Ecumaster forum

Hi,
I've got two major problems with stetting correct lamba/ve.

1) I allways get lean readings from lambda sensor at fully closed throttle, but I allready disabled overrun fuelcut and decel enleanment. Is it just a sensor reading error and why does it do that? Also autotuner allways try to set VE to brutal high values. I just put values in, which seemed more realistic to me.

2) I allways get a very low ve in mid range RPM. My VE table just doesn't look right. And also, when I tune VE to correct lambda and change lamda target table after that, lambda readings are not as they should be. Another issue i found, when IAT values rise, my lambda values go lean.

I allready thought, that my Injectors are probaply not set right? I've got 750cc five-o-motorsport injectors (flowtestet by five-o-motorsport, actually 755cc) and injector dead times are also set right. I allready checkt fuel pressure, it's correct.

Engine is a SR20DET, bored to 87mm, 9:1 CR, BC Stage 3 Cams 272°/272° without VTC, stock s15 ball bearing turbo, bosch 2x2 wasted spark, NGK 2668 (BKR8EIX) regapped to 0,4mm.

Somebody got an idea?

Did you try another Lambda Sensor?

Checked the wiring to the Lambdacontroller?

Lean reading could also come from unburned fuel/air mixture. Maybe your ignition timing is much too late? just an idea...

No, but the bosch 4.2 isn't that old. But I also do not have another one to try.

Wireing is ok. I've got the Lambda controlled by the EMU.

Timing isn't late in low pressure area. I attached my Tuning file, maby you could give it a quick look?

Are you using the onboard wideband or an external controller? Did you check for exhaust leaks?

If you're using the onboard make sure you click "Enable Lambda Filter"

Controlled by the EMU.

I think, i've got a tiny leak in my exsaust manifold, because of the EGT sensor. Does this influence Lambda readings that hard?

Any air leaking could do it. Do you have the lambda filter enabled?

Yes, I have. Ok so I will try to get it all leakproof and then post a reply. Thanks here

I dont have any leak, and my car wants same VE, its same engine, so maybe this engine wants that VE shape to run in the desired afr ...

If you could post a log file, it would have been easier to help.

Injector linearity will affect the VE numbers needed. I wouldn't pay any attention to the lower ve numbers needed at the midrange.

Regarding the issue you have with lean afr when iat is rising, read here :
viewtopic.php?f=19&t=8817

Hi,
just to give you a quick update:

I've got a complete new exhaust (which doesn't leak) and lambda readings are still bad at overrun, but hey, dont give a fuck, i think the fuel is just not burning right at overrun. My timing isn't late at overrun (something between 35 and 40 degree btdc). I really don't care, engine is running good, but just for my interest in engine physics, does anybody know, what's causing that phenomenon?

I also got my problem with the weird looking VE table under control, I just manualy flatend out the table and voila, engine is running at desired lambda. I think autotuner just pics too much transient data and has a problem with this rpm/map area.

The engine heat soaking problem has also almost gone since I managed my IAT to be heat shielded and vented my engine bay. The rest does the EGO correction

Thanks for helping
Thilo

You know that you shouldn't give the engine any fuel during overrun?
Of course your lambda won't show realistic numbers during overrun, no air into the engine + exesive fuel = kaoz for the lambdasensor.
Your sparkplugs, oil, lambdasensor, cylinder walls hatching will take a beating.

You have to set the fuel cut options correct. In this case, the fuel under (kpa). 17-20kpa is fine. It's not good for your engine to inject fuel at overrun, like mentioned already, plus you are raising your fuel consumption.

Yes I know that, I was just hoping for some sort of popping noise and overrun flames