Closed loop but 9929?

[JusNoGood]

Hi All,

IB10's MOT's are always touch and go whether it passes the emissions test. I found out one of my cats had broken up and was blocking the exhaust year or two ago so that didn't help, fixed now by removing it. Today I thought I'd see which Prom was installed. Assuming it had been upgraded to an S2 one before it left Lotus, after all it does have CATS, O2 sensor and various S2 cosmetic bits installed so surely it had a 1499 installed right? Booting up Elanscan it shows I have a 9929, does that mean I probably have a chip installed to make it work? Guess my next step is to pull out the ECU and have a butchers.

Regards

J

[RonR]

The code for closed loop was completed for US and ROW SEs long before the development of the S2, so I'd be surprised if they played with a 9929 prom when the 1499 was already available.
You might be able to check if closed loop is being used by checking in Elanscan: Air Fuel Mode (Flag 40) Bit 7, which is set when closed loop is requested. It's in the code for both proms, but not used in my 9929.
If you don't want to disturb your ECM yet, you can use Elanscan 9.something to download the prom image to a .bin file. If you send it to me I can do a binary compare with my own 1992 9929 prom to see if they're the same.

[RonR]

Hi Justin,

It just occurred to me that if your car's running a standard 9929 prom it must use a CO potentiometer or you'd get a code 54, so you could check if there's one present.

Another approach is to have a look in Elanscan at the graph for Oxygen Sensor (Integrated) vs Time - If it's a straight line then your prom is reading the CO Pot value, not taking account of the oxygen sensor output. If it's a wavy line the ECM is reading the oxygen sensor values so should be using closed loop code.

Maybe the factory had a trick ECM in the car but replaced it with one from spares before selling it off - The parts man would find out it was an early car and hand over an open loop ECM?

[JusNoGood]

Hi Ron

Very sorry for not replying, I didnt get a notification.

Thank you very much for the reply. I'll check out Elanscan at the weekend to see what I can see.

Regards

Justin