Jump to content

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)
tristancboyd@gmail.com

Lopey Idle and intake pops on a cold start

Recommended Posts

Hey all, here's a video of the problem I'm having.  It was happening when I was getting a MAF sensor code.  I've replaced it, reset the codes, driven two tanks and am still having this issue.  Other than this issue, the car runs great and is getting 24-26mpg average.

 

2002 Boxster S

6-Speed

 

https://www.youtube.com/watch?v=zFVuFkICEPk

Edited by tristancboyd@gmail.com

Share this post


Link to post
Share on other sites
    You can remove these ads by becoming a Contributing Member.

I can't remember now exactly. I believe the description had something to due with low voltage or something with the MAF.  Low-something.  helpful, I know but I cleared it several weeks ago.

 

Also, tonight I noticed that where I thought it was running fine, there seems to be a dip or hesitation between 2000-2700ish RPMS.

 

Still no codes

Share this post


Link to post
Share on other sites

Sorry, but I am not familiar with the reporting values diagnostics tool you are using; Porsche systems fuel trims are rated according to reading your FRA (load) and TRA (idle) adaptation values for each bank, with the FRA range limits on adaptation for both banks are Rich: 1.25 and Lean: 0.75 (For example, an "in spec" "long term" FRA trim would be around 1.0 +/- 0.1 and an in spec "idle range" fuel trim would be in the range 0.00 +/- .2).  Porsche also set the MAF values at 10-20 Kg/Hr. at idle, and 30-60 Kg/Hr. at 3K RPM (no load).  If your tool is reading in gram/second, 6.8 gram/sec at idle would equate to 24.5 Kg/Hr., which would be a high air mass at idle (a possible lean condition).  I also note that your secondary air system is reading "incomplete", which could be related to the problem you are seeing.

 

If at all possible, I would suggest getting the car rescanned with a Porsche specific tool (PST II, PIWIS, or Durametric system).

Share this post


Link to post
Share on other sites

Sorry, but I am not familiar with the reporting values diagnostics tool you are using; Porsche systems fuel trims are rated according to reading your FRA (load) and TRA (idle) adaptation values for each bank, with the FRA range limits on adaptation for both banks are Rich: 1.25 and Lean: 0.75 (For example, an "in spec" "long term" FRA trim would be around 1.0 +/- 0.1 and an in spec "idle range" fuel trim would be in the range 0.00 +/- .2).  Porsche also set the MAF values at 10-20 Kg/Hr. at idle, and 30-60 Kg/Hr. at 3K RPM (no load).  If your tool is reading in gram/second, 6.8 gram/sec at idle would equate to 24.5 Kg/Hr., which would be a high air mass at idle (a possible lean condition).  I also note that your secondary air system is reading "incomplete", which could be related to the problem you are seeing.

 

If at all possible, I would suggest getting the car rescanned with a Porsche specific tool (PST II, PIWIS, or Durametric system).

 

 

I don't have access to one of those but using this information, I'll see if I can't clean up the read-outs to something a little more useful for this troubleshooting.  And also, I appreciate your help.  Thank you.

Share this post


Link to post
Share on other sites

Agree with John your MAF reading is way too high at warm idle. It should be around 4g/s at idle speed ~680-700rpm.

What kind of MAF sensor you put in and are you sure it's the right one for your model?

It would be useful to log the following (at idle) in Torque during cold start and after fully warmed up:

- short term fuel trims on both banks

- long term fuel trims on both banks

- Bank 1 O2 sensor 1 voltage

- Bank 1 O2 sensor 2 voltage

- Bank 2 O2 sensor 1 voltage

- Bank 2 O2 sensor 2 voltage

- MAF

- coolant temp

- rpm

  • Upvote 1

Share this post


Link to post
Share on other sites

Btw, any intake mods and have you tried driving the car with the MAF unplugged?

From your data, looks like the MAF is over reading the intake air flow at idle so the DME has to pull fuel like crazy (negative short term fuel trim) on both banks at idle. To compensate, the DME has to add back fuel when under load hence the positive long term fuel trims.

