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Steeleagle
Posted on Monday, June 09, 2014 - 05:39 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

1190RS with race pipe and EBR race tune. The symptom of note is backfiring on decel and under constant throttle/steady state operation. I first thought: Race system doesn't like steady state, but it didn't do it when I first installed the pipe/ECM and has gotten more annoying, so...

My next thought: exhaust leak, so I went through the exhaust system and found nothing obvious.

Then I checked the O2 readings. Both are at 0.4 V with engine off. The front runs 0.0, but ramps up to 0.8 V when I roll on the throttle, which to ME is OK. The rear sits at 0.8 even at idle, indicating a rich condition to me. Examination of the headers confirms this (soot). I swapped out the O2 sensors (F/R to R/F) to be sure it wasn't a sensor error. Nope. Rear cylinder rich. The sensor colors also tell me so (front is chalky white, rear is black).

I pulled the rear plug and while it wasn't really bad, it was blackened. So the rear is clearly running rich.

I checked for a injector leak by cycling on the fuel pump a few times to make sure the fuel rail had pressure. No signs of weeping or leaking appeared with the engine off, but... I have NOT done a visual with it running.

Since it's an EBR, I don't think any recommendations with ECM Spy will be useful. I plan to change the spark plug and am debating about the coil to ensure I have good spark.

Question: Is there a way to test the coil without just replacing it? Pulling the front to swap them to see if the problem moves is an option, but a messy one!

Any other ideas on what to check an how? I'm trying to avoid "fix by replace" unless there's some logical reason. Right now I'm thinking either I have an over-active injector or an ECM error. BTW: I have no error codes.

Any help or suggestions is appreciated.
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