Welcome to 911UK
The only place for Porsche, 911uk is the definitive enthusiast and resource site for the Porsche 911.
Registration is fast, simple and absolutely free, so join up today for full access to the site and benefit from latest member offers.

Porsche Classifieds
Porsche Buyers Guides
Sell Your Porsche on 911uk
Create a Free Classified Advert
Search Ads
Classified Adverts FAQ
Trade Classified Information
Buyer & Seller Fraud Protection
Consumer Rights Act
Pre Purchase Inspection (PPI)
Porsche Car Sourcing
Porsche Cars Wanted
Official Porsche Centre Reviews
Model
Stock
Porsche 911
991 : 2011- 16
997 : 2004- 76
996 : 1997-2005 48
993 : 1993-1998 5
964 : 1989-1993 5
Carrera 3.2 : 1983-1989 0
Carrera SC : 1977-1983 1
930 Turbo : 1975-1989 0
Early 911 : 1964-1977 0
Porsche Other Models
Classic : 1950-1965 0
Boxster : 1997- 18
Cayman : 2005- 15
Cayenne : 2003- 9
Macan : 2014- 1
Panamera : 2009- 1
912-914-924-928-944-968 3
959 - CarreraGT - RaceCar 1
Car Parts For Sale & Wanted
Other Items For Sale & Wanted
Wheels Tyres For Sale & Wanted
Number Plates For Sale Wanted

Porsche Services
Porsche Body Shop Repair
Paint Protection & Wrapping
Porsche Classic Insurance
Porsche Classic Parts
Porsche Classic Restoration
Porsche Design Collection
Porsche Engine Gearbox Rebuild
Porsche Heritage & History
Porsche News
Porsche Picture Gallery
Win a New Porsche 911

Porsche Parts
Body Parts, Body Styling
Brakes, Clearance
Electrical, Exhausts
Engine Cooling, Engine Electrical
Engine Rebuild, Heating Cooling
Interior Incar, Lighting
Rubber Seals, Service Parts
Steering, Suspension
Transmission, Workshop Tools
Early 911, 911 - 930, 928 - 968
964 - 993, 996 - 997, Boxster
Cayman, Cayenne, Panamera

Porsche Model Range
911 [991] 2011-Current
Porsche 911 [991]
911 [997] 2004-Current
Porsche 911 [997]
911 [GT] GT1-GT2-GT3
Porsche 911 [GT]
911 [996] 1997-2005
Porsche 911 [996]
911 [993] 1993-1998
Porsche 911 [993]
911 [RS] RS-RSR
Porsche 911 [RS]
911 [964] 1989-1993
Porsche 911 [964]
911 3.2 1983-1989
Porsche 911 3.2 Carrera
911 SC 1977-1983
Porsche 911 SC
911 [Early] 1964-1977
Porsche 911 [Early]
Boxster & Cayman
Porsche Boxster & Cayman
Cayenne & Panamera
Porsche Cayenne & Panamera

911uk Site Partners

Post new topic   Reply to topic
Author Message
hacka1979
Silverstone


Joined: 29 Nov 2013
Posts: 101
Location: North West


PostPosted: Wed Jul 11, 2018 6:04 pm    Post subject: 996TT rough idle, codes & MOT emissions problem Reply with quote

My car has had an erratic idle problem for a while now which I've been struggling to track down. It runs quite rough when first started and the rpm dips too low and almost stalls after revving the engine or when coming to a fast stop. The idle problem also seems worse once the engine is warmed up.

I eventually got a CEL and read the following codes using Durametric:
P0171
Porsche fault code 360 - Oxygen sensing adaption idle range bank 1

P0174
Porsche fault code 361 - Oxygen sensing adaption idle range bank 2

Things seemed much better after the CEL came on but went back to running rough and erratic idle once I cleared the fault codes. The car then ran rough for the next 30ish miles before the CEL came back on again with the same codes as before. This cycle can be repeated by clearing the codes again.

I initially suspected unmetered air entering the system via a loose hose so did a boost leak test. However I pressurised the system from just behind the air box and it held pressure fine so I don't think that's the issue.

The issue also goes away if I unplug the MAF which led me to suspect that was knackered. So I replaced with a brand new one which initially seemed to help but the problem quickly returned Sad

This has been a minor annoyance for a while but has now turned into a major problem as the car failed the MOT emissions test today with CO and HC values well over the limit and lambda of 0.947 which is just under the acceptable range. The car has been mapped and has a Speedtech exhaust with 100 cell CATs but this has been the case for the last 2 MOTs without issue so I'm sure the failure this time is related to the above problems.