  • Upvote 1

Share this post


Link to post
Share on other sites

Agree with John your MAF reading is way too high at warm idle. It should be around 4g/s at idle speed ~680-700rpm.

What kind of MAF sensor you put in and are you sure it's the right one for your model?

It would be useful to log the following (at idle) in Torque during cold start and after fully warmed up:

- short term fuel trims on both banks

- long term fuel trims on both banks

- Bank 1 O2 sensor 1 voltage

- Bank 1 O2 sensor 2 voltage

- Bank 2 O2 sensor 1 voltage

- Bank 2 O2 sensor 2 voltage

- MAF

- coolant temp

- rpm

 

I set these up in my app almost exact but messed up the logging, I'm going to try again in the morning.

 

The only Mod I have is a desnorkle, everything else is otherwise stock.

 

I put a few screen shots below

 

The MAF I ordered is this one

 

F2THI5d.png

 

GWIE2NP.png

Share this post


Link to post
Share on other sites

STFT 1 appears twice and LTFT1 is missing. The two "F/T..." are not needed. We still need the O2 sensor voltage from all 4 O2 sensors. Not clear to me but is the MAF by Bosch? If not, I think it's a strong suspect.

Not familiar with the desnorkle mod but can it be reversed?

Share this post


Link to post
Share on other sites

STFT 1 appears twice and LTFT1 is missing. The two "F/T..." are not needed. We still need the O2 sensor voltage from all 4 O2 sensors. Not clear to me but is the MAF by Bosch? If not, I think it's a strong suspect.

Not familiar with the desnorkle mod but can it be reversed?

I missed that I had repeated read outs.  I put it up in a hurry.  I'll set up the read out dashboard now and make sure its good to go for the morning.  The MAF is probably not Bosch, I do not remember seeing anything that would link it to Bosch.

 

The desnorkle is more of a sound modification than anything.  It's removing a sound baffle from the intake tube in the side of the car.  

Snorkel+0011388699077.jpg

Share this post


Link to post
Share on other sites

I don't have the PET handy but maybe John can shed some light on the correct p/n for your year and model. If the MAF is $50 from ebay, I would not trust it. The Bosch ones are about $250 each and those should be good.

You can still try to drive your car with the MAF unplugged and see if that makes a difference, maybe after you finished logging the data with the curret MAF.

Share this post


Link to post
Share on other sites

I come up with at 996-606-124-00 as the correct part for your car.  Should retail somewhere between $250-275, or list for about $600 at a Porsche dealer.

  • Upvote 1

Share this post


Link to post
Share on other sites

The desnorkle itself should not cause any CELs because it is upstream of the air filter and MAF.  It just changes the sound.

 

But, in doing it, connections that could cause a CEL could have been disturbed.

 

Get the CEL diagnosed and report the Pnnnn values. Many car parts places can do it for free and the emissions control codes are readable with basic code readers.  The Porsche specific diagnostic tools such as JFP suggests may be needed after you see the basic reported code and post it here and someone reads the manual for your specific ECU revision and tells you the typical causes that cause that CEL and codes to be displayed.

 

Think of the diagnosis as moving down from CEL on the dashboard to codes via a code reader and then to more specific engine operating parameters via the specialized Porsche tools.

 

But I'd take the basic and cheap steps first.

 

Also, when you post, tell us what on the car, engine, exhaust is not perfectly stock. And what has been changed since the car ran without problems.

 

I might even put the old MAF in as I too suspect the new MAF and we'd get better diagnosis with the part in there whose operating characteristics match what the software in the ECU expects.

Edited by mikefocke

Share this post


Link to post
Share on other sites

I think I got some really good data today and I have it uploaded to the torque web viewer.  It can be seen publicly but putting my torque ID in, no password required for viewing.  I'd just snip it and paste but then you cant see the specific values as you mouse over them.  I also have the  CSV values for the logs if someone is able to view those.  Oddly enough, it behaved today at idle.  Still a little hesitation starting around 2200.

