Mileage Tuning ideas..

[johnh]

Given the price the gas...

What are some ways to tune for better mileage?

- Changing AFR from 14.7 to something leaner 15.2?
- Adding timing when not in PE? How much?
- use of 87 vs. 93? (larger pulley/less boost).

I am thinking of changing the pulley to the 3.3 (largest I have, but too big for the XP cam?) and tuning for mileage...

[Perforator]

Take the supercharger belt off. This way you won't go into boost.

[BlackGS]

More cruise timing and earlier TCC apply help a lot. Of course, the basics of less pedal and good maintenance will always yield the most mpg.

[johnh]

Take the supercharger belt off. This way you won't go into boost.

True, but the car will be a dog with the cam and low compression.

My TCC is pretty much optimized, I spent a bit of time on that previously....

[JerryH]

A small taste of the coming new tuning notebook:

Tuning Tips:

- VE will change in colder winter months, its a good idea to optimize it for the colder air, so do it again. Make the trims as "perfect" as you can.

- Check your LTFT/STFTs after doing the VE, you will likely need to do a complete MAF tune afterwards as well. Make sure the trims always lock in at zero anytime you are in PE.

- Keep out of PE as long as possible! Reset your PE ENABLE TPS % back to stock or as close to stock as KR permits. Higher number means less change of going into a mode that will increase fuel usage.

- Use the stock 195 degree thermostat. Not only will it aid in making the car heater significantly warmer, the car will give you better mileage with a hotter T-stat than with a 180, more so if temps drop under the 20F or -10C ballpark. While we are on the topic, never ever use a 160 any time of the year, unless you live somewhere that the average winter temps during the winter are over 85F and the summer months are much hotter. No matter what T-stat you use, make sure the PT has the correct temperature ranges for the T-stat that is installed in your car.

- Make sure your IFR is the correct one for your car. This does 2 things. First is that your DIC indicated mileage indicated will be pretty accurate, and second is that it will be better able to meter the fuel out more accurately. Stock injectors = stock IFR.

- Run the biggest pulley you can. I run a 3.4 in the winter, but if I still had my original 3.8, that's what would be on the car.

- The boost valve mod is reversed. Meaning that most lower the boost valve so that boost comes on sooner. Mine is raised as far up as I can make it. This not only reduces the chances of part throttle KR but makes it a little more difficult to get into the boost at lower throttle settings, hence increasing mileage.

- Run the narrowest snow tires and lightest rims you can for mileage reasons and the fact that narrower tires run through deeper snow better than wide ones.

- Make sure all 4 tires are at 35PSI. An under inflated tire not only runs hotter, it increases drag significantly.

- Reset your tranny settings to stock (if you have performance shift, just reset the NORMAL mode). The stock factory settings are already designed with economy in mind and are quite good. I would not play with the TCC to lock up any earlier nor get the car to shift into 4th sooner. Its not always the best to be lugging the engine at low RPMs. In fact, what I still suggest is that 4th gear low RPMs still disengage the TCC a little sooner than factory because I found that I can get up the steep hills at lower TP% levels then of the TCC was locked, car is in 4th and the engine is lugging. Experimentation on your end will decide what is best for your car. Another related hint is to decrease shift speed. Slow, smooth shifts mean slipping the clutches longer and that is keep you from applying the power sooner. Perhaps decrease them so that they are quicker than stock but NOT harsh.

- Limit boost to as low as possible by disconnecting the boost solenoid. This limits you to 2-3 PSI of boost. Watch your O2s, they may rise a lot and you may have to increase the Base PE A/F (lean it out). While you are playing with the Base PE A/F, you may need to lean it out a little more due to the cooler air and less boost, so feel free to lower your summertime optimum O2 numbers by at least 10-20 (KR will be your deciding factor as to how much you can lean things out).

- You may wish to lean out the fueling only slightly and increase timing. The O2 vs timing is a juggling act... be careful to not go to the extremes with either parameter, you do not want to chunk pistons!

- Timing: You can likely get it 2-3 degrees higher during cruise during the cooler winter months than in the summer heat. In low RPM and low load situations you should be able to touch 40-43 degrees of timing. If you can maintain 39-47 degrees of timing while at a steady 60MPH cruise, consider that excellent. The stock timing for my 99 was between 25-28 at 70 MPH. I realized quickly that I could easily run 35-45 degrees without KR. That's a HUGE increase. I found that the 05GTP timing tables are a good starting point for my car in the winter months running on 87 octane. The only thing is that I reduce WOT timing from 21.5 to between 17-18 degrees as a safety factor because I use 87 octane. I then tweak areas between 1600-3500 RPM for slightly additional timing without inducing KR. Makes the job that much easier. I avoid the low RPM areas underneath 1600 for the simple reason that the stock 05GTP tables are already much more aggressive than my '99 tables and I do not wish to introduce the chance of low RPM/high load KR. You can make it even more aggressive on the low/no throttle or decel settings of 50 degrees timing. This is about the maximum permitted by the PCM.

