Joined: 26 Feb 2008 Posts: 144 Location: Manassas, VA
Posted: Tue Mar 25, 2008 2:09 pm Post subject:
I have seen several O2 sensors (both narrow and wideband) read full lean when the engine is actually very rich (note that he has ~1.6ms PW reading 22:1, later where it reads 1ms, it's actually showing closer to 14:1). O2 sensors can be very helpful, but they can be lying bastards too. I note also that he seems to have a narrow band sensor. So 22:1 could mean anything from barely enough fuel to make the engine run to around 15:1, which is still lean, just not as lean as it seems to suggest.
Thinking about it now, the surging at idle could be explained by a leak in the intake or a loose butterfly. That could also explain the eventual jump in RPM but not necessarily. _________________ Jon
Project Engineer
Electromotive, Inc
jon at emi.cc
www.distributorless.com
Thinking about it now, the surging at idle could be explained by a leak in the intake or a loose butterfly. That could also explain the eventual jump in RPM but not necessarily.
This makes sense Jon. Engine warms and butterfly gets loose enough to increase the idle. Add this to a wacky or ill trimmed IAC and you would get these type of results.
Nef... r u running a NB sensor on a 2 bar MAP sensor at 25 psi? Please tell me you have have a seperate WBO2 in the car.
Joined: 19 Feb 2008 Posts: 148 Location: Everywhere In, FL
Posted: Tue Mar 25, 2008 8:46 pm Post subject:
4SFED4 wrote:
Yes, send me a copy of your bin too.
Questions on the data file:
1. Why is your AFR so high? Running at 20.X:1 at idle? Did you notice when your idle jumps to 38xx your AFR's drop to 14.X:1. Not sure what it means but they seem connected.
2. Are you using IAC? Why the surging before and after elevated idle?
3. Was the car fully warm at this point? Based on CLT it is only at 40C but if the engine was fully warmed you CLT is reporting incorrectly.
4. What was ambient temperature the day this log was made?
5. Why does your MAP read 120kPa before start? Do you live well below sea level?
No answers yet.. but perhaps if we answer enough of the right questions we will get to the bottom of it.
Joined: 19 Feb 2008 Posts: 148 Location: Everywhere In, FL
Posted: Tue Mar 25, 2008 8:52 pm Post subject:
4SFED4 wrote:
Jon@EMI wrote:
Thinking about it now, the surging at idle could be explained by a leak in the intake or a loose butterfly. That could also explain the eventual jump in RPM but not necessarily.
This makes sense Jon. Engine warms and butterfly gets loose enough to increase the idle. Add this to a wacky or ill trimmed IAC and you would get these type of results.
Nef... r u running a NB sensor on a 2 bar MAP sensor at 25 psi? Please tell me you have have a seperate WBO2 in the car.
heated wibe band sensor, yes 2 bar map @ 25 psi, i know the map sensor should be a 3 bar, i have one, however its never been an issue, so i've never got around to swappin it out,
the butterfly verywell may be the problem, as i've recently had it off, blasted and coated, so i'll give er a better look, the seal on the t/b is tip top, that i know for sure
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