As usual with Superspecs I struggled again with the emissions at this years MOT. I got hit with a double whammy as the testers appear to be being especially hard this year, with the new regulations, and we have a 'checker' in the area doing spot checks so there was no chance of a 'close enough' reading.

 

After fitting a different cat/exhaust I got it through at the second attempt, but by the narrowest of margins.

 

Natural Idle CO, max 0.3 Actual 0.294

Fast Idle CO, max 0.2 Actual 0.197

Fast Idle HC, max 200 Actual 142

Lambda, max 1.03 Actual 1.022

 

I really don't want to have to through this every year so am looking for a permanent solution. The problem is we have a Fuel Injected Rover engine with a non-programmable ECU so as far as I know there is nothing we can do to effect the emission levels, they are pre-decided by Rover back in 1995.

 

I guess we could try to find some firm that could re-program the ECU, but these boxes date back to 1995 so there is not much expertise around. My only other thought (apart from an engine change ) is to replace the ECU with a newer one that is programmable to change the emissions.

 

Would this work ? Anyone have any other thoughts on a solution ?

 

BTW, for Superspec owners, I only got through at the second attempt because I had a 'bung' in one of the two exhaust outlets. Without the 'bung' fitted the emissions were way out of limits.

 

what about tweaking the fuel trim level via mems scan down by about -50. it may not like it but can be tweaked immediately after mot

Presumably the ECU adapts the fueling based on the lambda feedback in which case could you adapt the output from the lambda so the ECU thinks it's running richer than it is while it's being tested. A bit like a Volkswagen.

i megasquirt could be fitted easy to tune and you could have a second map for MOT time

what about tweaking the fuel trim level via mems scan down by about -50. it may not like it but can be tweaked immediately after mot

 

Unless I'm wrong, adjusting the long term fuel trim will simply make the short term fuel trim compensate and you will get the same result. I really need access to an analyser for the day to test that.

i megasquirt could be fitted easy to tune and you could have a second map for MOT time

 

I just checked out their site and I get the impression from the wiring diagrams that megasquirt uses wasted spark ? My engine is too old for that and is fitted with a dizzy. Or can I just remove the dizzy and then use wasted spark ?

Would make life easier if a more modern ECU could be easily fitted, might be able to tune the "old girl" up a bit as well. I think Red Robin has a different ECU to the rover one. not sure what it is though and his is a turbo version so may make a difference.

Wasted spark just needs a trigger wheel to read from and throttle position or manifold actual pressure.

If the dizzy does not drive anything else (such as oil pump on a Pinto) you can bin it

 

Unless I'm wrong, adjusting the long term fuel trim will simply make the short term fuel trim compensate and you will get the same result. I really need access to an analyser for the day to test that.

 

I have one here, but obviously bit of a journey for you but you're always welcome!

 

 

Would this work ? Anyone have any other thoughts on a solution ?

 

Aye, aftermarket ECU is probably the most direct approach to fixing, assuming the engine is genuinely healthy and can make the required figures if the fueling was controllable enough.

Try a canems ECU awesome bit of kit and not as expensive as some of the big boys, had one on my car works faultless

Easy conversion to wasted spark opens up opinions on many ecu,s I am biest towards megasquirt obviously cos I have one whilst initially it was very daunting once you understand it

Its a great bit of kit and fully open so a very expensive specialist tuner is not required

Have you any idea of the target emissions/target lambda that are set in the ECU software or how much compensation the ECU can make? Can you alter target lambda? Tricks such as a slight reduction in fuel pressure or fitting slightly lower rated injectors are possible. Is the ECU clever enough to compensate for these strategies? If it is then aftermarket ECU running with closer to stoich lambda target or no lambda feedback would be your best option, IMO. Setting the natural idle speed to as fast as permitted may also help.

Edited August 17, 20188 yr by Longboarder

On www.trigger-wheels.com the microsquirt generic 4-cyl package comes with a new coil pack.

Have you any idea of the target emissions/target lambda that are set in the ECU software or how much compensation the ECU can make? Can you alter target lambda? Tricks such as a slight reduction in fuel pressure or fitting slightly lower rated injectors are possible. Is the ECU clever enough to compensate for these strategies? If it is then aftermarket ECU running with closer to stoich lambda target or no lambda feedback would be your best option, IMO. Setting the natural idle speed to as fast as permitted may also help.

 

Afraid not. The MEMS 1.6 ECU is fairly crude. We have figured out how to get status reports and figured out some of the values. One of the values is 145 all the time, across all cars so we think that might be target mixture. As Dean said, we also think we can 'tweak' the long term fuel trim, but we think the short term fuel trim immediately compensates so you don't see any other change. We are working a bit in the dark as all the documentation on MEMS 1.6 disappeared to China when Rover was sold. Once I can get access to an analyser we can experiment a bit. All our cars seem to idle at 1000 rpm, which is already 250 rpm above standard, so maybe that trick has already been tried.

Hi Alan have you got the readings on the failure sheet, im keeping an eye on this topic as i presume most super spec owners are. we all need a permanent solution to overcome the emissions issue,mot's are normally ok until they put the emissions tester on then your on hands and knees praying.

 

Afraid not, the failure sheet just said "CO & HC levels exceeded the manufactures levels". The levels were laid out on the eventual pass sheet, as detailed in my original post.