 

It's the 3.2, 6-speed.  

Other than the desnorkle, its completely stock

 

http://view.torque-bhp.com/

 

Device ID: 990005434631165

Share this post


Link to post
Share on other sites

I saw two issues with your engine:

 

1) Bank 1 sensor 2 (red line) too slow to respond. That's likely why your SAI readiness flag is not set. You can see engine starts at ~150s and close loop is achieved at ~190s and Bank 1 sensor 2 lags behind Bank 2 sensor 2 when detecting the extra O2 introduced by the SAI pump (excessive O2 => low voltage).

 

post-5282-0-51003400-1450768223_thumb.jp

 

2) MAF reading / fuel trims are erratic. Long term fuel trims (on both banks) drifted from +15% to -10% between your first drive to your last drive. I saw that when idle, sometimes the MAF reading is in spec but a lot of time it's not. Suggest you remove the MAF, reset the DME and re-log.

Edited by Ahsai
  • Upvote 1

Share this post


Link to post
Share on other sites

Between yesterday and today, the idle has not acted up once.  Today there was not any hesitiation to be found.  I decided to look at the system status again, and everything has completed.  I'm debating on whether to pursue this further or let it be and hope it doesn't act up again.  You guys are a wealth of information!

 

HgU0naA.png

Share this post


Link to post
Share on other sites

The easiest is to check the LTFT when you feel the engine is not smooth (either idle or under load). Those should be +/- 10%.

 

If the engine is smooth, I would just keep monitoring the fuel trims and CEL and do nothing yet.

  • Upvote 1

Share this post


Link to post
Share on other sites

BTW, cleaning the throttle body will help smooth out the idle too if it's dirty.

  • Upvote 1

Share this post


Link to post
Share on other sites

Thank you all very much.  I will continue to monitor for a bit.  If it continues to behave without issue, I'll mark this solved.  The feedback between y'all has been so informative and helpful just in learning a few things is why I decided to contribute to this forum.

Share this post


Link to post
Share on other sites

So I'm back.  I haven't really noticed anything lately but it's also been unusually and record-breaking warm here.  

 

I went out before work this evening and started the car to let it warm up before leaving (I wanted heat!!!)  After about two minutes I went back outside to let my dogs out and didn't hear the car running.  The engine stopped.  I started it back up, a little lopey, no CEL but it settled and I went back in.  About two minutes later, I heard the idle start to get a little erratic and lopey again and then the engine quit again.  I went out and started it a third time, gave it a few revs and held some small revs for a few seconds.  This time it stayed running but I shot some video for you more knowledgeable folk.  

 

It was roughly 35F outside and the car had not been driven since the day before.  

 

Still no CEL and once it was warm, it ran like a scared cat, zero issues.

 

https://www.youtube.com/watch?v=N2M1U3IKcTc

Edited by tristancboyd@gmail.com

Share this post


Link to post
Share on other sites

So I'm back.  I haven't really noticed anything lately but it's also been unusually and record-breaking warm here.  

 

I went out before work this evening and started the car to let it warm up before leaving (I wanted heat!!!)  After about two minutes I went back outside to let my dogs out and didn't hear the car running.  The engine stopped.  I started it back up, a little lopey, no CEL but it settled and I went back in.  About two minutes later, I heard the idle start to get a little erratic and lopey again and then the engine quit again.  I went out and started it a third time, gave it a few revs and held some small revs for a few seconds.  This time it stayed running but I shot some video for you more knowledgeable folk.  

 

It was roughly 35F outside and the car had not been driven since the day before.  

 

Still no CEL and once it was warm, it ran like a scared cat, zero issues.

 

https://www.youtube.com/watch?v=N2M1U3IKcTc

 

 

Sometimes, when the MAF in these cars is starting to age out or is dirty, you will get the kinds of issues you describe.  I would pull the MAF and thoroughly clean it with an appropriate cleaner like CRC's, then reinstall it and see if the situation improves.  If it does not, I would scan the MAF PID's at idle and 2K RPM; if the values of the MAF are all out high, or even near the high end of the range, your MAF is aging out and needs to be replaced.

