PerfTech
Well Known Member
... We had one of our customers who had installed virtually all of our products on his RV-7 (vacuum evacuation system was one) contact us for help recently. He said that the e-vac. system had changed his mixture and temperature readings. I went to his airport / hangar to offer assistance, was able to find the problem. I thought I may help the next guy from encountering this issue by posting my findings here. He has automotive type electronic fuel injection installed on his 0-390 that uses a wide-band 0-2 sensor signal for mixture feedback. This signal trims the fuel curve and attempts to maintain a stoichiometric Air-Fuel Ratio. I discovered he had installed his vacuum check valve upstream of the 0-2 sensor and this introduction of oxygen at this point was effecting the 0-2 sensor signal, causing the computer to alter the fuel map. The vacuum evacuation valve needs to be downstream or in the other pipe, away from the 0-2 sensor. Thanks, Allan...
