Thread: Tuning for Gas Mileage

That's right there should be a way to wire it in. I should do that, would avoid me spending another dime on an O2 sensor.

But I will have to first move my wideband to the down pipe, to reduce the possibility of the gaskets leaking and causing issues.

I wonder if data logging would be fairly accurate using the wideband too?

The jerking is from the map going really lean to really rich. Since I reduced the K value it affects the whole map. What I don't get is, the jerking happens when I press on the gas, before O2 sensor goes to open loop, yet A/F's still spike to 16-17. So that tells me that at cruise the ECU is just forced to stay at 14.7.

the wideband should be just as accurate as ever, now placement of he wideband can slightly effect read outs, but you should be fine. i would definitly suggest trying to get rid of that factory o2 sensor and try to use the wideband as primary, then do a few off boost runs and on boost runs, and then make fuel changes as needed ten compare.

that stock o2 definitly seems like a bottle neck and is hindering you from being able to make the changes needed

I used to have a NewZealand made Link ECU in my last turbo NX, with a gt2540 turbo, 550cc injectors. The link used map/tps, and had no closed loop. I had a hand controller and could edit the current zone while driving, and i was able to sit a light cruise in zone 1 (the lowest load zone apart from idle) and hit the minus button until it started to buck and hesitate, then bump it up a couple of points. I never had a wide band, the rest was done on a dyno, but i could easily get 650km on 40l of petrol (406mile on 8.8 gal) 46 mpg. This compared to when it was NA, and what my current primera with daughter boarded ecu can do of about 10km/Litre (28mpg).

I was playing tuning with Romeditor the other day, and changed the closed loop area to fixed value's, so the wideband wouldnt kick in, and was able to get cruise mixtures of high 16's, but still mid 11's on full power.

I have this tune still saved to play with further, just working on some other issues atm.

I just got back from a weekend full of highway driving. This time I tuned the Timing in the 3200 RPM range, I map traced to make sure I was there while on the highway.

Results: No significant gain, if any at all. 28 MPG as before basically. While MAP tracing I noticed that while on a straight road I would be around 15 TP, on road changes, it was 43 TP, 50 TP, and 69 TP. This is with 10-0 Vacuum.

I'm thinking about increasing the TP ranges, but not sure about the ill effects of doing that.

My updated map is right below Calum's map, my timing is in Red. I also wouldn't consider that map too safe, car did not feel too "safe" from detonation.

Found another article about ECU tuning for gas mileage. It's interesting, I don't necessarily agree with everything they stated though.

Fuel Economy Tuning - Tech Review - Honda Tuning Magazine

Like the cold start deal. When you first start the car it will idle at 14.7, but I noticed that if I drive it, I will get 13's just form regular driving until water temp gets to 160*F. DC Scotty also tried this a while back, for a period of time (I think a week), he let the car fully warm up before driving and he saw at least 2mpg improvement.

Another thing to mention, when my car's O2 sensor died at the SR20 Convention, on the way back I was stuck at 16-17's A/F ratios. The O2 sensor was not stuck in Open Loop, but was miss reading the ratios. I got 35 MPG with my ocassional flooring of the car to cool down the engine from the higher A/F ratios. This is before I knew that going above 15:1 yields lower exhaust temp temperatures.

This brings the next point, leaning out engine doesn't always mean it will have higher EGT's.

Neverless nice to see tuning for gas mileage articles. Now going back to my 15/28 mpg monster

From something i read a while ago, the reason they set the target to 14.7 is to keep the egt up, and the cat working, leaner doesnt create enough heat to keep the cat burning.

Dont need Cats in NZ, so im working to lean it out aye.

You are correct sir. I don't have a CAT myself thus I don't have to worry about the mixture being at 14.7 either.

Now keep in mind that going leaner then 14.7 might result in power loss, thus you would have to press the throttle more to get the same response, thus could essentially make you waste more gas.

I'm trying to lean out my engine to test this and see how it actually does on my car.

The way i got around that with my old standalone, was that as soon as any load came on it moved to the next load zone, which was normal mixtures, so it was only on the light cruise when it would run mega lean.

I'm using a Daughter board atm, but want to invest in a Nistune realtime board asap to be able to play with things like this easier.

I downloaded NissanDataScan, looking at the site it says its free, and the software is a free download, but there is no real sign it needs to be registered, and even the registration key on the program itself just says to email the code to the address supplied to activate, turns out you need to find someway to pay for it, so far i havent got around to finding where, how much and how. Anyone got any opinions on this program? I want it for map tracing mainly, any free options anyone is using?

Nissan Data Scan is far from free, and far from being expensive on how useful it is.

The only thing it does is let you connect to ECU and see if it supports your ECU other then that you would need to register.

Look up DataScan's site to find out how to register etc.

Also, if you want something free, use Calumsult. Index of /calumsu/CalumSult

Download and install CalumSult Full.zip, then use the beta's or the 0.08b

Looks like we might have found the culprit for bad gas mileage on our maps. The TP (engine load) is set to be too low.

What does this mean and what is going on? Last column is set to be 69 TP, when a boosted engine has load at or above 100TP depending on boost levels. So when your driving regularly and you hit 69 TP, ECU puts you in the last column like your WOTing the engine. When really 69 TP is pretty much within normal driving levels.

This can be corrected by increasing the WOT TP, so that you don't go into the WOT column unless you really are flooring the car.

I was noticing as something being wrong while driving on the highway, and throttle being less then 1/2 pressed and my A/F ratios would be at 11:1 or less, while when I would press the gas pedal all the way the A/F Ratios would go up to 12's like I set it.

Basically at 69 TP the fuel was being added like fully flooring the car, while there was not enough oxygen, because throttle is only 1/2 open.

I will be testing an updated TP map and see how it does

Read more about that here.

A huge thanks goes out to BenFenner for sitting there and helping with figuring out how on earth Nissan deals with TP (Load), and the problem with having too low of TP.