Unusual boost leaks ?

[MartinF]

So just to add to this I have performed a compression test and a leakdown test.

1 - 180psi - 20%
2 - 179psi - 30%
3 - 180psi - 30%
4 - 179psi - 30%

So at least I know that my engine is in good health even if the mystery thickens about the boost leak.

[MartinF]

So to bring this one to closure, and to help any other poor souls who end up battling with a similar issue......

My car ended up quite consistently building boost to around 14psi and then dropping to around 4psi between 5k -5.5k RPM. So after spending many an hour online researching, pressure testing, reverting back to stock boost control etc, I finally gave in and took it to TDI for them to load up on their dyno.

It turned out to be a broken VTV on the recriculating valve...

As soon as this was bypassed the car held boost fine all the way upto redline.

I am very happy that the issue is now resolved, but for the life of me can't understand how this failure only showed up at 5k+ RPM ... but is definitely sorted.

So as part of the diagnosis i ended up with the obligatory power graph, see below. 208BHP at the hubs is not bad for an old Rev1 engine running a CT20B on stock ECU with Walbro at around 14psi.

[rev2rich]

Nice to see .... Simple things make so much hard work

Unrelated was my car still their lol

[MartinF]

Is yours the grey one ? Didn't look that closely at the other cars but saw a grey MR2 there.

[rev2rich]

Ya that's mine

[mrfil13]

Glad its finally sorted.

Out of interest how did they bypass the recirc valve?

[MartinF]

It wasn't the recirc valve they bypassed but the VTV which helps control it.

Pic showing it bypassed.


And how it should be;

[SonicSW20]

Oh! I just assumed that was in place.

Yes, as you discovered, the VTV is vital to the operation of the BPV!

[MartinF]

Oh yes it was there, but just faulty.

It was bypasssed (as per the first pic) and now holds boost to the redline. Last night I fitted a spare that i had (as would prefer for things to work as Toyota intended) and it did the same thing so seems like I have two faulty VTV's.

Have just ordered a new one.

[SonicSW20]

Was it fitted the right way round? Its directional.

[Ryan S]

Was it fitted the right way round? Its directional.

As above. Switch it around and see how you get on.

[MartinF]

It looks correct to me, black side (port B) towards the gearbox end of the engine.

[steven63]

So to bring this one to closure, and to help any other poor souls who end up battling with a similar issue......

My car ended up quite consistently building boost to around 14psi and then dropping to around 4psi between 5k -5.5k RPM. So after spending many an hour online researching, pressure testing, reverting back to stock boost control etc, I finally gave in and took it to TDI for them to load up on their dyno.

It turned out to be a broken VTV on the recriculating valve...

As soon as this was bypassed the car held boost fine all the way upto redline.

I am very happy that the issue is now resolved, but for the life of me can't understand how this failure only showed up at 5k+ RPM ... but is definitely sorted.

So as part of the diagnosis i ended up with the obligatory power graph, see below. 208BHP at the hubs is not bad for an old Rev1 engine running a CT20B on stock ECU with Walbro at around 14psi.

Image Replaced With URL For Quote http://mkivsupraownersclub.com/images/M ... une-19.jpg

[hojoos]

Sounds like your wastegate might be getting stuck open, perhaps?