Coming home last night, my car felt very sluggish. Turned my dash screen to the boost gauge, and it's building 1-3 psi just cruising at 55-60 mph. Fuel pressure is higher than normal, mileage is lower than usual. Around 900 psi cruise, normally 800. Usually 30-32 mpg cruise, now 25. Idle is very choppy, and acceleration is drastically underpowered, seeing fuel pressures of 1100-1200. Also smells noticeably rich. Afr's at cruise range from 14.6-15.0 via the dash gauge. The car was tuned by the previous owner, and I have no idea what was actually done. Suggestions?

 

If fuel pressure is too high that means your in tank fuel pump is likely fine.

Two options here

1. Your High pressure fuel pump may be going bad
2. The wiring to your fuel pump is going bad. Mine was rubbing.

 

if you need a HPFP, I have one in good shape.

 

Is there an easy way to tell aside from visually checking the wiring? The car has 108k on it, and sensors have been going bad left and right lately. Where was your wiring rubbing at? Close to the high pressure pump?

 

The main wire loom runs along the right side of the engine. It rests against the hpfp on the black metal housing. Check to make sure no wires are rubbing. But most people just change the hpfp. Idk how you test the pump itself. You would need to log with HPTuners desired verse actual fuel pressure

https://photos.app.goo.gl/5Jnkzy33jL5cHBoh1

 

Update: Tested a known working pump, and I have the same results. Cleared codes, P0089 is still present, but P0088 is not. I only took it around the block after swapping pumps, so I'm not ruling out the P0088 returning after a longer period/few cycles. Visually the wiring looks fine, but I don't have a way to be certain. A few other searches have shown possibly a bad sensor at the end of the injector rail, or a bad O2 sensor. The fuel pressure sensor being bad doesn't make much sense, because while being very rich, my fuel pressures on the dash gauge show that. I would think if the sensor was bad, my pressures wouldn't reflect how rich it is.

I am curious about the O2 though. I need to drive again and see how dynamic my AFRs are at different throttles. I only really paid attention to cruise AFR, but if it seems fairly static, is that possibly a culprit? As rich as this thing is running and smells, it should be extremely evident while viewing AFRs. I'm thinking that if my ecm isn't seeing super rich conditions from the O2, it's not cutting any fuel. Thoughts?

Edit: Also considering the regulator on the low pressure side of the HPFP.

 

Another update, changed out in tank pump and regulator assembly, no difference. Not sure where to look next. Thoughts?

 

Can you check the voltage at the main connector to the hpfp? I think you have narrowed it to the wiring or ECM.