DarkDragon Posted October 17, 2011 Share Posted October 17, 2011 Need help here guys/gals… My 95 PF is acting up again. I just changed the plugs, wires, cap, & rotor not even 2 months ago. I cleaned the MAF and changed the fuel filter about 2 weeks ago. Yesterday, started acting like its misfiring. This is only happening when it warmed up, (want to say closed loop) and mostly under load. Once in a while in park or neutral. You can hear the backfire while trying to drive. Yet when the engine is cold, (open loop) and get the lubes up a few minutes…, it runs smoothly. This happens under load as well. In park it free revs. I unplug the MAF and it free revs up to a certain point (rev limit, then the check engine light come on). So I want to rule the MAF out because the ECU sees it connected / unconnected. I have no check engine light with this misfire. could it be the o2 sensor? And the MIL pick it up. Will be checking for codes here in a minute. Please help. Thanks Tony Link to comment Share on other sites More sharing options...
DarkDragon Posted October 17, 2011 Author Share Posted October 17, 2011 Ok here is the deal. The ECU had no codes. So I did the following: Checked battery voltage, 12.89v off and 14.39v car on. Connected my AEM wide band o2 kit to the exhaust, and started the car. WB- 16.2 AFR open loop / idle WB- 16.6 AFR closed loop / idle 1200 RPM cold, down to 1000 RPM warmed up on all 6 plug wires (multi meter) PF starts to stumble in park. Using my digital multi meter at the ecu: MAF Signal 1.103v / idle MAF Signal 1.7v / light rev O2 heater (-0.514v) (pin 106) O2 signal (-0.262v) (pin 19) O2 signal 0.214v heavy revving (pin 19) Driving in my drive way, which is long enough to test a few things, the car was now smooth. My WB read 13.0 AFR in closed loop at WOT up to 30mph as I had to hit the brakes to slow down. I did notice this odd thing, my WB was a steady 15.8AFR which equal to (-0.333v) at idle, 990-1000 rpm. What is this? Is my o2 going bad? The ECU I have looks to be new. In any case the numbers on it are: H9 MECM-V260 A1 4831, if that means anything: Also one last thing, I did notice a loose plug. It’s a blue with white plug, with female pins on it. Colors are: Orange White / Pink Black / empty Any ideal? Thanks a bunch. Tony Link to comment Share on other sites More sharing options...
DarkDragon Posted November 6, 2011 Author Share Posted November 6, 2011 it ended up being a bad o2 sensor.... Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now