e30 m3 running lean

morning guys

had mot on sat morning and am pleased to say the car passed fine. One thing the tester did say was that the car was running very lean. The CO figure was showing at 0.23% where the tolerance ws upto 3.5%.

What effect does this have on the engine and performance of the car and also what is needed to alter this. Must stress which will make a difference is that the cats have been removed.

cheers

Adrian

UweM3 wrote: unplug the Lambda probe and measure again. Or swticht the ECU to 98 ron and measure again (but this might no stay in limits of 3.5% CO)

How do you switch the ECU to 98 RON ?? 

Also, i have heard that they are meant to run better with the lambda disconnected (only if the cat is removed obviously !!)

here

No it runs to rich if the ECU is set to Lambda ON and the sensor is unplugged! Nobody could confirm this 100% by now, but it seems that the ECO is going into safety mode if the sensor signal is missing. You need to connect BOTH, blue-blue AND black-black. Keep us posted if you can feel any difference when driving. I installed a switch in the das to close and open the black connectors and my chip is mapped for 95 and 98 fuel.
BTW if you keep it on 98 setting all the time you can unplug the sensor. Saves it heating up for nothing and might extend it's lifespan.

When I bought my car the PO had disconnected the Lambda sensor. I didn't know that and was driving for 6 month like that. Car was stinking like mad because of the mixture to rich and the cat still in place. Connected it after I failed Emission test and the cat was still fine.
I have the same type of chip than you have. There are 8 maps on the BMW chip anyway and by connecting and disconnection the blue and black connectors you choose on which map the car is running. The 98RON setting is open loop (Lambda disabled). If you are running on 98 you can disconnect the sensor. Most of the time when a remap is done the tuner writes the map he designed on ALL 8 adresses of the chip and disconnects the sensor anyway. Personally I don't think this is a good practice.
I wanted my chip to be like original with different maps just in case I can't get hold of 98RON petrol. I just press the button an the ignition is retarded. You just need to find someone who knows which of the maps is used with the different connectors.

Cheers for the info........i'll stick to the 98 map and Optimax.  Makes you wonder why they had the lambda then disabled it on the map !!

Uwe

Had a look at your website - nice car !!  What spec is your engine ? I read somewhere that you had changed the cams ? What cams, power etc ?

UweM3 wrote: Mags, why do you want to boost 98RON further? Are you running compression 13.5plus?

That's exactly what I was asking for, so Octane booster is of no benefit in our cars if standard and using Optimax.

Thanks

UweM3 wrote: I should put that up somewhere saves me typing EVO3 block(with oilsquirters) and 215bhp head 290/290 cams standard header and Exhaust (decat) 48mm throttles AFM still in place dependig on DYNO between 245 and 251bhp torque above 200lbs (can't remember have to look it up)

Sounds good - are they Schrick cams ??  I have read a lot about removing the AFM but you have a respectable output with it still installed.

I have a standard 2.5 engine - (installed in a 2002 I might add !!) no cat - custom exhaust - it puts out about 225BHP on the rollers - not the 238 that BMW claim...was thinking abot a change of cams but wasn't sure how wild to go with the AFM in place.

I have never know an Evo Sport put out more than 225BHP in standard form. Mine put out 224BHP with 50,000 miles on it.  Just changed the cams to 284 Schricks both inlet and exhaust but no other mods.  Will some be starting up but no idea on BHP.

 

Hopefully more than 225!

Regards

Andrew