Boost Spikes to 24-25 psi

TheEvolutioner · Jan 7, 2008, 03:41 PM

I've notice sometimes only in low gear (2nd, 3rd, sometimes 4th) that my boost spikes to 24-25 PSI then shoots down to 20-21 PSI. On high gears, 5th and 6th the boost is on target, 22.5 psi then tapering to 21 psi. Any reason for this??? Has this happen to any one running stage 2 93 octane?

Thanks
Jason

Chris @ COBB · Jan 8, 2008, 10:56 AM

Give us a little more information if you would. What engine mods to you have on the car? What part of the country do you live in (i.e. what elevation are you at)?

**MR Turco** · Jan 8, 2008, 10:58 AM

His location is queens so he should be at sea level. I would assume it is from the cold weather. 24-25 spikes should be ok on pump gas. I have never seen knock up to 24psi spikes.

CPA5 · Jan 8, 2008, 11:04 AM

Im running stg2/91oct .....tucson az...about 1800-2400 elevation

COBB TBE, Nisei ICPIPES, Okada Coils, WORKS filter

in 3rd/4th/5th I have been consistenly hitting above 21.5 psi....my gauge has the light come on at 22psi for warning....in those gears when at WOT it never stays below or on target...the highest reading so far from a couple weeks ago was 23.75psi.....from another thread ROB said this was okay.....and at wot I haven't ever seen any knock...maybe 1

BUT.........the other nite going up a little hill in fourth gear at around 3200 rpm at less than half throttle.....I pinged a 6 count on knock...WTF!!!!!!!!!!!!!

Should I be concerned about that?

IX Lives '08

TheEvolutioner · Jan 8, 2008, 06:08 PM

Quote:

Originally Posted by Chris @ COBB

Give us a little more information if you would. What engine mods to you have on the car? What part of the country do you live in (i.e. what elevation are you at)?

Chris, I am running the stage 2 93 octane with cobb TBE, cobb intake, megan O2 housing. I notice this about two days ago. 1st gear hit about 15psi then I shifted to 2nd, the boost spiked to 25psi then shooting down to 21psi and holding then I shifted to 3rd gear, boost spiked again to 24-25psi then quickly shooting down 21 and holding, then 4th, 5th and 6th gear is normal to 22.5 psi tapering to 20.5-21psi. It's fairly warm out for this time of year, about 60 degrees, but 2 days ago it was around 50 degrees. Could it be the weather changing so fast?

turbo271 · Jan 18, 2008, 06:04 AM

I got the AP a couple of days ago, and I have the same problem. I'm pretty sure that it is a boost leak. The trick is finding it.

I haven't seen any knock either, so no biggie. Just gotta fix the boost leak because sometimes it fluctuates down to about 17 psi and then back up to 21. but only at around 4000 rpm.

Rob@cobbtuning · Jan 21, 2008, 11:05 AM

Quote:

Originally Posted by CPA5

Im running stg2/91oct .....tucson az...about 1800-2400 elevation

COBB TBE, Nisei ICPIPES, Okada Coils, WORKS filter

in 3rd/4th/5th I have been consistenly hitting above 21.5 psi....my gauge has the light come on at 22psi for warning....in those gears when at WOT it never stays below or on target...the highest reading so far from a couple weeks ago was 23.75psi.....from another thread ROB said this was okay.....and at wot I haven't ever seen any knock...maybe 1

BUT.........the other nite going up a little hill in fourth gear at around 3200 rpm at less than half throttle.....I pinged a 6 count on knock...WTF!!!!!!!!!!!!!

Should I be concerned about that?

IX Lives '08

You should be ok, but have Steve take a look at that area of load when you get ProTuned.

Thanks,
Rob

CPA5 · Jan 21, 2008, 11:16 AM

Quote:

Originally Posted by Rob@cobbtuning

You should be ok, but have Steve take a look at that area of load when you get ProTuned.

Thanks,
Rob

Rob--thanks for answering.....now that I get to view this knock stuff I must admit it has made me more paranoid

.....im sure when the car was stock and I couldn't see that value it was worse.

Stephen is aware of this light load higher knock issue....I'm sure he'll be able to tweek here and there to make it better.

I hope to get tuned asap