Tuners: Economy map

Any of you enginuity or street tuner guys make your own Economy map? I'm just wondering whats safe to do.

 

I'm looking to do it on the stock turbo/shorty catless DP/UP. This is my plan for a starting point.

 

Leave the timing alone for the first revision.

Zero out WGDC

target 11.5 A/F ratios for WOT

 

Does this seem too far towards the edge for the 10ish psi I should be seeing? Should I be adding or pulling timing if the car reacts well to the first revision.

 

Thanks for any help you guys can offer.

 

EDIT: I know I could just baby the throttle and get nearly the same results but I don't have self control like everyone else does So don't offer that advice. Thanks.

Don't touch the AFR.

DEFINATELY DONT lean it up on top or at WOT, I would just work on the lower load (cruising speeds) portions of the map.

You won't save any fuel by changing your WOT tuning strategies. That's very dangerous and won't save you any fuel because you don't spend that much time in that range.

 

For fuel economy, you have to look at the closed loop range between 2000 and 3600 rpm and below 1 g/rev.

 

Some people have lowered their tip-in for small throttle movements. I wouldn't do that because it can cause lean stumble and affects driveability. Also, the front O2 sensor will make a poor attempt to auto correct it anyway.

 

There is a way to tune for a leaner than stoichiometric AFR at cruise. You would have to advance the timing to counter the slower fuel burn. I haven't tried it but some people are experimenting with it. If I ever decide to experiment with this, I would install an EGT probe in my exhaust manifold / header.

In a way it will save fuel because after you blow the motor it won't use any fuel at all

 

Tuning for leaner than stoic at cruise is nuts.

^^ Tell that to Honda

^^ Tell that to Honda

 

I am sure Honda is using an aftermarket software system that reprograms the stock ECU to design their lean burn motors. It is one thinig for a manufacturer to design a system that allows lean burn to work; it is quite another to take a known system that is not set up to run lean and decide to make it one to improve gas mileage by .0001

 

Have at it

In a way it will save fuel because after you blow the motor it won't use any fuel at all

 

Tuning for leaner than stoic at cruise is nuts.

 

I really don't know why you have to bring in opensource into this.

 

I personally would not do this, but I know a couple of people who are. One of them uses street tuner.

 

Methinks you are a serious Cobb Fanboi.

The lean burn system is just computer tuning with a great oxygen sensor and a cat designed for NOx emissions. The reason that manufactures burn cars around 14.7 is strictly for keeping NOx emissions down. I don't recommend tuning lean burn, but it could be done by someone who had advanced knowledge of the system fairly easily.

that's funny. I will edit my post to refer to any aftermarket software system that uses reprograms the stock ECU.

The lean burn system is just computer tuning with a great oxygen sensor and a cat designed for NOx emissions. The reason that manufactures burn cars around 14.7 is strictly for keeping NOx emissions down. I don't recommend tuning lean burn, but it could be done by someone who had advanced knowledge of the system fairly easily.

 

Of course it can be done, the question is why and to what benefit?

 

Really, set up your car to run at 18:1 or so and enjoy yourself in the process

The benefit would be the 12-15% improvement in fuel economy. It would be a pain in the ass to set up and you would fail some strict emissions tests, but if somebody was that worried about gas mileage they could do this. My suggestion would be to buy a different car cause the LGT will never get great gas mileage.

Absolutely; and your safety margin is a approximately 0 so all those savings could, and probably would, literally go up in smoke.

You can tune for leaner than stoic at cruise. As long as you don't go overboard it is perfectly safe. Something like 15.5:1 AFR is perfectly acceptable. As someone mentioned earlier, the biggest downside to lean burn is higher NOx emissions, which is why most cars are tuned to run 14.7:1 under cruise conditions. Granted running 15.5:1 won't make a big difference in fuel economy but it will help a bit.

 

I wouldn't touch the WOT maps much, but if the car is only running 7 psi then even 12:1 is perfectly safe with reasonable timing. Heck, at that low a load level, even the OEM maps would have the car quite a bit leaner than 11:1.

load < 1 g/rev isn't even 0 psi boost.

 

Several people have tuned their cars for AFR 15.5 with mixed results. Some people seem to think it's okay. Others have driveability issues. Implementation is everything. It's a lot more complicated to figure out. For example, you can't just type in 15.5 in the OL fuel table. That table is just an enrichment table that is made to look like an AFR table.

At one point I started generating tables to skew the cruise AFR to 15.5-16 but didn't finish the task. I got too tied up with work. In the end I ended up optimizing for economy at 14.7 by playing with AVCS and ignition timing. I ended up with 6.8 - 7.5 L/100km at 105kph cruise.

 

Self EGR (using cam phasing) can be used to gain some economy while maintaining a stoich mixture but I found that things got too lumpy transitioning in and out of the few cells where it was adjusted that way. I opted to sacrifice a little (less than 0.1 L/100km) economy to get a much smother transition to higher loads.

 

With a 15.5-16 AFR vs 14.7, you would need to advance the timing 5-10 deg to compensate for the much slower burn rates. I only tried experiments on a few cells this way before I got too busy at the office.

Great response guys. Looks like I'll start researching alot more. I don't know why I though targeting WOT fueling would help much. LOL As far as targeting leaner cruise conditions does anyone think the stock o2 sensor will be accurate enough to monitor this? I have a wideband available to me but I can probably only get it in day intervals and theres a wait time to even get it.

the stock o2 is pretty good near stoich as long as the manifold pressure is low.

 

one thing to consider is that the lifetime of the sensor may be shortened if the mean cruise AFR is far from stoich. it will probably be ok but I haven't seen the cell life vs mean pump current curves yet. regardless, with the current gas prices, even a 5% gain in economy will pay for a new sensor really quickly. just be careful with your tip-in curves if you tune for lean cruise. the last thing you want to do is slowly destroy an engine and eat up your $avings

Great response guys. Looks like I'll start researching alot more. I don't know why I though targeting WOT fueling would help much. LOL As far as targeting leaner cruise conditions does anyone think the stock o2 sensor will be accurate enough to monitor this? I have a wideband available to me but I can probably only get it in day intervals and theres a wait time to even get it.

 

If your doing any kind of tuning you should always have a wideband of your own. The Innovate LC-1 can be had for under $200.

If your doing any kind of tuning you should always have a wideband of your own. The Innovate LC-1 can be had for under $200.

If only it worked... Should have checked the innovate message boards before I bought..

^^^

I run a Zeitronix myself....