Question:


My understanding is that stock fuel pressure in an Ap1 is about 38-46psi

If I am running a Walbro 255 with stock regulator, I should still be in the same range correct?

I am trying to track down small issues with my tune, namely the car's willingness to go into the 10's and 11's just cruising in 6th when experiencing light load. The fuel cells have been tweaked to death by the tuner but no joy. I found something in a G37 thread about fine tuning Haltech and someone mentioned injector latency times are critical for proper functioning of cruise control. The car runs a tad on the rich side when cruising and is not matching the target fuel range in the map, for example it will read in the mid 13's when the target map shows mid 14's when cruising. It will bounce between 13 and 14 instead of bouncing around in the mid to high 14 range like it did with a piggyback. (I am not using VE mode) The tuner sold me new ID725's and set the latency times, and I want to double check what he entered.

ID has latency times for 40, 43, and 45 psi for that injector. Given that I am running a higher flow pump with stock regulator, should I be assuming I am at the high end of the stock range and be using latency times for 45psi?

I can experiment with all thre sets of latency times, but if anyone has used a Walbro 255 with stock regulator and can chime in on your experience, it would be very helpful. I have been to this guy 4 times and I am not going back. I am going to try another guy who has a million years experience and is well thought of, but he is over an hour away so I want to sort out what I can before pulling into his shop.

 

I want to know what you find. I have the stock fpr as well and have the same problems you describe. Even partial load in lower gears at low rpms and my afr will dip into the high 11's. Same thing cruising in 6th.

I have also attempted to adjust my fuel table only to revert back to what it was before because nothing was helping. I even adjusted the o2 feedback as well only to revert for the same reason.

I don't know if it is the changes in temp (tuned when it was about 45 degrees outside) or the changes in my exhaust, but doing a pull my afr's will even drop down to the 10's especially in lower gears.

Edit; Fuel setup is...

Stock fpr
AEM 320 single pump
FID 1200cc's
stock lines and rail
2005 with return system

 

This is the part that mystifies me (and apparently the tuner). The tune says "run 14.4" and it has O2 signal but it will go ten and wobble for a long while before recovering to 14.4. The fuel cells only will allow for a 10% correction so it should not get as bad as 10's but it does. The computer should be saying "look jackass, you are in the 10's, freaking correct yourself" and it should be able to do it quickly.

My Emanage was able to do this without issue, I don't understand why it does not see it is not running the target ratio and correct in miliseconds. So something else in the tune is off, it is getting a strange signal from a sensor (which I never see when I montior them on the laptop) or the latency times are off.

 

Shouldn't be a pump/pressure issue. Your pressure won't really increase much until you're into positive boost pressure
Just sounds like it needs some tweaking based off of Throttle percentage
There is a shit ton of time that goes into making a car run as smooth as it would as factory
Things will be "close" but not always perfect
It's just in the tuning not anything mechanical
My car probably has at least 10 hours or more into idle and partial throttle tuning

 

Do you guys that run flex fuel mapping just buy the GM stuff or the zetronix (sp) kit
I won't be doing the aem stuff with tuning this year but would like to view my ethanol content

 

Anyone ever have this issue with the AEM v2 EMS + AEM Data? I'm recording engine logs at the fastest speed and it's giving me really jacked up readings all over the place. It was saying my RPM's were over 25,000 at one point (Yea I wish)

 

I think the majority just buy the GM sensor/plug (which is all you need if you have AEM Series 2 or Infinity) and buy the Zeintronix gauge if you need it (like I did with my Haltech). The AEM Series 2 and Infinity can accept the signal straight from the GM sensor, but the Haltech needs analog signal so you have to use the Zeintronix gauge outputs.

 

So my coolant temps were somewhere between 205-220 deg. F today. Its hot, a bit humid, I had the AC on, and I was sitting in traffic. Plus when I was actually getting some speed I was stuck behind a giant SUV killing my air flow. It was the hottest I have seen my coolant temps. I know that's still kinda in the OK range, but I was one bar away from pulling over, lol. When I finally got into clean air it dropped a bar pretty quick (down to 190-205 range), so I'm not too concerned.

 

You have bigger ones than me...I pull it over when I see 205... I was out earlier and after a few high end pulls I saw 196...and that was awesome! I don't have much traffic driving, thank goodness...I did remove the mishimoto shroud...and that has helped quite a bit. I also blocked the sides of the radiator with foam, so everything is going through vs. around.

 

I got a bit of that just the other day, just thought it was something I did wrong...but that mess is ugly.