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

[Jettage1]

I just recently put a new clear fuel line on my TD ...  A good clear line does help diagnose things though

Not to go much OT here, but what did you use for your clear line?

Tx!

[Doakster]

I just recently put a new clear fuel line on my TD ...  A good clear line does help diagnose things though

Not to go much OT here, but what did you use for your clear line?

Tx!

My ECO came with clear lines from the factory, but as they age you usually can't see much through them. I replaced my return line with just some clear plastic tubing, but i'll due something more permanent in the future, maybe get the original clear line that has all the proper bends if VW still sells it.

[Baron VonZeppelin]

...the original clear line that has all the proper bends if VW still sells it.

they do ........ for almost $300.
its ridiculous

[Rabbit TD]

I just recently put a new clear fuel line on my TD ...  A good clear line does help diagnose things though

Not to go much OT here, but what did you use for your clear line?

Tx!

I checked with some other people and they had been using a clear tubing that is chemical rated from tactor supply for like $.30 a foot.  They have it in all sizes.  Seems to me it was 1/4 in. from the filter to the pump but make sure you put at least 2 clamps on each connection, the good banded ones not the worm screw ones.  Take one of your fuel fittings in with you to get the right size.  You might be amazed to see how much air some of these old connections and lines can let in the system.  I've had this line on now for over a month and it seems to be holding up fine with diesel fuel.  I don't think any of those old lines were pre-bent, just the fact that over the years they get stiff from age or whatever along with the clouding.  You will cure a lot of hard starting problems very cheaply by seeing the real problem of air getting in the pump instead of going off in another direction from diagnosing it wrong.  Just remember the air can be coming in anywhere clear back to the tank outlet which I believe was 3/8 in.  From what I saw changing mine I recomend changing every flexible line clear back to the tank.  Luckily I had already installed a lift pump which made the bad spots get a little wet but under normal suction they don't show up but let air in.  One of the common problems seems to be especialy when in a Rabbit for example, when you move the fuel filter over to the drivers side on the firewall or whever you put it to make room for the turbo version air cleaner that the old line seems to start allowing air in after moving it the other direction.  Those old lines have been sitting there for 30 years now and don't like changing their shape very much

[Sierra94]

What if I canīt reach the higher pressures?

I have built a M-Tdi IP following the faq and Heyīs instructions. My IP has the right pressures up to 1200 IP rpm. But maxes out at 7 bar at wot. And it doesnīt rev past 4000 rpmīs although I have done the governor mod. Iīve also made sure the governor regulator shuts the tiny hole at wot but still no higher pressure or higher revs.

I used a 1.6 TD IP as base with TDI camplate, rollers, advance mechanism with covers, spring etc, and a 12 mm head. Modified levers as hey described in the FAQ. It pulls really hard up to about 3800 rpmīs, WG set at 28 psi and static timing to 1.0mm. I also use a water/meth injection system that kicks in at 15 psi.

What could be wrong? Iīm almost out of ideas. I have also shimmed and tested different springs for the advance mechanism. But still no luck.
If I tap the regulator the pressures increase at higher revs but itīs really loud from idle (I set the pressure to 4 bars at idle just to check) up to 1/2 throttle. But It still doesnīt rev more than 4000 rpm.

[Sierra94]

And do I need shims at each end of the advance spring to keep it from eating itself into the material in the piston and cover? Maybe the thinnest ones just keep it safe? I made a testrun without any shims in there but not much difference.

Sorry if I hijacked the thread BTW

[Sierra94]

Thanks Andrew  

I still use a 1.6 regulator. I tried installing 2 thicker shims today. And I can now make it rev past 4000 rpms again.
I tapped the regulator so it now has 3.5 bar at 500 IP rpms, and some rattle. It takes alot of tinkering to get an IP
like this to work really great.

Iīve understood that my internal pressure might not be that linear as the graph someone drew in the thread over at
vwdieselparts but I have to start somewhere, right?  

But Iīm pretty satisfied with itīs performance anyway. But the older IDI was a hell of alot easier to tune.

What would diesel tuning be without this place? Keep the ideas coming, because I sure need them.

[Quantum TD]

I'm curious to see how your mileage improves by increasing the pressure. I've got a diesel pulse adapter. Waiting to get a good deal on a Snap-on timing light with tach function to check my pressure.

My pump is low mileage, but has never been rebuilt/recalibrated in 15 years. My mileage is like 35-39 if I'm lucky. I need to take care of the air leaks first (at the tank), but I know my compression is good, and I rebuilt the injectors about 5k ago with no improvement. So, pump is the only thing left. Also, my power is kinda soft too.

[Sierra94]

Hmm, can we discuss something else? 

My mileage is 0.8 liter / 10 km with the current IP setting. You do the math to get it to miles/gallon 

Might be a bit lower when the pressure is raised.

[Mark(The Miser)UK]

Hmm, can we discuss something else? 

My mileage is 0.8 liter / 10 km with the current IP setting. You do the math to get it to miles/gallon 

Might be a bit lower when the pressure is raised.

That's 35mpg uk imp.   My first QuantumTD did that when I first got it. Ended up capable of 62mpg imp. Turned out cam was out by a tooth or so on the flywheel, and pump too retarded. It's written down in my gasser Haynes somewhere.

