Club 80-90 Forums

Does anyone out there have experience with doing away with the TDI ECU and running a mechanical injection pump instead?

I've seen a pump available to do this from a German T25/Syncro specialist, his 1.9TDi demo van is 130hp! but the pump is €2500!!!

I would love explore this option as I'm no computer specialist and neither is anyone down here!

I think you'll find Russel at Syncro-Nutz, Shotts knows as much as anyone here on both mTDi's and eTdi's

http://www.syncro-nutz.com

+44 (0) 1501 829 400
info@syncro-nutz.com

Hi, Ive just clocked up 10,000 miles runnig a 1.9 AHU TDI on mechanical AAZ pump.....no problems....
You do need increase fuel delivery by adjusting the main fuel screw on the back of the pump, this is because of two reasons....
1. The AHU engine has tiny enjectors
2. The fuel boost pin on the AAZ pump is not suited to heavey vehicles
( A pin from a 1.6TD is what you need.....)
You also need to run much more advance timing injection to help overcome the late opening of the high pressure injectors. The AAZ pump takes longer to build up pressure, so fuel injection needs to start earlier. by a whole 1 deg......

Forgot to mention, dont expect the factory BHP output running the AAZ pump, the pump is smaller and does affect overal power output, I would say you get around 75bhp similer to AAZ or very well maintained 1.6TD.
Although torque is amazing and capable of destroying the gearbox or clutch should you try and 'spin the wheels' on a dry day!!!! 1st gear is only required for hill starts....
GaV

veeery interesting, 10,000 miles is a good mileage to build up experience...

suppose the main difference is the AAZ pump is originally intended for indirect injection, AHU is direct

1 degree equates to how many mm when timing the pump, assuming tis normally set to 1mm advance at TDC - just to get a feel for how much this is?

last time i looked there were 2 tdi,s in my local scrappy,injectors(clamp style)all missing other wise pumps/engines complete.
also he had 2 aaz and a 1y engine
just incase any bits are needed!
he may want 100£ for a complete motor prob 25 for a pump!

HarryMann wrote:veeery interesting, 10,000 miles is a good mileage to build up experience...

suppose the main difference is the AAZ pump is originally intended for indirect injection, AHU is direct

1 degree equates to how many mm when timing the pump, assuming tis normally set to 1mm advance at TDC - just to get a feel for how much this is?

Sorry, I meant a whole mm extra advance.....E.G aim for around 1.8mm Advance at the pump, that helps AAZ pump get a 'head start' on building pressure to open those high pressure injectors.
The main difference on the pumps are
AAZ pump only has 9mm pump head/plunger
TDI has 10mm (some have 11mm)
AAZ cam plate has less lift (so plunger has less movement
TDI cam plate has far more aggressive lift = more plunger movement = longer fuel stroke.....

In short, the AAZ pump is smaller, delivers less fuel at not designed to work with the high injectors pressures......
But they work with a bit of tweeking.......and are the cheapest most sensible way of fitting a TDI deisel to a T25 without any wiring mods or ECU headaches......
GaV

Thanks a lot for that...

Do you find any downside, other other then the performance reduction...

e.g. getting good economy?

(My AAZ is not an award winner in that direction)

Hi, I get 40MPG average....have had 42, have also had 36-38....depending on load......

AHU injectors are tiny....so give great eco but will slow down on hills because engine is under fueled slightly.....can drop to 50mph on steep motorway hills, but no need to change down from 5th to 4th......

Remember, AHU engine was designed as eco diesel engine for the MK3 Golf, its only 90bhp, less with AAZ pump.....bur ultra reliable.....
Gav

HarryMann wrote:Thanks a lot for that...

Do you find any downside, other other then the performance reduction...

e.g. getting good economy?

(My AAZ is not an award winner in that direction)

Broken pump shafts with small high pressure injecters, just a question of time.

Hi Andy...
You will only break an AZZ input shaft if you try stuffing a TDI cam plate and pump head on it......
Use them in stock form, they are fine.

But yes you are right, if you insist on 'upgrading' an AAZ pump with TDI spec internals, you risk breaking the 17mm input shaft (TDI pump has 20mm shaft), however I know of many AZZ hi brid pumps, non of which have broken (yet)

GaV

HOT 1200 wrote:Hi Andy...
You will only break an AZZ input shaft if you try stuffing a TDI cam plate and pump head on it......
Use them in stock form, they are fine.

But yes you are right, if you insist on 'upgrading' an AAZ pump with TDI spec internals, you risk breaking the 17mm input shaft (TDI pump has 20mm shaft), however I know of many AZZ hi brid pumps, non of which have broken (yet)

GaV

You will be increasing stress on shaft due to pump having to pump harder to overcome injector pressures. I have a hybrid AAZ pump and accept its a ticking bomb.

Whot is the point in fitting a TDI for 75 bhp.By the sounds of things to is that u are not getting anything near the talk u should.Using a standard cluch wouldnt last me 100miles.Even on a hoted up AAZ the clutch suffers.
Whot Andy has got to say about ure pump shaft is very true.U are runing a pump at a build up preshure(injector to pump)that it is not desighned for
this will not last,i am very suprized it has lasted this long.Going into winter will make a differece aswell with cold thicker diesle putting more strain on ure pump.
And to some other questions:there are cheaper(by a lot) hybread pumps out there that will give u 100bhp+

Russel at Syncro-Nutz wrote:Whot is the point in fitting a TDI for 75 bhp.

Errmmm 42mpg, ultra reliable daily driven 80 mph caravelle that did have 1.9 waterboxer petrol gussling water leaking piece of crap in the back of it..

Now do you get my point........

I didnt go the TDI route for power, i did it for economy. If I wanted raw speed, I would of stayed petrol and fitted something else (scooby?)
And, as for worrying about high injection pressures, I have a set of injectors on the bench that have been 'reshimed' for lower injection pressures......VW only use the very high injection pressure to achieve the required emissions/atomisation for ever tighter emission laws....
Each to their own, but I think Im heading in the right direction

ive been looking at mech pumps from other non vw engines..
got to clean up and get the info numbers off a pump from a 2.5 iveco lump in the breakers... itsa bosh unit...

ive heard that the guys over in the states are using non higher pressure non bosh pumps with good results..

ive heard that the guys over in the states are using non higher pressure non bosh pumps with good results..

Adict, can you be a bit more specific in what they are saying... which pumps in particular ? Ta!

Is this from VWGTD forum?