Still going lean with FM clamp
- Thread starter Matthew
- Start date
The clamp restricts the maximum voltage passed through. For example, if the O2 sensor is returning 0.9v (rich!), the clamp will only allow 0.365v to get through. However, if the O2 sensor is returning 0.2v, then 0.2v will be passed through.
Remember that the clamp only activates under boost. So if you're running rich under non-boosted conditions (say, a raised base fuel pressure) the ECU will see it and react. If your O2 sensor is failing and reading low, the ECU will also see this and react.
If the clamp is wired properly, it's altering the signal from the front O2 sensor. The presence (or lack thereof) of the second is completely irrelevant. It's really not very smart.
We were closed on Thursday and Friday, not exactly "the entire end of the month"
We'll be open on Monday.
If you're never seeing more than 0.09v from your O2 sensor, you have a bad O2 sensor or wiring. At idle, it should be bouncing around 0.45v.
Keith
Flyin' Miata
Remember that the clamp only activates under boost. So if you're running rich under non-boosted conditions (say, a raised base fuel pressure) the ECU will see it and react. If your O2 sensor is failing and reading low, the ECU will also see this and react.
If the clamp is wired properly, it's altering the signal from the front O2 sensor. The presence (or lack thereof) of the second is completely irrelevant. It's really not very smart.
Matthew said:
We were closed on Thursday and Friday, not exactly "the entire end of the month"
We'll be open on Monday.If you're never seeing more than 0.09v from your O2 sensor, you have a bad O2 sensor or wiring. At idle, it should be bouncing around 0.45v.
Keith
Flyin' Miata
i thought the bad o2 sensor didnt affect the way the clamp worked then? cut and dry, is it the clamp or something else thats causing the problem to go lean? I am going lean from 0psi all the way to 6.5psi until i hit like 5-6k rpm.
to me it sounds like ok its only seeing .09v so the ECU is pulling fuel because it thinks its running SUPER rich...which means i need to replace my first o2 sensor before the clamp will work?
to me it sounds like ok its only seeing .09v so the ECU is pulling fuel because it thinks its running SUPER rich...which means i need to replace my first o2 sensor before the clamp will work?
Hmm....
I would suggest go check the codes, it should show a problem on the O2 sensor and even be specific on what is wrong on it.
In my case, like I said before, I had the heater circuit of the O2 sensor wired wrong. And thats the code it showed in the logger. Cant remember right now which number was but the description was specific.
And yes, the 2nd O2 sensor is irrelevant, been 2 years without it. And I dont even bother with a MIL eliminator because it will still be there because of the EGR.
I would suggest go check the codes, it should show a problem on the O2 sensor and even be specific on what is wrong on it.
In my case, like I said before, I had the heater circuit of the O2 sensor wired wrong. And thats the code it showed in the logger. Cant remember right now which number was but the description was specific.
And yes, the 2nd O2 sensor is irrelevant, been 2 years without it. And I dont even bother with a MIL eliminator because it will still be there because of the EGR.
yeah, I know, I did even triggered the clamp FULL TIME, and the ECU was still pulling fuel. HOW??? I DONT KNOW...no clue yet as of today, because I dont have the 2nd O2 installed...WHERE THE HELL IS SEEING THE FUEL???Matthew said:
it sucks...
think about this, it happened to me one day I was going to the tracks, spend ALL DAY tunning and inspecting everything in place, then when in route to the tracks, suddently the car starts to lean out....and I was WTF!!, while still on route....I even added so much fuel to the point that the car stalled!!!!!! and nothing, lean lean until 5000rpms aprox then it bogs down.
- :
- ‘19 CX-5 GTR Tu
Yeah..i had these same problems not to long ago...I remember one time..as i was on the way to the track...i was fine tuning..my nitrous map...and the car started to pull fuel like a mofo..I put huge number into the mpi software...and still didn't matter..it would lean out..
I reset the ecu and loaded my daily driver map..and the car ran rich...not sure what happened..and haven't had any time to try & retune my nitrous map..
mathew are you still running no extra injectors?
Chas
I reset the ecu and loaded my daily driver map..and the car ran rich...not sure what happened..and haven't had any time to try & retune my nitrous map..
mathew are you still running no extra injectors?
Chas
you see???acidbbg said:
Thanks man, Im not crazy...!!!
I was even resetting the ECU and...NO WORKY!... as soon as I started the car after the reset, a Blinking CEL!!!!
I was so damn angry I though it was the MPI, I was even going to swap the stock ECU, have one spare just in case.
Thats why I say that the MPI relies on the O2 sensor working correctly...something wrong on the O2, NOTHING WORKS!
Run the car up to normal driving temps (sensor needs to be heated), stop the car...disconnect the o2 sensor from the main wires on the engine bay (i would stall the car and start it with the sensor disconnected).
Start the car, and use the voltimeter to see what voltage the o2 sensor is sending right there.
Also, do not use the wire-clamps that comes with the FM kit, SOLDER IT.
Start the car, and use the voltimeter to see what voltage the o2 sensor is sending right there.
Also, do not use the wire-clamps that comes with the FM kit, SOLDER IT.
i dont understand what youre saying about the o2...i tested the o2 and got .02v. if i disconnect the sensor how am i going to test the voltage? i have a little butt connector that my multimeter lead fits into perfectly for testing the voltage on the blue wire from the first o2 sensor (which becomes the pink blue after the harness)
