Fuel mileage think tank thread

[IndyIan]

Hi Kiwi,
Well, reading from your other post, a plan to convert the tracker to diesel is not going to improve mileage much. Although I could then plant 10 acres of canola and blend the oil in... Not better mileage but cheaper mileage!

Also, its remarkable around here the number of Volkswagon diesels parked in farmers driveways, not that they are using biofuel but offroad diesel, which is significantly cheaper.

Just thinking out loud, the GV engines must get their ignition timing from some sensor which could be played with to advance timing, and then fooling the mass airflow sensor or O2 sensor could lean it out. I don't have the service manual in front of me to look at.
Also probably the ultimate option is to get a standalone engine management computer and then you can do whatever you want. I've never heard of anyone going this way for mileage, usually its used for boosted engines for max performance. Would it ever pay off? Only if you kept the system for a few cars in succession...

Ian

[*Kiwi]

Of course those farmers using off road diesel are breaking the law if they drive on a public road. Here in NZ diesel fuel is not road-taxed at the pump - that is paid separately per km driven and vehicle weight class, 3.3 cents per km for me.

I've modified two carbureted engines in the past for better economy by leaning out the mixture as far as I could, but along with the perhaps 20% improvement I had to accept loosing quite a lot of power. A hot ignition system and .05" to .06" spark plug gaps are an essential part of this. I got the info from SAE papers published in the early 70's when auto companies started thinking about fuel economy. The problem is that lean mixtures were not compatible with three-way catalysts that are needed for emissions control.

Yep, the less-than-stellar economy from my diesel points right back to the poor aerodynamics.

[IndyIan]

I have a little "discovery" to share. I was doing the front brakes last night and when I took the top off the fluid resevoir I noticed the cam position sensor at the back of the engine. I then noticed that it had a slot instead of a hole for one of the bolts. Hmmm.... Off to the service manual, it turns out you can set the time on both the 4 and 6 cylinder with a regular timing light.

I've attached a picture of page 6F2-7. When I have a little time I'm going to check my timing as my tracker seems especially weak at low rpm and has been since new. I know on some cars the manual trans version gets the timing backed off a bit compared to the automatic, so people don't kill the engine lugging it. I hope the timing is very conservative on my engine.

This might be an easy 1 or 2 mpg adjustment for us.

Here is where I found the service manual.
Free download Suzuki Vitara Service Manual: Volume 1 Service Manual SQ416, SQ420. SQ625.pdf » Free Ebooks Download @ OnlineFreeeBooks.net

[murcod]

Originally Posted by IndyIan

I have a little "discovery" to share. I was doing the front brakes last night and when I took the top off the fluid resevoir I noticed the cam position sensor at the back of the engine. I then noticed that it had a slot instead of a hole for one of the bolts. Hmmm.... Off to the service manual, it turns out you can set the time on both the 4 and 6 cylinder with a regular timing light.

Yes, I mentioned that on the first page- but nobdy seemed interested in investigating!

Originally Posted by murcod

You can change the timing settings on the 2.7l engine so I've guessing the 2.5l is the same?

You need to set the ECU to a "base timing" mode before changing the timing- that's what the special tool is for. There is also mention of a plug under the dash which can be shorted out if you don't have the "special tool" but I haven't searched on mine yet to see if it exists on my RHD model.

[Sasquatch]

Made the first mod. I will be tracking mileage change. Installed a set of superwinch hubs. It is noticeable spinning the wheel by hand between locked and unlocked. Weather or not it will make a difference in mileage remains to be seen.

I did pull the bearings and repack them while I was in there. They are close to needing to be replaced. I will do them this winter. If you have over 100k on your rig, take a look at them.

It will be a week or two to get some data, but I will update this thread.

[murcod]

Keep the updates coming.

On the sublect of advancing the timing, I'd be very careful. I filled with 91RON fuel two weeks ago (which is supposed to be fine for the XL-7) and have since had noticeable detonation under even moderate loads.

[tredegarboy]

I can't explain it but after fully using synthetics everywhere for several years,I finally bought and installed a rear spoiler on my 03 GV, and lately I have made several long trips where I have kept my speed to around 95-100 KPH (~60 MPH) and several times have achieved 10L/100Km or 28.5MPG. I have never seen this before no matter what I tried. The best I had seen previously was around 12.5 L/100Km (~23 MPH). I have 114K mileage.

[IndyIan]

For more good fuel saving strategies check out Ecomodder.com
I have started doing pulse and glides and engine off coasting where practical. I used these for the last half of a tank and got 9L/100km which is my best tank since winter and I am almost ready to fill up again, this tank is looking atleast as good if not a bit better even towing my trailer for 120km.
I have also ordered a scangauge2 which plugs into the OBD port and monitors and displays many readings related to mileage. It also reads engine light codes and can reset the computer.
My next mods are to block part of the radiator and get manual hubs for the front axle. My tracker is supposed to get 8.1L/100km but I've only done one tank getting this mileage... Many people on the ecomodders get 10-20% better than EPA mileage using a few techniques and mods. My first goal is to get 8.1L/100km for my regular commute.
Ian

P.S. Sasquatch, how's the quality of the superwinch hubs, some others don't sound very good. Thanks

[Sasquatch]

Quality seems good. Noticed no MPG improvement as of yet. Put the rig back up for sale today. With the miles my wife commutes, we need to get an older Honda or Toyota that gets better than 30mpg.

[murcod]

Sadly that sort of matches up with other repsonses I've had when researching the hubs. I guess you would have done a lot of mileage since fitting too?

IndyIan did the Scangauge work OK?