Anyone got experience of similar issues or any advice on what to check next ?
 
  
View user's profile Send private message
   
e92
Monza


Joined: 25 Apr 2016
Posts: 171
Location: Reading


PostPosted: Thu Jul 12, 2018 6:19 am    Post subject: Reply with quote

Unfortunately I don't know the answer to your problem, however I wouldn't boost leak the just after the airbox as that is the low pressure side. The boost leak test should be done and the outlet of the turbo. A good place to ask help on your issue is on the 996 turbo forum on FB, there is a guy on there called Markski who will know what your problem is. thumbsup
_________________
2001 996 Manual Turbo - Markski Remap, 964 RS LWFW, GT3 gearbox mount, Cargraphic Exhaust, 997 GT2 SSK, Forged DV, PSS10 Coilovers, GT3 front brakes, RSS Engine Mounts, Recaro seats, GT3 front control arms, GT2RS Intercoolers
2008 E92 M3 - Sold
 
  
View user's profile Send private message
   
hacka1979
Silverstone


Joined: 29 Nov 2013
Posts: 101
Location: North West


PostPosted: Thu Jul 12, 2018 7:15 pm    Post subject: Reply with quote

Thanks for the advice. I've ordered one of the kits from Markski which will allow me to leak test from down at the turbos rather than behind the airbox. I also think this approach will identify problems that testing from behind the airbox doesn't (eg. #16 check valve).
 
  
View user's profile Send private message
   
e92
Monza


Joined: 25 Apr 2016
Posts: 171
Location: Reading


PostPosted: Thu Jul 12, 2018 9:26 pm    Post subject: Reply with quote

Did you ask him what he thinks the problem could be? I hope you don't have to change the #16 check valve, I had to change mine 2 years ago and it was a pain to get to. Good luck Thumb
_________________
2001 996 Manual Turbo - Markski Remap, 964 RS LWFW, GT3 gearbox mount, Cargraphic Exhaust, 997 GT2 SSK, Forged DV, PSS10 Coilovers, GT3 front brakes, RSS Engine Mounts, Recaro seats, GT3 front control arms, GT2RS Intercoolers
2008 E92 M3 - Sold
 
  
View user's profile Send private message
   
hacka1979
Silverstone


Joined: 29 Nov 2013
Posts: 101
Location: North West


PostPosted: Wed Jul 18, 2018 10:07 am    Post subject: Reply with quote

I've asked the question on the FB group so will see if anyone's got any ideas there. Just waiting for the testing kit to arrive from the Markski so I can properly leak test. Fingers crossed it will be something simple!
 
  
View user's profile Send private message
   
deMort
Shanghai


Joined: 21 Mar 2015
Posts: 4779
Location: Brighton


PostPosted: Wed Jul 18, 2018 6:35 pm    Post subject: Reply with quote

The fault codes relate to a weak mixture on both banks , the car is adding more fuel to try and maintain Lambda but has reached the maximum amount of fuel it can add and so has flagged a code saying so.

All cars compensate for small leaks or general wear and tear , owners will never realise untill they go out of limits .

The car opens the injectors for longer to give it more fuel .

Lambda = correct fuel / air ratio.

So .. couple of things which you are already on top of ..

Air leak and on a Turbo theres all the intercoolers to consider as well so a smoke test there .

Maf sensor contaminated .. i would look at the voltage readings for the sensor but perhaps a clean of the sensor might be in order , actually you have replaced it so ignore that .

Any type of oil based air filter can cause issues with the maf .

Exhaust blow , air getting into the exhaust near the pre cat lambda sensors will confuse it .

There are other things but we are moving into the unusual category so ill not go there yet .


EDIT ..

When you clear the fault codes the car resets the adaptions .. it WILL run like a sack as its way to lean at that point .. the car will slowly adapt and give more fuel untill it reaches its limits and flags a code plus eml light .
_________________
Mechanic

7pm - 9pm
At an Indy these days !
 
  
View user's profile Send private message
   
Display posts from previous:   
Post new topic   Reply to topic   All times are GMT - 12 Hours
Page 1 of 1

 
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum
You cannot post calendar events in this forum