ToyoCel

My car was tuned at 8 psi. I noticed today however that when im at max boost it jump to 10 or even 11. What could cause this and is it something to worry about. It only happens sometimes. Thanks for your help.

gingles

iTrader: (1)

its called boost creep.....are you running off wastegate pressure or do you have a boost controller?...what did your afrs look like at the higher psi?....i had a 5 psi spring and it would creep up to 8

ToyoCel

Im new to boost so i dnt really understand your first question. I know theres a hose that goes from the compressor housing to the wastegate. Is that what your refering to? I havent installed my AFR gauge yet so im not sure whats going on with that. Any advice? And what is boost creep? How bad is it for my motor?

jsg93085

from how you have described it, you are running off of wastegate pressure

boost creep is the inability of the wastegate to regulate exhaust gases entering the turbine side of the turbo. this inability causes the turbo to spin faster, thus creating more boost. to solve boost creep you will either need to get a bigger wastegate or a new manifold that positions the wastegate in a different part of the exhaust plumbing...

i am not suggesting a boost controller as a solution because a lot of tuners see this as just a band-aid. but to each their own...

btw, i have the worst creep, 10 psi on a 4 psi spring...

oh and get your wideband installed pronto, that will let you know if your engine is leaning out when it hits 10 psi or not (which is bad, as in motor going "pop" bad)...

ToyoCel

What the spring you guys talk about? If the wastegate is the problem, why wouldnt turbonetics make them with the correct size wastegate? What kind of wastegate should i go with or manifold? Thanks again! I dont want to go "pop" again. Already happened once.

Ace83

iTrader: (6)

1st from what you described boosting on 8 psi then goes like 10 then 11, yeah its boost creep as mentioned..

is it bad? depends but not necessarily bad as long as the higher boost level you creeping is tuned to be safe or optimal and is not too much for the motor to take.. 10-11 psi if fine on stock motor as long as tune to those boost levels are fine

and as mentioned, boost creep results when you are not dumping enough exhaust gases to keep the turbo from over spinning to a certain rpm to build a certain amount of boost..

in other words, the lesser exhaust dumped --> more exhaust going to the turbo
more exhaust to spin the turbo --> more boost

creep occurs in different ways.. like using a big turbo on low boost with a small wastegate, manifold design, faulty wastegate, faulty/ineffective boost controller, too restricted exhaust dump

wastegate spring is what we are referring to, different wastegate spring pressure gets you different boost levels.. stiffer spring more boost

20tCDude05

Happened to me once, went from 10 lbs to 14 lbs. Felt good, but it was the wastegate actuator hose. It touched the manifold and burnt a big hole in it.

ToyoCel

Someone should make a section for common problems and solutions for boosted tC's. It would be alot of help for noobs like me. I use the search button but sometimes it doesnt bring up what I need.

Ace83

iTrader: (6)

^^ its just hard to make it possible.. forced induction issues is so broad, many of them are flagged in stickies and many are not