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Recommended Posts

Posted

Even w/o durametric, you can use any obdii scanners that can display real-time data to check if bank 1 sensor 1 o2 sensor is swinging between 0.2 and 0.8v at idle about once a second.

Is the b1s1 disconnected?

Posted

No, b1s1 connected but bought a generic O2 .Loren said that the 02 sensors are specific to before and after cat ? this true. ? if so, I bought two of the same. problem ?

o2 Bank 1 Sensor 1 (v) was between (approx.) -41.6 and .598.

o2 Bank 2 Sensor 2(v) was between (approx.) -.38 and -.400

shrtft B1 S1, between -8.6 and 13.3

shfrt B2 S1 between -0.8 and 1.6

shrt FT1 % between -22.7 and -25

LONG FT 1% steady at 26.6

shrt FT2 % between -0.8 and 1.6

LONG FT 2% -19.5

Posted (edited)

O2 sensors are the same pre/post cat, but the stock parts have different length wires (can't remember if connector is the same). If you want plug and play stick with the right part numbers pre and post, the Bosch equivelant cost about the same. Otherwise you might have some re-wiring to do when using aftemarket versions. The one that is most important is the pre cat sensor, this is what the ECU uses to adjust ratio. The post one is just monitored to see if the cat is in good health. A bad cat should show similar numbers for both pre/post cat. (edit corrections for accuracy based on RFM's post)

Member Mike F has a great write up here: https://sites.google.com/site/mikefocke2/oxygensensors

Is that a typo -41.6? Do you mean -4.16???

Double digit voltage during idle running is way out of spec (read, faulty), and in fact that might be the smoking gun unless there is a serious, read, huge problem getting fuel to bank 1.

I would think seeing -41.6V O2 and 26.6 LTFT should throw a code for system too lean on most cars. IIRC 25 is the threshold.

These figures were taken with the engine running correct? Was it warm?

You did reset the ECU after the most recent engine install right?

Bank 2 looks a little more normal, and slightly rich which makes sense with the 3.8L injectors on a 3.4L map.

So where is the imbalance? I'm guessing bad data at this point.

Try swapping the O2 sensors between banks or replace the pre cat sensor on bank 1.

Edited by logray
Posted

my writing was sloppy but I initially t

02 sensors are the same pre/post cat, but the stock parts have different length wires (can't remember if connector is the same). If you want plug and play stick with the right part numbers pre and post, the Bosch equivelant cost about the same. Otherwise you might have some soldering to do. The one that is most important is the pre cat sensor, this is what the ECU uses to adjust ratio. The post one is just monitored to see if the cat is in good health. A good cat should show similar numbers for both pre/post cat.

Member Mike F has a great write up here: https://sites.google.com/site/mikefocke2/oxygensensors

Is that a typo -41.6? Do you mean -4.16???

My mistake , it varied between -4 and -6

Double digit voltage during idle running is way out of spec (read, faulty), and in fact that might be the smoking gun unless there is a serious, read, huge problem getting fuel to bank 1.

I would think seeing -41.6V O2 and 26.6 LTFT should throw a code for system too lean on most cars. IIRC 25 is the threshold.

These figures were taken with the engine running correct? Was it warm?

engine running and warm

You did reset the ECU after the most recent engine install right?

yes, ecu reset, battery dissconnected

Bank 2 looks a little more normal, and slightly rich which makes sense with the 3.8L injectors on a 3.4L map.

So where is the imbalance? I'm guessing bad data at this point.

Try swapping the O2 sensors between banks or replace the pre cat sensor on bank 1.

I will reset ecu, swap pre cat o2s and post new data.

thanks

Posted

I certainly hope this is it... you certainly have had your fair share of issues to weed out....

Actuator, gasket, and now an O2 sensor (and I'm pretty certain you would have eventually run into the same issue I did with undersized fuel injectors)...

