So, i had a feeling that i had a boost leak because a few weeks ago i noticed a loss in power so I just installed a boost gauge. At idle the vacuum is only around -13. I know that is should be around -18 or so when stock correct? So, I checked all of my air hoses to the turbo and intake mani and couldn't find any holes/cracks or anything disconnected.

Any idea what else to check before doing a complete boost leak test as I don't yet have the tools or time for this?

Just FYI just in case these mods may change anything with the vacuum.
I have: turbo back exhaust w/ down pipe and a
K&N intake with upper and lower inter cooler piping.

Please help, any ideas are appreciated!

 

my stock evo vacuum is -20

 

https://www.evolutionm.net/forums/ev...er-5-02-a.html

Make this. Extremely useful! set the compressor to around 5 more psi than you're running.

 

I hadn't seen that before..... that's brilliant.

 

thanks, yea i have read several cases of it being anywhere from -18 to -20 or so

 

Wow that is extremely useful and i will do this probably this weekend as soon as i have time thanks!

But... does anyone have any answers to my questions, the how to is helpful on how to create the tool but doesnt answer my other questions???

When i do the boost leak test i will just search another how to so no need to worry about explaining how to do that as i know that there is plenty of info already out there on the procedure.

 

Bump

 

have you check your vacuum hoses and clamps?

 

Yes I have and couldn't find anything loose but it was just a quick check and I need to do a complete boost leak test with soapy water being sprayed around all joints/fitments.

Also my maximum boost is at about 12psi. The guy I bought it from said he had the boost turned down but I'm not sure if he would turn it down this far.
My question: would the turning down of the boost change the vacuum at idle OR would the boost leak cause the boost to be lower than it was actually tuned to, say turned down to 15psi but reading 12 as it is right now???

 

You are running wastegate pressure right now. Don't overthink it or do what if's until you boost leak test it. Changing the boost settings will not affect idle. Mine idle's -14 to -18 depending on the day. Not all boost gauges are perfect, your idle vacuum seems fine unless it is running real rough.

 

mines at 19 with the same mods hopefully u fix it

 

I'm at -17/18 at idle. You probably do have a boost leak. Check all of your intercooler pipping couplers to ensure they are well fitted and properly clamped. Also check your intake for the same problem. What are you using to control boost atm. I'm using an AEM Tru Boost and I'm around 12-13psi with it off. With it on I'm at 21psi.

 

Well it's running a bit rough/ rich but that's a different problem, It needs a tune/reflash and I plan to buy a a/f gauge as well as a tactrix cable soon but again, this all comes down to money, and especially with the tune, time.

I'll run a boost least test in the next week or so if I have enough time off of work

 

Unfortunately i am not running anything for boost control atm. I plan to buy a Hallman Pro RX soon but until i have the money that will have to wait. Plus i believe i need to do a complete boost leak test before i bother changing the boost manually so first i will do that, then tune engine/adjust boost.

for the other comment on boost gauges not all being correct (above this quoted comment) i am using an autometer cobalt series 30/30 boost/vacuum gauge im pretty sure that autometer is extremely reliable

 

what cams are you guys running? I'm around 12-14 in either Evo I had with Kelford and HKS 272s


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