Best year of TDI

[Seafarer12]

Hey Guys.
I just wanted your opinion. What do you consider the best years of Jetta TDI and why. I am more interested in economy and longevity that more power.
Thanks.

[QuickTD]

My vote is for the 96-99 A3 jetta and B4 passat TDI's (1Z and AHU). Simple, rugged and reliable. There are really no known issues with these engines.

 The ALH used in the newer cars has a couple "features" that bug me. Water pump on the timing belt, nearly every car company has been through this and it has been conclusively proven to be a bad idea. The VNT turbo is a good performer but the sluggishness of the control system tends to shorten the life of the unit, especially on modified cars. The ALH also suffers from some unreliable electronics, particularly the mass air flow sensor.

  The jury is still out on the PD engines, so far they've proven fairly reliable? The same water pump on the timing belt as the ALH... The need for special oil is a headache. The cam lobes had to be narrowed to make room for the unit injector lobe and the loads on the lobes are therefore considerably higher, hence the need for special oil. Not sure if the cams will last, europeans may offer some input here, they've had the PD longer than north america. The turbo controls have been refined to include a vane position sensor, perhaps to solve some of the overshoot and boost spiking problems of the old setup. I haven't heard of a PD turbo failure.

[Baller]

I have just bought a 94tdi Passat which I plan to take the engine out of to put in my mk1 Golf.I have been hunting around this sight to try and find any info on the wiring.I havn't taken the engine out of it yet because I have got some other jobs to do first.I have only recently bought it and havn't yet looked at the engine code.It must be one of the first of the vw tdi motors.If any body can point me in the right direction it would be much appreciated
                                         Baller

[Slave2School]

I'd say the ALH as it has the most updated internals and is the last of the rotary pumps.  MAF is fine as long as you don't have a leaky seal in the air filter or have an oil type air filter.  (K&N)

If you get an ALigator chip the boost will be controlled better than oem

[RabbitGTDguy]

I have just bought a 94tdi Passat which I plan to take the engine out of to put in my mk1 Golf.I have been hunting around this sight to try and find any info on the wiring.I havn't taken the engine out of it yet because I have got some other jobs to do first.I have only recently bought it and havn't yet looked at the engine code.It must be one of the first of the vw tdi motors.If any body can point me in the right direction it would be much appreciated
                                         Baller

Your motor is a 1z more than likely...

[Ziptar]

I put 187K on a 98 1Z before the turbo went, traded it on a 03 ALH which just turned 187K.  The only things I ever have done to either is filters, belts, and oil changes.

It's tough for me to say which is better but, I'd have to give the ALH a bit of an edge, just because it's still going and outside of an occasional ticking lifter or nailing injector (not sure which it is yet) engine seems just as tight as it was at 50,000.

Now when it comes to getting a motor for the 89 Carat I'd be seeking out an AHU for sure.

Also may get a chance to see how the 2.0 PD motors are, just about convinced the wife that her 2003 Volvo XC90, that seems to need something every week just about and flashes the "GO TO THE DEALER SPEND $$$$!!!" message on the dash display every other stop light needs to get traded in for a 05 Passat TDI Wagon. Which is What I wanted her to buy when she bought the Volvo a year ago....

[RabbitGTDguy]

I think the biggest drawback to the ALH is the fact that the water pump is driven off the T belt. I've heard quite a few stories about ones having there lovely plastic impellers implode and freezing up the pump altogether and then a domino effect occuring with the t-belt. Eventually, valves meet pistons, head, piston, etc. damage occurs.

However, this all goes back to proper maintenence and care for your motor. Diesels are built much more robust than gas motors just to handle the compression style ignition and the forces/stresses involved with that. But they do require care as with any car.

I don't think I'd be put off buying either style/type of engine, be it the 1z/AHU variety or the ALH.  The PD I'm a bit more shaddy on because it moves into a different realm, requires electronics, etc. but if they prove reliable (lots of issues out there with tight/close tolerances, oil consumption, smoke,etc) it could be a possibility, but then look how quick the VW switch was from one to another. It'll def. be nice to be looking forward to VW's new common rail system though.

