O2 Clamp

phredren · Post by **phredren** » July 18th, 2005, 1:01 am

I've got a MX3 cylinder head on my B6T bottom end in my Festiva. Since I'm using an MX3 ECU, you guys know the answer to my problem. Anyway, I just got my car running again and now I'm trying to tune my engine (1994 B6DE ECU and wiring) for proper fueling under boost. I'm using an EManage wired to the air meter, 330cc GTX injectors and I've got a Zeitronix wideband O2 system with the narrow band output hooked up to my Autometer air fuel gauge so I can tell where the AFRs are. Anyway, when I'm driving along and I step on the gas, the AFRs still oscillate between lean and rich whereas with my old setup (B6T ecu) the AFR would go to rich and stay there. So any fuel I add will be pulled out by the stock ECU because it's trying to keep the AFRs where they should be for a non-turbo car. That, and there would be no way to read what the baseline fuel ratio is because it is never a constant AFR.

The problem I believe is that the ECU is still reading the O2 signal, and when the turbo produces pressure, the stock FPR kicks up the fuel pressure through the 330cc injectors and then the AFRs go way too rich, which is seen by the stock O2 sensor, causing the ECU to pull fuel.

So, has anyone else had this same issue, and if so, how did you overcome it? I believe I need to find an O2 clamp device, that tees into the O2 signal line and then under boost sends a proper O2 voltage so that the ECU won't pull fuel.

Any help or suggestions are appreciated.

papa roached · Post by **papa roached** » July 18th, 2005, 11:22 am

i dont know if its the same on the 4 cyls as the V6s, but when my TPS was out of adjustment it wouldnt go WOT and read rich on my A/F gauge and still occilate

BuGS · Post by **BuGS** » July 18th, 2005, 8:55 pm

I have that problem with the BP right now, What I do is just kick up the MAF/VAF signal by loosing the spring and that has seemed to help.

mazda20 · Post by **mazda20** » July 25th, 2005, 5:49 pm

Long time no post....

Has anyone actually installed the O2 Clamp on the mx-3, I am planning on it, I Radio Shack'd one together, but I am not sure about it. If anyone has good links to nice write ups on the O2 Clamp especially for the MX-3 than I would really appreciate it.