boost weirdness
Posted: Thu Nov 13, 2008 5:31 am
Here is one I haven't been able to figure out.
When I first start up the car cold or hot, I consistently get one overboost to 20PSI with fuel cutoff if I don't back off. (It is a fun ride though) Here is the weirdness, after that first overboost it will consistently regulate boost at 5PSI no matter what I am doing. It also doesn't matter how long the duration from startup to the first overboost is. e.g. it takes me 15 minutes from my house before I can get on the car or if I start up running errands and get on it in a couple of minutes it behaves the same.
I should say the car is relatively new to me, but I have replaced a broken piston, done a valve job and any number of other things trying to chase down a rough idle. Including replacing a lot of vacuum, PCV and intake lines and components. I do get 18inhg at idle and 24inhg when decelerating and usually a rock solid 5PSI and a very smooth idle now.
I haven't checked for a restrictor in the line to the boost controller, but I would expect consistent problems with boost if it were missing.
93 SS auto Bone stock with a boost gauge.
When I first start up the car cold or hot, I consistently get one overboost to 20PSI with fuel cutoff if I don't back off. (It is a fun ride though) Here is the weirdness, after that first overboost it will consistently regulate boost at 5PSI no matter what I am doing. It also doesn't matter how long the duration from startup to the first overboost is. e.g. it takes me 15 minutes from my house before I can get on the car or if I start up running errands and get on it in a couple of minutes it behaves the same.
I should say the car is relatively new to me, but I have replaced a broken piston, done a valve job and any number of other things trying to chase down a rough idle. Including replacing a lot of vacuum, PCV and intake lines and components. I do get 18inhg at idle and 24inhg when decelerating and usually a rock solid 5PSI and a very smooth idle now.
I haven't checked for a restrictor in the line to the boost controller, but I would expect consistent problems with boost if it were missing.
93 SS auto Bone stock with a boost gauge.