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Old 09-08-2020, 04:47 PM   #21
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Actually I believe I was wrong about the post cat O2 sensor voltage that I posted previously.

If the cat is working properly then it is using up all the oxygen in the catalytic process.
Therefore the post O2sensor should show a relatively flat high voltage reading.
This is fully warmed up and RPM held steady around 2000 RPM.

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Old 09-12-2020, 05:45 PM   #22
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Started the O2 sensor swap.

They are seized in there pretty good. I'm soaking them in PB Blaster overnight. I will tackle again tomorrow.

Relatively easy so far though. All 4 connections are easy enough to reach and the red "plunger" on the connections came loose with a small screw driver a little leverage.
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Old 09-12-2020, 05:53 PM   #23
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Started the O2 sensor swap.

They are seized in there pretty good. I'm soaking them in PB Blaster overnight. I will tackle again tomorrow.

Relatively easy so far though. All 4 connections are easy enough to reach and the red "plunger" came loose with a small screw driver a little leverage.
I always use a 50-50 mix of Acetone and transmission fluid.
Shake the hell out of it, apply several times over 24 hours.
Has always worked better then anything purchased off the shelf.
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Old 09-12-2020, 08:19 PM   #24
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I always use a 50-50 mix of Acetone and transmission fluid.
Shake the hell out of it, apply several times over 24 hours.
Has always worked better then anything purchased off the shelf.
Are you talking about automatic transmission fluid?
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Old 09-13-2020, 06:48 AM   #25
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Are you talking about automatic transmission fluid?
Yes automatic transmission fluid.

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Old 09-13-2020, 04:08 PM   #26
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3 of 4 removed. Some good removal tips. I needed to cut the wires because the slotted socket was def going to round out the O2 sensor. Box end wrench, a little heat and a few whacks and 3 of them came loose. The other one is being an *-hole.



I'll try again on the last one tomorrow.
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Old 09-14-2020, 10:32 AM   #27
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Slow and steady you'll get it.
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Old 09-14-2020, 04:19 PM   #28
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I got it.



Now to install the new sensors. I opted to buy Bosch 15738 units. These are the OEM sensors with a DIY connection to use the original connectors. The Bosch connection system is pretty slick so I think it will work.



So main question: does it matter how long the wire leads are? The existing O2 sensor leads are about 6" long. Seems to me that a little extra wire wouldn't do any real harm right? Can just coil up the extra?
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Old 09-14-2020, 04:46 PM   #29
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I got it.



Now to install the new sensors. I opted to buy Bosch 15738 units. These are the OEM sensors with a DIY connection to use the original connectors. The Bosch connection system is pretty slick so I think it will work.



So main question: does it matter how long the wire leads are? The existing O2 sensor leads are about 6" long. Seems to me that a little extra wire wouldn't do any real harm right? Can just coil up the extra?
I don't see what it could hurt as long as you don't kink it.
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Old 09-14-2020, 09:29 PM   #30
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All sensors swapped. Plugged in the durametric and ran car for 5 mins to confirm they were all sending signals. They were. Then shut down for the night. Will run thru paces tomorrow and post up results.

Wondering if there is a run-in period for O2 sensors. Assume I got to get them good and hot etc. Read someone say that it take some time for the ECU to adjust the fuel mapping etc for new sensors. One post talked about disconnecting and reconnecting the battery or something. Didnt sound right to me.

Anyways. Thanks all for the advice and Blue62 for guidance. Look forward to posting up results.
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Old 09-15-2020, 06:31 AM   #31
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All sensors swapped. Plugged in the durametric and ran car for 5 mins to confirm they were all sending signals. They were. Then shut down for the night. Will run thru paces tomorrow and post up results.

Wondering if there is a run-in period for O2 sensors. Assume I got to get them good and hot etc. Read someone say that it take some time for the ECU to adjust the fuel mapping etc for new sensors. One post talked about disconnecting and reconnecting the battery or something. Didnt sound right to me.

