Resetting ECU - better mileage? How to?

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Spamcan
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Resetting ECU - better mileage? How to?

Postby Spamcan » Tue Jun 15, 2010 10:52 am

I recently bought my '05 PF SE 4x4 (53k miles on it). I just finished my first real tank of gas that I could evaluate the mileage. Now, I know it's a heavy 4x4 and most of the driving was stop and go city road traffic. But I just got to the high 13's in mileage (13.8 MPG to be exact). I drove it VERY foot friendly (like an egg was under my foot), hardly any flooring it. My Xterra SE OffRoad (4x4) gets upwards of 16 with the same driving (35k miles on it) and should be similar in weight. I know the PF is older, but is the same engine as the X and was hoping for a similar MPG. So my question is: Since the ECU was "programmed" by the driving style of the previous owner, would resetting the ECU to learn my driving help?

If so, what's the best way to do this? And would it de-program my keys or any other pitfalls I should be aware of?


skinny2
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Postby skinny2 » Tue Jun 15, 2010 11:14 am

Pathfinder is about 300# heavier...which doesn't sound like much but that's 6-7% more. So a solid 1mpg hit could be expected particularly around town where objects NOT in motion tend to stay NOT in motion.

It will learn your driving over time anyway but shouldn't be a big deal if you want to try and reset. It won't change your keys or anything, but you may have to reprogram radio and such. The only place this thing really shines for mpg purposes is out on the highway. Around town it just guzzles fuel.

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Spamcan
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Postby Spamcan » Tue Jun 15, 2010 11:24 am

Thanks for the info skinny2! Will just unplugging the battery reset the ECU? Or should I just let it go and it will re-learn?

I did wonder about the hwy driving, haven't been able to do a long ride on the slab yet. This could give me a reason to swap rides with the wife (her X for my PF). :lol: She does a 90 mile round-trip drive each day. Don't get me wrong, love the PF, but the X is downright fun (probably the shorter wheelbase and tighter turning radius)! Feels like I can whip it around.

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richardekirby
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Re: Resetting ECU - better mileage? How to?

Postby richardekirby » Tue Jun 15, 2010 11:25 am

Spamcan wrote:I recently bought my '05 PF SE 4x4 (53k miles on it). I just finished my first real tank of gas that I could evaluate the mileage. Now, I know it's a heavy 4x4 and most of the driving was stop and go city road traffic. But I just got to the high 13's in mileage (13.8 MPG to be exact). I drove it VERY foot friendly (like an egg was under my foot), hardly any flooring it. My Xterra SE OffRoad (4x4) gets upwards of 16 with the same driving (35k miles on it) and should be similar in weight. I know the PF is older, but is the same engine as the X and was hoping for a similar MPG. So my question is: Since the ECU was "programmed" by the driving style of the previous owner, would resetting the ECU to learn my driving help?

If so, what's the best way to do this? And would it de-program my keys or any other pitfalls I should be aware of?
I don't have an answer to your question, but I do have something to add. We have an '06 LE 4x4 with a little over 60K. A few months ago, I had to take it in to the dealer for service. The check engine light came on right after I put fuel in it. They replaced the fuel sending unit in the tank. Since then, the mileage has dropped by about 2mpg. We used to get around 19-20mpg on the road, now it is about 17-18mpg. I figured they reflashed the ECU. I would be very upset if it was below 14mpg. While in Colorado a couple weeks ago, we still got a little above 15mpg going up and down steep mountain roads and loaded down most of the time.

I'm interested to find out what others have to say regarding your question.

deezx5
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Postby deezx5 » Tue Jun 15, 2010 1:18 pm

I found this on another forum never tried it though

------------------------

The following procedures will allow you to clear the ECU memory as well as erase any DTC codes which may illuminate your SERVICE ENGINE SOON lamp. This will clear the following data:

- DTC's (Diagnostic trouble codes)
- 1st trip diagnostic trouble codes
- Freeze frame data
- 1st trip freeze frame data
- SRT (system readiness test) codes
- Test Values

The following procedures are effective for both the R50 and R51 models. It is recommended that after completion of the reset procedure you complete the "Accelerator Pedal Released Position Learning" (If applicable), "Throttle Valve Closed Position Learning" (If Applicable) and "Idle Air Volume Learning" procedures as this data will also be erased and may need to be relearned.

