Re: [T3] Type three and Type 4 ECU's

["Craig Webb" <craig_webb@ntlworld.com>]

<x-flowed>> Jim Adney, jadney@vwtype3.org
> Madison, Wisconsin, USA

> If you
> wanted to emulate a 1.7L type 4, then you might do well if you put in a 
> matched
> (from the same year) set of ECU, pressure sensor, injectors, and throttle 
> body.
> They were made to work together as a set. Just swapping in one part of the 
> set
> assumes that the whole adjustment was done in that one part, which is 
> clearly
> not the case.

I've got both a 72 type 3 and 72 type four unit.  The injectors are the same 
for both (not sure if that's right for the type four 1.7, but the injectors 
are the same number as the type three).  I've already run a type four 
pressure sensor on the type three set up and it didn't make a huge 
difference.  Throttle body is perhaps just slightly larger dia.  Not checked 
the throttle switch yet.

> Are you sure that you need more fuel? If you've already cranked the fuel
> pressure up to the max, then I'd expect you to be way over-rich already. 
> What
> is your fuel pressure? Have you measured it while driving? If your filter 
> is
> clogged, then the pump won't be able to maintain the pressure under load, 
> and
> that would lean things out when you're not expecting it.

I'm running about 34psi (as long as my gauge is accurate!)  Fuel pump is a 
brand new NOS item with new filters. Fuel pressure stays good whilst revving 
when stationary.  My main bible is an innovate motorsports LM-1 unit with a 
wide band sensor plugged into the exhaust.  I'm currently running rich at 
idle and low speeds (12:1 afr).  When I get up to speed I'm slightly lean at 
15.2:1.  I was holding out fiddling with the pressure sensor until the last 
resort.  I thought I would try the type four ECU as its closer to my engine 
size, plus its got the idle pot.  If I can transplant this, I may need just 
a tiny amount of tweaking on the MPS.  I would also like to bring that fuel 
pressure down some to 30ish.

MPG is good on the highway (because its slightly lean) approx 26-27 MPG 
(US).  MPG is not so good around town (because of the rich idle and low 
speeds) - approx 17-18 MPG.

When I get this baby set up right, I'll post all my stats and findings on 
here.  It would be a big help to someone wanting to run a 1776cc with 
stockish FI


Craig 


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