Audi WUR necessary?

[Rusto GTI]

I have been collecting all the parts for a Junkyard turbo setup on my 83 GTI, my question is, Is the Audi 5k WUR really needed for moderate boost on my car? I have seen a few posts where people either didn't have it at all, or had it unhooked (no boost signal to it). I have even read that with both the 5k WUR and the 240T FD, that the mixture is actually too rich under boost, so much so that it starts chugging the engine.

So on to the question at hand. If I wanted to theoretically run around 10psi, would the 240T fuel distributor do fine by itself, or is the audi part really needed to complete the setup?

Thanks!

Rusto

[Peter Tong]

For moderate boost (ie 6-8 psi) you can run with the stock CPR - just wire a pressure switch to trigger your OXS coolant temp wires when you transition at around 2psi or so. I have a wide band meter, and with the 240t injection I was seeing a/f ratio's in the 10s with the Volvo 240t setup hooked to boost pressure. Stephen Webb has good results with his Audi 5k CPR hooked up to boost and with the lambda circuit enabled all the time. So either way works. With the pressure switch set in the above manner (and CPR disconnected from boost) I was seeing 12.x with mild boost. I am hoping to have the wideband permanently mounted in the car tomorrow (extra bung welded onto the header for it) and so I can fine tune it a bit better....for mild boost though the 80% frequency valve setting triggered by shorting the OXS temp switch wires seems to do ok...

[Stephen Webb]

I just wanted to add that the coolant temp switch doesn't necessarily trigger the same duty cycle on all cars. On my '89 cabriolet I'm pretty sure the FT switch and the coolant temp switch trigger the same pin on the computer (pin 7, I think) whereas on other cars they are different pins, and different enrichment levels. (I believe this is the case).

So if you are going to hook up a pressure switch to the coolant temp switch, it may be a good idea to measure the duty cycle that it triggers-- maybe the FT switch actually enriches more (??)

-Steve

To answer the question about running with the boost sensitive CPR -- YES it runs too rich (I see low 11.x values with no FT switch -- with the FT switch it bogs) I will probably start using the FT switch triggered by a boost pressure switch and get rid of the CPR - I just have to find one of those boost pressure switches. Anyone know where to get one?

-Steve

[Peter Tong]

Thanks for the correction Steve, my reply was based on the assumption that all of the Jetronic boxes will behave like mine - something that is just not true...

The pressure switch I'm using is pretty small - about the size of the end of a thumb and its adjustable. It came with the ERL MF2 kit that I never installed. It would be hard for me to believe that they wouldn't sell them seperately. Their site is http://www.aquamist.co.uk...

Steve, with the wideband on there I should be able to tell you how those modded injectors do...I can say now that they run better than the 047 units...

[Rusto GTI]

Ok, so let me see if I understand this.. I can use just the 240T FD, as long as there is also a pressure switch set to about 2psi and it engages the full throttle switch? Do I still need to run a boost signal line to the FD? Can the stock cpr keep up or do I need the audi one just no boost signal to it? Will the non audi cpr setup work for 10psi as long as I wire up the full throttle pressure switch? or is the junkyard setup just limited in this way to about 7-8 psi?

Thanks!
Rusto

Stephen - You can purchase a adjustable hobbes pressure switch at NAPA, most don't stock it at their stores but they can get it from the warehouse in a few hours..


Modified by Rusto GTI at 3:29 PM 6-3-2003

[arvcube]

let me get this straight....running the cpr with a boost signal attached makes it run TOO rich? wouldnt this be good for higher boost levels? if doing this would cause it to bog under low rpm or lower boost levels, cant a resistrictor or some sort be put in line in the boost signal to "activate" the cpr at a higher boost level?