I was at the track today and was running just horrible. Mods are buschur turbo back exhaust with high flow cat, k & n panel filter and dynoflash and an added mbc (added on after dynoflash). I had it set properly 2 days ago running 20.5 psi but it still fell to 17 psi.

Well today at the track the car started to act up and only boost a maximum of 17 psi and falling off to 15. Did three runs and only average 97 mph. I did a quick check for leaks but didn't see any loose hose. Decided to turn up the boost without testing it and still got a best peak at a little higher than 17 psi. and trapping bout 97.

Well got disheartened and drove home, but I decided to run it through the gears again and it was boosting 22 psi....what the hell. It is still running 22 psi and thats with the same mbc adjustment from the track. What is going on?

On another engine oddities....does the knock sensors detect mad rumbling sound and vibration from outside sources such as american muscle drag cars revving up because my engine almost died not once but twice when i was next to those car revving up their engine. Sound stupid but I don't know why my idle drop to zero twice.

 

are you sure u are comparing boost in the same gears? lower gears usually doesn't peak as high as for example 3rd 4th and 5th with full load on the engine...

 

Yup comparing same gears It was like it was possessed.

 

yep that seems to be the concesus on the knock sensor, it's happened to a buddy and I several times at the track to both of our cars, mine has always stumbled when I shut the hood while running.

for the boost controller how do you have it installed? is it running to the wastegate and the bov vacume line with the turbo outlet nipple capped off? or is it running the turbo outlet and the wastegate? I have found that running it the second way is better, just my opinion though, seems to spool faster really.

 

it connected to the turbo outlet and the wastegate. still confused, it's running high boost now.

 

hmm... odd, checked hose to boost gauge yet? I was having a weird leak in mine the other day and replaced all of the autometer plastic hose with copper

 

how long was the car standing when you were waiting to run

prolly what happened was the intercooler got hot and when you started going down the track, the air wasnt getting cooled off very well.

and when you were cruising, the intercooler was cold again

hot air is less dense so in order to make the came pressure, the turbo needs to work harder

 

Christine!!!!!!!!!!! I second what SilverEvo8owner said!!!!!!!!!

 

this is your problem friend... your dynoflash was programmed so your stock MBC would adjust boost to prevent engine knock by reducing your PSI alittle.... i believe by adding the aftermarket MBC after ecu flash, you take away the ecu's power to adjust PSI and on a track with high revs, you start going lean and knock occurs badly.

im not a tuning pro so dont quote me on the details but your MBC is definetly your problem.. have your ecu updated and you'll be ok. this happened to me to a few month ago....

i had a few light mods on and a dynoflash... my air/fuel gauge would show me only minor variation in fuel mixture even when i hit higher revs... but once i installed the aftermarket MBC.. the fuel mixture started leaning out much more noticably and my stock bumper melted slightly (from the hotter exhaust gas)... once i got my dynoflash updated for my new MBC.. everything returned to normal as well as no more melting of my bumpers....

 

Dude...were you at Bradenton??? I had the exact same things happen, too...my car was running like crap, including the engine bogging down and almost stalling when a loud muscle car went by...I figured it was the knock sensors, too...my car should be good for about 12.8 at 105 MPH...I couldn't do better than low 14s at 97-98 MPH...once I got back on I-75 for the drive home, the car ran strong again...I can't wait for December...

 

I have the same thing happen to me everytime i go to the track. I have a Profec B SpecII and i can't get more than 20 pounds of boost at the track. I keep on turning the boost knob higher and higher and it still stays at 20 psi

When i drive it on the street my boost goes back to normal. I can boost as high as i want. I scared the crap out of myself driving home from the track because i almost hit 24psi. I forgot to turn the boost knob back down.

Very Strange............

 

I've had a 4G63 powered car ever since 1997 in some form or another. A Manual boost controller hooked to the INTAKE MANIFOLD will not have this problem. A Cheap electronic boost controller like mine (Blitz dual SBC) I have to adjust it up 10% duty cycle at the track because it doesn't modulate boost by pressure, only by duty cycle (until it hits peak/warn of course). So when I'm revving the crap out of it, the gain and duty cycle it thinks is fine is all wrong. I want an AVC-R so bad, I wish I didn't get this piece of crap.

 

Always happens to me....