What if I unplug my EVP sensor?
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Fleet Mechanic
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What if I unplug my EVP sensor?
Ok, so my truck has this issue, where I just can't get it to idle properly (again) and what's happening is sometimes when sitting there, the rpms will randomly jump from ~1k to 2000-2500, with 0 input. I believe the EVP could be causing this, as there is a point in the sensor shaft movement with much higher resistance than it should be. Maybe this could be telling it to open the IAC all the way? Also causing my rpms to drop very unreliably?
Unplugging the IAC completely fixes this. Which leads me to believe this issue is electrical.
Would it be an issue if I reset the computer, and left the EVP unplugged.
I very reliably get code 34 in CM, and most of the time in KOEO
Sometimes I get code 31, I have it now. (CM)
Unplugging the IAC completely fixes this. Which leads me to believe this issue is electrical.
Would it be an issue if I reset the computer, and left the EVP unplugged.
I very reliably get code 34 in CM, and most of the time in KOEO
Sometimes I get code 31, I have it now. (CM)
FTE Legend
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From: Ottawa, Ontario
Sensors don't tell each other what to do the computer makes all the decisions, so even though you appear to have a bad EVP sensor that won't normally cause any idling issues.
What happens if you disconnect and cap the vacuum line attached to the EVP sensor? Any change in idling behavior?
What happens if you disconnect and cap the vacuum line attached to the EVP sensor? Any change in idling behavior?
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Fleet Mechanic
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Sensors don't tell each other what to do the computer makes all the decisions, so even though you appear to have a bad EVP sensor that won't normally cause any idling issues.
What happens if you disconnect and cap the vacuum line attached to the EVP sensor? Any change in idling behavior?
What happens if you disconnect and cap the vacuum line attached to the EVP sensor? Any change in idling behavior?
Unplugging the EVP vac line has no effect at idle. But results in code 33 if I drive with it that way. (I forgot to cap it when I drove, but this shouldn't effect too much.)
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Fleet Mechanic
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[QUOTE=Conanski
OK good that is the correct result. But did you still have the high idle problem when coming to a stop?[/QUOTE]
Most of this happens when at a stop, BUT a big issue is my rpms hang and/or rise when driving and trying to shift. And if they drop, they drop at unreliable/slow rates. Again fixed by unplugging IAC.
I don't know why sometimes, while 'idling' it decides to just rev up for 0 reason at all.
OK good that is the correct result. But did you still have the high idle problem when coming to a stop?[/QUOTE]
Most of this happens when at a stop, BUT a big issue is my rpms hang and/or rise when driving and trying to shift. And if they drop, they drop at unreliable/slow rates. Again fixed by unplugging IAC.
I don't know why sometimes, while 'idling' it decides to just rev up for 0 reason at all.
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
Yeah so something electrical/electronic is causing the computer to command the IAC to slam wide open, prime candidates for that are the TPS and the computer itself but you could also have a wiring issue between the computer and IAC or TPS.
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Fleet Mechanic
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Guess what? Code 63 
my TPS seems to be pissing the computer off. My second new TPS, I'll put the other, higher quality one back on, to see if that fixes it.
On a bright note, I've taken the throttle body off so many times, I could probably do it with my eyes closed
my TPS seems to be pissing the computer off. My second new TPS, I'll put the other, higher quality one back on, to see if that fixes it.On a bright note, I've taken the throttle body off so many times, I could probably do it with my eyes closed
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Fleet Mechanic
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Update
Quality tps is back on, truck seems to be running good, still having idle down issues.
I will update again after I let the truck do it's "learning" process and see where that leaves us.
I will update again after I let the truck do it's "learning" process and see where that leaves us.
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Fleet Mechanic
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New update
Putting good TPS back on completely removed code 63. No more random engine runaways for no reason. Idles incredibly smooth. No jumpy idle, it actually drops to where it should.
Still having "rev down" issues when driving, particularly when cold. it happens most when only using part throttle, my rpms will hang between shifts.
Still having "rev down" issues when driving, particularly when cold. it happens most when only using part throttle, my rpms will hang between shifts.
Hotshot
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That could be the IAC. Were you having that issue before? What brand IAC?
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Fleet Mechanic
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