I'm def. more than happy with my 1z. For certain power goals, etc. I changed things to suite my needs and such but its been an awesome motor and lends to still looking pretty "old school" under the hood of the 79 MK1.  It was a long, and detailed build but well worth the effort and extra insurances I put into the motor.
 The longblock I'll be getting for the b3 swap here in the next year or so will be a 1z as well (already have it lined up...just a matter of getting it) and I'll do similar things but leave it more in a stock form.


Joe

[wolfsburgnut]

Once VW goes to the common rail, the ability to run megasquirt will be there, as I think megasquirt has just come out with a new add on board for full multiport fuel injection...

[Ziptar]

I think the biggest drawback to the ALH is the fact that the water pump is driven off the T belt. I've heard quite a few stories about ones having there lovely plastic impellers implode and freezing up the pump altogether and then a domino effect occuring with the t-belt. Eventually, valves meet pistons, head, piston, etc. damage occurs.
Joe

I have heard about the plastic Impeller issues too. At 116K I put in a dieselgeek 100K Mk4 ALH Timing Belt Kit with the Laso brass impeller water pump.

Working great so far

[Slave2School]

Yeah when my car had the timing belt done I had the long life kit put o mine too ditches the phenolic (SP) POS and uses a nice metal pump.  Change it with every belt and you will be fine it is cheap too, only ~$65.

[QuickTD]

Once VW goes to the common rail, the ability to run megasquirt will be there, as I think megasquirt has just come out with a new add on board for full multiport fuel injection...

 Don't think megasquirt is quite capable of running a diesel. Megasquirt can control the ignition spark timing event with some degree of precision and can control the fuel injection duration quite accurately. The problem arises when you combine those events, as in a diesel. The hardware cannot precisely control both the timing AND the duration of the injection event on a single channel, nor can it support multiple injections per cycle (the design advantage of common rail), nor does it incorporate inputs/outputs for rail pressure control or common rail pump plunger de-activation, nor can the outputs support the high currents necessary for common rail injector firing. Something completely new will need to be developed to support diesels, given the demand I kind of doubt it will happen...

[wolfsburgnut]

As far as inputs and outputs go that is all a matter of reprogramming the microprocessor, which is not really hard to do if you have the know how.  Megasquirt supported the low impedance bosch injectors, which have a heck of an amount of flyback.  They include a circuit on there for flyback draining.  MOSFETS can handle some pretty high currents, as the ones I am using for an H-Bridge to drive some window winder DC motors for a project at school are rated at 47A continuous... and I bought them for 1 dollar a piece.  Perhaps there is some truth in what you say that the 8 bit micro used in the megasquirt is maybe not quite up to the task, however with 32 bit micros becoming very cheap, it will only be a matter of time before they come out with something better, I would imagine.  

Peter

[Seafarer12]

It doesnt take much of a computer to run an engine. As long as it has enough inputs and outputs. I work in the instrumentation and control field. An engine just has simple control loops if you look at a wiring schematic. The control systems on modern engines are a lot more complicated then they use to be but still not very complicated compared to an oil refinery or a chemical plant.
Does anyone know of any programs that would help fuel economy or other modification that would help mpg numbers.

[jackbombay]

The EDC 16s (PDs) have 2 GB's worth of data to make them run, the next generation (EDC 17?) is rumored to have 30 GBs of data to make them run. Sure, they won't NEED that much to make them run if you designed a stand alone system to make them run, but it would still be a hell of a lot of work. Why not just have a competent tuner re-map your car? If I want anything changed I just send off an e-mail and with-in a day or 2 I have a new file in my e-mail box ready to load into my removable chip/ECU. The ALH (EDC 15) only has 512 KB.

  That said, I quite like my ALH, the VNTs have their issues, butr mine has been fine, max of 10 PSI under 2000 RPM and mo WOT over 4,000 RPM and its happy. Plus there is a HUGE aftermarket for them and they (at least in this hemisphere) make way more power than PDs, or anything else currently available from VW.

[wolfsburgnut]

My thought is that if people want to start putting in common rail diesels into their older cars, a stand alone ecu might be a lot easier to do than trying to get the entire wiring harness out of a newer car.  Right now if somebody wanted to put a PD in their Golf or Jetta, they would have to get the entire car, in order to make it run from what I understand.  While I will agree that the VW ecu probably has alot more programming and data behind, does it make the PD run 4 times better than an ALH(4 times as much data)?  I think not, a stand alone ecu might allow people who want to, to work on their own cars without going to the dealership.

Peter