Boost spiking. Where to start?

When setting up manual boost control it helps to keep the length of tube between Dawes/Tillix as short as possible. Got a pic of your setup?

fix the known busted stuff first and go from there or they will distort any setting changes you make.

Unscrew the Dawes valve a bit as you obviously don't have it set to 20psi max.
Digital gauges are also generally too slow to give you accurate spoolup readings as they are always playing catchup due to limitations in the display. (Will generally be accurate when using it for data logging)
Many gauges show higher maximum boost readings than what it really is.
Did the previous owner play with the settings? If it was put on a dyno after the remap. What did the tuner set it to?
Depending on the age/generation of the Dawes valve. It is very possible that the spring is no longer strong enough to contain the boost to set levels.
Try opening the needle valve a little bit to slow the spool rate in order to limit overrun.

Sent from my SM-S901E using Tapatalk

I have the 14 in 1 JRP gauge and have set my Tillex to 20psi max boost pressure. I test drove the car today with new upgraded HPD Ebay copy intercooler, I also have the BAET mail in tune. Occasionally I will see a spike around 20.6 on the gauge. Have set the boost alarm to 22psi in the 14in1 settings. The boost gauge seems to react quite quickly.

read the last posts of this thread if you want to learn more about your VNT. and also the one dawes-two needles thread.

Thanks for everyone's help and sorry for the late reply. I consulted the workshop that tuned the car and it was recommended to me that the dawes valve is likely worn out, so I've ordered a tillix kit. I'll fit that and see what happens. Cheers

Jako4537 said:

Thanks for everyone's help and sorry for the late reply. I consulted the workshop that tuned the car and it was recommended to me that the dawes valve is likely worn out, so I've ordered a tillix kit. I'll fit that and see what happens. Cheers

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Interesting, not much in there to wear out, ball and a spring. It is possible for the seat to be contaminated so a strip down and clean often helps, there is a how to among my chanel video clips.

geeyoutoo said:

Interesting, not much in there to wear out, ball and a spring. It is possible for the seat to be contaminated so a strip down and clean often helps, there is a how to among my chanel video clips.

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Ah didn't know that. That's alright, I've heard tillix is better anyway

Jako4537 said:

Ah didn't know that. That's alright, I've heard tillix is better anyway

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Not better, I've run both over the years and didn't find a difference, they both work on the same principle. By all means fit the Tillix but don't throw the Dawes away, pull it apart and have a look and maybe learn something.

Jako4537 said:

Ah didn't know that. That's alright, I've heard tillix is better anyway

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Nothing wrong with Dawes 3barracing (black body). Sounds like someone trying to find fault in the tool and not ones own work.

Do back to back comparisons (Dawes against Tillix) but with the one you choose, try fitting a second needle valve fitted down stream of chosen boost controller. Set boost controller (Dawes/Tillix) at say 10-12 psi and then the 2nd needle downstream at 20psi.
Fresh air pick up needle valve adjust for lever to just touch stop screw. Hear back from you maybe.

Hewylewy said:

I have the 14 in 1 JRP gauge ...The boost gauge seems to react quite quickly.

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Hi Hewylewy, a few questions about the JRP 14-in-1 as a gauge set to support the Tillix installation :
1. Which sensors did you install? and how easy was the overall installation (sensors, gauges, plumbing/wiring)?

2. How responsive are the gauges? and how accurate do they seem?

3. Where have you placed the monitor screen?

4. Any other comments on this gauge?

Thanks

Thanks for that info, very helpful. I want to sort out gauges before I start down the Tillix/3-needle road, so that I can compare 'before' with 'after', but don't want to spend $600-800+ on good-quality individual gauges for EGT, boost etc.