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

[Rabbit on Roids]

Tires are too fat,.. maybe.
 205s are pretty wide, I have them on my Golf but haven't checked the mileage lately.

thats what i was getting at. my jetta got horrible mileage with 205/40/17's on it. the wheels are alot heavier, and alot wider.

[Doakster]

To answer everyone's questions.

What RPM do I upshift at? I don't have a tach since it was orgininally and ECO car, but I don't rev it too high or too low when i shift, just enough so i'm in the power a little bit and I shift.

As far as the Odometer is concerned....let me reiterate...it's been checked against a GPS. On a 125 mile run (with the GPS) it got 121 on the odometer. The odometer is not off enough to cause this much of a mileage decrease. With that difference, i only see a few tenths difference in checking on the odometer vs the GPS

As far as the fuel system is concerned, there a NO leaks in the system, I went through the entire system when i installed my Giles pump. I have a new pump, new injector supply and return lines, new injectors, and various new supply and return lines to and from the tank. There are absolutely no leaking the system. Before and after going through the fuel system the poor mileage was the same.

For the alignment, it was aligned about 8,000 miles ago...but the car runs straight as a arrow when taking my hands off the wheel, and my tires have never worn unevenly.

As far as the 205 wide tires go....after I redid the entire front end I put on the 205s, and I got 43mpg for a long time, then the sudden drop...so it's not the tires.

I still think I should check the CV joints, they are the only thing in the front end that are not new. What's the method for checking CV joints.

[Doakster]

Oh and to add....I have and EGT gauge and boost gauge in the car....car runs anywhere from 650-900 in highway at 5-7 psi boost, going 65mph

[Runt]

If you are certain that you are not leaking the fuel, then you are burning it.  Question is why?
If it's timed properly, and not billowing unburnt fuel all the time (you dont trail a smokescreen, do you?) then it's probably running right, and maybe we are chasing the wrong goose.  Next time you drive it, as soon as you stop, walk around it and feel the wheel centers to see if one is warm.  For mine (I drive a little hard) they would normally be warm, but not uncomfortably hot.  Fronts and rears may be a little different, you are really looking for one wheel hotter than the others, but if the rears were both any hotter than the fronts, I'd rip them apart and see what you find.  Basically, I'm looking for bad bearings, or more likely dragging brakes.
Again, good luck.

[rabbitman]

Oh and to add....I have and EGT gauge and boost gauge in the car....car runs anywhere from 650-900 in highway at 5-7 psi boost, going 65mph

That's weird, I have an EGT gauge and no turbo and it runs 550-850F at 65mph on flat ground.

With that much boost just cruising it seems like you should have a lot lower exhaust temps.

[Doakster]

Keep in mind, a have a little more fuel going to the motor with the new Giles pump.

By new pump I mean is has like 250miles of driving on it, it's brand new, the car does not make a smoke screen, it's not burning too much fuel, before and after the new pump I was getting low 30s, so it's not the pump or too much fuel that is the issue. There is light smoke when accelerating somewhat hard, but to be expected with the new pump.

The timing is not off either, it's set to .95mm, I've done timing checks on this car many times, and played with it either way, and got no change in the mileage.

As far as balancing the wheels, they were balanced when i first got them, so about 8,000 miles ago, but i don't feel that is the issue. The ride excellent and no shaking on the steering wheel like a typical unbalanced wheel would.

My wheels bearing in the rear a brand new, wheels spin extremely easy and smooth by hand. Up front they have about 8,000 mile on new front wheel bearings. Wheels spin freely up front, a little harder up front but to be expected with my LSD in the trans.

I'll say this again, MY BRAKES ARE NOT DRAGGING, i've done the touch the disk/drum/wheel test after 50-100 miles of driving and they are always cold to the touch, never hot.

All they typical stuff that usually causes poor mileage has already been checked or replaced on this car, with no luck.

I found a coolant leak coming from somewhere tonight, which i'm not too happy about, I was planing on going through the entire coolant system anyway, so that is next on the list, at some point, I'm getting sick of putting money into and working on this car, to find the mileage problem.

Anyone want to buy a low mileage car where nearly everything is new on it?

