Boost spike...Is this normal?

[HouTX87]

Hey guys, I have a stock turbo with an adjustable wastegate actuator recently installed. Stock downpipe and stock intercooler. I've been tuning the car and on pump gas I've been limited to 15-16psi with no knock (ambient temps in the high 80's), but when I first go to WOT and the turbo spools the boost will spike to around 19-20 psi and then settle back to 15-16. Once it settles it does not creep back up. Is this normal or am I overlooking something? I had it turned up to 20 psi a few weeks ago on 100 octane and did not notice boost ever showing above 20. Now that I've had to decrease the boost again I've noticed this.

 

[HouTX87]

Anyone?... I had hoped this would be an easy question.

 

[jasjamz]

Check and replace vacuum hoses to the wastegate, compressor hosing and boost solenoid on the passenger side valve cover. Dry rotted or cracked hoses seep pressure and cause issues.

 

[CGASTON]

Have you or did you change your DP?

Sent from my iPhone using Turbo Buick

 

[SHADOWII]

Are you sure there is no knock at the 19/20# mark retarding the timing? Try adding the 100 octane again and see if it goes away after vac. inspection.

 

[HouTX87]

No knock at all when I had 100 octane in the tank and 20# boost. I only noticed the boost spike when set to 15-16 on pump gas. It only spikes when the turbo first spools. DP is stock with cat delete and flowmaster catback. I definitely need to replace the vacuum hoses, they are dry rotted.

 

[HouTX87]

I've been planning to buy the silicone vacuum line kit from gbodyparts, guess I need to move that to the top of my shopping list!

http://www.gbodyparts.com/product_info.php?products_id=66&osCsid=44571be351b6d9d5b66f9d97fd701795