Rough Idle and Btssm data logging

Posts specific to the 2.0 litre Turbo engine

Rough Idle and Btssm data logging

Postby dean_026 » Thu Feb 06, 2020 10:27 pm

Hi all, experiencing a rough idle in my 03 Liberty Gt Auto.
Seems to get a lot worse sitting at the lights in gear at operating temperature.

I've fitted a new front O2 sensor a couple of months ago to fix another issue, fitted a Kobe motorsport silicone intake pipe, checked it for vacuum leaks, cleaned the MAF sensor, I've removed all my banjo bolt filters and cleaned all of the OCV's. There's no fault codes.

Also recent maintenance includes, new air filter and throttle body clean, new timing belt kit, spark plugs and in tank fuel filter. Rough idle was a problem before the timing belt replacement, and the timing is correct.

Running out of ideas as to what to do next to try and fix this thing. I've downloaded the Btssm app and ordered a cheap vagcom kkl cable with USB adaptor to connect to my android phone. I was going to try and do some data logging however I can't get the app to recognise my vehicle.

Does anyone have any ideas about what to check next or how they have gone about connecting/logging with the Btssm app?
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Re: Rough Idle and Btssm data logging

Postby bigBADbenny » Fri Feb 07, 2020 7:34 am

Basic Btssm info link in my signature.

Logging and LV can help pinpoint the issue.

Checking basics related to the air/fuel/fire triangle can help, eg inlet tract pressure test with smoke or bubbles.

Try Sharpie’s uec fuel rail soak and or source new injectors, inspect and replace inlet manifold gaskets at the same time. That’s the gaskets above and below the injector housings (aka tgv bodies on thus equipped cars).



viewtopic.php?f=17&t=36178&p=446851#p446851


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Last edited by bigBADbenny on Fri Feb 07, 2020 7:45 am, edited 1 time in total.
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Re: Rough Idle and Btssm data logging

Postby bigBADbenny » Fri Feb 07, 2020 7:42 am

Specifically what vagcom?
I recommend a clear blue case vagcom from an Australian Ebay vendor (in case return is required).

Your android must support otg (use the OTG? App on playstore to confirm this).
Then you set the appropriate adapter in Btssm settings. Probably k line or similar.

If your ecuid is not recognised, use an ecu alias as per the instruction manual.

In Romraider you’d use a defined ecu id one number or letter different to your ecu id, might be similar for Btssm but an alias usually works.

If you’re still stuck you may need to play with android USB permissions, toggle Developement mode, etc.
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Re: Rough Idle and Btssm data logging

Postby dean_026 » Fri Feb 07, 2020 2:20 pm

Thanks for your reply, a few more things to try there. I've uploaded a photo of the vagcom cable I bought, is this the correct one? Would you have a link to the specific cable you recommend?
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Re: Rough Idle and Btssm data logging

Postby bigBADbenny » Fri Feb 07, 2020 2:43 pm

Yep that’s the one :good:

So try the connection type selection in Btssm app settings.

Take a peek at the Btssm PDF instructions on the Btssm com website.

Then if you’re still stuck, have a play with USB permissions or developer mode etc.
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Re: Rough Idle and Btssm data logging

Postby bigBADbenny » Tue Feb 25, 2020 8:26 pm

But to address your issue, inlet leaks, I guess they can affect idle.
But on the pre 05 Gt’s, the injectors were a known issue fixed in later models.

I’d try getting the injectors cleaned, replace the upper and lower inlet manifold gaskets or try sharpie’s uec fuel rail trick:
viewtopic.php?f=17&t=36178&p=446851#p446851
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Re: Rough Idle and Btssm data logging

Postby BlessedKarma » Wed Mar 01, 2023 9:44 am

I was having major idles issues for months, had random codes being tripped like Throttle Acuator Control Bank 1,Camshaft position, Manifold absolute pressure etc.
But after driving and turning the car off and on the code went away.
The worst part was my idle dropping and spiking and hunting... it would drop to 300 or 400 RPM and then shoot up to 1200RPM and back to 600 and was bouncing all over the place.

After months of checking electrical connections and sensors i took off my TMIC and found that the mechanic who replaced my slave cylinder hose left a major hose off from the cold side of the turbo into the BOV... i connected the hose again and after months and months my idles was back to perfect.

not sure if this helps your situation but this was the issue when my idle was rough and hunting.
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Re: Rough Idle and Btssm data logging

Postby bigBADbenny » Wed Mar 08, 2023 4:38 pm

Absolutely, and an inlet pressure test, especially with smoke, would get to that leak if you couldn’t get to it via a visual inspection.
viewtopic.php?f=6&t=36513

Personally I use heat shrink and or tiny zipties on all unsecured pressure reference hoses: boost control solenoid, fuel pressure regulator, map sensor and its pressure damper.

Here’s the updated how to log post:
viewtopic.php?f=6&t=36932

Still amazes me that a boost control issue can cause a TPS code, yet not surprising since we have drive by wire idle control.
You’d hate to be a parts swapper and not realise.
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