Horrible Mileage...STILL...after alot of work/troubleshooting

[Doakster]

No problem on touching a nerve...the family member, was my mother.....and she's actually is a good driver, really easy on a 5spd and always tentative...i trust she didn't do anything out of the ordinary when she was using the car on her .75mile commute to and from work. I had a company car at the time, so I gave it to her to use. She'd tell me if she did anything wrong.

Even it she did put gas in it (which she didn't), i wouldn't care, cause since i've tested the compression good, new IP, new injectors, timing set correctly, that alone should equal a solid running engine (which it is).

When I started using the car again is when I noticed the mileage drop....I started using the car again Feb of 2009, since then I've done all the troubleshooting that I mentioned.

Believe me, after a year of troubleshooting, I've touched every nerve I have already.


As far as ripping the head off, why would I go to that extreme when I have a perfectly good running engine with great compression? Just rechecked my notes on the compression, had 440-450psi all cylinders, 490psi being the new spec, 417psi being a ware limit.

I'd say that's pretty good for a motor with 113k on it. No coolant in the oil either, no logical reasons to pull the head as I see it.

[Doakster]

One more thing, that's popped into my head related to the coolant system.

Occasionally when the car Idles for awhile, the temp will keep rising on the cluster temp gauge, rise all the way up 3/4 on the gauge....what's that tell you? Then again it's always reacted this way, even when I got good mileage.

I'm trying to think of anything that is out of the ordinary on the car to point out for thought.

Once I go through the whole coolant system I'm going to install my sensor for my Isspro temp gauge.

[rabbitman]

Man I can't believe it's giving you so much trouble.

I wouldn't worry about compression much anyway, about the worst thing it'll do is cause hard starting. A few years ago I had around 370psi in all of 'em and still got low 40s mpg. Strangely enough I now have 420psi and get the same mileage.

Does it smoke at full power?

If it ain't smoking then you should be getting *complete* combustion, I wonder if your boost is higher than it should be and the added exhaust manifold pressure is killing efficiancy?

[theman53]

Turn up the fuel.
If you are getting 33MPG you might as well have fun with it

[Quantum TD]

One more thing, that's popped into my head related to the coolant system.

Occasionally when the car Idles for awhile, the temp will keep rising on the cluster temp gauge, rise all the way up 3/4 on the gauge....what's that tell you? Then again it's always reacted this way, even when I got good mileage.

That's normal for the ECOdiesel. They tend to run a bit high on the temp gauge. Once the fan kicks in, it should drop to just over the mid point.

The only thing left that I can think of is crappy winter fuel, and the switch to ULSD? You are in the north. I'm wondering if it won't improve with more driving, and some summer fuel. Maybe some cetane boost? My MPG always suffers with winter driving. It's usually in the 2-3 MPG range, not in the 8-9 range, but it could be a combination of factors.

What else can it be? Fuel injection is all new. Turbo's producing boost. Airbox is not restricted. And the motor's got great compression.

I think the only thing left is pump timing. When it's fully warm, retard the pump until it just starts to want to stall, then rotate the pump back towards the block a touch. Don't fool with the timing gauge, it will give you a false sense of accuracy. After you've timed it, let it cool overnite. Try to start it in the morning cold with the cold start pulled out. If it still starts fine with the cold start out, leave it where it is and drive it for a while.

Go through at least a tank, and see what happens (or, fill the tank all the way up the filler neck, drive about 100 miles, and then refill all the way up the neck again). That should give you an accurate reading.


For comparison sake. I sold a 1991 ECOdiesel to a coworker of my GF. It has 210k miles on the original motor and head gasket (which leaks oil down the front). The motor has never been touched, neither has the injection pump or injectors (well, I did reseal the pump). It has the original AVX trans, Working AC and PS. I checked the compression on it before I sold it to her, and all were at about 440 PSI. I went through the cooling system, and it's all new. She consistently gets 39-42 MPG. I think with an AGS or AOP trans, that number could be a consistent 41-44 MPG.

[Mark(The Miser)UK]

I think the key is your high boost at cruising. Surely the purpose of a 'Giles' pump is to give lots of power when you want it, but to use no more, and maybe less than a stock pump, when cruising??
With car turned off is it easy to push it? If so, then it's not binding up. Do you have a basic un-Giles'd pump you can swap in? If not, can you do a pressure test on the pump, to be sure it's advancing correctly?
I am shortly to reveal some readings for my pump, where I think I've cured my 'permanantly around 45mpg [UK] curse' for my car.
For years I've struggled to get it as good as my other car's 62mpg. It looks like the missing mid-speed high economy was down to pump pressure being low, as I just achieved 53.4mpg. The best ever for this engine, be it only a gallon used, and subjet to errors on fill...