Good to look at data then ask questions, then replace... I think that was pointed out early on, otherwise you are just "swapping parts".

  • Moderators
Posted

Still some concerns here, the post-cat sensor should vary only slightly and slow with a cat in good condition, if the pre and post sensors show the same variation, the cat is shot. It is not recommended to solder the wiring of the sensors, the wiring is part of the outside oxygen compare versus residual oxygen in the exhaust, the solder poisons/affects the readings and will not correct, even more important in broadband probes. Such wiring is also difficult to solder by the nature of the wiring material, as they have taught me.

Posted

just a note. I replaced b1 s1 o2 with a new sensor when I rebuilt, but keeps showing it as P0130 and p1128.

It was $39.00 on ebay. Could I have purchased a defective one?

I will swap with the stock b2 s1 sensor and see what happens.

Posted

just a note. I replaced b1 s1 o2 with a new sensor when I rebuilt, but keeps showing it as P0130 and p1128.

It was $39.00 on ebay. Could I have purchased a defective one?

I will swap with the stock b2 s1 sensor and see what happens.

Also, the car had coolant in the exhaust (intermix) when i bought it and it sat for months. I am wondering if i have a clogged, shot cat. I am going to swap o2s first and then take off bank 1 cat and look in there anyway. Hope to find a rats nest, clogged or something obvious.

Posted

just a note. I replaced b1 s1 o2 with a new sensor when I rebuilt, but keeps showing it as P0130 and p1128.

It was $39.00 on ebay. Could I have purchased a defective one?

I will swap with the stock b2 s1 sensor and see what happens.

If the $39 one is not Bosch and is not an original sensor throw it in the trash. Do you still have the old one laying around?

Posted

Still some concerns here, the post-cat sensor should vary only slightly and slow with a cat in good condition, if the pre and post sensors show the same variation, the cat is shot.

It is not recommended to solder the wiring of the sensors, the wiring is part of the outside oxygen compare versus residual oxygen in the exhaust, the solder poisons/affects the readings and will not correct, even more important in broadband probes. Such wiring is also difficult to solder by the nature of the wiring material, as they have taught me.

Which data is for the post and which for the pre-cats.

I am not that familiar with the OBD II terms; shrt FT and long FT ????

Posted

just a note. I replaced b1 s1 o2 with a new sensor when I rebuilt, but keeps showing it as P0130 and p1128.

It was $39.00 on ebay. Could I have purchased a defective one?

I will swap with the stock b2 s1 sensor and see what happens.

If the $39 one is not Bosch and is not an original sensor throw it in the trash. Do you still have the old one laying around?

Yes, swapped it with no luck but that was before I installed the missing intake manifold gaskets on !!!

Posted

I certainly hope this is it... you certainly have had your fair share of issues to weed out....

Actuator, gasket, and now an O2 sensor (and I'm pretty certain you would have eventually run into the same issue I did with undersized fuel injectors)...

Good to look at data then ask questions, then replace... I think that was pointed out early on, otherwise you are just "swapping parts".

No more $$ to throw parts at it and too afriad to drive with all of the codes. don't want to hurt my new engine.

Posted
Which data is for the post and which for the pre-cats. I am not that familiar with the OBD II terms
I'm not sure if your generic OBD2 scan tool can read the post-cat O2 sensors, but the readings you got are likely pre-cat sensors.Although, at this point focus on the pre-cat reading of -4V and -6V which is way off.Again, I would not use the ebay version unless it is genuine Bosch. It could be providing the bad reading.For a 99 model year car, I bought my Bosch sensors on Amazon here (they are identical to the Porsche version):Pre cat: $72.24http://www.amazon.com/Bosch-13564-Oxygen-Sensor-Fitment/dp/B000BZG6WAPost cat: $77.82http://www.amazon.com/Bosch-13723-Oxygen-Sensor-Fitment/dp/B000BZG79C
Posted

Which data is for the post and which for the pre-cats. I am not that familiar with the OBD II terms

