2 questions about me boosting

[4BangerV8Killer]

one is when im off throttle i am at -20 vac but if i put it in neutral then i go down to -15 vac is that bad or what could it be a vaccum leak? and another thing is when i hit my full 14lbs of boost my car sputters nothing before that but as soon as i hit full boost at WOT i sputter other than that i run perfectly what could that be? started doin it right after i was topping out my car one night (stupidity)

 

[Defiant]

one is when im off throttle i am at -20 vac but if i put it in neutral then i go down to -15 vac is that bad or what could it be a vaccum leak?

You've removed the weight of the coasting car driving the pistons to try and suck air against the closure of the throttle plate.

Don't coast in neutral. Ever.

 

[4BangerV8Killer]

could you put it in lamens terms thx

 

[doodie]

Have you check your plugs and wires? Do you have a CEL? Might be your CAS.

Defiant - can you explain on why you shouldn't coast in neutral?

 

[4BangerV8Killer]

its not my plugs most likely not my mas the wierd thing is if im idleing my vac goes from-20 which is normal when im off throttle but it i put in the clutch or put it in neutral i got down to -15 vac

 

[oldman]

You 've already kindda answer your question, If you suspect a leak just do a leak test.

 

[4BangerV8Killer]

gona do a compression test in a few minutes and reset the ecu what else could it be?

 

[oldman]

Compression test and boost leak test are different but sure, why not do them both.