Share this post


Link to post
Share on other sites

It's been a busy week or two with my four year old going to daycare/preschool for the first time ever and getting adjusted to new schedules.  I do have somewhat of an update, but no resolution.  

 

The idle issue has correlated with showing its ugly face with the car not being driven for a couple of days or longer.  I've also noticed that the car turns over noticeably slower, but not completely weak and the lights in the car seem to have a bit of a pulse for a few minutes.  This has me wondering if perhaps the battery is beginning to fail and properly supply the vehicle with the required voltage and current needed to operate properly until the alternator is able to catch it back up.

Share this post


Link to post
Share on other sites

What's the voltmeter reading at

1),cold start

2) driving with low beam and a/c ON

If the headlight flickers, you definitely have a problem with your battery or charging system.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Similar Content

    • By Graeme Tate
      I hate my pig but I love my pig, can anyone please help me before I send it for scrap. Over the space of the last 4 years of ownership my car has been in the Porsche dealers for 2 years in total with suspension problems, to cut a long story short this is now sorted and was due to a faulty replacement air bag being fitted. Moving on after 3 months of (almost) trouble free motoring this is what’s happening now and would love some advice as the closest porsche dealers is over 200 miles away from me.

      When I picked up the car from Porsche  it ran out of petrol before I got to the garage at the end of the road and although I filled it up it  the engine warning light remained on I assumed this was just fuel related and drove home with it on and reset it when I got home.
      Wind on a few weeks and the engine light came back on and gave me a camshaft position sensor error p0016 so I sent the car to my local Porsche mechanic who changed out the sensor and did a full service on the car including plugs filter oil etc etc. All this time the car has been running fine but as I wanted the sensor light out it was changed. However after changing it out the light came back on almost straight away. The car has been a bit sluggish to start sometimes and sometimes on pulling away from a stop has also been hesitant. 
      This was about 3-4 weeks ago and now it is worse again, at tickover it’s noisy, it doesn’t like acceleration and is running really rough although if you are going over 50mph it doesn’t have a problem and seems to run fine. The EML is now flashing rather than being a solid light. I attach a video of it running.
      Any thoughts would be a help before I decide to get it hauled back across again 



      Sent from my iPhone
    • By Wisefurn1
      Recently had my air oil seperator replaced. At start ran a little rough now runs super rough and wants to stall. Changed 2 pre cat o2 sensors and mass air flow sensor. These are the current codes, 0112, 0300, 0301, 0302, 0303, 1316, 0102, 0130. Prior the car ran perfect and I cant believe I have all those cylinders misfiring because of plugs or coils. Please help
    • By Danny Hammoud
      Unfortunately, I am back with another problem or problems........
      A couple of days ago a check engine light popped up on my 997.2s and because it is my daily driver, I was not able to immediately diagnose the issue. I went ahead and ordered a "Carsoft POR II" scanner off amazon as i thought it would help my understanding in what the problem was. (Getting to the point.....)   Today while I was driving home from class, the car was running very rough. I decided to pull over and give the scanner a go...
      DME CODES;
      P0660 INTAKE PIPE SWITCHOVER FINAL STAGE
      P0153 02 SENSOR AHEAD OF CAT BANK 2 DYNAMISM 
      P2099 A/F  RATIO CORRECT. BEH. CAT. BANK 2 ABOVE RICH CONTROL UNIT
      P2198 02 SENSOR AHEAD OF CAT. BANK 2 TOO RICH SIGNAL
      P0174 BANK 2 TOO LEAN
      P0171 SYSTEM TOO LEAN
      P2196 02 SENSOR SIGNAL BIASED/ STUCK BANK 1 SENSOR 1
       
      Being the person I am, I went ahead and cleared the codes dreaming my problems would magically go away. ?
      About 10 minutes into my commute the codes again popped up but this time, there was something a bit different.......
       
