Looking for 5.2 (96 and newer) owner who's installing straight pipes

I have a 2.7 with no cats and I had the solid Slow Down light(s) in my car.

There were two-three scenarios when addressing this:

(1) Ignore the lights;

(2) Remove the dash lights for Slow Down 1-4 and 5-8 -- not the most elegant;

(3) Disconnect and remove the CAT ECUs -- lights stayed on solid;

(4) Provide an input to the CAT ECUs where they think a thermocouple is connected but thermocouple reads ambient temperature

Some of these options were discussed in earlier threads...

My worry with (1) - (3) is whether the light that goes to the dash also may trip up some computer function in the ECU such that the engine banks may be shut down unexpectedly.

I've therefore developed my own mini-thermo-couple/connector that plugs in the CAT ECU directly. On the 2.7 (my 96 Euro CH and a friend's 95) this has the desired effect - the light goes off.

I was thinking on whether this would be useful to the 5.2 (96 - up) cars where the owners want to get rid of cats but don't want to re-program the ECU to get rid of the light?

Therefore I'm looking for anybody who may be interested in testing this free of charge and seeing if it works on a 5.2 system. I will guarantee that it does not damage your ECUs or I'll pay for them straight up.

Thank you.

 

In my case I have a straight pipe all the way from the headers to the back of the car. The car came with two CAT ECUs -- one in each rear fender.

These CAT ECUs were plugged each into one of the two Bosch 2.7 ECUs located right next to them -- this was through a 4 pin connector which was hooked up to the main ECU.

However, the *input* to the CAT ECU is a 2-pin connector which goes to a thermocouple (my car has 2 of these, I think the 5.2 versions have three?). This connector was left disconnected.

The thing I built just plugs into the place where the thermocouple would be.

Just as an example of a thermocouple -- here's one set that was for sale recently used:

http://www.ferrarichat.com/forum/ferrari-parts-collectibles/413529-355-thermocouple-temp-sensor-set.html

In my case I have the black connector, a short low-cost thermocouple of the same type (K) and everything is epoxied together in a package. You just plug in these things in and away you go.

The alternative is (at least to my understanding) programming the main ECUs so they do not care about the CAT ECUs; then you can remove the CAT ECUs altogether. However, this creates the issue of passing inspection and reinstalling them/cats, etc.

 

If test pipes replace cats then I think your thermocouple goes away because it doesn't make sense to measure the temperature of the test pipe and feed that into the CAT ECU.

However I'm very confused to see the connection between a SDL and Gold Connector Kit unless your light was related to something else?

 

I think this has been done through the ECU reprogramming? I don't think the info regarding CAT ECU <-> Motronic communication is easy to find out or to tweak.

My solution is aiming to be a < $50 fix or test low-cost solution rather than an overall answer to this issue. However, on two F355s with 2.7s it works remarkably well so far.