[Mark(The Miser)UK]

Oh and to add....I have and EGT gauge and boost gauge in the car....car runs anywhere from 650-900 in highway at 5-7 psi boost, going 65mph

So is that 5psi when cruising along the flat, or are we talking 5 to 7 as you zip past someone?
I'd expect from my Quantum, to be nearer 2psi or less on cruising, beyond 70mph as well, unless up an incline.
Now I've changed my air filter, maximum boost driving 'reasonably' up a '1 in 3' is about 9 or 10psi.
Prior to that it was about 6psi.

Is your turbo calling for more fuel unneccessarily  
Is you exhaust carrying more heat than it should, ie retarded?
Are your injectors set on the high side of bar spec?

[Runt]

OK, I was pondering this a little further last night, and I figured perhaps rather than guessing at the problem, I could suggest some more testing that may help locate the problem.  I figure if you are burning extra fuel, and the motor is running nicely, there must be an added load somewhere.  What I did was go out on the road near my house, I ran it up to a steady 80km/h (almost exactly 50mph)  and then I let it decel, clutch down (disengaged), in 4th gear so that it was spinning the whole tranny, to 40km/h (25mph).  This took 40 seconds, give or take a couple of tenths.  I may go out and check to see if there is any difference if I do this in 5th, or neutral, but this should be enough to get you started.  This is testing the rolling load of the car, if your results are similar to mine, then I would be looking at engine setup, but if yours slows down ~30% faster than mine, then you have a rolling load somewhere between the engine and the ground. 
My car is a 91, big bumper, 350000km, with Passat front and rear disk brakes.  I'm running 205/50/15s on the front, and 185/65/14s on the rear till I can find a nice pair/set to replace my rear 205s.  I know that both rear rotors are just a little bit warped, so they may drag just a little bit, but I get almost 40 miles per us gallon even when I beat on it, so there can't be too much of a drag. 
Again, I hope some of this may help.

[Doakster]

I might try the rolling test Runt suggested, not a bad idea, can't hurt. I also might try to get the tires rebalanced and checked for warpage. But now that I think of it, I installed a brand new (different set of wheels) on 195/65/15 tires for the winter, and still got the same poor mileage, so it's regardless of what wheel/tire set up I run.

To answer some of the questions, is my turbo calling for more fuel? I don't believe so since my original IP pump was an ECO pump (no boost enrichment), got 32 miles on that pump and when I switched my Giles LDA pump I got the same mileage.

Is my timing retarded?....no, it's set to .95, per Giles suggestions.

Are my injectors one the high side of the bar setting....no, they were rebuilt by Giles, pop tested to 155 bar for TD injectors, I trust him.

I run 5-7psi boost, cruising on the flat at 65mph

I still need to tear into the coolant system, since i now have a leak, and I will probably tear apart the front end at some point, I have no indication of bad bearings, but I can never tell with this car.

[Mark(The Miser)UK]

Hi,
Well, being a citizen of the UK , I don't have ay experience of Giles' pumps, but I do know he has a great following.
However,  if that were a standard pump,then 0.95 for a pump supplying 155bar injectors,is slightly retarded, or are we not talking 1.6TD stuff here?
A retarded pump will give more heat in the exhaust, so give more boost won't it?
Cruising at 65mph in my Quantum can be as little as 0.5 psi, but certainly under 2psi. 5psi makes me think your engine is being loaded, with a resistance of some sort. (I could of course be talkin' rubbish though )

[burn_your_money]

Do you still have the stock K14?

I have a K24 on my mk2 big bumper car and on the highway around 55-60 I'm making 1-3 psi.

So to get this straight, your car was making 43mpg then one day you got in it and filled up and you were at 33 so you started checking/replacing things?

On page 7 when you installed the new pump you said that the return line blew off. Was the car running for a bit then it popped off? Have you looked any further into this?

[Vincent Waldon]

if that were a standard pump,then 0.95 for a pump supplying 155bar injectors,is slightly retarded,

Right you'd be... if it was a *standard* pump.  A Giles pump has oodles and oodles of dynamic advance, so a slightly retarded static setting is appropriate in this very specific case.

[Quantum TD]

I'll add my $0.02

Sounds like everything fuel is covered

Sounds like the mechanical stuff is also covered (brakes, tires, odometer, compression, etc).