Below are three separate procedures, any one of which will successfully clear your ECU's memory. Only one of the procedures needs to be performed. If an error occurs during reset procedure, you can start the procedure over without harming ECU. The following procedures will only clear emission-related DTC's.

The first procedure is the most difficult and time sensitive of the three. This procedure (if chosen) must be timed accurately or you may get a DTC and the SERVICE ENGINE SOON lamp will illuminate. It is recommended that you use a timer or stopwatch, if neither is accessible then implement accurate counting methods (one one-hundred, two one-hundred, etc..). The second procedure is medium difficulty and is still somewhat time sensitive. The second method is a variation of the first method using simpler timing which allows for easier counting (no need for timer or stop watch). It is still suggested that you use accurate counting method for the second procedure (one one-hundred, two one-hundred, etc..). The third procedure is the easiest of all and requires almost no effort. This method is recommended if the vehicle is not needed for use. It is required that you wait a full 24 hours to reconnect the battery as this will ensure that all memory has been erased.


______________________________________________

METHOD ONE (Most difficult procedure):"]______________________________________________

1. Confirm that accelerator pedal is fully released, turn ignition switch “ON” (without starting vehicle) and wait 3 seconds.

2. Repeat the following steps (2a and 2b) procedures quickly five times within 5 seconds.

2-a. Fully depress the accelerator pedal (HARD).
2-b. Fully release the accelerator pedal.

3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approximately 10 seconds until SERVICE ENGINE SOON starts blinking.

4. Fully release the accelerator pedal (while SERVICE ENGINE SOON is still blinking).

5. Wait about 10 seconds.

6. Fully depress the accelerator pedal and keep it for more than 10 seconds.

7. Fully release the accelerator pedal (The SERVICE ENGINE SOON light will continue to blink).

8. Turn ignition switch to “OFF” position and now you can start the vehicle. The SERVICE ENGINE SOON light should be gone.

If the SERVICE ENGINE SOON light continues to remain ON, repeat the above steps. Timing is EXTREMELY critical to resetting the ECU.

______________________________________________

METHOD TWO (Medium difficulty):"]______________________________________________

1. Turn ignition "ON" (without starting vehicle), count to 3 seconds.

2. Depress/Release accelerator pedal 5 times...hard and fast.

3. Count to 10 seconds (not 7!) and fully depress accelerator pedal.

4. Count to 12 seconds (SERVICE ENGINE SOON should be blinking), release accelerator pedal.

5. Count to 10 seconds, depress accelerator pedal.

6. Count to 10 seconds, release accelerator pedal.

7. Turn off ignition, then start engine. Done!

______________________________________________

METHOD THREE (Extremely Simple):"]______________________________________________

1. Remove negative battery cable from vehicle battery.

2. Allow vehicle to sit for at least 24 hours with negative cable disconnected.

3. After 24 hours, reconnect negative cable to battery.

Good Luck!

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Spamcan
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Postby Spamcan » Tue Jun 15, 2010 1:54 pm

Awesome, thanks deezx5.

So wondering, once up and running again, do I use the gas softly? Or gun it for a while? To get the best/optimal mileage...

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mar1
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Postby mar1 » Tue Jun 15, 2010 2:10 pm

take the battery leads off and give it a few minutes.
reconnect, adjust ur clock, and drive casually, dont push it and dont egg-under-foot it.

u wont really see any major difference in mpg.
alternatively, come to the middle east, gas here is cheaper than water :P

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madrock
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Postby madrock » Tue Jun 15, 2010 3:28 pm

I travel 17 miles one way to the park-and-ride for work. Five of those miles are on the highway while the rest of the miles are stop and go. I averaged 17.5 MPG after my first real tank full. When I say "first real tank" that's after I did the air box mod and changed to the oil to Mobil 1 Extended Performance. I have no idea how/if those mods affected the MPG.

