Grim Reaper Posted September 22, 2005 Share Posted September 22, 2005 Rover Mini...2000 model, multipoint injection with Cat fitted on Rover MEMS. Long centre branch manifold, Single rear box and K&N air filter are the changes from standard. MoT test failed on Lambda being too high (1.145-1.172) but CO is 0.0% and HC is 22ppm so the Cat is working OK. I think the high lambda means the mixture is too lean, so would something as simple as putting the original air filter back on reduce the air/fuel ratio or is it the lambda sensor that is up the swanny? I have another sensor but it is going to be a bugger to get it on. I'm not sure if I can increase the fuel pressure easily (I think the regulator is in the tank mounted pump) to get round it from the other direction.(could maybe restrict the return hose slightly to see if that has any effect) Bloke in the garage says the Lambda sensor is buggered (but I don't think he has tested it in any way other than from the readings off his emissions tester) and only changing it will make any difference. Is he right? Do I need to swap it out for a new one? Link to comment Share on other sites More sharing options...
Pooh_R Posted September 22, 2005 Share Posted September 22, 2005 YOu can test the lambda sensor by looking at its output voltage. It should swing between about 0V and about 1V at least once per second. an oscillope is ideal for measuring this, but a fast responding volt-meter should be OK. The system was in closed loop control wasn't it? The engine warm etc? You could check for vacuum leaks on the inlet side of things which could introduce un-metered air, so allow a lean misture? Pooh A Bear of little Brain! Link to comment Share on other sites More sharing options...
Myles Posted September 22, 2005 Share Posted September 22, 2005 My lambda (admittedly a wideband) has a 0-5V output - and there's almost no way of checking the output because it needs the additional connections for the heater etc... Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Grim Reaper Posted September 22, 2005 Author Share Posted September 22, 2005 Just had a look, the fuel pressure regulator is on the rail as in the K series so it might be possible to up the pressure a little there, I will get an oscilloscope on the lambda once the exhausts have cooled a little and I can get in to the connector, the temps were correct (fan cutting in) I suspect that the exhaust and inlet changes have increased the flow through the engine and possibly, despite the ability of the MEMS to richen the mixture up, it has gone outside its limits to allow it to richen it up enough to maintain Lambda 1 (I could/may well be wrong about this though) Increasing the fuel pressure slightly should put more fuel in to the system and it can lean it down from there? Next stop is a 7 port head and a set of throttle bodies/emerald methinks. Link to comment Share on other sites More sharing options...
Mick Day Posted September 22, 2005 Share Posted September 22, 2005 Why not try putting the original filter back on, make sure it's good & dirty & that should compensate for the lean mixture. Edited by - Mick Day on 22 Sep 2005 13:25:52 Link to comment Share on other sites More sharing options...
Grim Reaper Posted September 22, 2005 Author Share Posted September 22, 2005 Thought about doing that too (anyway) The question is, can the guy tell from the emissions readout on his MoT machine that the Lambda sensor has failed? I asked if it was running lean (I thought it might be with all the mods) but he said that had no bearing on the reading?? Surely not, that's what it's there to tell you isn't it? Link to comment Share on other sites More sharing options...
Mick Day Posted September 22, 2005 Share Posted September 22, 2005 The only real way to tell would be to fit another lambda probe & see. I would have thought the bloke in the garage could have swapped it out in 30 seconds & tried again. Link to comment Share on other sites More sharing options...
Grim Reaper Posted September 22, 2005 Author Share Posted September 22, 2005 30 seconds??? You obviously haven't seen where the sensor is on a mini!! I reckon about 3 hours to change it... inlet manifold off, maybe exhaust manifold too. Link to comment Share on other sites More sharing options...
Mick Day Posted September 22, 2005 Share Posted September 22, 2005 And here was me thinking it would be easy peasy. Should have guessed, had a mini in the 70's. Remember it was fun changing the fan belt & keeping water out of the distributor! Link to comment Share on other sites More sharing options...
grumpy the 7th Posted September 23, 2005 Share Posted September 23, 2005 Grim Don't know! but you might have an air leak between the Lambda and the back box. My se7en had it's MOT yesterday. CO = 0% HC = 23ppm and initially the lambda failed >1.03 limit. SAME PROBLEM AS LAST YEARS MOT - I take the 4:2:1 off & insert the Cat section and last year I had to hold welders mittens round the primaries to cat joints for 30 seconds for it to pass. This year I put paste and beer can segments into every gap I could find. It still failed as it was still blowing (nowhere near as bad as last years) Another session with the welders mitts got it down to 1.02 (Just in 😳 Phew!). It's worth checking for air leaks round any joints rog C7 TNT - it's Dynamite!(Honda Irish Green and Peugeot Graphite grey) Link to comment Share on other sites More sharing options...
Grim Reaper Posted September 23, 2005 Author Share Posted September 23, 2005 Well, I've changed the Lambda sensor and whilst reassembling the exhaust system I have used HT gasket sealant on all the joints as far as the cat (only two after that and they seem OK) retested it with the original air filter on and it still fails Taking it in to the local Rover (non dealer) repair place on tuesday to get the engine management interrogated to see if anything is wrong there. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now