lambda 4-2-1 questions

sterry9454

sterry9454

Hey
Ive just bought a 4-2-1 manifold and was wondering what people do to try and get around the 2nd lambda sensor. Im planning on running a 100 cell cat but due to the cell count im presuming it will be as effective as having none fitted in terms of exhaust emmisions. Its for a rally car so mot is not really an issue... And a cat has to be fitted. So what do people do. I dont want it to run in limp home mode so what are my options.... Fake the voltage, lambda extende, extend the cable and hope the 100cell cat does enough to keep the management system happy or fit an aftermarket ecu..... What do people suggest
Thanks ste
 
Yep, the second sensor is just an EGT one, its there to make sure the cat is working, i didnt disconnect it per say, just cable tied it out the way, and my omissions come MOT, well lets just say the gov should be paying me to drive my car they were that clean, that was on a new cat mind tho, so you will be ok
 
Nope, it seems i got the fueling spot on, it runs and drives fine under all throttle conditions, tho more on heavy throttle :) with the QG injectors i am only running 3.5 bar ish, i will need to check this mind. I think the C/P ecu is a bit more advanced and can actually help with basic mods. I do have intake and obviously exhaust mods too. I havent found a sub 150bhp car i cant stay with or more than often beat off the line, but this may be due to the "its a micra" mind set. With QG injectors you would have thought it would be more rich tho tbh, but it does run fine on WOT or on long runs
 
I found second lambda removal can bring a MIL light, and it affected afr too. (Was a long time ago that I was last messing with this though).

Its true those ecus are much more capable of learning. However they are also quite held back. Remap or replacement will see big gains.
 
The first should affect AFR when fitted with the janspeed as it only takes a reading from 2 of the 4 ports. My old almera GTI failed emissions test badly as the hotshots manifold only took a reading from 1 port but after moving it there was a noticeable fuel saving and car was smoother to drive
 
Forgot to mention, i am using a Frank mani, so my first lambda is still in its original position, not sure if that makes a difference or not tho. Seems i am either lucky with my set up, or the second sensor is as i thought and just an EGT sensor for reporting to the ecu that the cat is working properly, my reasoning behind this, is that on the first sensor there is cut outs for the gas to go into, but on the second one, on my car anyway, it is just a solid lump of metal with no cut outs. I may be wrong mind. I have the CGA3 lump too if that helps
 

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