- Insulated air intake. The colder the air coming in, the better. This goes for the summer months too!

- Setting your AE tables back to stock or as close to stock as possible is great. Nowhere will we use greater fuel than at acceleration and during the winter months, we should be able to do more with less. Get those tables back to as close to stock as your car permits.

- PE A/F vs TPS table: For me, I used to have massive flash KR using a 1999 bin, but this table in stock form, contributed to good mileage. A fair compromise would be to leave it at the stock settings between 0-25% TP and then drop it drastically to 2002 bin values at TP % values of 30% and higher (this is still theory as I have not tested this yet).

- Remove things from the car that unnecessarily add weight (do you really need those 200lb subs in there during the winter?)

- Try a lower grade of octane (when possible, not everyone has cold winters and can get away with this one). I run 87 in the winter and summer safely enough.

- Very cold days making your car take longer to warm up? Use a block heater. Add a 5 dollar timer and a nice 30-45 minutes of the block heater turned on will make your car's warm-up time drop by 50-100% depending how cold it really is.

- Driving technique is paramount and can likely make the biggest difference in your quest for good fuel economy. You have suddenly just started driving almost like a little old lady. By this I mean:

- No burnouts, no races, heck no hard acceleration (nothing over 25-35% TP). This one has to be the hardest to accomplish for us performance enthusiasts.

- No hard braking.

- Any throttle movement is slow and steady, you learn to compensate by looking farther ahead. This is a proper/safer way to drive anyways. If you want to take it to an extreme, imagine a raw egg between your foot and the gas pedal (lol).

- Hill coming up? Increase speed a few MPH now instead of fighting to maintain speed going up the hill. Going down that hill, do not go over your speed unless there is another hill right after that. If there is no other hill, do not let the car accelerate over your cruising speed by more than 2-3MPH and slowly regain your cruising speed.

- Your cruise control will never give you economy as good as your right foot can for the simple reason that it cannot look down the road and predict in advance and plan for changing conditions and road elevation changes.

- Speeding will cost you big MPG losses fast. Approximate an easy loss of 5-7 MPG drop between 60MPH and 75MPH. In a rush? Leave earlier and don't speed. A 15MPH difference over the average 30 mile commute saves you a mere 7.5 minutes but costs you 5MPG or more! Leaving 15 minutes earlier gives you the theoretical equivalent (in terms of arrival times) of you having traveled over 90MPH with a ZERO loss in fuel economy!!

[n0dih]

I have found that coasting has given the most improvements.

Think of it this way, if you had to hit the brakes, you were on the gas too long. Nothing can bring that burned fuel back. So the less time you are accelerating, the less fuel burned (this is why going faster is often a mpg loser, you spend more time getting there, even though you may not see much if any loss in straight line mpg at a little faster speed). If no one is around, I do my darndest to coast down so I am hitting the brakes @ 30 mph than 60 mph on the back roads where I drive a lot.

Good tips Jerry! You really can't over emphasize them.

Look at your MAF readings. Anything you can do to lower the MAF reading means that you have less fuel being used (14.7:1 is pretty fixed as long as you aren't in PE). I notice even following a semi @ 100 feet I am seeing slightly (~5 gm/sec) MAF readings vs not following one. But don't tailgate, they don't like it and is isn't safe, but if does help mpg. The more aero the car is the more sensitive it is. My 99 K2500 454 Suburban makes no diff.... A brick wall is a brick wall at 70 mph.

I like to drive by the instant mpg reading on my car, it keeps me thinking about it, I can usually squeeze 1mpg more to a tank simply by paying attention.

Westers has some good tips too.
http://westersgarage.eidnet.org/mileagetips.htm

The jury is still out on heated intake air vs cool intake air. My car on E85 responded very favorably to warmer (even 10-15C) intake air on the mpg than cooler. The more alky, the warmer it likes it. A lot of nutty Civic guys like to breathe exhaust manifold air to boost mpg, but a noted loss of hp too.

- The boost valve mod is reversed. Meaning that most lower the boost valve so that boost comes on sooner. Mine is raised as far up as I can make it. This not only reduces the chances of part throttle KR but makes it a little more difficult to get into the boost at lower throttle settings, hence increasing mileage.

What is the boost valve mod? I have a 00 L67 PAU.

[JerryH]

What is the boost valve mod? I have a 00 L67 PAU.

The supercharger boost valve has the ability to be controlled a good range. When pressed all the way up, it will permit boost to hit sooner/faster at the expense of MPG. Pushing it down delays the activation of boost, increasing MPG small amounts.

I had it set to come in ealier... all it did was cause me to break the tires loose easier and increase burst knock.

There is a 3rd option, and that is to disonnect the power to the boost valve, but it does nothing to delay or increase the on-come of boost... but to limit maximum boost to 2-3 PSI.