Lean tip in continued...
 

Ok so I’ve always been haunted by this problem. I’ve never ran closed loop because it gets really bad. Taking off from a stop afrs go way lean and car feels like it hits a wall. In open loop it’s better. Car has been down for a while and I’m messing with it again. Now it’s hot as hell here in fl and even in open loop it does it. Unless I rev it to 1500 + while taking off it’ll do it. Now, I really want to get this issue resolved. I would love to run closed loop and use the o2 sensor. I’ve read tons of pages and a lot of people have this issue but I haven’t seen a def solution. Can someone please tell me what causes this?

Anyone on here anymore?

Ok so raising rpm ve at 500rpms helped a lot. If I raise the ve at idle it helps the issue but then the car idles rich. Any idea how I can combat this? Remember I’m in open loop until I can figure it out and go closed loop.

You've tried step 6a?

Thx for the suggestion. I tried that but it did nothing. According to some of the gurus on here while in closed loop the ecu doesn’t refer to the fuel map while using the o2 sensor. If in full time open loop I see how that would work but the goal is to be able to use closed loop.

can you please provide more details about the mods? What injectors are you running?
I have FIC2150 and a fuel damper helped with the issue although did not eliminate it completely. Ultimately, I ended up running open loop between 1500 to 2000 rpm and the car feels a lot better.

Sounds like it just needs tuning.

Add fuel the VE map where it wants fuel? Is that insane to suggest
Also if the narrowband operation significantly impacts the low speed fueling long term memory negatively (either "too lean" or "too rich") That means the oxygen sensor IS BAD.

https://cimg6.ibsrv.net/gimg/www.evo...78218a7bfb.png
The car is on stock injectors. Stock block with gsc s2 cams, evo 9 turbo, speed density, open dump, 255 pump, 93 octane, etc. No adding ve is not insane to suggest. In fact, I said adding ve at idle somewhat helps the issue but then idle is rich. This is all in open loop as closed loop is worse. It has a new o2 sensor but aftermarket. I’ve read on here people saying aftermarket works and other day it’s no good. Either way, i figure if I can get it fixed in open loop then closed loop should be close.Here is my ve settings. Also, have some enrichment settings there for the hell of it.

Hold on you need to go back to diagnosis 101
First things first. Does the O2 voltage swing from 1v to 0v during normal narrowband operation, and
B. does it correlate with 14.7:1 on the wideband metre

Gota do the basics first

Its been a while since i used closed loop due to this issue. It was alot better in open loop so i just tuned it in open loop. When i installed the o2 sensor yes voltage would jump around but i dont remember now. Have to check it again. What i do remember is that cruising and idle the 02 sensor helped alot. My stft were within 2%. It was just this take off issue.

Aftermarket sensor? Can you please clarify on that?
Is it a Bosch sensor that you wired? You should definitely log the o2 sensor and see what sort of voltage it is giving.

I am running a Bosch sensor that I wired with the stock connector. Car ran like crap and I realized it wasn't done correctly. I redid the wiring and all was good to go.

It is a plug and play sensor from advance. A lot of people on here recommended it. I believe it’s Bosch. The sensor seemed to work fine but taking off from a stop is the issue. It’s doing it even in open loop just not as bad so makes me believe sensor had nothing to do with it.

Okay. First of all. All narrowbands use the same signal for the ECU. So you can use any narrowband from any car. I.e. walk into parts store, rummage through their boxes of O2 sensors until you see the cheapest one with the right thread, and wham it will work fine as long as you can identify the signal wire. It doesn't matter how many wires they have, 1,2,3,4, I've used 1-wire oxygen sensors in place of 3 and 4 wire sensors before because all the extra wires do is ground and heater element which isn't necessary. You can even leave those wires unconnected and just run the 1 signal wire, because narrowbands create their own voltage signal. The reference is ground through the sensor housing to exhaust tube on a 1-wire sensor, but the 2 and 4 wire sensors include an additional ground wire.

Alright that settled. I Agree with leaving the engine in open loop. I haven't run a narrowband sensor or closed loop in any of my cars for over 10 years. Closed loop is for people that just want to ignore the computer/engine and drive the car. With open loop, we have far more control over the air fuel ratio, e.g. I hold mine around 15.2-16.4 for highway cruising and this additional 1~mpg is achieved in a "lean cruise". The issue you are likely experiencing is a "lean tip in" and should be verified on a WIDEBAND before trying to 'tune it out'. If you touch the air valve (gas pedal) and the engine a/f goes lean on the wideband you must first recognize the transient delay. The time it takes for the lean condition to show up on the wideband after the fuel was sent into the engine, burned, and released, can be as long as 1 second at low rpms. It depends how big the exhaust tubes are and what RPM. So you must be aware of that delay to finely tune the AE.
Next determine if the base map needs the fuel, or if the problem is in the AE setting. You can hold the engine inside the load cells where the car initially accelerates and use wideband data to determine this step. Or you can randomly enrich the off-idle regions and add some arbitrary fuel to the AE to overcompensate, and gradually lean them back out until the issue re-presents itself.
Before doing that however. make sure the engine is running properly. Do compression test. Make sure the FPR is getting a vacuum signal. Make sure the fuel pressure is staying up. Do the basic stuff first before trying to potentially tune around a problem that will only get worse. Some large injectors have significant delay times when opening at low voltage, and some alternators on 4-cylinder engines produce low voltage near idle speeds, so sometimes injector latency values are what need adjustment (not the VE map)

If you can provide a log from a stop that would greatly help diagnose the issue.

While I do agree with you that open loop gives you more control, but in countries where weather temperature fluctuates a lot, it becomes very involving to always adjust the fuel map every time.
My evo 9 is modded from top to bottom, with FIC2150... and flex fuel ... I couldn't imagine running my car in open loop full time. Specially when it hits 120F during summer with 100% humidity and 60F in winter. I rarely need to make any adjustments to my fuel map.