mileage has dropped drastically

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May 27, 2006
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Hi I bought an 89 hilux last fall,and was getting about 600km per tank(60L). This winter my mileage has propped down to about 425 and has stayed there even after weather had warmend up.
I am having some brake service done, and hopefully my mileage will rise back up. what other contributing factors could there be?
There is no smoke coming out of exhaust, think fuel is burning well, but performance has dropped too, lacking power on hills.
still think it is brakes, but a 30% drop in mileage due to rubbing brakes seems high.
I have heard about some people bypasssing the EGR valve. Is there anyone who knows a bit more about this?
thanks
mika
 
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If a caliper was dragging a brake pad, it would create a fair bit of heat and or pull to the side of the dragging pad. Winter diesel will also cause your milage to drop but not 30%. Worn injectors or a injector pump which is not calibrated properly will cause bad fuel milaege. However, you would likely have a fair amount of black smoke from the unburnt fuel. A quick clean out of the fuel system using Sea Foam from NAPA may help injectors which are carboned up. However, it will not fix worn injector nozzels.

I think if you are seeing a 30% drop in fuel economy, it is just not one thing. It is a combination of factors: dragging brakes, bad injectors, worn IP, winter fuel, more drag (from roof rack), bigger tires, etc.
 
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It is likely the winter diesel giving you the poorer fuel ecconomy..

I jump up to 12-13L/100km during the winter months in my Surf whereas the rest of the year I average 10-11L/100km.

Before doing anything drastic wait a couple more tanks. Not sure where you are located but summer diesel should be back on tap soon if it isn't already.
 
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It is likely the winter diesel giving you the poorer fuel ecconomy..

I jump up to 12-13L/100km during the winter months in my Surf whereas the rest of the year I average 10-11L/100km.

But he is saying his fuel economy went down 30%.:eek: Either he is not factoring in the tandem trailer with the backhoe he has been hauling around or he has other issues than just winter fuel. Best if he fills the truck up again and re-calculates the milaege. Could be just a simple math error. Never happened to me ...:rolleyes: .
 
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If Psilocin's numbers are correct, going from 10 l / 100 km to 13 l / 100 km is about 30%. I see about the same going from summer to winter, but I think it might be a combination of the driving conditions and fuel which causes the huge drop in fuel economy.
 
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Yes, Psilocin's #s work out to about 23% which in MHO is a bit high for summer to winter. I really can't judge that well as my 4.2 L was getting about 12-13 on summer fuel. However, in Jan I had the IP rebuilt and new injectors installed. My last trip I calculated on had me doing 11.1L/100kms going into the interior on snowy roads and city driving around Abby. So, the inew njectors and IP rebuild did have an impact. My dad had a FORD diesel and it did not seem to make much difference between summer or winter. It just drank a lot of diesel. Still it was not a 30% impact from summer to winter.

I missed jmika's comment about the EGR valve. My truck does not have an EGR valve. I was unaware that diesels had them. I thought it was a gas thing. I know on a gas Toy I had when the EGR went, the fuel economy went down the tubes, but it effected other pollution control devises as well.

Like I said, the only time I have ever seen big swings in fuel economy in any of my previous vehicles is between towing a heavy load and unloaded. I will be interested to hear what happens when he does a tank of summer diesel.
 
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My numbers are real...I've been keeping track since late summer 2005. I've had the same pattern over 2 winters now. If you want to get down to decimal points I would say my average summer is 10.5L/100km and the average winter is 12.2L/100km. Also, I almost exclusively get my diesel at Petro Canada so there shouldn't be any formulation confounds in the data (hey knowing how to buy Petro Canada gift cards at 20% off pretty much makes a one gas station kind of guy out of ya! :D ).

As for blocking the EGR valve, its an easy job but I never noticed any difference in fuel ecconomy after doing it. Some say they have more power after doing it.

If you simply want to block the EGR from recirculating there is a good howto here. I did this mod immediately after buying my Surf in 2004...should take less than an hour. [I would start there, its easy and does the trick, if you feel the need to reclaim some engine bay space then you could move on top the complete removal of all the EGR pieces.]

If you want to completely remove all the EGR related gear then that is a little more complicated and you need some beefier blanking plates esp for at the exhaust manifold. You can either have some made or I believe Crushers has some sets for sale. I did this mod in summer 2006 and it was one of those jobs that should have been easy but ended up being very frustrating. Getting those nuts off the the EGR pipe at the back of the exhaust manifold was tough...at least the studs didn't break as that would have been a DISASTER! I'm glad I did it though as I used the opportunity to install a pyronometer in the blanking plate I had made for the exhaust manifold.
 
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yep, i have 30 plates in stock.
(and it has been found out that the smaller plates work well for blocking off the cold start)
the removal of the pipe from the exhaust manifild can be a bear...
 
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This is a total thread hijack but Crushers can you tell me more about blocking off the cold start on a 2LT? What does doing that mod do for you? Pluses/minuses?

I ask because I don't think the cold start system functions at all or just isn't setup properly on my 2LTII Surf. My Surf has lower power and I have to manually adjust the rpm speed with the idle up knob until the engine is warmed up. On my 2LTE Surf the power is there right away even on cold mornings.

Again sorry for hijak but its the first time I have seen anyone make any mention of cold start system let alone blocking it.
 
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well, my fuel economy has come back to normal, or almost.
I had replaced my left from caliper(aftermarket), and had the rest of my brakes serviced.
getting about 10- 10.5l/100km.
still think there might be something else.
will try the sea foam. , and thninking about the egr blocking.
can someone explain the benifits and drawbacks.
looks like a simple fix.
will this help out power as well?
I know I should just turbo it but have other projects on the go like trying to build house etc.
maybe after the shop is built I will turbo the 3l.
thanks
mika
 
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Oct 19, 2006
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I have a Hiace (91) w/ a 3l engine that totally sucks (fuel) and is also is seriously guttless I sure hope that summer fuel helps... if it doesn't I've got a 3l engine for sale and a really slick looking chicken coop
 
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Dread...have you cranked up your fuel set screw yet? I had to do that on my '89 Surf for it to be able to get out of its own way. Fuel ecconomy didn't suffer noticably after doing it either. What kind of milage are you getting with the 3L in the Hiace?
 
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Not sure about fuel set screw I'll ask my guys, probably, though thats a good description, not being able to get out of it's own way,:) Mileage is poor, so far 14-18 l /100km
I found it on a picture of a 2l injector I assume it's the same (the middle screw between idle and max) What's the proper way to fiddle with it? (I'm a noob when it comes to engines)
 
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You can find out very quickly as your truck will react immediately to very small adjustments in your fuel screw. Even 1/8 turn is noticeable as soon as you try to move. So you will know within seconds which way to turn the screw.
 

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