I'm not sure if your generic OBD2 scan tool can read the post-cat O2 sensors, but the readings you got are likely pre-cat sensors.Although, at this point focus on the pre-cat reading of -4V and -6V which is way off.Again, I would not use the ebay version unless it is genuine Bosch. It could be providing the bad reading.For a 99 model year car, I bought my Bosch sensors on Amazon here (they are identical to the Porsche version):Pre cat: $72.24http://www.amazon.com/Bosch-13564-Oxygen-Sensor-Fitment/dp/B000BZG6WAPost cat: $77.82http://www.amazon.com/Bosch-13723-Oxygen-Sensor-Fitment/dp/B000BZG79C

gonna swap em tonight, check cat and readings and report back. fingers crossed...again

Posted

Agree that -4v and -6v makes no sense. If indeed that's what the DME sees, you found your problem. Again, the O2 sensor 1 on both banks should swing between 0.2v to 0.8v about once a second when fully warmed up and idling. If it does not, either the sensor is faulty or you have a wiring problem.

The post-cat sensors should read very steady at around 0.6v and swing only from time to time (much less freq than once a second) if I remember correctly when idling and warmed up.

Posted

Logray, Dharn55, 987-RDC, dcdrechsel,RFM, txhokie4life, and Ahsai,

Thank all of you for your help !!

I thought I was going to have to purchase a pistol and blow my brains out before Obama outlawed them.

The car runs perfectly !!!!!!!!!!!!!!!!!!!!!

First, I had a clogged fuel filter that my wife so easily diagnosed

second, installed variocam plunger upside down on bank 2.

third, I did not install lower intake manifold gaskets and had a vacuum leak,

fourth, my injectors were undersized for a 3.6 and I reused the old o-rings. I replaced withe 3.8's from 987_RDC ( they are beautiful and thank you) and with new o-rings.

and fourth ....wait for it...........

I had the bank 1 o2 sensor wires reversed, (pre 02 wire to post cat and post o2 wire to pre cat ) because I bought cheap replacements and they were "white" and I mismarked them. When I went to swap bank1 to bank 2 O2 sensors to work on misfire, I checked orientation of the black and grey O2 wires and they

were reversed on bank 1. all the voltages are now right on the money dand rove for 40 minutes and no CEL's.

It was beautiful

Thanks to all of you, I can rest now momentarily and an my wife can see that my mood is much better !!

third

Posted

Good news-no great news !No more cold garage floor !Dave

and clay on floor AND in car and on car and on mats and on me , and pulling my hair out !!....

relief

Posted (edited)

Agree that -4v and -6v makes no sense. If indeed that's what the DME sees, you found your problem. Again, the O2 sensor 1 on both banks should swing between 0.2v to 0.8v about once a second when fully warmed up and idling. If it does not, either the sensor is faulty or you have a wiring problem.

The post-cat sensors should read very steady at around 0.6v and swing only from time to time (much less freq than once a second) if I remember correctly when idling and warmed up.

LOL that this was selected as the best answer (read post#104) . :)

I think the thread is full of best answers. :) :) :) :)

Loren, can you mark the whole thread as a best answer?

Anyhow, awesome news.

Edited by logray
Posted

actually didn't know how to do that. my mistake, my intent was to acknowlege all of you as best answer

what a relief !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Posted

Yeah no worries... I wasn't pointing fingers, just thought it was kinda funny since there were so many great contributors to the success of your project... your wife deserves a pat on the back too.

Posted

Heres' the old girl.

post-78135-0-26576200-1358209114_thumb.j

Of course, the first day I get it running in VA, its raining and I have a long gravel driveway. My 13 year old son and I had the best wet drive home from school today !! Looking forward to a sunny day, and top down, and a long cruise through the shenandoah mountains.

yeah, it's a funky color but I bought it not running for $8k.

Thanks again to all !!!

  • Upvote 1

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