Mark's 1G Winter Projects

[asshanson]

Originally Posted by Mark Leasure

I sold my AEM EMS Series 1. I purchased a series 2 ems and a 4 channel wideband O2 controller with the exhaust back pressure monitor kit. Now I can monitor each cylinders AFR and tune accordingly.

Sorry to bring back such an old post, but I had some questions.
O2 sensors read differently pre-turbo because of exhaust pressure right? They are designed to be on N/A or post-turbo pressures. Does the AEM setup adjust for this with an exhaust pressure sensor? From your post it sounds like it does, I was just curious. I'd like to know what adjustments have to be made due to pressure.
This could be quite handy on a single turbo system on dual banks, like a boxer or v6/v8 engine where you normally have to read the AFR post turbo, when one bank's exhaust travel is much longer than the other.

[Mark Leasure]

Originally Posted by asshanson

Sorry to bring back such an old post, but I had some questions.
O2 sensors read differently pre-turbo because of exhaust pressure right? They are designed to be on N/A or post-turbo pressures. Does the AEM setup adjust for this with an exhaust pressure sensor? From your post it sounds like it does, I was just curious. I'd like to know what adjustments have to be made due to pressure.
This could be quite handy on a single turbo system on dual banks, like a boxer or v6/v8 engine where you normally have to read the AFR post turbo, when one bank's exhaust travel is much longer than the other.

No worries on bringing an old post up. Yes you’re correct, due to the pressure in the exhaust, pre turbo, the wideband O2 readings are not valid. The exhaust gas pressure transducer will allow for a calculation to be made to compensate. The pressure transducer input and algorithm processing is built into AEM 4 channel wideband module. I’m not sure of the algorithm/calibration curve of the AFR vs pressure.

This is a great feature; I mainly use it to determine health of each cylinder. The combined AFR post turbo can only detect major differences. I can detect a slightly clogged injector or a torn insulator with the per cylinder wideband. I detected a torn insulator, one cylinder was off by over a half point of AFR but the feedback error on my post turbo 02 sensor showed a 2% change. You can explain away a 2% difference day to day. However, a half point on one cylinder difference is significant and made me investigate the issue further.

Update on the car: I tried to dyno the car last week, my clutch slipped and we initially thought it was tire spin. This was in 3rd gear. So we tried 3rd gear again same thing. It hit the ignition rev limiter when the spin happened. Then still thinking it was tire spin we tried 4th gear. It was not tire spin and it was my clutch slipping, it was like an on/off threshold. Once the clutch started to slip the RPM shot up extremely fast and banged off the rev limiter and hit fuel cut at 9600RPM. It hurt the motor. I have coolant in cylinder #1. I don’t know the extent of the damage at this time. It’s disturbing since it was not pushing coolant, but burning it. I’ll be working as fast as possible to salvage the race season. Not good news.