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.
Unusual boost leaks ?
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Re: Unusual boost leaks ?
Blue Lexus RCF
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Re: Unusual boost leaks ?
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.
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.
Blue Lexus RCF
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Re: Unusual boost leaks ?
Nice to see .... Simple things make so much hard work
Unrelated was my car still their lol
Unrelated was my car still their lol
Re: Unusual boost leaks ?
Is yours the grey one ? Didn't look that closely at the other cars but saw a grey MR2 there.
Blue Lexus RCF
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Re: Unusual boost leaks ?
Glad its finally sorted.
Out of interest how did they bypass the recirc valve?
Out of interest how did they bypass the recirc valve?
Re: Unusual boost leaks ?
It wasn't the recirc valve they bypassed but the VTV which helps control it.
Pic showing it bypassed.
And how it should be;
Pic showing it bypassed.
And how it should be;
Blue Lexus RCF
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Re: Unusual boost leaks ?
Oh! I just assumed that was in place.
Yes, as you discovered, the VTV is vital to the operation of the BPV!
Yes, as you discovered, the VTV is vital to the operation of the BPV!
Re: Unusual boost leaks ?
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.
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.
Blue Lexus RCF
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Re: Unusual boost leaks ?
Was it fitted the right way round? Its directional.
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Re: Unusual boost leaks ?
SonicSW20 wrote:Was it fitted the right way round? Its directional.
As above. Switch it around and see how you get on.
Re: Unusual boost leaks ?
It looks correct to me, black side (port B) towards the gearbox end of the engine.
Blue Lexus RCF
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
Black MKIV UK Manual Supra
Green MK2 MR2 Tin Top
had 250whp on a rev2 with those mods
MartinF wrote: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
Re: Unusual boost leaks ?
Sounds like your wastegate might be getting stuck open, perhaps?