      THE NEW CODES INCLUDED;
      P0174 SYSTEM TOO LEAN BANK 2
      P0171 SYSTEM TOO LEAN BANK 1
      P0306 MISFIRE CYLINDER 6
      P0305 MISFIRE CYLINDER 5 
      P0304 MISFIRE CYLINDER 4
      P0300 MISFIRE - TOTAL ERROR
      P0660 INTAKE PIPE SWITCHOVER FINAL STAGE
       
      About 2 months ago I installed a new O2 sensor bank 1 sensor. While at it, I had a new AOS installed as well ( OEM parts). There are some theories I have in mind but as for now, I am truly stumped on this issue. Does anyone have any experience with this madness?! Thanks for reading! ?
       
      This morning I started my car again and a puff of white smoke shot out of the tail pipes. The smoke did clear up really quick. 
       
      MORE NEW CODES;
      P2A04 O2 SENSOR CIRCUT RANGE/ PERFORMANCE BANK 2 SENSOR 2
      P2099 POST CATALYST FUEL TRIM SYSTEM TOO RICH BANK 2
      P0153 O2 SENSOR CIRCUIT SLOW RESPONSE BANK 2 SENSOR 1
      P2198 O2 SENSOR SIGNAL BIASED/ STUCK RICH BANK 2 SENSOR 1
      P0171 SYSTEM TOO LEAN BANK 1
       
    • By hugo kohl
      1999, 996,  117k miles
       
      Due to leaking I recently changed my coolant reservoir tank, which involved disconnecting and re connecting 2 fuel lines..  Upon restarting the car I had a rough idle and CEL.  I purchased a $100b code reader, read a bunch of stuff online and decided to clean the MAF sensor, change the air filter, spark plugs, plug tubes and coils.    
       
       
      upon today's startup I get an erratic/rough/low rpm idle, flashing CEL and the following codes:
       
      P0102  mass air flow circuit low
      P1319 misfire emission related
      P1318  misfire cylinder 6 emission related
      P1315 misfire cylinder 3 emission related
      P1313 misfire cylinder 1 emission related
       
      Somehow I went from a leaky tank to some bad stuff based on a do-it-myself moment.
      I wonder if the coil packs might not be perfectly seated?
      I'm thinking a new mass air flow sensor and all four O2 sensors need replacing??  
      Please advise.
       
      Hugo Kohl
    • By Los996
      Hello all,
      This is a continuing repair to what started as a camshaft deviation out of spec leading to the replacement of the chain tensioner pads / brake pads / chain ramps on my 2000 911 - 996 5-Chain engine. Seen here:
      That odyssey has since been resolved but I now have a new issue.

      Quick background:
      Removed camshafts, readjusted the camshaft chain timing "marker" positions, replaced tensioner pads, reassembled everything per factory specs.
      On first start up got very rough idle and bad misfires. At first I thought it may have been my timing was off but went back and visually inspected all and all looked correct (visually). Upon further inspection realized parts guy had given me Bosch 7403 plugs instead of Bosch 7413 (2000 Porsche 911).

      Current issue:
      Switched out and installed the correct spark plugs and no more continuous misfires / backfires. Did the initial reset (wait 1 min with ignition on / turn ignition off / wait 10 sec) On the first start up it did misfired / back fired once but I assumed that was left over fuel.

      Car now runs but very rough and threw 2 codes:
      - P0300 : Porsche Fault code 62 - Misfire damaging cat. converter
      - P0301 : Porsche fault code Cylinder 1 misfire damaging to cat. converter
      Also, took these readings:
      Actual angle for camshaft bank 1: -12.53
      Actual angle for camshaft bank 2: 3.05

      On positive note the main reason for doing all this work was the original problem / issue of tensioner / brake pad wear which was giving me a -10 / -2.92 reading is now:
      Camshaft position 1 deviation: 0.00
      Camshaft position 2 deviation: 0.00

      So the question is now are the Actual angle for camshaft readings within specs and could incorrect timing be attributed to these new issues?

      And... Do I have to give the DME time to "relearn"?

      Txs all
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.