Overboost on stock BF1

[rjn]

So, looks like I have an overboost problem. I will take it to a mechanic shortly but just interested in a couple things.

 

Still completely stock, except for springs and shocks, bought new for the missus June 2006 (130km) and has been faultless for all these years.

 

I noticed it overboosting a few weeks ago, which is very enjoyable until it would go into limp home mode. A simple turn off and on again fixes it. Has been in for a service, found some intercooler pipes a bit loose, tightened up which helped but it's still overboosting and cutting out (fuel?) now and not going into limp so much more manageable.

 

Attached a Jaycar OBD reader, installed Torque Pro and if it's reading correctly it's cutting out at 12psi which I believe is way over the 6-7psi for standard?? There is a fair bit more (what I think is) turbo noise too.

 

It never gets there when the missus drives it (at least that I know of!!) so really only a problem for me.

 

So, couple questions;

 

How accurate is the Torque Pro when reading the boost? It will run between -12 and +12 (+12 is where it cuts out)

Have done a bit of research and it seems actuator and split hoses can cause these issues, anything else to look at?

The "tune" folk talk of, is this possible on stock gear? If not, what's required?

If we leave it as it (I do quite like the extra go :-) ) what damage will it cause if we occasionally hit 12psi?

 

Last but not least, any recommended mechanic\tuners in the area Gladesville to Paramatta?

[k31th]

1. No idea how accurate it is, but it is only as accurate as the sensors it's connected to, so you'd imagine it's quite accurate for boost as the stock sensor needs to be very accurate for the PCM to control the boost.

2. Firstly check the hose from the turbocharger front housing nipple to the boost solenoid and then from the solenoid to the actuator nipple and make sure there's no leaks from these two hoses to check on this issue.

3. Overboost can happen on a completely stock vehicle easily, so only a minor mechanical failure (split hose, loose hose etc) can cause overboost... along with a couple of other possible major mechanical failures (stuck wastegate etc) that can cause overboost.

4. If you leave it as it is and it's not tuned for it, overboost WILL DESTROY YOUR ENGINE. If you don't have or want to spend the money to replace it, then you should not hit boost until it's sorted.

 

The "cut" you speak of is the engine protection systems stopping the boost from building any higher to ensure your engine doesn't grenade in a situation it knows it cannot supply enough fuel for.

[rjn]

Thanks K31th, that's great info and somewhere for me to start looking.

 

Is it tuneable with stock gear or does it need something else attached?

[k31th]

stock gear is tune-able, yes.

[4321]

Check that the turbo actuator diaphragm is not leaking, not uncommon fault with cars this old. It needs boost to open the waste gate & if the actuator is leaking it needs even more boost before it opens & starts bypassing the exhaust flow. Like k31th said, leave it at your own peril