Anyways. Thanks all for the advice and Blue62 for guidance. Look forward to posting up results.
There is no run in period needed for the O2sensors
I would take it for a good cruise, 20-30 minutes should be enough time for the DME/ECU to readjust fueling to the new sensors. No need to disconnect and reconnect the battery.
Make sure you clear all your codes first.
Looking forward to your follow up post. Expecting good results
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Old 09-15-2020, 08:14 PM   #32
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Success I think. Ran it for 40 mins in town this evening with durametric plugged in to monitor. No CEL or codes. Seems like the O2 sensors are doing their thing.

The car feels different somehow. The noticeable feeling of increased power at 3500 rpm onwards has smoothed out. So I think that means that I should have a bit more at the lower end? Anyways. Need to drive it a bit more to see what else is different. I think it's going to take a while to get the ECU to figure itself out as well, so more fun KMs ahead!

Here is a snapshot of the graph after the drive (warm engine) at idle.

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Old 09-16-2020, 05:37 AM   #33
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Good to hear things are working out.
I would be interested to know if things stay good a few hundred miles on.

Most codes if they are not harmful to the cats take two back to back drive cycles to set the CEL.
But codes can be stored in the pending code area of memory on just one instance.
So I would keep an eye on the pending codes as well.

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Old 09-18-2020, 06:51 AM   #34
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Got another 100kms from driving yesterday. 50 kms to work and back. On the way back home I didn't get a CEL but I did get a recurrence of an issue if have been trying to chase down.

The car will "stumble" or loose all power at higher revs. It will just bog right down under load. It feels like it's not getting fuel, but when I take my foot off the gas it returns to idle just fine and does not stall.

To remedy this, I shut off the car and restart it. After the restart it works fine again like nothin happened. During previous occurrences it would sort of stumble along for a min and then return to normal, be like nothing happened. But I just restart now. This happens very infrequently. Maybe once every 800kms to 1000kms? Sometimes I get a CEL and sometimes I don't.

To address this issue specifically I have replaced the fuel pump. Then I did the coils and plugs and all O2 sensors. Plus earlier I replaced MAF. Apart from the fuel pump, the latter items are all related to clearing codes and needed to be done anyways. (So I'm not throwing parts at the car for this issue specifically). But thought that getting some of these parts would take care of this issue.

Anyways, because the issue is so intermittent, I'm asking if checking fuel pressure or injectors will even help? Could this be something to do with the ECU itself maybe?
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Old 09-18-2020, 07:25 AM   #35
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Got another 100kms from driving yesterday. 50 kms to work and back. On the way back home I didn't get a CEL but I did get a recurrence of an issue if have been trying to chase down.

The car will "stumble" or loose all power at higher revs. It will just bog right down under load. It feels like it's not getting fuel, but when I take my foot off the gas it returns to idle just fine and does not stall.

To remedy this, I shut off the car and restart it. After the restart it works fine again like nothin happened. During previous occurrences it would sort of stumble along for a min and then return to normal, be like nothing happened. But I just restart now. This happens very infrequently. Maybe once every 800kms to 1000kms? Sometimes I get a CEL and sometimes I don't.

To address this issue specifically I have replaced the fuel pump. Then I did the coils and plugs and all O2 sensors. Plus earlier I replaced MAF. Apart from the fuel pump, the latter items are all related to clearing codes and needed to be done anyways. (So I'm not throwing parts at the car for this issue specifically). But thought that getting some of these parts would take care of this issue.

Anyways, because the issue is so intermittent, I'm asking if checking fuel pressure or injectors will even help? Could this be something to do with the ECU itself maybe?
Difficult issue to diagnose remotely but your sense that it may not be getting enough fuel may be a starting point.

Good diagnostic procedure says start with the simplest things first so:

With the age and mileage on your car when was the last time your fuel filter was changed?

I am going to assume your air filter is clean

I would do a fuel pressure test just so it is not an unknown. Not difficult to do.

How is your throttle set up?
Is it mechanical? Or throttle by wire like my 2000S?
I ask because I am wondering about possible throttle position sensor signal issues.

Does the issue happen at the same RPM range every time?

The fact that you can shut it down - restart it and everything is fine sounds like an electrical gremlin.
Which would make one think ECU issues, but if it is an electrical issue it could be in any number of places.

