaptation -3

Ambient pressure 760

Injection time 3.9 to 4.0

Exhaust temp. after cat. Converter 52C

Oil temperature 72.8C

Engine compartment temp. 54.8C

Oxygen sensing cylinder 1-3 1.25

Oxygen sensing cylinder 4-6 1.25

Ranger 2 Cylinder 1-3 (FRA) 0.98

Ranger 2 Cylinder 4-6 (FRA2) 0.98

Ranger 2 Cylinder 1-3 (TRA) 0.37

Ranger 2 Cylinder 4-6 (TRA2) 0.37

O2 sensor voltage ahead of cat. conv. 0.00

O2 sensor voltage ahead of cat. c. bank 2 0.00

Camshaft position 1 deviation -2.0

Camshaft position 2 deviation (USA model only) 3.0

HO2S heat. Res. Ahead of cat. conv. 3.1

Rough-running threshold 8.5

Rough running 0 to 4.0 most of the time 0 to 2.8

Segment A 1

Segment B 1

Leam. progress sens. Wheel adapt. 0.0007

I hope this gives you more info to work with. Any other suggestions please let me know. Sure appreciate every ones help!!!!!!

[Ahsai]

Are you sure the MAF connection was tight after you cleaned it? The MAF code is new. As John pointed out before, your engine is running lean at idle, TRAs are at the rich limit. Have you checked for air leak after the MAF?

Although the O2 codes seem to be gone, the precast O2 still read 0.00v. What are the readings of the postcat sensors?

Can you tell us what else was done on the engine other than IMSB? E.g., did you take off the intake runnings? AOS? Basically candidates for air leak. Are plugs and coils in good shape? Did the engine have any symptoms before IMSB?

[Reebuck1]

Last question first.

I removed the Bank 2 intake so I could get the rear (back) bolt out on the air conditioner. Did not touch the Bank two coils or plugs. On the Bank 1 side... I removed the coils for

cylinders #4 and #5 and removed plugs to check condition while I was testing Bank 1 solenoid . Motor ran fine before I changed the IMSB. Should I remove and re-clean?

I will recheck MAF and re-clean this afternoon. At idle I was under the impression that the MAF does not come into play?

I am going to recheck voltage on pre-cat O2 sensors this afternoon and will get the Post cat. voltage at the same time. I'll send you those results later tonight.

NOW.....when I start the car cold it starts well but then still wants to die. If I keep RPMs above 3000 it will run steady. When I let off gas slowly at around 2200-2500 RPM

it will lose RPM very quickly even though I have stopped letting off gas. If I push down only slightly on the gas peddle RPMs sharply come up very quickly (not a steady increase).

I tried spraying carb cleaner around suspect areas looking for possible air leaks with no noticeable idle change. The motor still sounds to me like it is missing.

I also suspect air leaks but can not get to every possible location.

[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.

[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. However, Durametric keep reporting 0.00v precat reading on both banks. What gives? 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.