Overboost

[Steve A]

Good investigative work there Trev,

[TrevorB]

OH NO! Problem back. Took 'Merlot' for a drive tonight and was going fine even pushed it for my outward drive and everything good but that intermittent problem came back on the return journey. I'm not even really pushing just a gentle throttle increase until I reach 4000 rpm and then boom the dreaded overboost. Frustratingly she drives beautifully outside of this issue. Back to the drawing board, think porting the wastegate may now be needed.
I'm now away for a couple of days but on Sunday I will do the 'paper clip' test to see what codes are stored in the ECU. Then get back in touch with MSC next week.
Will update you as soon as I have any more information.

Trevor

[Tuga2112]

Trevor,

have you made sure the boost solenoid valve rod moves freely in both directions ? i know its the first thing to look at,but sometimes people forget the obvious, i'm wondering if there may be some rust getting it stuck but only sometimes ? which would explain why only after heating p the engine and cooling a little made it happen.

I had that issue on mine many moons ago, and i used sandpaper to get rid of the rust and brake fluid to "lubricate" the rod. (i know, not the right fluid, BUT its a very heat resistant fluid, and what i had at hand back then) and the issue with the valve never returned in 7 years.

[TrevorB]

Trevor,

have you made sure the boost solenoid valve rod moves freely in both directions ? i know its the first thing to look at,but sometimes people forget the obvious, i'm wondering if there may be some rust getting it stuck but only sometimes ? which would explain why only after heating p the engine and cooling a little made it happen.

I had that issue on mine many moons ago, and i used sandpaper to get rid of the rust and brake fluid to "lubricate" the rod. (i know, not the right fluid, BUT its a very heat resistant fluid, and what i had at hand back then) and the issue with the valve never returned in 7 years.

Whereabouts is this rod? Or are you talking about the wastegate wiggle?

[Tuga2112]

Trevor,

have you made sure the boost solenoid valve rod moves freely in both directions ? i know its the first thing to look at,but sometimes people forget the obvious, i'm wondering if there may be some rust getting it stuck but only sometimes ? which would explain why only after heating p the engine and cooling a little made it happen.

I had that issue on mine many moons ago, and i used sandpaper to get rid of the rust and brake fluid to "lubricate" the rod. (i know, not the right fluid, BUT its a very heat resistant fluid, and what i had at hand back then) and the issue with the valve never returned in 7 years.

Whereabouts is this rod? Or are you talking about the wastegate wiggle?

yes, im talking about the wastegate wiggle XD i forgot the comon name for it

[TrevorB]

Completed the 'paper clip' test and codes 24 and 33 are indicated:
24 Vehicle Speed Sensor
33 Manifold Absolute Pressure Sensor (High voltage / Low vacuum)

Is there anything I can do to resolve these issues, although I very much doubt it with my lack or mechanical expertise, or what can I tell MSC tomorrow when I ring them?



Trevor

[TrevorB]

HOW FRUSTRATING!
Took 'Merlot' for a drive just to confirm problem still there. Yes, you've guessed it. No problems on this drive. What am I supposed to do with this annoyingly intermittent problem?
Ahhh!! Grrrrr!!

Trevor

[Tuga2112]

What am I supposed to do with this annoyingly intermittent problem?

check for ground wires badly connected maybe ? im just throwing guesses here, but intermittent flaws generally go in that direction

[Fredjohn]

Surely you know the answer Trevor....give it another polish!

[TrevorB]

check for ground wires badly connected maybe ? im just throwing guesses here, but intermittent flaws generally go in that direction

Spoke to MSC and they want the car back to investigate further. I mentioned the above and they will look at all options.
Can't get her in just yet as I have some shows to go too.
Take care
Trevor

[Tuga2112]

Trevor,

do you get any dashboard lights flickering when this happens ?

[TrevorB]

Trevor,

do you get any dashboard lights flickering when this happens ?

I do look at Engine Management light but NO nothing shows. Obviously working because I did 'paper clip' test.
It's very strange as so intermittent. I'll be taking her out again sometime this week so we will see if it reoccurs.

[Tuga2112]

ive had an intermitent issue after the head gasket change which was giving odd behaviour of the car while driving, under unpredictable circustances it would "choke" flicker the dashboard lights in the samer maner they do when you first plug the key, and then it would proceed to operate as normal.

i eventually found out there was a grounding wire at the rear of the engine that was not attached properly. (the bolt was not snug enough and every now and then with the engine vibrations it would completely cut off power to the ECU

not exactly the same symtpoms with exception that it was unpredictable, and performance related, but i guess also worth a look maybe ?