If you know how to data log with the Durametric ( I have never tried it) and you can force the issue to occur.
You may be able to spot something in the data log that could give you some clues as to what's going on when it looses power.

Last edited by blue62; 09-18-2020 at 07:35 AM.
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Old 09-18-2020, 08:06 AM   #36
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Thanks Blue62 for the feedback and willingness to help out. To answer your questions:
1: fuel filter was changed with the fuel pump (approx 2000 kms ago) Sorry, forgot to mention

2: the air filter is a k&n unit that came with the car. I cleaned it and made sure it's not over-oiled. I suspect the PO over-oiled it, which may be why the MAF went bad. Anyways, I plan on swapping that out for an OEM paper filter one of these days

3: 10-4 on fuel pressure test. Have looked up the procedure and will get to it eventually.

4: it's throttle by wire. Mine is a 98. There is a sensor for throttle angle. I should note that when I did the MAF I took the air intake piping apart and cleaned it all based on advice found here. There was def some oil build-up in and around the throttle body. AOS and maybe air filter over-oiled etc. Anyways. That got cleaned up.

5: yes, around the same RPM range is when is starts bogging. Above 3000 I would guess. Car revs up great, then on the way up starts stumbling and sputtering and complete loss of power. I pass the gas and it just bogs down and feels like it's gonna stall, but doesn't. Maybe it's ignition related? Or fuel supply problem.

6: I'll have to look up durametric logging. I know it's on there and easy enough to figure out. The issue for me is logging while the issue occurs. It happens so infrequently that it's always a surprise :-).

Speaking of electrical gremlins: my CLU is messed up. I got all kinds of them (windows don't roll down, but do the drop, FOB and alarm don't work etc.). I will get to fixing it eventually. But the car has always started and run etc. Considering the frequency of occurrence maybe the engine and CLU do a self diagnosis every so many KMs and because the cLU is messed up it forces the car to stop providing fuel or something (thinking the car is stolen?). Sounds far fetched to me, but maybe?
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Old 09-19-2020, 02:42 AM   #37
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Thanks Blue62 for the feedback and willingness to help out. To answer your questions:
1: fuel filter was changed with the fuel pump (approx 2000 kms ago) Sorry, forgot to mention

2: the air filter is a k&n unit that came with the car. I cleaned it and made sure it's not over-oiled. I suspect the PO over-oiled it, which may be why the MAF went bad. Anyways, I plan on swapping that out for an OEM paper filter one of these days

3: 10-4 on fuel pressure test. Have looked up the procedure and will get to it eventually.

4: it's throttle by wire. Mine is a 98. There is a sensor for throttle angle. I should note that when I did the MAF I took the air intake piping apart and cleaned it all based on advice found here. There was def some oil build-up in and around the throttle body. AOS and maybe air filter over-oiled etc. Anyways. That got cleaned

5: yes, around the same RPM range is when is starts bogging. Above 3000 I would guess. Car revs up great, then on the way up starts stumbling and sputtering and complete loss of power. I pass the gas and it just bogs down and feels like it's gonna stall, but doesn't. Maybe it's ignition related? Or fuel supply problem.

6: I'll have to look up durametric logging. I know it's on there and easy enough to figure out. The issue for me is logging while the issue occurs. It happens so infrequently that it's always a surprise :-).

Speaking of electrical gremlins: my CLU is messed up. I got all kinds of them (windows don't roll down, but do the drop, FOB and alarm don't work etc.). I will get to fixing it eventually. But the car has always started and run etc. Considering the frequency of occurrence maybe the engine and CLU do a self diagnosis every so many KMs and because the cLU is messed up it forces the car to stop providing fuel or something (thinking the car is stolen?). Sounds far fetched to me, but maybe?
I wonder if a solenoid on one bank or the other is not kicking the Variocam system in when your lose of power issues occurs???? Just a thought.
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Old 09-19-2020, 10:55 AM   #38
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I wonder if a solenoid on one bank or the other is not kicking the Variocam system in when your lose of power issues occurs???? Just a thought.
Researching now. I'll hook up durametric and snoop around a bit. See if I get consist actuation and look at the deviations etc. But it does look like others have reported similar symptoms with variocam.

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