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428street

Need help with 986 troubleshooting - rough idle, etc.

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Looking for some technical help please 🙂 01 S with 28k, original owner never had a problem until last month. Have done all my own work, basically maintenance stuff like AOS, water pump, plugs, etc. CEL came on 7/31 put durametric on and codes were P0133 & P1275 both 02 sensor issues, cleared CEL and kept going. All month with steady driving no issues. 9/4 CEL put durametric on and multiple codes, P1130, P1128, P1126, P1133, P0102. Up to this point if the CEL did not come on I would have not know there was a problem as the car ran well. 9/5 CEL came back on with 1126, 1133, 0300, 0304, 0301, 0302, 0306. Did a little research online and it was general opinion to start with easy stuff so I cleaned MAF, TB and air cleaner. Upon startup after doing all this work (cleaning) car ran worse.  Rough idle and engine knocking.  I did not run the car long. I read after cleaning all the items to disconnect battery for about a minute then turn the key on for a minute, then turn off and let set for 10 seconds before starting.  In the meantime I took out my Bentley manual and PP 101.  I read the MAF section and I think I fried the MAF because I cleaned the whole sensor including "diode" looking wire on the MAP which seems to be a no, no.  I did have another used one on the shelf (same part number .125) so I installed that one, did the battery and key thing again and it seems to run a little better but still rough and still have engine knock.  What would have caused what I cleaned to make it worse?  Looking for someone to help me wade through the process to track this problem down as I'm going further down the rabbit hole and things are getting worse. I prefer not to throw parts at it but my sense is MAF and an O2 sensor(s) could be bad. Any help would be appreciated.  BTW, there is nothing you can say to me that will hurt my feelings, I know for this one I might be a bit over my head but I love learning and I'd love to get back on the road.  I have a ton of tools, durametric, etc.  Not a professional mechanic but very mechanical.

BoxsterCEL7:30.png

boxsterCEL9:4.png

BoxsterCEL9:5.png

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OK, let's start with the obvious:

 

P0133 and P1275 both indicate that the O2 sensor ahead of the three way cat on bank 1 has aged out and needs replacing.  I would get that done, clear all the codes and see if anything returns.  Some of the other codes (P1126) indicate mixture issues and a possible vacuum leak, but with the O2 sensor out of wack may just be ghost codes.

 

 

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Thanks JFP.  I just checked my Bentley Manual and see the Exhaust System Diagram and looks like I have a pre and post 02 sensor before each cat.  What I don't see is a designation for bank 1/2 which I assume is left and right side.   I hope I am reading and understanding this correctly.  I quickly did a search and looks like Bank 1 is on the right side or passenger side of the car and in reading your description looks like I need to order the pre cat 02 sensor correct?  986-606-127-01-M14

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Your part number is correct except for the M14 at the end, which tells me it is a Pelican number.  Don't buy it from them, they a known for swapping out non OEM for the real thing.  Get it from board sponsor Sunset Porsche.

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Looks like from Loren's post they offer discounts to renntech members which means you have to call them to get it vs. buying from their website?  Any specific contact there to talk to?

 

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1 minute ago, 428street said:

Looks like from Loren's post they offer discounts to renntech members which means you have to call them to get it vs. buying from their website?  Any specific contact there to talk to?

 

 

You can talk to anyone, just tell them your are from RennTech.

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5 minutes ago, 428street said:

Fair enough sir.  So all my info is correct, drivers side before cat 02 sensor correct?

 

 

Bank1 is the passenger's side on the Boxster.

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JFP, you did see the way I cleaned the MAFS correct?  I spray the CRC on the whole thing not just the two bottom channels.  I did not touch it or brush it with anything.  I'm only asking because I'd like to make one parts order and these guys (Suncoast) are 3000 miles from me and I can see this taking weeks (which is my problem) so wanting to see if you think i FUBAR'd the MAFS.  I know this is troubleshooting and we have to remove the varaibles which is exactly what you are suggesting, tackle one thing at a time.

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1 minute ago, 428street said:

JFP, you did see the way I cleaned the MAFS correct?  I spray the CRC on the whole thing not just the two bottom channels.  I did not touch it or brush it with anything.  I'm only asking because I'd like to make one parts order and these guys (Suncoast) are 3000 miles from me and I can see this taking weeks (which is my problem) so wanting to see if you think i FUBAR'd the MAFS.  I know this is troubleshooting and we have to remove the varaibles which is exactly what you are suggesting, tackle one thing at a time.

