Fluctuating brake pedal pressure affecting car performance

[bigBADbenny]

Get a tactrix and log it.

[Richie]

Thanks will looking into getting one ...

Apologies for the questions but from what I can see with this is that I just plug this into car & it takes readings ?!?!

The garage / mechanic should then be able to read / interpret these for me & this iD the problem !?

Is there a specific programme required to read post recording ??!

Can one be purchased in super cheap auto etc ?!?

[bigBADbenny]

Have a read of this: viewtopic.php?f=56&t=20196&start=0

Reach out to a local member and borrow one, you just need some info from the logs which may help you pinpoint the issue.

In the meantime I'd stop spending any money on the issue, till you establish a repeatable pattern of any type regarding the symptoms.

Then get it logged during that specific condition.

It could be so many things its hard to know where to start.

But go with the basics: fire, fuel, air systems.

If your ecu is not a Hitachi, consider getting tune, you may get some diagnostic info through that process. Kido, west_minist iirc do NA tunes...

[dr20t]

Hey Richie

Without being flippant but most guys on this forum are very sceptical of the abilities of most mechanics (including Subaru themselves) in even diagnosing let alone fixing issues like this

Case in point is your experience to date, as had you not asked on here, most of these mechanics probably wouldn't have checked the map sensor and other suggestions per previous posts

A Tactrix cable needs to be purchased direct from Tactrix inc in the usa. Google Tactrix and also bigbadbenny's signature links above for further info

The scan tool mechanics use won't delve into most issues unless there are error codes which you have stated there are none

What Benny is suggesting is "logging", which is the process of plugging in your Tactrix the car on one end and laptop on the other, and using a programme called romraider to "log" or monitor/ record various ecu functions

This will reveal any discrepancies even when there are no error codes

The reason being error codes and check engine lights are only triggered when set parameters for that particular error / sensor are reached. For example if the map sensor totally failed, if would not register a voltage reading and the ecu would detect this and think something's wrong so bam error code and light. The parameters for low voltage might be say 0.05v for example, which indicates complete or almost complete failure, although a reading of say 0.1v might still cause your engine to run like shit but not register a code / check engine light (cel)

And without knowing what these high / low parameters are for each sensor / ecu function, then its hard to determine exactly what is happening. Which is why logging helps because your exact actual readings can be recorded and compared to what we know are functional values / readings.

One other thing I would suggest is to check your abs module. This ties into your tcu and biu circuit in an automatic canbus car, and therefore may be causing this erratic behavior.

Hope this helps

Mick

[bigBADbenny]

[KiDo_Tuning]

Where do you live? I am happy to take a look at some logs

[bigBADbenny]

Since there is a high/low fuel condition to the symptoms, plus a brake feel component, I cant help but to think of the subaru evaporation control solenoid system:

https://www.google.com/search?q=subaru+ ... CDsQ9QEwAg

You can see here its related back to vac sources from the intake manifold, as is iirc the brake booster system.


And with a casual google around I found this: symptoms-of-a-bad-throttle-position-sensor
http://www.buzzle.com/articles/symptoms ... ensor.html

[Richie]

Hi chaps,

I live in Sydney's East ......would be happy to travel though if it helped resolve .

Agree that I need to stop spending $$ on it but it's just do frustrating - I love driving the car when it's in top mode ......

1 or 2 garages (suburb rose berry especially ) really took me for a rise ........

I'm not very familiar with cars / engines so hard to try figure this out........

[bigBADbenny]

See if you can find what triggers it.
It can't be completely random.