gawd diddly dammit....low boost!

[SITHV6]

After attending the Street Legends event this past week...I decided to add a quick mod to see if i can improve my hot weather tune. Purchased a ZZP High velocity L67 throttle body to challenge their claim of a .2et /2mph gain...out of the box the new IAC it came with was stuck and threw my idle into 2100rpm. With a scan we tried playing with the throttle stop to get it to calm down so we could figure it out. scan said 0% IAC...hmmmmm. Swapped out the new IAC with the old one and fixed the idle right away! OK, ready to go racing at TNT the next day. Left the shop at WOT and right away the car felt...lazy. Was already late in the day and my mechanic was swamped, so i decided to harrass him about it the next morning. Having owned an 86 turbo buick for over 20 years, the first thing that popped to mind over anything to do with fruity RPM values and slow WOT was TPS values, plus we were playing with the throttle stop screw so Something had to be off? So the next morning we started playing with both fiddling with the TPS screws and the throttle stop to try mimicking turbo buick TPS idles as an experiment .42-.46 at idle and 4 volts at WOT it was .35 and barely touched 4 volts at WOT. Left the shop again at WOT with the dump open as a THANKS! And left straight for the track.
Fun Ford event is this weekend so u can imagine the amount of mustangs and stuff were at the weds TNT to shake down. So no supriae my first run was against an 86 foxbody with drag shoes, oh joy...
I Redlight with a -.027 to his .072 already a bad start to a night. It gets worse... Door to door all the way down i dont even Think to peek down at my boost gauge to see if the new throttle body has affected my numbers! I may have beaten him to the line but when i got my timeslip...14.973 @92.85 !!!! Common sense would have told me right away to go park somewhere and double check for loose vac hoses or if someone snuck a boat anchor in my trunk! So what do i do? I decide to line up with a new BMW M4 and take a look under the hood while cooling down! ! Found nothing! Hmmmmm....
Next and what i find to be my LAST run... This M4 driver has a skyline back home and he's heard about my tendancy to strive for a perfect light...so He tries to tree Me and Redlights! I get a lazy .068 to his -.190 .
What happens now is kinda comical in my own mind. Well, of course at this point he's leaving me for dead and i have a lot of time to myself to actually look around my cockpit and glance down at my factory boost guage... 3.5 lbs of BOOST?????? Srsly??? Normally with a 3.2 pulley its rock solid at 13.5! OK My night is done... SOMETHING is obviously wrong if all the hoses to the boost solenoid and BBV are fine. M4 went a respectible 12.760@ 113.15 to my dismal 14.984@ 92.89 .
Went to a few forums and saw others had similar problems with only 3psi . So now I'm playing with unplugging the solenoid and blocking off the BBV to isolate the cause of my boost loss. Will keep u all informed of my findings and pray for my SANITY!

 

[Trannyman95]

Make sure there is not a crack in the plastic vacuum line that connects to your map sensor behind the supercharger. If the boot or line Is cracked it will read low even though it may not be. Also- on the BBV you can unhook the line from the solenoid and leave the port on the BBV open to atmosphere- DON'T block it! This will prevent the solenoid from causing issues, though on the other hand if the PCM sees a big problem it will open this up for a reason to limit engine output but you can do it for a quick diag. The pcm should not open this up at WOT during a 1/4 mile run. Check to make sure that the BBV is pushing the lever down all the way too, I have seen these stick which will also lower boost. Make sure the top port on the BBV is still connected to the vacuum tree on top of the blower housing.

 

[SITHV6]

Yes, someone at Regalgs suggested the same thing with a photo and it fixed the low boost problem right away! I may not be OCD but seeing that BBV open to atmostphere with the hose just laying there is driving me nuts! May just trim the hose to Appear connected and still leave it open lol! Earlier today i romped on it and when the boost came up i immediately got off it and heard a tell tale sound of belt sqeak... just one more thing to hunt down in pursuit of sanity ! XD!

 

[SITHV6]

FIXED!!! That unconnected hose was driving me nuts, so i decided to start ordering stuff to fix the problem rather than get around it. Ordered GM part # 1997244 thinking it was the round black actuator that i disconnected the hose from. When it arrived, out of the box comes this tiny gizmo that we turbo buick ppl would immediately call a wastegate boost solenoid...tiny foam cover and all!! Replaced the old solenoid with this one and reconnected the open hose....took it around the block and mashed the pedal to the floor to see what happens and INSTANT Tire smoke and 11 psi !!! Heading to the track tomorrow and will post and new findings!
for those who are curious...

GM parts # 1997244 is the solenoid called a "VALVE"
GM parts # 89018120 is the bypass actuator or "ACTUATOR"

Hope this helps others!