The only things that come to my mind are:

1) Cam timing to rest of the system. You seem pretty comprehensive, but I just wanted to point it out as a possibility. The cam sprocket must be loosed and the cam locked in place when the TB is done. Then, after the TB has been tightened, then you can tighten the cam sprocket down.

2) Clogged fuel return line? I think you said you blew it out, but just in case...

3) Bad "OUT" bolt on the pump? Someone here was having a HELL of a time with air bubbles and fuel starvation at higher RPMs. It turns out that they had put a standard "IN" banjo bolt where there should have been the restricted OUT bolt. This would make sense after the pump install, but cannot explain the sudden loss of MPG with the old pump, unless the screen/check valve in the pump suddenly crapped out.

This might also explain why you blew a return line.

4) Libbybapa mentioned this, and it sounds like you're looking into it, but T-stat can affect MPG. Get a good Whaler brass one for 87 degrees Celsius. Your T-stat could be stuck open, and reducing the thermal efficiency of the diesel burn.

5) Alternator/AC draw? I'd assume the idle would be low if they were really drawing engine power, but who knows...

I'm out. Those are the only things left that come to mind. I'd start with the OUT bolt and see.  Also, it can't hurt to play with the pump timing. You could retard it a bit and see what happens. I generally find that despite what the dial indicator says, I can generally time a car better by ear than with the dial (just twist the pump while the car is running). From there, advance it or retard it to your desired power/MPG zone.

[Doakster]

Thanks for all the replies guys....here's my answers to your replies.

The timing....the new Giles pump is a TD pump, the .95mm came from Giles suggestions. I've messed with advancing/retarding the timing with the car, a few times when I had my original ECO pump in, maybe only 1-2mph difference.

My turbo....still is the stock turbo, K14, with a 2.5in downpipe

When did I notice the issue?....I had the car being used by a family member for a few months, after the use it got mid 30s mileage, I did all the front end and brake work prior to this and was getting 43mpg, this was all about a year ago, and I've been troubleshooting (and replacing parts) since trying to look the whole car over for issues.

On page 7, when i mentioned the return line blowing off, this was due to a cheap temporary piece of clear tubing I had installed, my fault.

Quantum's questions/comments....

Cam Timing....It's dead on, I've been through the pump and cam timing on the car many a time, I thought it was the cam timing myself, so it's been checked and double checked....I even did the timing belt when i first got the car (did all the front end work at the same time) and got 43mpg afterwards.

Clogged Fuel Return Line....not the case, I've blown down EVERY line in the fuel system multiple times, I can easily blow down each line by only using my mouth, and basically every line in the system is new except the hard plastic lines under the car.

Bad Out Bolt....good suggestion, but I have a few Out bolts kicking around, all are near new condition, not plugged, and I've blown/cleaned out the OUT bolt multiple times.

Alternator/AC draw....good thought, anyone know the what the current draw should be at Idle, I'll check with my clamp on amp meter.

Even though all my front end parts give no indications of issues, the right front might be suspect, the car sat over the winter while i worked on the fuel system, pump and interior gauges.

Upon restart, they was a noise similar to a tire rubbing the inner fender in the right front only with the wheel hard to the left, no tires were rubbing, the noise eventually went away, might have to tear that side apart and take a look.

[Runt]

When did I notice the issue?....I had the car being used by a family member for a few months, after the use it got mid 30s mileage, I did all the front end and brake work prior to this and was getting 43mpg, this was all about a year ago, and I've been troubleshooting (and replacing parts) since trying to look the whole car over for issues.

OK, I may touch a nerve here, but I think this is the missing peice of information.  I hope you understand, working in a shop, it seems like we are always playing a game of 'Guess what the customer didn't bother to tell us this time!'.  In this case, you lent the car out, and it came back with the mileage changed.  My first question is, what could the operator have done that would cause a drop in mileage?  How about top up the tank with gasoline?  To be honest, I haven't seen the car, I don't know how it starts, or how smooth it runs, but if your rolling load test is about the same as mine, I'd rip the head off.  You may see your problem right away.
I hope I'm wrong, and it just occurred to me that you may have been able to rule this out if the injectors you pulled didn't show any sign of it, but I'm just throwing out what went through my head.