Boost loss - any troubleshooting tips?

[ChicagoMike]

As you know I have a 3.1 upper and 6 lbs. lower. When I dynoed it was making 16-17 PSI holding steady to redline. So I actually took the car out this weekend, the weather was cool (70's).

The car seemed to pull HARD before. I thought I got used to it.

So on the highway, I decide to measure my boost. It peaks and holds at 14 PSI and doesn't go any higher. Everything else is good; fuel pressure, oil pressure, A/F, everything is reading normal. It doesn't appear to be slip because it pulls right to 14 PSI and stays there on both the stock guage with the overlay AND the autometer boost/vac gauge.

Only thing that has changed is:

1. JLT oil separator (right now this is my suspect, might bypass all oil separator stuff to take it out of the equation)

2. RR tensioner (the stock tensioner wasn't holding up when I stabbed the throttle, it would hang at 8 PSI). If step one doesn't fix, will try new belt, because I had lots of belt dust in the past? Belt seems OK though and is tight)

3. Borla Stingers changed to Borla 14858 mufflered system.

4. Changed the FPRS.

Unfortunetly, I haven't driven the car much since the dyno to pay attention to the amount of boost it was making since the dyno pull. Now I just noticed the 14 PSI .. which is pretty low for a 3.1/6#-2.93/4#-2.76/2# combo.

Click to read more...

 

[The Pun]

Tighten da F outa the belt, I have the RR tensioner and it runs better tight.

 

[Flyn]

So I actually took the car out this weekend.

This is the only line worth mentioning in your post. STOP ANALYZING THE DAMN CAR! Drive it and don't worry about every little detail.

 

[gnxs]

:rantoff: :sucks: :welcome: :welcome2: :rantoff:

 

[ChicagoMike]

I ask for help and this is what I get ... what did I do wrong?

I'm not making the amount of boost I am supposed to and your answer is "just drive it"

I hope your car starts making 5 PSI max and I say just drive it!!!

The reason I spent $20,000 in mods is so I can handle and support the max amount of horsepower. If I'm missing 3 PSI that's a whole pulley size difference.

 

[ChicagoMike]

Thank you for the good answer, I will try that before changing the belt.

Tighten da F outa the belt, I have the RR tensioner and it runs better tight.

 

[ProChrgedStang90]

check all the vaccum lines, and make sure none are disconnected too

 

[hj16]

Your gauge couldve just gone AWOL

Going down from 17psi to 14psi is a big feel difference. You wouldve felt a noticeable difference till 4500-5000rpms or so. Did You? Or is all this fret from just the gauge?

 

[ChicagoMike]

Well since I have hardly driven the car, and when I have I did not press the throttle all the way down ... until this past weekend on I-57

1. Repeated the test several times WOT different gears. 14 PSI, maybe 14.5 PSI max. Holds steady till redline. Both gauges, stock with overlay that reads up to 15 PSI and the autometer (so 2 sources).

2. Car doesn't pull as hard, sure seems like 14 PSI instead of 17 PSI. I remember hitting 17 PSI after the hermann tune and hanging on for dear life. Now at 14 PSI, it just feels like I am accelerating with just a 2.93 upper pulley or something.

Your gauge couldve just gone AWOL

Going down from 17psi to 14psi is a big feel difference. You wouldve felt a noticeable difference till 4500-5000rpms or so. Did You? Or is all this fret from just the gauge?

 

[BIGONTS]

It could be the weather too. In the cooler months I see higher boost then now when it's hot and humid. Maybe not 4lbs but 1-2lbs due to heat, etc...Just a suggestion.

 

[ChicagoMike]

Problem solved.

Removed the JLT oil separator from the drivers side. Boost magically appears at WOT at 15.5 - 16 PSI.

My guess is that the metal sponge wire stuff inside the separator created a blockage at high RPM causing a drop in boost. Bummer for that product.