[Doakster]

Bad News Guys. Did a mileage run, about half a tank on the new IP internal pressure and I only got 33mpg, so really not a bit of change. Other than the fact my car smokes a lot more than it use to.

I really am about fed up with this and all the troubleshooting i've done with no luck. My thought is it has to be something wrong with the IP or the turbo, i've checked just about everything else.

Why would i have no change in mpg when bringing my internal pressure up?

Here's another thought as to why it might be my IP, based on what happened previously when i got my injectors rebuilt (3 times so far).

-Sent injectors to a local shop for rebuild, they got rebuilt with a NON bosch nozzles (don't recall which make exactly). Mileage increased from 31 to 35 on the new injectors, but they leaked from the bodies.
-Sent injectors back for another rebuild, reinstalled and they still leaked.
-Decided to send them to Giles, he rebuilt them and ran them in his car for testing, he stated the nozzles put out way more fuel that stock bosch nozzles, he had a lot of smoke in his car.
-He decided to build me a set with different cores and stock bosch nozzles.
-Reinstalled those recently and mileage went back down to 31mpg (the same mileage before i decided to get the injectors rebuilt, by the way i still have 3 of 4 leaking )

What this tells me is that with more fuel the car got better mileage, but the injectors are not the problem because my mileage was the same with old or newly rebuilt bosch injectors.

I'm really thinking my IP isn't supplying enough fuel. But with my increase in the internal pressure setting the car is smoking fairly bad when on the peddle.

So what the heck is going on, i'm about to sell the car and get a TDI.

[Doakster]

Are you calculating mileage based on the odometer?  Have verified it using GPS?

yes, calculating mileage based on the odometer, I have verified the odometer using a GPS, it's only off maybe 2 or 3 mph above 50-55mph, mainly due to my 205-45-16 wheel size.

About a year ago(didn't have my mileage issue then) i switched to the bigger wheels, and calculated my mileage (using odometer) got 43, which is exactly what i got before the wheel swap, to make a long story short the wheel size and the 2-3mph difference in the odometer didn't make a bit of difference on mileage calculation, when my car was getting good mileage.

My mileage just suddenly took a nose dive during last winter months, and no changes to the vehicle as far as parts replaced and how i check mileage were done.

[Rabbit TD]

Are you calculating mileage based on the odometer?  Have verified it using GPS?

yes, calculating mileage based on the odometer, I have verified the odometer using a GPS, it's only off maybe 2 or 3 mph above 50-55mph, mainly due to my 205-45-16 wheel size.

About a year ago(didn't have my mileage issue then) i switched to the bigger wheels, and calculated my mileage (using odometer) got 43, which is exactly what i got before the wheel swap, to make a long story short the wheel size and the 2-3mph difference in the odometer didn't make a bit of difference on mileage calculation, when my car was getting good mileage.

My mileage just suddenly took a nose dive during last winter months, and no changes to the vehicle as far as parts replaced and how i check mileage were done.

I know you said you checked it with a GPS but did you actualy verify that the odometer is actualy registering the miles it should be.  I know on almost every one of these old Rabbits that a little gear in the speedometer cracks eventualy and it will skip a tenth of a mile when it gets to a certain point  I had 3 clusters from different cars and everyone of them did it.  The fix is to take the speedometer apart and slide the ear off, drill the hole in the gear to the dia of the shaft and slip it back in place and superglue it.  Evidently the plastic gear deteriates from age and changing temps and finaly splits on the one side from the tension on it allowing it to slip.  I forget where I read about this fix but I tried it 4 years ago and it's still holding, I didn't think it would last 25 miles at the time.  You said it started last winter and it might just finnaly decided to split from one too many temp cyles.  Like I said before i took 3 different clusters out my friend had and everyone had the same exact problem.  They register miles but not accurately, you can see a tenth coming up and then it will jump back a little and finaly catch eventualy but your miles will be off.  I'd deffinately check your ODOMETER.

[Doakster]

Well it's worth a try to check it. Can you tell by watching the odometer tenths closely and see if one of the tenths skips?

I'll be able to do another GPS run tomorrow, and i'll track my miles driven with the GPS verses the odometer and the trip meter.

Unfortunately i think it's not my problem, because i usually do a long drive on the start of the weekend and then back on sunday. The distance according to google maps is 120 miles, and I might register 115-120 on my trip meter.

We'll have to see what i come up with for numbers.

Do the trip meter and the odometer run off the same gear?

[Rabbit TD]

Well it's worth a try to check it. Can you tell by watching the odometer tenths closely and see if one of the tenths skips?

I'll be able to do another GPS run tomorrow, and i'll track my miles driven with the GPS verses the odometer and the trip meter.

Unfortunately i think it's not my problem, because i usually do a long drive on the start of the weekend and then back on sunday. The distance according to google maps is 120 miles, and I might register 115-120 on my trip meter.

We'll have to see what i come up with for numbers.

Do the trip meter and the odometer run off the same gear?

  I'm pretty sure the trip meter is driven by the odometer itself which is where the little problem gear is.  I'm gonna try to find the site where I  found this fix at.