2 different DSMCHIPS settings, and still not right on the a/f ratio on the wideband.

[MarkAngelo05]

Hi!

This is what I'm experiencing. 10:1 A/F ratio chip, Stock base fuel pressure/regulator, FIC 650cc injectors (285 uS Deadtime settings on chip), 18 to 20 psi boost.

Okay, well, I keep having to add around 13- 18% positive on the AFC to achieve a 10.5:1 Air Fuel Ratio. Jeff said that without AFC settings, I should be close to the target air fuel ratio, but it's not working out right. The chip has fuel maps for 10:1 A/F Ratio target, but it is never close.

With 0% AFC corrections, I'm at around 12.5:1 Air Fuel Ratio.

I have an EVO IX Fuel pump, rewire kit, stock FPR. I do not know what the problem could be. I thought it may have been the fuel pump, but my air fuel ratio does not drop with more boost.

The reason why I would like find out what is wrong, is so I can use less AFC corrections, so my timing/mas air signal is not altered as much by the increase AFC correction %.

I am using a PLX DM-5 Wideband setup. My idle A/F Ratio is around 14.7:1 to 15:1

What else should I check? Could I have a bad MAS... Could I have a bad front o2 sensor, but I don't think it matters at WOT. A boost leak would make me run richer.. I'm running a stock 2G VIRGIN mass, with the stock intake system, all tightened up..

I have bybassed the FPR solenoid, still the same symptoms.. Could it be that my EVOIX pump is just not cutting it?? Even at 15PSI, I'm at 12.5:1 AF ratio WOT 0% AFC corrections..


Thank you all for your help in advance...

 

[zippyshoe]

A couple of things you may want to try:

1. How do your long-term fuel trims look - are they close to 0%?

2. Connect a fuel pressure gauge to your fuel system (somewhere along the pressurized-side of the fuel pressure regulator). Measure the fuel pressure with the vacuum hose disconnected from the regulator to verify base pressure is close to 43.5 psi. Connect the vacuum hose and verify that the pressure falls by roughly 9-10 psi. This will give you some level of confidence that your regulator and fuel pump are working properly and your injectors are operating at their rated fuel pressure.

3. If possible, you may want to log intake temp, barometric pressure, and mass airflow to see if the values you log seem reasonable - if any of these values seem "off", this may indicate a problem with your airflow sensor.

 

[MarkAngelo05]

A couple of things you may want to try:

1. How do your long-term fuel trims look - are they close to 0%?

2. Connect a fuel pressure gauge to your fuel system (somewhere along the pressurized-side of the fuel pressure regulator). Measure the fuel pressure with the vacuum hose disconnected from the regulator to verify base pressure is close to 43.5 psi. Connect the vacuum hose and verify that the pressure falls by roughly 9-10 psi. This will give you some level of confidence that your regulator and fuel pump are working properly and your injectors are operating at their rated fuel pressure.

3. If possible, you may want to log intake temp, barometric pressure, and mass airflow to see if the values you log seem reasonable - if any of these values seem "off", this may indicate a problem with your airflow sensor.

Long term Fuel trims look okay. Intake temps are around 72 degrees at night. and up to 100 during the day. Mass airflow is around .83 at idle... and around 3lbs a min at 2.5k rpms cruise...

How often do stock Fuel pressure regulators fail? I have a spare stock 2G fpr, I'm thinking about swapping.

Thanks!

Mark

 

[zippyshoe]

Sounds like your intake temp sensor is working properly - what barometric pressure do you typically log? You should see a value somewhere around 30 inches Hg. If your fuel trims are within a couple percent of 0%, then your injectors are probably flowing at their rated value and your fuel pressure is probably at the proper value under idle and cruise conditions. It is still possible that your fuel pressure under boost conditions is not rising at a 1:1 rate with the manifold pressure - this could be due to a faulty fuel pressure regulator, a faulty vacuum hose connection between the regulator and the manifold, a faulty fuel pump, etc. The stock fuel pressure regulators seem to be pretty reliable - there doesn't seem to be a lot of cases of these failing. You may want to try another piece of known-good vacuum line between the regulator and the manifold.

 

[MarkAngelo05]

Sounds like your intake temp sensor is working properly - what barometric pressure do you typically log? You should see a value somewhere around 30 inches Hg. If your fuel trims are within a couple percent of 0%, then your injectors are probably flowing at their rated value and your fuel pressure is probably at the proper value under idle and cruise conditions. It is still possible that your fuel pressure under boost conditions is not rising at a 1:1 rate with the manifold pressure - this could be due to a faulty fuel pressure regulator, a faulty vacuum hose connection between the regulator and the manifold, a faulty fuel pump, etc. The stock fuel pressure regulators seem to be pretty reliable - there doesn't seem to be a lot of cases of these failing. You may want to try another piece of known-good vacuum line between the regulator and the manifold.

Hey bro.. thanks for your comments on my thread... I'm logging .53 lbs/min of air at idle 850rpms.. I swapped out my fuel pressure regulator with another one, and I also changed the vacuum line, and made sure to secure it onto the manifold and the FPR, but still not changes...

I am now assuming its a faulty seal at my fuel pump. I have an EVO IX fuel pump in there, but I reused my stock oring, and hardware to install the pump because the EVO oring and other parts did not fit, and were just way too large... anyways, is there some kit that I can buy to refurbish that oring, and connector area??

Thanks!

Mark

 

[Maglin]

Barrow a fuel pressure gauge. Route it behind your hood and tape the gauge to the window and do some pulls. Then you can see your fuel pressure during boost. If it doesn't change or drops then you can suspect a fuel leak somewhere. But I wouldn't suspect the pump at this time. Not everyone's car is the same. Hell you might have a small exhaust leak under boost causing your lean readings on your WBO2. what are you LTFT and STFT at idle after you driven it for at least 30 minutes?

Have Jeff reburn the chip if everything is ok. It could be that their is to much injector deadtime as well. It would cause a lean high flow condition. It's just something else to look into. Also you mention you are using the stock Intake. Try taking the breather off the intake (the one from the valve cover) and put a plug in the intake. Also make sure that your BOV isn't leaking and ensure it's tight. Could be under a high load the vacuum in the intake is pulling air from either a crack or loose connection somewhere. Most likely the breather if it has no cracks. That would cause you to also have this lean condition. As it's unmetered air. That is about all I can think of to look into at this time.

 

[Maglin]

doh... opps.. double post.