Cummins93

I am looking for someone with a 96 to 99 XJ that can tell me what their LTFT is when in open loop. Stock injectors preferable or 4 hole. Please and thank you.

tiger02

This morning I was reading between 2.3 and 5.5 with engine temps below 150°, so I'm assuming still open loop just after start up. 25 mph roads heading out to the highway. I don't recall the conditions for when it goes closed loop. I should add that the measurement is as a percent.

jordan96xj

I watch mine every day (scanner hard wired in). I also have stock injectors.

Closed loop comes on faster than you would think. It is typically closed by about 60 degrees F. Within about 1 minute of starting when dead cold (provided the o2 sensor heaters are working properly).

I'll note my values when I start up after work today (COLD!) and post when I get home.

Cummins93

Thanks for the info guys. I am looking for hot running condition WOT LTFT.

jordan96xj

That would have been helpful in the first post. I figured you just meant normal cold start open loop. Jeep is in for the night now.

Cummins93

Yea probably, next time you are out can you keep an eye on it?

jordan96xj

Here was the video I filmed for you...before I realized you needed something else. lol

Cummins93

Hey still a great video and it still is useful for me so thank you.

GreaseMonkey17

jordan96xj

I did a WOT test at operating temperature (205-210) today.

As soon as the system detected WOT, it went open-loop. Then the LTFT and STFT both immediately went to 0.0 and stayed there until I let off.

I let off the pedal, and it returned to normal (closed-loop, normal fuel trims).

Cummins93

Thanks. That is what I am looking for. When I hit my MAP clamp and go into open loop my STFT goes to zero but my LTFT stays at 28. My AFR is fairly stable and where I want it but I want to get the LTFT in check so I can keep turning up the boost.

5-Speed

STFT will go to 0 at WOT, typically above a certain rpm. It happens in every vehicle with a narrow band o2. LTFT will still stay at whatever its at even under WOT. LTFT is just a general adjustment made to the entire fuel map based on what the STFT has seen. STFT is what the ecu is adjusting at that exact moment. You really do need to get your LTFT close to 0 to make your tune accurate. Just keep in mind that WOT pulls only use the base fuel map, not the o2, so get that base map right!

I am not sure what piggy back system you are running but some have 3 different LTFT to adjust. They have low, med and high. All based between different rpm bands. Take my Evo for example. Low LTFT is from 0-2000 rpm. Med LTFT is 2000-4000 rpm. High LTFT is 4000-6000 rpm. Anything over 6000 rpm does not use the o2 sensor for fuel correction and is strictly run off the base fuel map. Depending on what piggy back system you are using, you may be very limited on what you can adjust and may have to make some compromises.

Cummins93

I am using an AEM FIC. I have managed to force open loop at any RPM when I am in boost on my 96 standard. I had thought for a while that the last STFT before open loop affected the rest of the map all the way up till redline. I created a fixed voltage map which has started to decrease the LTFT. It will take a few days for it to balance out.