Quote:
Originally Posted by john70t
Offhand, I would tend to think "over-pressurization" will never cause full throttle WOT stumbling.
Low FP pressure problems usually only occur under high load..
So forget about "too much" line pressure.
(i.e. that relief valve)
Put a fuel pressure gauge on the rail schrader valve(same as a bike pump) and measure it directly!!!
(And forget about what the lying computer says.)
It will be par for the course I'm just guessing.
As a stupid mechanic from the internet, I suspect the throttle body is gunked up.
There is a throttle bypass mixture circuit.
The Mass Air Flow/Manifold Absolute Pressure/or a combo of the two might be off.
(I honestly don't know what the modern pcars cars use)
Some "carb cleaners" will damage the delicate MAF wire. Use the approved one.
Another possibility might be low system voltage at idle may confuse the computer.
Car computers don't function below 9V.
Start from the basics:
Battery. Alternator charging amps at different rpms.
Those are known good. Move onto the next.
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I appreciate the reply but this would be under-pressurization. These GDI engine run almost 2k psi (which makes testing pressure tough without special tools).