 

I would not write the MAF off just yet, and Sunset is well known for quick shipping and great customer service.

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Having never done this and not having a lift, is this something easier done without the wheel on or doesn't matter.  I have a set of ramps to drive car on or I have two jacks to use (one for each side) to raise the rear then jack stands for the weight...please advise.

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7 minutes ago, 428street said:

Having never done this and not having a lift, is this something easier done without the wheel on or doesn't matter.  I have a set of ramps to drive car on or I have two jacks to use (one for each side) to raise the rear then jack stands for the weight...please advise.

 

I can be done on jack stands.  One of the beauties of the 986 is that these are exposed from underneath:

 

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You are going to need a sensor socket (about $10 on Amazon) that is open on the side to allow the pigtail to hang out while doing this, and you are going to need some anti seize for the sensor threads:

 

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I will get the socket for sure, have the AS...traditionally do these fight you coming off?  wheel on or off?  no ramps but jacks will work?  I'd feel safer with the ramps but jacks will work...

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3 minutes ago, 428street said:

I will get the socket for sure, have the AS...traditionally do these fight you coming off?  wheel on or off?  no ramps but jacks will work?  I'd feel safer with the ramps but jacks will work...

 

They do take a heat set after years of thermal cycling, which is why anti seize is needed.  I don't remove the wheels, but I am working on a lift.

 

If you don't have the car on ramps, it MUST be on jack stands, not jacks...…………..

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I also have a MAP torch and o/c which I'd prefer not to use but I can if I need to heat them up...understand on the jack stands 100%...TY

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last question (lol), after I replace is there anything I need to do special with the car to reprogram for the new 02 sensor?

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Just now, 428street said:

I also have a MAP torch and o/c which I'd prefer not to use but I can if I need to heat them up...understand on the jack stands 100%...TY

 

We only apply the "blue wrench" when hanging on a 40 inch breaker bar won't budge them, in order to prevent removing the threads with the sensor; usually they pop loose with enough grunt.

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1 minute ago, 428street said:

last question (lol), after I replace is there anything I need to do special with the car to reprogram for the new 02 sensor?

 

Clear all remaining codes and go drive it like you stole it...…………….

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Just to give you some peace of mind, I did the original sensors on my 00 986 with +110k mi and they came off easily using a simple box wrench. One of the sensors on the right side is a bit of a pain to access the plug. Definitely recommend taking off the wheel for easier access. Also, one bit of caution is that I have received a bad “new” o2 sensor that immediately led to codes for o2 sensor heating which was a new/different code than I was getting originally. I was convinced I did something wrong but found somewhere how to check the resistance between the pins on the sensor plug which confirmed that the sensor itself was bad.

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So, it's fixed and I hesitate to say running better than before.

 

First, thank everyone for their help especially JFP with the cool head that got me off the ledge.

 

I'll spare everyone the drama but there were two main issues, one was the 02 sensor was bad, I didn't want to wait so bought one local (Bosch), I actually changed both because I was under there and they were close to each other.  Secondly, I put the plenum tube in cock-eye'd, I thought I had a good seal all the way around but that was not the case.  Once I fixed that seal (leak) issue, changed the two 02 sensors and put back my original MAFS it purred like a kitten and I took it out for a beat down run 🙂

 

More than likely going to change the other two 02 sensors but for now I'm going to enjoy this beautiful early Fall day.

 

Again, thank you for the help.

Edited by 428street

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21 minutes ago, 428street said:

So, it's fixed and I hesitate to say running better than before.

 

First, thank everyone for their help especially JFP with the cool head that got me off the ledge.

 

I'll spare everyone the drama but there were two main issues, one was the 02 sensor was bad, I didn't want to wait so bought one local (Bosch), I actually changed both because I was under there and they were close to each other.  Secondly, I put the plenum tube in cock-eye'd, I thought I had a good seal all the way around but that was not the case.  Once I fixed that seal (leak) issue, changed the two 02 sensors and put back my original MAFS it purred like a kitten and I took it out for a beat down run 🙂

 

More than likely going to change the other two 02 sensors but for now I'm going to enjoy this beautiful early Fall day.

 

Again, thank you for the help.

 

Glad to hear you got it sorted.  Often, what appears to be a complicated multiple issue problem is actually simple if you stop and look at what the codes are telling you.

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