It is not correct that the Omex ECU can not be remapped. It has a 9 pin serial port and Omex supply the software and an instruction manual that you can download from their we site free of charge. I am now up to the 30th variation of my calibration, making small changes and recording the results in on-road testing. I am now pretty happy with the result for both hot and cold running. The calibration of the ECU involves much more than just the fuel map and also includes many corrections for various conditions such as altitude, air temperature, coolant temperature and so on. I would not recommend that anyone who is not technically minded attempts to change the calibration. Variations can be made using on-road testing but obviously the controlled conditions of a rolling road are much better.

I'm not surprised to hear of a Plus 4 SS that has problems with emissions.

My car was supplied new from the factory with a sports exhaust system that was essentially the same as the Plus 4 SS (but without throttle bodies). The only difference was that it used the post cat sonda lambda sensor (sometimes called an O2 sensor). Even before we left Malvern we had an engine warning light due to the insufficient functioning of the cat as read by the post cat sensor. This was rectified by the factory but came out again after about 80 kms. When we got home I had several discussions with the factory (Aero Racing), and when I said that we had a rich smell at times in the cockpit they said several SS owners had made the same complaints. I had some emissions tests done at their request and it was clear that the car would fail an MOT. The factory responded by sending me a 400 cell cat to replace the 200 cell unit. Other than reduce the noise levels of the exhaust, and reduce mid-range torque, it made little difference. They then supplied exhaust wrap and had it fitted by my dealer in an effort to keep the exhaust gasses hot and get, and keep, the cat up to its correct operating temperature. All of this was only partially successful. I have heard conjecture that the heavy flanges on both sides of the cat may be carrying away too much heat from the cat.

I then fitted a set of Omex throttle bodies and the Omex ECU. The kit, by the way, was developed by Omex in conjunction with Williams. I have to say that when the engine is hot we no longer get the rich exhaust smell coming into the cockpit, so I think it has improved in that respect. I have not had a gas analysis done yet so I don't know if it would pass an MOT.

To get back to your problem.
1) It is possible that you have an ECU that has an incorrect calibration. For example some twit may have installed the calibration for a 4/4 with throttle bodies.
2) Whatever the fuel map in the calibration once the coolant reaches 70º C the fuel mix is controlled by the sonda lambda feed back. Unless the fuel map is way out this system will always deliver the correct fuel mix. If you are getting a constantly rich mixture, enough to blow out black smoke, there is something very wrong. If you have done a lot of miles with the engine running like that you may have exhaust system problems that must be rectified. Firstly your sonda lambda sensor would now be so contaminated it is probably necessary to replace it. The same, unfortunately, goes for the much more expensive cat.
3) My first thought is that either there is a problem with the sonda lambda not functioning correctly or that the engine temperature sensor is not functioning correctly. This may not show up on the dash instruments because (at least in my case) the dash instruments are still controlled by the Morgan ECU. Hooking up the Omex ECU to a computer (and the Omex software) would soon check this. If the Omex ECU is not seeing the temperature rise above 70ºC then it would be constantly running as though the engine was cold. This could also be a problem of bad electrical connections. Under the cold running regime it would naturally have a rich mixture and the symptoms would match your description.

There may be issues with with other sensors or with mechanical issues such as the balance of the throttle bodies but after checking that the ECU has the correct calibration I would then replace the sonda lambda and check the correct functioning and reading by the ECU of the engine, and perhaps also the air, temperature sensors.

I have found Omex to be very helpful but I would suspect that in this case they see the issue as being outside their control as their components are part of a complete car and therefore better handled by Morgan or a Morgan dealer.

I would certainly suggest that if you are near to Williams you have a chat with them. They have a very close relationship with Omex and also have the possibility of changing exhaust systems and the cat if necessary in order to have the car pass an MOT.

Sorry for the long ramble. I hope it helps.

Last edited by Gambalunga; 01/03/15 11:44 AM.
Peter

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