Lancia Scorpion

Chris used our PSC1-009 air/fuel calibrator with a Bosch MAF sensor on his Lancia Scorpion. Since this was a very unique car, there was a certain learning curve associated with making this kit work. Chris was very methodical about troubleshooting and solving various problems along the way. He was rewarded with a very nice running car.


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Here is the before and after comparison of air flow meter and MAF sensor installation.


After getting some of the bugs worked out, Chris posted this note:

[kinda long, sorry, but I’m excited!]

So for all you dual-carb guys, this probably won’t mean much. But I finally got my EFI to “dither” around stoich! Woohoo!!!

In my battle to get the maf conversion to work, I reverted back to the vane meter to find that it really wasn’t any better than the maf. So that meant something was fundamentally wrong somewhere in the base efi system. Overall, the car ran pretty well but it wasn’t running closed-loop and it should have been.

So I shot it with both barrels, and today, I:

  • changed the fuel pressure regulator with a new item
  • put in a hotter (180degF) in-head thermostat with a 7/64 hole drilled thru for easy bleeding and a little flow to keep the water temp sensor warm
  • swapped ECUs
  • pulled the wiring loom apart, checked each and every joint of the splice to ensure no loose or bad connections

Put it all back together, and it now dithers (weaves back and forth) around stoich, which means the computer is now in closed-loop operation. And oddly enough, it runs closed loop a lot of the time (I had the impression there were only a few conditions that put the system into closed loop, but it weaves back and forth almost all the time…hard acceleration and wide open it does not dither).

So the maf is back in and the system is running fine (and predictably!).

So why is this significant, you ask? This means that I should now be able to set a map for the maf sensor that’s right on the nose, then hook up the O2 sensor and *keep* it there. Any time spent on the dyno to perfect the top end will be *worth* it now. 🙂

The problem I had before was that a perfectly set up map one day, would be too lean or too rich the next day. Now that the system runs closed loop, the ecu is adjusting for daily variations to keep it on map.

Of the changes:

  • I don’t believe swapping the ecu was really an issue, could easily put the other one back to verify but why bother.
  • The fuel pressure regulators tend to go really bad, not just a little bad; but I do believe the regulator was getting tired and was behaving unpredictably. A fuel pressure gauge would verify this, but for the cost of a gauge, I could just buy a new regulator…which is what I did.
  • The hotter stat keeps the water temp sensor *at* “normal” temperature *all* of the time now (but also means the fans run a LOT more than before). Of the changes I might undo someday, this is one of them. Head temp is pretty much 195-200degF now, was 185-190 before (with 160degF stat). I understand a hotter motor does better on
    emissions and driveability, so, eh.
  • And I didn’t find any loose wires in the loom, but I did find some sharp solder joints which when bundled or bent might poke thru the insulation and touch other wires in the loom and cause false signals which I believe *was* happening.

Anyway, that’s the summary of what happened today. Am looking forward to some seat of the pants dyno time tomorrow to get the map dialed in.