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 ?

[Bryan M]

I have an overboost issue with my car - it has been into Unit 4 and had the wastegate checked - it looks to be a standard exhaust and Gav & I can't tell if it has been chipped but it goes like stink up (keeps getting faster and faster) until it cuts out and the EML light comes on - it is difficult to tell where the revs are as the rev counter goes on holiday from time to time

Gav reckons a new hall sensor may help - any thoughts or how do i check if it has been chipped?

[Richmmm]

Elanscan will report the MEMCAL version on one of the first lines, ie 9929, 9930, 1499.

Not sure if the mountain chips changed this identifier number.

Rich

[Rocklobster]

Sounds identical to mine when I bought it. It does sound like your wastegate isn't opening. If it's been checked and you're sure it's free, it may be worth checking that the actuator is doing its job. It tells you how to check it in the Service Manual, it's quite easy.

[TrevorB]

'Merlot' is going back to Maidstone Sports Cars today as despite all the other work which has been done over the past month, which has been explained on the LEC Facebook page, the overboost problem still exists.
I appreciate all the advice and help and will mention the various possible fixes that have been suggested.
I did another paper clip test the other day and since disconnecting battery and running car the only fault code apparent is 24 - Vehicle Speed Sensor, MSC know about this. I get NO engine Management light when problem occurs and like the other problem it is very intermittent.
I am hopeful that the problem will finally be resolved.

[texas2201]

I have an SE and years ago had the overboost problem.... this was after fitting the Peco exhaust and Everest chip and 02 sensor. Fixed by reaming out the Turbo from 16 to 21mm

[TrevorB]

'Merlot' is going back to Maidstone Sports Cars today as despite all the other work which has been done over the past month, which has been explained on the LEC Facebook page, the overboost problem still exists.
I appreciate all the advice and help and will mention the various possible fixes that have been suggested.
I did another paper clip test the other day and since disconnecting battery and running car the only fault code apparent is 24 - Vehicle Speed Sensor, MSC know about this. I get NO engine Management light when problem occurs and like the other problem it is very intermittent.
I am hopeful that the problem will finally be resolved.

After 3 weeks in MSC hands they have contacted me today to tell me that there is a crack in the wastegate housing and they have sent the whole turbo off to a specialist for repair. Fingers crossed for a successful resolution. It's going to be another 3 weeks of anxiety whilst they hopefully fix the issue.
What are the experts thoughts on fixing a crack in the wastegate housing

Trevor