Engine ping
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New User
Joined: Nov 2002
Posts: 15
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From: Illinois
Engine ping
96 Bronco 125K 302 with E4OD. When the engine is warm and cruising at highway speeds, 60 or faster, engine starts to ping on any kind of acceleration. Any time I hit the gas to pass or go up a hill it detonates. Only when the engine is warm. Will not detonate when I brake torque it. Had a few issues in the past new computer, trans wouldn't shift, new ign module, new O2 sensors, fuel pump, new maf, flushed the injectors, and fresh tune with new filters. Fuel pressure is 36 psi running, timing is 10 degrees, and a fresh tank of 93 octane. When checking the scan tool 02 sensors seem to be switching properly and keep switching between 250 and 900mv, so it does not look like it is running lean with long term fuel trims at about +4%. Any Ideas? The only thing I could think of is the hall effect sensor is acting up. But timing is impossible to check while flying dowm the highway.
Tuned
Joined: Jun 2003
Posts: 489
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Is the O2 sensor reading supposed to be switching? I tried to measure mine and it seems to stay at .9v all the time, cold or hot...I replaced it and it does the same thing?? My CEL isn't on, so I assume it is working and I don't have any codes...is this right?
Lead Driver
Joined: Nov 2002
Posts: 9,555
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From: Concord, NC
The O2 sensor should bounce between approximately .4-.6 volts. Stoichiometry (14.7:1 air/fuel ratio) is at .5V. Make sure you are measuring voltage from the correct wire. Two wires power the heater element (+12V and a ground), and one wire goes to the computer.
Tuned
Joined: Jun 2003
Posts: 489
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how frequently should it be bouncing? Does the meter I am using have anything to do with how it can measure it? It is a digital VOM from sears.
Mine stays stable, I have replaced it and now am wondering what could cause it to stay at the same voltage.
Mine stays stable, I have replaced it and now am wondering what could cause it to stay at the same voltage.
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New User
Joined: Nov 2002
Posts: 15
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From: Illinois
I've had the Motorvac decarbonizing done. I'm watching the 02 sensors through a scan tool, which is slow, and a fluke scope. I've also checked the EGR and it is functioning, and passes the KOER test. I think I'll try running with the O2 sensors out of the manifolds incase I have a back pressure issue with the cat converters. I had a friend with an Isuzu that when the engine would get warm, the converters would choke off. Make sure the 02 sensors are hot enough. Usually run the engine at 2000 rpm for 3 minutes then test the sensor. Make sure you get the right wire, one is for the computer, one for heater and the others are grounds. Once the 02 is warm and functioning, at 1500rpm is should cross the .5 volt going from rich to lean .100-.900v atleast 6 times in 10 seconds. Sometimes you can see it with a DVOM, that is where the scope comes in. Reads much faster and you can see the line passing the .500 mark.
Last edited by Bob 86; Dec 28, 2003 at 06:23 PM.
