Sunnyvale-951

Hello everyone,

I seem to be having some performance problems with my car and I'm looking for advice. The car seems NO faster now than it did when I originally put APE II chips and the banjo bolt on it (if anything, it may feel slower). My car is a 1987 951 that is stock other than the following:

- Vitesse k26/6 AFM Chips
- Tial 38mm Wastegate in single port mode
- LBE hooked up by bypassing CV
- Aftermarket boost gauge

Everything is in top shape with the car maintenance wise (new fluids, spark plugs, wires, timing belt, clutch, etc).

The car is making great vacuum (16 at cold idle, 18 at warm idle, 22 when driving off boost).

I get full boost (15 psi) in 3rd gear at about 3200 rpm. However, the boost falls to around 6 or 7 psi by redline (this happens in at least 2nd and 3rd gears). I don't know if the boost is dropping this low due to the turbo running out of steam or something else. I've checked out the intercooler boots, J-pipe, and other joints and have found no leaks or cracks.

Also, that cat looks like it might have been hit a little by the previous owner (I picked the car up about 4 or 5 months ago). It has some small ridges and bumps in it but no holes or leaks. The car passed CA emissions last December.

What the heck is going on? Why is my car not making more power now than when it was completely stock with only APE II chips and banjo bolt?

Any advice, comments or questions would be great appreciated! Thanks!

rberry951

Did you install the LBE and bypass the CV or did you have someone else do it? It sounds like either the LBE is backward, or one of the old CV lines didn't get properly plugged. To check it all out, you can use this vacuum line diagram on Lindsey's website:

http://www.lindseyracing.com/Merchan...ry_Code=VACDIA

Also, the APE chip banjo bolt has a tendency to get clogged. You may have been pushing way more boost than you meant to. But that doesn't explain your boost dropping like it is. I suspect the LBE installation/CV bypass.

Regards,
Russell

87944turbo

Which spring are you running in your Tial?

njim3

Your boost should drop from 15 down to 11psi at redline if your boost drops that much than you loose power at top end. You should try MBC to replace the LBE or call LR to get a replacement spring
inside LBE to hold your boost.

Jim

Sunnyvale-951

I installed the LBE and bypassed the CV. I know that the LBE is installed correctly. I can adjust the peak boost just as I should be able to. I even took the LBE apart to make sure the spring and plastic plug thing looked fine (and they did).

As far as plugging the CV lines. I plugged the line coming off the J-boot that goes to the CV (the actual CV line is still open). The CV line that used to come from the intercooler banjo bolt I just left open. I also left the CV line open that normally goes to the wastegate. Is this all correct?

Also, I had the aftermarket boost gauge when I had the APE II chips and banjo installed. I was making 15 psi. I also removed the banjo bolt and hooked up the LBE with the APE II chips and set it to 15 psi. I saw no difference in doing this.

Any more suggestions?

Sunnyvale-951

The Tial 38 came from SFR racing and it said 0.7 Bar (10.3 psi) on the box.

Sunnyvale-951

I bought the LBE brand new. Do you think I could have received a bad spring from the factory? I'm able to easily adjust the LBE for peak boost (rotate one thread for a 1 psi increase or decrease).

rberry951

Sounds like you did everything right, but something is amiss here. I've never had any problems with the LBE, but anything can be defective. It sounds like for one reason or another your wastegate is opening or you're losing boost pressure some where else. I know this sounds redundant, but have a good look at everything under the back side of the intake around the CV and make sure no other vacuum lines have popped off. Do you have a pressure tester?

Regards,
Russell

87944turbo

It sounds like you have done everything right. Like someone else said, I think the LBE is your problem. If you want to try a known good working MBC, just send me a PM.

toddk911

"As far as plugging the CV lines. I plugged the line coming off the J-boot that goes to the CV (the actual CV line is still open). The CV line that used to come from the intercooler banjo bolt I just left open. I also left the CV line open that normally goes to the wastegate. Is this all correct?"

Ok, shouldn't the hard metal line from the CV be plugged???

Also, that cat could be causing a lot of back pressure in the higher rpms and thus your making more backpressure than boost in the high rpms.

Sunnyvale-951

So even though I have a tial with a 10.3 psi spring that can't hold 6 or 7 psi at redline you still think that the LBE is the most likely cause? I'm definitely willing to try another MBC to test things.

Also, I don't have a pressure tester. Would there be a leak big enough to cause this much of a loss of boost that doesn't show up with a vacuum loss?

Any other suggestions?

Sunnyvale-951

toddk911, I didn't think that I had to plug any of the hard CV lines since nothing is coming into the CV or going out of it. The electrical connector to it is also unplugged.

I also suspect that it could be something with the cat causing high backpressure at high rpms. How hard is it for me to remove the cat far enough to look inside and see its condition?

toddk911

Yes, you can have a big boost leak and perfect vacum.

BUT, usually a boost leak will allow you to only make X amount of boost and hold. The boost will not roll off.

However, a bad DV/BOV I have seen make full boost and then it rolls off.

Is yours still stock?

Sunnyvale-951

Forgot to mention that. I have an EVO forged unit from Lindsey.

rberry951

I just realized you said you have a Tial running in single port mode, which side do you have your boost controller connected to?