In the morning, I open the sunroof and crack the rear windows while on surface streets. I close all of it when I am on the highway only leaving the vent open. On my drive home, I turn the AC on. Oh, and I try to use the cruise whenever possible.

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Spamcan
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Postby Spamcan » Tue Jun 15, 2010 3:39 pm

See, I totally think I may be getting less-than-desirable MPG. I'd be thrilled with 16+. That may still be a "on highway" MPG issue too. So I'm skeptical about resetting the ECU - is it necessary.

BTW - what's the air-box mod? Did a search and nothing found...

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madrock
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Postby madrock » Tue Jun 15, 2010 8:46 pm

The stock air box has a long snorkel that sends air to one area of the drop-in filter. This is evident with older drop-in filters because it always seems like one area is dirty while the rest of it is not. The air box mod is where you shorten the snorkel inside the factory air box so that incoming air is directed at the entire drop-in filter. Some of the guys on TitanTalk swear by this saying the shortened snorkel equals less resistance so it increases air flow. I decided to give it a shot before investing in a K&N CAI.

I simply removed my drop in filter and carefully cut off a section of the snorkel with a hacksaw (be careful not to damage the air box). After the snorkel was cut off, I used a utility blade to clean the edges, and then took my Shop Vac to remove all of the debris. After that replace the drop-in filter (or for better results install a new dry drop-in filter).

The picture below is borrowed from TitanTalk:

Image
Last edited by madrock on Tue Jun 15, 2010 9:40 pm, edited 1 time in total.

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Spamcan
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Postby Spamcan » Tue Jun 15, 2010 9:31 pm

Nice and SUPER EASY mod!! Love these kind. I'm gonna drop in an aFe Pro-Dry filter - did that in my Xterra - see if that mod can be done there too. Thanks for the info and pic!

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madrock
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Postby madrock » Tue Jun 15, 2010 9:41 pm

I had to edit my previous post. You would want to use a dry filter, not an oiled filter. AMSOil makes a good one too.

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disallow
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Postby disallow » Wed Jun 16, 2010 6:24 am

don't mean to hijack, but does anyone else have problems getting their air box to seal up properly? I find that the side closest to the engine seems warped, making it difficult to line up the tabs properly. If proper care isn't taken, I could engage the clamps and not have a proper seal between the top of the air box and the part attached to the wheel well...

t

skinny2
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Postby skinny2 » Wed Jun 16, 2010 7:03 am

disallow wrote:don't mean to hijack, but does anyone else have problems getting their air box to seal up properly? I find that the side closest to the engine seems warped, making it difficult to line up the tabs properly. If proper care isn't taken, I could engage the clamps and not have a proper seal between the top of the air box and the part attached to the wheel well...

t
I noticed that too. Swapped out my oem filter at 20k (filthy) and wasn't impressed at all with the airbox. The speed clips are nice and handy, but most have moved to screw down boxes these days. If you just don't get the clips perfect on the engine side it does not seal well.

deezx5
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Postby deezx5 » Wed Jun 16, 2010 10:03 am

Spamcan wrote:Awesome, thanks deezx5.

So wondering, once up and running again, do I use the gas softly? Or gun it for a while? To get the best/optimal mileage...
Just drive like normal. I'm not sure about the Pathfinder but in my Ford Focus I have to do a brief procedure so it can relearn its idle faster. This involves idling with ac on and off, revving engine with ac on and off and cycling ac fan speeds, driving a few miles of stop and go and repeating the idling with ac. If I don't do this it will run rough for a few days before it teaches itself. It's also a little 2.0L DOHC 4 banger so the AC running zaps about 20% of my power.

Also my wife has been driving the 09 Pathfinder with 87 octane gas 60/40 Hwy/City and she gets 18-19 MPG avg.


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