[Doakster]

Does it smoke at full power?

If it ain't smoking then you should be getting *complete* combustion, I wonder if your boost is higher than it should be and the added exhaust manifold pressure is killing efficiancy?

What do you mean by "full power"....when cruising, no it doesn't smoke....when getting on to accelerate, yeah it will smoke a little, but not ridiculously more than I would expect with the added fuel from the Giles pump. 

[Doakster]

One more thing, that's popped into my head related to the coolant system.

Occasionally when the car Idles for awhile, the temp will keep rising on the cluster temp gauge, rise all the way up 3/4 on the gauge....what's that tell you? Then again it's always reacted this way, even when I got good mileage.

That's normal for the ECOdiesel. They tend to run a bit high on the temp gauge. Once the fan kicks in, it should drop to just over the mid point.

The only thing left that I can think of is crappy winter fuel, and the switch to ULSD? You are in the north. I'm wondering if it won't improve with more driving, and some summer fuel. Maybe some cetane boost? My MPG always suffers with winter driving. It's usually in the 2-3 MPG range, not in the 8-9 range, but it could be a combination of factors.

What else can it be? Fuel injection is all new. Turbo's producing boost. Airbox is not restricted. And the motor's got great compression.

I think the only thing left is pump timing. When it's fully warm, retard the pump until it just starts to want to stall, then rotate the pump back towards the block a touch. Don't fool with the timing gauge, it will give you a false sense of accuracy. After you've timed it, let it cool overnite. Try to start it in the morning cold with the cold start pulled out. If it still starts fine with the cold start out, leave it where it is and drive it for a while.

Go through at least a tank, and see what happens (or, fill the tank all the way up the filler neck, drive about 100 miles, and then refill all the way up the neck again). That should give you an accurate reading.

Is the ECO coolant system any different than a TD coolant system..the only thing different on my car is the ECO turbo, everything else on the motor down to the trans final drive ratio is the same as a TD car.

For winter fuel....it doesn't have any in it anymore, plus over the last year the mileage would be poor regardless of winter/summer blend fuel. I thought that might be the case also.

I always check my mileage with the "fill to the neck" method you mentioned, on a 120ish mile trip, 95% of that highway.

As far as timing goes, i don't see why i would mess much beyond what Giles suggested, plus I had played with the timing when I had my original ECO pump in, not really any difference.

A little more info on the Injector pump...This car has had two Giles pumps in it, the first one ran only about 60mile before it died, that was totally my fault due to an over tightened timing belt which smoked the pump seal, I didn't do a full mileage test on that pump, but based on the fuel gauge usage it seemed to be about the same poor mileage.

After that Giles rebuilt another pump for me, this is the one I have in now. So, to sum up, the car has seen three different pumps in it, the original ECO, First Giles Pump, Second Giles pump, all got poor mileage, and the ECO pump was really the only pump a messed with the timing on, if I remember correctly I advanced that one.

[Doakster]

I think the key is your high boost at cruising. Surely the purpose of a 'Giles' pump is to give lots of power when you want it, but to use no more, and maybe less than a stock pump, when cruising??
With car turned off is it easy to push it? If so, then it's not binding up. Do you have a basic un-Giles'd pump you can swap in?

I need to do another confirmation of my boost numbers a cruising speed.

With the car in neutral, on a flat concrete garage, I can push the car easily myself.

I don't have other pump to swap into the car....but as I mentioned above, I've been through a few pumps on this car and the same results. I trust Giles built me a good pump.

[arb]

Might not be your case, but when I ordered my first 7.3L powerstroke 4x4 I was getting 20 mpg. I took it to the dealer for my first free oil change, and it dropped to 16 mpg - 20% less just like yours. The problem was, International uses synthetic in the factory to get better performance from the engine, and the dealer put 4 gallons of mineral based oil in. I switched back to synthetic and got 20 mpg again...

What trans do you have ? Could your Mom have had trans problems and a shop swapped your trans for a non-diesel trans ? What's your 70 mph engine speed ?

