O2 Sensor Issues
Racer
Joined: Jan 2008
Posts: 270
Likes: 4
From: SoCal
bad news, i took a closer look at the procedure for the knock sensor (P1386) and says to replace the ECU. Perhaps Loren of Systems Consulting can help with this.
Thread Starter
Rennlist Member
Joined: Jul 2009
Posts: 7,234
Likes: 10
From: Costa Mesa, CA
I have questions regarding the knock sensors. To review, I have a PST2 code of
222 - Knock Pulse Test
and also get knocking codes which are retarding timing and causing car to have poor performance.
Points to bad knock sensors. I have looked at the wiring around the engine compartment that I would have messed with during the engine R&R and all looks fine.
This points to the knock sensors being bad.
If I buy a set of sensors, can I just plug the new sensors in without completely installing and see if that corrects the problem?
Do the sensor bodies need to be grounded to the engine?
Do I need to run a bolt through it?
222 - Knock Pulse Test
and also get knocking codes which are retarding timing and causing car to have poor performance.
Points to bad knock sensors. I have looked at the wiring around the engine compartment that I would have messed with during the engine R&R and all looks fine.
This points to the knock sensors being bad.
If I buy a set of sensors, can I just plug the new sensors in without completely installing and see if that corrects the problem?
Do the sensor bodies need to be grounded to the engine?
Do I need to run a bolt through it?
Thread Starter
Rennlist Member
Joined: Jul 2009
Posts: 7,234
Likes: 10
From: Costa Mesa, CA
UPDATE
I tried connecting new knock sensors to the unit and no change - did not actually install, so not sure if that was a valid test.
I did the wiring harness checks specified in the docs that George graciously provided - and all checked well.
PST2 hdd failure, so that doesn't help anymore.
I read a few threads about rough running engines and the distributors came to mind. I checked for running on the primary and then the secondary distributor. Car ran on secondary and not primary distributor. So that meant belt was fine. I switched the coil for the primary distributor and the car started and ran - albeit a little rougher than on secondary. So this leads me to a bad coil as being the problem. Just ordered a set of coils so keeping my fingers crossed.
Interesting that I tried this early on and both distributors were ok. There was a slight hesitation, but I thought it was related to an engine install issue. By the time I solved the O2 issue, the coil went completely bad.
I tried connecting new knock sensors to the unit and no change - did not actually install, so not sure if that was a valid test.
I did the wiring harness checks specified in the docs that George graciously provided - and all checked well.
PST2 hdd failure, so that doesn't help anymore.
I read a few threads about rough running engines and the distributors came to mind. I checked for running on the primary and then the secondary distributor. Car ran on secondary and not primary distributor. So that meant belt was fine. I switched the coil for the primary distributor and the car started and ran - albeit a little rougher than on secondary. So this leads me to a bad coil as being the problem. Just ordered a set of coils so keeping my fingers crossed.
Interesting that I tried this early on and both distributors were ok. There was a slight hesitation, but I thought it was related to an engine install issue. By the time I solved the O2 issue, the coil went completely bad.
Thread Starter
Rennlist Member
Joined: Jul 2009
Posts: 7,234
Likes: 10
From: Costa Mesa, CA
Good news, flags cleared and she passed inspection! After two drive cycles, the flags did not clear, but after about another 100 miles, they cleared.
An interesting note is that I believe the 222 code was the result of the failed coil. Streather says that the knock control is not sufficient to prevent engine damage from a failed distributor belt, which implies that knock is a problem when only one set of spark plugs is working.
An interesting note is that I believe the 222 code was the result of the failed coil. Streather says that the knock control is not sufficient to prevent engine damage from a failed distributor belt, which implies that knock is a problem when only one set of spark plugs is working.
RL Community Team
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From: Dallas, TX
Thanks for the reference materials George!
Bank 2 after the cat appears to be the dead sensor.
In the literature you posted, they talk about measuring continuity from the ECM to the O2 sensors. Is DME and ECM synonymous? Where do I access these pins?
So you read low voltages on the PST2 as well, that part is ok?
O2s were sourced from AutohausAZ and were not the ones where they get spliced into the harness. They came with OE connectors.
All the faults do return
Bank 2 after the cat appears to be the dead sensor.
In the literature you posted, they talk about measuring continuity from the ECM to the O2 sensors. Is DME and ECM synonymous? Where do I access these pins?
So you read low voltages on the PST2 as well, that part is ok?
O2s were sourced from AutohausAZ and were not the ones where they get spliced into the harness. They came with OE connectors.
All the faults do return
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Racer
Joined: Jan 2008
Posts: 270
Likes: 4
From: SoCal
Good news, flags cleared and she passed inspection! After two drive cycles, the flags did not clear, but after about another 100 miles, they cleared.
An interesting note is that I believe the 222 code was the result of the failed coil. Streather says that the knock control is not sufficient to prevent engine damage from a failed distributor belt, which implies that knock is a problem when only one set of spark plugs is working.
An interesting note is that I believe the 222 code was the result of the failed coil. Streather says that the knock control is not sufficient to prevent engine damage from a failed distributor belt, which implies that knock is a problem when only one set of spark plugs is working.
Yes, very interesting that fault code 222 went away. If you recall the diagnostic procedure for 222 says to replace the DME as the only remedy.
RL Community Team
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Joined: Jul 2004
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From: Dallas, TX
If you ever see this issue I would unplug the secondary if I was going to drive the car into service to avoid internal engine damage.
Thread Starter
Rennlist Member
Joined: Jul 2009
Posts: 7,234
Likes: 10
From: Costa Mesa, CA
Well, PST2 is working again. The 222 code is still present, so it is not the result of the bad coil. The knock codes are gone.
It is interesting that going back, when I had the PPI, the knock codes were there including the 222 code. At the time, there was speculation that the DMFW was starting to fail. With the new RS-style flywheel, this is not likely. So it may be very well a DME issue.
At least it causes no other problems that I see.
Last edited by vincer77; Aug 30, 2016 at 05:02 PM.
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Joined: Feb 2007
Posts: 41
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From: Florida Panhandle
On my 964 I had some rough running issues that turned out to be the ignition module connected to the coils. 964 has two, believe the 993 has only one. About $74 from Volvo, over $100 from Porsche. Cheper than a DME or distributor.