jwhipple

Hey everyone I am having a problem with detonation - badly! I have an 86' 951 with high miles but in good condition. Today I bolted an APE mass flow kit on and driveability is good but when I step on it - as soon as the engine sees some load or starts building boost it "pings" tremendously. Whats going on??
Previously it had Weltmeister chips with a shimmed wastegate which ran OK but occasionally it would detonate (nothing like the chorus of pings I'm getting now). Is there a way to adjust the timing manually? Could my fuel pressure reg. be bad (previous owner said he had a better one installed but it looks stock)? I am running 91 octane which is as good as it gets here in CA. I just got the car a couple of months ago so any tips are appreciated. Also can I run a manual boost controller on this car?

Jason

IceShark

You have the APE chips? I believe they demand 92 octane. You could run some toulene. Sort of tough lugging around on long distance trips though.

Toulene is 114 so a gallon a tank should get you above 92 with the 91 pump gas.

TurboGuy

I had the Weltmeister setup and the documentation said to use 93 octane ? I hope you removed the shim when you installed the mass kit they do not mix. There are a ton of things that could cause your problem from loose knock sensor, fuel, leaks etc. You need to find them before your run the car hard or you might not have a engine left. Ice is correct running high octane will help the knock but still wont tell you the root cause of your severe knock. Perhaps your kit is not installed quite right.

Danno

The MAF kit has nothing to do with boost-control. Is the shimmed wastegate the only boost-control system you have? What boost-level are you running? If you are running less than 15psi boost, then 91/92-octane at the pump should be fine. Increasing octane at low-boost levels to get rid of knock is just masking the real problem; which is either ignition or air-fuel ratio.

This leads to ignition issues. What chips are in your car now?

If ignition is OK, then what kind of an air-fuel ratio are you getting? Is it flat across the board? Could indicate a problem with the MAF-sensor or wiring in between somewhere.

One of the things you can try is the ignition and fuel-quality adjustment on the DME. Pop off the hole-cover on the DME, use a shaved golf-tee and try positions #4,6 or 7. I leave off the wood plate and the two bottom screws off the DME/KLR carrier so I can reach in and make this adjustment quickly.

Here's the table of rotary switch settings:
http://www.bonnevillemotorwerks.com/fqs.html

jwhipple

Before installing the kit (APE Mass Flow) I removed the wastegate shim, and my boost enhancer to return everything to stock as per instructions in the kit. I agree that it is not boost related, I am looking for ignition or fueling problems. Anyone know what the part number of the fuel pressure regulator is? Where does the knock sensor get its signal? Also can you adjust static timing on these cars?

Jason