Strange boost figures

[Bad-Trol]

I'm starting this tread based off a thread I had going about black smoke from my exhaust... The black stuff is sorted, but during test drives and a campin trip I stumbled upon the following situation..

If I'm cruising under 100kph, boost is sitting around 14-15psi, if I increase the speed and cruise around 110kph, the boost drops to about 6psi. With the higher boost I had low EGT's, with the low boost high egt's, and climbing hills put me well over 550C; this all resulted in me sticking to 100kph for the trip.

One suggestion is that with my blocked EGR, the ECU will try to divert gases thru it, and reduce boost (that's how I understood it).

Any ideas? How can I fix?

I have a Dawes valve fitted with no needle valve. EGR blocked. Dawes screwed in almost all the way.


Bad-Trol: 2004 GU3 ST-L. Sent from my iPhone

[Lieney]

I have yet to decide that 'more heat will be created because EGT is blocked due to increase in air / fuel', or
less heat created due to recirculating already burnt mixture. I have found many threads supporting both sides of the argument. I figure that recirculating already burnt, yet hot gasses will increase EGTs. Mine has a 3" pipe straight after turbo outlet. This can help with cooling.
More pressure and air, more flow, maybe faster removal of gasses and lower EGT?
If it has the VVT like mine, I experience the same / simliar issues travelling at 100-110kph in that turbo boost increases and decreases in a similar manner that you state.
I have to watch the boost gauge at present and I back off slightly when it gets upward of 18psi, then push the accelerator again and boost drops after a quick flick.
I have read the Patrol reference document regarding adjustment / testing the VVT and setting the boost and this sounds like something you might like to try. I am not familiar with the Patrol VVT and the way it is connected and reacts to different sensors and signals etc, although understand its function.
Anyone got a wiring / plumbing diagram of how the ECU and turbo work, please let me know.
Have you got a 3" pipe???
I do not have EGR blocked, nor do I have EGT gauge or dawes valve. Dawes and EGR installed next friday so I will be able to compare current issues.
Not sure if this helps, but hope it triggers a spark in your mind

[Bad-Trol]

Cheers for the thoughts. I have 2 3/4" mandrel bent exhaust. Once the EGR is blocked AND running Dawes (which is my current setup), there is no need to adjust VVT (as I understand it).
Let us know your EGT figures once you have it installed.
I've ordered a Needle Valve and will bypass the control solenoid completely which should solve the problem, but would still be interested in seeing comparisons.

Cheers


Bad-Trol: 2004 GU3 ST-L. Sent from my iPhone