Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post

H-Man · 06-29-2014, 01:35 AM

Due to the issues I've been having with my dad's car, I drove my 1994 geo prizm home with a multimeter watching the Ox (oxygen sensor) pin of the diagnostic connector to check how long it takes for an oxygen sensor to warm up and to check how fast the sensor is. I noticed on a 1.5% uphill grade I would go open loop/rich at 70-72 MPH (estimated power requirement: 25HP, RPM: 3500-3600.) I think it is triggered by throttle position, manifold pressure, RPM or potentially the EGR valve shutting (it stayed closed loop until at least 4000 RPM in 2nd gear so I know that it isn't purely RPM triggered.) The 4A-FE does not have a knock sensor so the ECU likely has very conservative settings. I did this so that I could simulate accelerating at high throttle at 3000-4000 RPM long enough for me to get an oxygen sensor readout.
Is there any way to get the engine to run closed loop at a higher power output so that I can keep the engine closer to the BSFC valley (BSFC valley for this engine is approx. 3500-4000 RPM)? As it is, the engine doesn't lend itself well to P&G.

I did find something useful: The 1994 Geo Prizm and the 1994 Toyota corolla with 1.6L 4A-FE (AKA ae101 on some forums,) stays in DFCO until the idle speed control kicks in, even with AC running it reliably stays in DFCO until this point.

The power steering idle up valve causes the engine to go openloop/rich. I'll see what happens when I plug that vacuum line (when I have the opportunity, I'll hook the pump up to a cordless drill to see if it provides enough assist for what I want.)

I need to put together a serial to TDCL cable (to read the OBD data stream that updates once a second) and an arduino oscilloscope (to watch the O2, EGT, and potentially the MAP sensor) so that I can get better data.

06-29-2014, 01:35 AM	#1 (permalink)
H-Man The brake pedal is evil Join Date: Jan 2013 Location: Arizona Posts: 401 Denny's Detector - '08 Mercury Grand Marquis Taserface - '17 Chevy Volt Thanks: 5 Thanked 57 Times in 52 Posts	Car goes open loop/rich at 72 MPH Due to the issues I've been having with my dad's car, I drove my 1994 geo prizm home with a multimeter watching the Ox (oxygen sensor) pin of the diagnostic connector to check how long it takes for an oxygen sensor to warm up and to check how fast the sensor is. I noticed on a 1.5% uphill grade I would go open loop/rich at 70-72 MPH (estimated power requirement: 25HP, RPM: 3500-3600.) I think it is triggered by throttle position, manifold pressure, RPM or potentially the EGR valve shutting (it stayed closed loop until at least 4000 RPM in 2nd gear so I know that it isn't purely RPM triggered.) The 4A-FE does not have a knock sensor so the ECU likely has very conservative settings. I did this so that I could simulate accelerating at high throttle at 3000-4000 RPM long enough for me to get an oxygen sensor readout. Is there any way to get the engine to run closed loop at a higher power output so that I can keep the engine closer to the BSFC valley (BSFC valley for this engine is approx. 3500-4000 RPM)? As it is, the engine doesn't lend itself well to P&G. I did find something useful: The 1994 Geo Prizm and the 1994 Toyota corolla with 1.6L 4A-FE (AKA ae101 on some forums,) stays in DFCO until the idle speed control kicks in, even with AC running it reliably stays in DFCO until this point. The power steering idle up valve causes the engine to go openloop/rich. I'll see what happens when I plug that vacuum line (when I have the opportunity, I'll hook the pump up to a cordless drill to see if it provides enough assist for what I want.) I need to put together a serial to TDCL cable (to read the OBD data stream that updates once a second) and an arduino oscilloscope (to watch the O2, EGT, and potentially the MAP sensor) so that I can get better data. __________________ Getting sensor data off of a pre OBDII Toyota ECU via TDCL. All of this is on E10: Project E is my current focus.