Contour Enthusiasts Group Archives Forums Modifications Forced Induction Fuel Pressure Drop @ WOT...

Hmm.
Fuel drops to 20 at 4K rpm.

Well it is going to richen the injectors on opening the secondaries.

What size injectors? You're saying you have a return-style system?

I'm guessing with that setup you have 39's or bigger. IF they all went static open then they might be able to drop the pressure significantly and the excess fuel would kill the power.

IF the car was starting to go lean then it should have had a bit more power before it got too lean but I'd guess at 12.5psi you'd have already hurt something.

If it is returnless like I thought most cougars were....then it is a programming issue I think.
Need to list injector size. I don't buy the whole voltage drop thing. The pcm code has parameters to change the fuel injector pulsewidth based on electrical system voltage. Meaning if the alternator died and the voltage dropped, the code will automatically adjust the injector parameters for it.

What does the maf voltage indicate when this happens? You probably should datalog with an obd scanner what the maf is doing and what the fuel trims look like when it happens.
You can easily watch the O2 sensor voltage and get an idea if it is falling or not to help narrow down a lean or rich condition, but don't trust a narrow band for exact fuel ratio.