Fatboy Posted March 7, 2014 Share Posted March 7, 2014 Gents, Its a top hatted rebuilt Rover V8 4.6. Tubular stainless steel, wrapped exhaust manifolds onto Longlife built stainless steel system. Llambda sensor mounted on the single pipe after the Y join. Megasquirt V29 with Nige's BASE 4.6 Map. PWM blanked off. Engine was bedded in as per recommendations (20mins above 2,000rpm). Took it for its first MOT on a trialer and there were a couple of niggles that I've now sorted but the biggest issue is it failed on emissions after the 2nd high idle. That is all it says on the ticket so I dont have any more details. I'm heading back for a retest in the morning but I'm not sure if I should change any of the Megasquirt settings or just confirm the appointment and drive it there in a spirited fashion to make sure it is well warmed up etc.(Insurance commenced yesterday). At the present time, I dont really want to start datalogging and fettling until I've got an MOT and I'm 100% road legal as it will not be a quick process until I've fumbled my way round MS. Any advise would be seriously welcomed...! Thanks, DC Quote Link to comment Share on other sites More sharing options...
Gazzar Posted March 7, 2014 Share Posted March 7, 2014 Knowing nothing about MS (yet) my comments are probably rubbish. Is it possible to get a "lean" map? Is the water temperature reading received by the computer looking real? If it was the first high idle I'd not be worried, that it was the second worries me, as I'd expect that to be better. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 7, 2014 Share Posted March 7, 2014 It's not quite as simple as being rich or lean, they are measuring different gas contents, so it's possible to have it tuned beautifully and still fail the emissions test. The emissions targets depend on the year of the vehicle, so knowing what you're aiming for will also help. This may or may not help you do some tweaking: Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted March 7, 2014 Share Posted March 7, 2014 They have to provide you with a printout from the stations ega. If they won't provide one ask for an appeals form! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 7, 2014 Share Posted March 7, 2014 I just googled and found the document that graph comes from, it's a pretty decent explanation of how combustion works and how tuning affects the various factors (power, economy, emissions), so I nicked it and stuck it on my server: Combustion_chemistry.pdf Quote Link to comment Share on other sites More sharing options...
Fatboy Posted March 7, 2014 Author Share Posted March 7, 2014 That looks interesting, currently on the office printer! ? Quote Link to comment Share on other sites More sharing options...
dirtyninety Posted March 7, 2014 Share Posted March 7, 2014 I didnt know MOT stations actually tested your emissions?! every time i go in they warm the temp probe up in the kettle (special emissions warming kettle) then stick the gas probe up a brand new volvo handily parked by the doors... would it not be easier to go to a different test station? Quote Link to comment Share on other sites More sharing options...
V8 Freak Posted March 7, 2014 Share Posted March 7, 2014 My old 4.6 was only ever tested for the hydrocarbons percent at tickover... As was old vehocle etc. was target below 3%. I have a map which was set lean at tickover and surrounding cells for the MOT, but generally having a map that Tunerstudio had shaped from driving and a review of the cells got it under 3% anyways. (I set the AFR slightly rich of the 14.7 ideal on the tickover cells, let Tunerstudio set the cells, adjusted to smooth out and then set Tunerstudio to leave the area alone thereafter.) Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.