[Doakster]

Might not be your case, but when I ordered my first 7.3L powerstroke 4x4 I was getting 20 mpg. I took it to the dealer for my first free oil change, and it dropped to 16 mpg - 20% less just like yours. The problem was, International uses synthetic in the factory to get better performance from the engine, and the dealer put 4 gallons of mineral based oil in. I switched back to synthetic and got 20 mpg again...

What trans do you have ? Could your Mom have had trans problems and a shop swapped your trans for a non-diesel trans ? What's your 70 mph engine speed ?

Funny you mention all that, my daily driver truck is a 03' 7.3 Powerstroke as well, has a few mods/upgrades done to it....i ran Rotella 15W-40 for about a year, got around 15-17mpg, switched to Rotella 5W-40 synthetic, mileage didn't change a bit, but the truck runs a little smoother, I'm switching to Amsoil 5W-40 on the next change. Keep in mind the truck has always run with 33x10.50 tires, soon to be 35x12.50 tires, mileage will probably drop a tick or two after the new tires go on it.

For oil in my VW, it's always had Rotella 15W-40 in it since I've had it, got great mileage when I first had the car, I still run the same oil and mileage if now poor....I could try switching to Synthetic maybe 5W-40, but I don't think it will help 12-15mpg worth.

For the trans, it's the original AVX case, but it's been rebuilt, when it was done a 3.94 ring and pinion was swapped in place of the original 4.25 Ring and Pinion that comes in an ECO diesel trans (the AVX), also had a Peloquin Limited slip installed at the same time too. This was all many months after my mother drove it.

And I personally helped/watched the guy rebuild the trans, from start to finish, I pulled and reinstalled the trans myself, did a new clutch at the time too.  The guy I went too is really good, been building VW race motors and trans forever now. It's not an issue with my trans, after the reinstall it didn't help my mileage a bit with the 3.94

[arb]

Yes, very interesting....  I used Mobil Delvac One.

One question, did you change shoes after you got it back ? Maybe the new shoes were made in China and the soles have loads of lead in them ?  LOL !!

Just a thought, I understand you tested the speedo with your GPS and it was off 3%, so the other 17% is what we are looking for. Did you change the tires since you got 44 mpg ? Tire type can easily have a 17% change. Have you been checking the MPG from a variety of differnent sources ? The volume / content of the fuel could be different - like are they adding ethanol in your area ? Some are doing experiment on adding ethanol. There an SAE paper out on it.

[mtrans]

What about adjusting  internal pressure,if put little more same talk achieved good mpg.

[ShoulderMan]

A few questions and ideas for you.

 Where do you buy your diesel?   (maybe they are buying cheeper/lower grade to save money)(Watered down)

 have you tried using a diesel additive (to boost c-tain by 8 points or so)

 have you replaced your thermostat  (the one in there may be worn out or stuck open)

 forgot if you have A/C, if so, maybe compressor is stuck to run all the time or the bearings are dragging
 
 alternator may be worn out, causing drag on yout system  (bad bearings)

 water pump or power stearing pump or any other accessory driven by a belt

 the fuel water seperator in the back may be full of water (needs drained)

what kind/type of grease did you use to do your wheel bearings,

did you go from drum to disk brakes? did you change your rotor sizes?

      Ok, so after replacing all of the parts you said you did
maybe lets say you lost 2 mpg by putting in the new injectors(better flow=more fuel), 2 mpg by using the new super pump, 2 mpg by fixing the air leaks (which allows you to use more fuel for more boost) (and becasue we are just saying) 1-2mpg for dragging wheel bearings due to bad machining and bad grease, and bearings maybe too tight as well (cause where just saying) If your belts are too tight or too loose and your accessories are dragging 2mpg(alt/power stearing, a/c etc...) if your thermostat is stuck or not working right that can also suck 2 mpg.   add some watered down diesel, restricted filters, and maybe a heaver foot (with all that extra power you now have) or even driving 10mph faster,  keeping up with traffic, or stop and go traffic. SO, if all that could be so, theres 15mpg in the mix there.  though its just me thinking aloud and assuming that these might be issues

just another thought, since you had your alignment,  how are you tires wearing,

Just a few more ideas, for you
Hope it helps

 -Ron

[burn_your_money]

I think the only thing left is pump timing. When it's fully warm, retard the pump until it just starts to want to stall, then rotate the pump back towards the block a touch. Don't fool with the timing gauge, it will give you a false sense of accuracy. After you've timed it, let it cool overnite. Try to start it in the morning cold with the cold start pulled out. If it still starts fine with the cold start out, leave it where it is and drive it for a while.

I would try this next.