New owner needs help with possible overboost issues?

[PLexo50]

I apologize for the long and boring post but I do need some help from you smarter fellas.

Oh yeah, long time listener, first time caller.

I just bought my 87 turbo! Bought it not running and from what I can see and what the PO has told me, has a lindsey upgrade kit(exactly what, I'm not sure). From what I can see, it has a lindsey wastegate(not sure of single or dual port), chip, boost gauge(autometer), a/f meter(autometer), aftermarket fuel pressure regulator). So after replacing the alternator the car runs and drives, and low-load driving and idle seems fine(idle speed is kind of high comparing to specifications 9-1000rpm warm).

My problem occurs under heavy load. Seldom in first, mostly in gears 2-5, it'll spike past 20psi(autometer gauge), and exhibit what feels like a overboost cutout. If I modulate the throttle at any speed and maintain below 18psi, the car pulls very well with no abnormalities. Some things to note during the alternator replacement: it appears the banjo bolt on the intercooler pipe has a vacuum line that runs the length of the manifold and ends up at a T on the firewall, which one end runs to the wastegate and doesn't look installed. Which I assume would explain why the boost pressure doesn't change no matter how many times or direction I turn the adjustment knob. Now I'll have to double check which WG I actually have and if the vacuum hose is connected(it's too cold right now), but I'm just stating what I can see at this point.

1) Would anybody know the specified boost range for said aftermarket parts?
2) What and where is the cycling valve and if possible resource a vacuum diagram?
3) Does the lindsey wastegate have a default(spring) pressure it opens at or is it dependent on the single vs dual port configuration?

It's late, I'm tired, nice to meet ya'll!

[rick13]

Welcome earthling

VACUUM DIAGRAMS at LINDSEY RACING - Your Porsche Performance Parts Center

If I remember correctly. Max boost is part of the programming. Definately check to see if waste gate is properly hooked up.

Cycling valve is the white and tan circular thing under the intake manifold towards the fire wall.

[Ky914Newbie]

Overboost is controlled by the DME chip. The specific cut out level will depend on the programming on the aftermarket chip. IIRC, aftermarket chips either remove the overboost protection or significantly increase it from stock.

[PLexo50]

I need to pull the intake manifold off to familiarize myself with this car. So looks like the wastegate is a single port and is T'd off from the banjo bolt on the front intercooler pipe. Next to the wastegate was this connector just hanging here. Anybody know where this belongs? lol

Some sort of three-wire connector.

Yay... double checking vacuum lines/routing... -_-'

[mikepellegrini]

I'd vote for the O2 sensor. The plug looks kinda like that, altho it usually comes up the other side of the engine.

The pasrts you have will take as much boost as you can make. Of course, get it too high and you may blow your head gasket or have other catastrphic problems. Most people wouldn't push it past 18-20 PSI.

If you've got a manual boost controller, the cycling valve should be disconnected. The manual boost controller takes the place of the cycling valve.

The cycling valve controls the wastegate - limits the boost to (I think) 12 PSI or thereabouts.

Lindsey sells a couple types of wastegates - rebuilt stock wastegates in both dual and single port configurations.

[Ky914Newbie]

I am having a hard time getting my bearings from the picture. The 02 sensor would normally be on the firewall side of the intake where the speed and reference sensors should be located in their bracket.

At the rear of the cam tower connected to the engine lift ring, there is often a diagnostic test port used by dealers back in the day. I believe it was for determining TDC. I think that is what this looks like. Not sure from the angle though.

[968 GUY]

Prob the O2 sensoer plug.

[vonsleigh]

HI There,

Welcome to area 951.

I had the same problem and to make a long story very short it turned out to be the LR boost enhancer internals were assembled backwards. spring and blunger or blunger and spring can't recall but an email to LR will confirm.
Nice, by then I had sprouted oil leaks everywhere as my car was boosting 35psi. I could not believe the power !! It cost me alot of money to fix there mistake.

If the internals are right then the boost enhancer is turned up too much and you need to adjust downward. LR could fax you the 1 page instructions. Super easy to do.

best of luck