Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
ive got a 94 ranger with 4.0 v6. obdi. when you try to acclerate, its as if it cuts out, then comes back, cuts out then comes back. if you kind of ease into it, it wont do it. watching the limited data on the scanner, when it happens, both o2 drop to double digits. im having a hard time wrapping my head around it. i noticed the ground was loose and corroded on the battery, so replaced the cable end and exposed new wire, everything is good and tight there. positive is good. now, if i unplug the maf, it wont do it and it runs correctly down the road. when i test the maf, its got ground, power, both of which do not cut out when the problem occurs. it appears that im getting a good signal coming from the maf. looking at the scanner data though, its low. im thinking maybe the incorrect signal is getting to computer. my question i guess is this, in unplugging the maf, does the compute simply quit looking at the data it provides and just runs off the o2s?
You will need to test maf waveform signal for drop outs and glitches. What hz readings are you getting at idle and through the acceleration?
What are the g/s readings? Post a photo of pid data of maf, map, tps and o2 sensors. What is your fuel pressure looking like at idle and acceleration?
You will need to test tps, iac, fuel pressure, map and maf for these symptoms.
Opps got to typing and didn't look back. That is possible though looking at o2 with scope would give some "live data so to speak" along with probing tps or maf signal at same time. To determine when the glitch happens during the acceleration.
I'm blown away! I owned a 94 explorer for years and even with the adapter I couldn't get anything out of it except for koeo output test and trouble codes.
there is a bit of data that i am able to read. i went ahead and tried a new maf on this one, but to no avail. when reading the data through the scanner, maf voltage reads .04 at idle and will go up when the throttle is manually turned, but never above one volt. with a meter hooked to the signal wire at the pcm connector, i can see the voltage is going up properly like it should.
does anyone know what the signal return wire should read? im assuming it supplies the voltage for the sensor but i cant find the information anywhere.
im leaning towards the pcm reading the voltage improperly, but i can't put my finger on why.
Finally got this one. after exhausting myself too much, i pulled the computer and then removed the cover since it was a simple two or three screws to do so. there was a definite spot of damage at one of the tiny capacitors and the board looked corroded some. i decided to try my hand at trying to replace the capacitor. that made it worse, it just made the reading open. so, that lead me to believe that that was indeed my problem. finally ordered a computer for it, and after a number of weeks i just got it back. replaced it and fired it up, and the maf reading in the data stream was what it should be, instead of .04 and barely rising, it was .9 and went up as the rpm's increased. next time, i wont doubt myself as much.
