You have two things to think about:

1. Is your BCS/BCA providing full boost? If not, is it because of a mechanical problem or the PCM determining there is a need to LIMIT boost?

2. Your MAP sensor is reporting an incorrect value or you have a vacuum leak in that circuit.



I'm thinking we need to move your topic to Forced Induction for further troubleshooting and verification. Are you up to a little work?

how many miles on the car?

stock is 7psi. are you using the original belt?

i have 154500 miles. no SES light. the bcs/bca valve is operating properly. full movement. i checked all vacuum lines. and i do have stock belt. im changing that tomorrow to a shorter belt to see if that helps.

95riviera- trust willwren on this.
The very first thing you need to do now is get a scan tool and check KR. I almost bet you get getting a good amount even with that 2.5 because 2.8 is stock.

My car ran Great and got 0 KR with the 2.8, as soon as the 2.55 went on i got KR and it got pretty bad at higher RPMs And the car got slower when over 60% throttle.

as soon as i put the 2.8 back on it got faster and KR is gone.


Get a Scan tool and check for KR i bet you have some or a lot.

if thats the original tensioner (with 150 it probably is), that could be a cause too. weak tension = slippage.

here is a list of stuff done to my car.

all new idler pulleys
new belts
new sc coupler and oil
new power steering pump
new plugs/wires/coils
removed cat and resinator
installed flowmasters
currently running 2.55" pulley also have 2.3" which i will install after more mods
have a 3" cold air intake

yes that could be... but the First set in doing a pulley is scanning for KR.
even is he gets more Boost with the new belt and better tension he could still kill his motor with KR that he could and will still be getting.

iv learned a lot int he past 3 weeks with pulleys and KR and stuff.
Thanks willwren / boosty

ummm why did u remove the cat?

you need some back pressure for the low end power.
thats part of your power problem right there.

ok. i am gonna buy the cable from slug and the scanner this week end. and check kr.

what do i need to do to get rid of KR. i have sc delco platum plugs. do i need to install the autolite 104s or the ngk tr55s?