PROM ID 9239/9929 vs 9930

[pjohn151]

I've just changed the memcal in my '90 Elan SE as per bulletin 1995/24 (chassis Lxx59 - 59th one built?) for the later 9930 cal. As a matter of interest I have a couple of questions about the change in calibration (sorry I do not have Elanscan as I probably could of answered these myself)-

Does the CO pot only change the mixture at idle for when being tested, or does it shift the complete fuel map for all operating conditions?

The memcal I removed was marked 'ANXZ 9909'. Is this the PROM ID or is this just a chip ID? (the outside of the ECU did have '16179239 ANXZ' on it)

The one I replaced it with from Lotus (A100E0097S) is marked 'No 22. S2 Elan Turbo' on a sticker over the chip. I presume that this will probably contain logic for open and closed loop control?

Many thanks

Phil

[pjohn151]

Ok having dug around a bit, I'll answer my own questions...

Does the CO pot only change the mixture at idle for when being tested, or does it shift the complete fuel map for all operating conditions?

The CO pot only changes the mixture at base ECU controlled idle

The memcal I removed was marked 'ANXZ 9909'. Is this the PROM ID or is this just a chip ID? (the outside of the ECU did have '16179239 ANXZ' on it)

The PROM ID can be read by elanscan (oh for a laptop) or a Tech 1 unit at a dealer. Looking at pictures of ECU's, it would appear that the PROM ID should match part of the number quoted above from the label on the ECU (unless this update has been carried out, in which case the ECU should have 'CO' written on it in marker pen)...

The one I replaced it with from Lotus (A100E0097S) is marked 'No 22. S2 Elan Turbo' on a sticker over the chip. I presume that this will probably contain logic for open and closed loop control?

Apparently Lotus have mis labelled some of the 9930 memcals. They should say 'Elan S1 Turbo Open Loop', or words to that effect, but come in the correctly labelled packaging with the right part number...

Phil