Got 43psi of fuel pressure with the ignition on. Waited a few minutes and it wouldn't drop.<br/>With the engine running the pressure goes down to 35-37psi and stays there (on idle and engine load).<br/>Fuel regulator seems fine, pressure increase when i remove the vacuum line and no fuel residue.<br/>Im guessing my fuel system is fine?<br/><br/>Sorry for keeping u guys busy with me<br/>Thank you

 

Could be a dead spot in the TPS.

 

Seems ok. Usually the test is done with the engine running and vacuum line disconnected to simulate WOT. That it holds pressure is good, assuming you are stock. What happens when you do a WOT run on the road? Pressure should momentarily drop but hold at about 43 or so. I know mine does.

 

Make sure the maf is clean.

 

Now your Cranking!!!! Your previous gauge reading. Was out of scope for your Mileage.
as above keep the FP gauge on the windshield toward you. Monitor while driving then WOT.
if your pressure drops down. As you already stated 35Psi.. It's almost a guarantee you have a weak pump.
other defective sensor components would not drop your pressure.

 

When I had a bad TPS it acted like I turned off the ignition when it hit the dead spot. Moving the gas pedal brought it back to life.

 

I have noticed everytime i remove the maf plug, the throttle responses like an animal. No hesitation no chocks no nothing. How is that possible? Could it be a dirty maf? Or im miss understanding how it works?

 

Well if the maf is giving a false signal then yeah it could run better with it unplugged. Some guys search all the junkyards & internet for good used maf sensors because they seem to work better the aftermarket or rebuilt mafs.

 

Hmmm yes that could be my problem! although the maf is not throwing a code but the throttle response is much better without it.
Btw is it safe to run it unplugged?

 

If that's the case it could potentially be a bad MAF or vacuum leak. My bet is you still have a vacuum leak.

 

What you might need to do is go to the tune and scan section and ask around. If you datalog the car you can send them a information and they might be able to tell you if those values are plausible. So just because it is working and sending information within the window the ECM wants to see doesn't mean the information is right. You could try take a sensor from a known good source and test.

No it isn't.

 

Ironically, you have discovered the most effective answer to your own question.

When the MAF is unplugged, the MAF signal is driven by the default airflow calculation, rather than the sensor's voltage. The default airflow calculation uses tps, rpm and IAC position and a constant offset to approximate the airflow.

Move the throttle (or tps sensor) and the calculated signal will respond instantly (next revolution) resulting in additional fueling likely in advance of the actual airflow.

Its not necessarily accurate fuel control, since there is no pressure or temperature compensation, but it is fast and since it is directly proportional to the throttle position, this mode of operation provides the fastest throttle response possible for this system.

With the MAF sensor in the loop, opening the throttle will cause an increase to the actual air flow along with manifold pressure, but it takes some time for the MAF sensor to respond to the change in air flow. As result, the fueling will slightly lag behind the actual air flow.

This delay can be noticeable under normal conditions, and it can also be adversely affected by unmetered air or a malfunctioning MAF sensor.

Tuning the acceleration enrichment parameters and/or reducing the MAF signal filtering can help to reduce the delay and improve the response.

Log some data and compare the tps and MAF signals to quantify the delay to better determine if your MAF is responding properly. Compare against a known good sensor, if available.

 

Thank you for your explanation.
Very helpful