Silverado 408 Code Help!
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Teching In
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Silverado 408 Code Help! Hello, I need advice with this truck. It's a 1999 Chevy Silverado 1500 2wd with a 408. It is drive by cable, it has a nick Williams 90mm throttle body. The Code is a permanent p0122. Will not erase. Voltage for tps sensor is perfect. Closed at idle .61 volts and smoothly goes to 4.60 at wot. The code trips with truck not even running. I have tested voltage and continuity on all the wires that have anything to do with the path involving the code and they are all fine. I've tested from the pcm terminals to the connector ends of the tps, iac, and fuel tank pressure sensor. I have replaced the pcm, tps twice, and the throttle body. Nothing helps. Any ideas of any sort at all let me know, this has been like this for 7 months an I don't know what to do
Teching In
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From: Nebraska, The Good Life.
Hello, I need advice with this truck. It's a 1999 Chevy Silverado 1500 2wd with a 408. It is drive by cable, it has a nick Williams 90mm throttle body. The Code is a permanent p0122. Will not erase. Voltage for tps sensor is perfect. Closed at idle .61 volts and smoothly goes to 4.60 at wot. The code trips with truck not even running. I have tested voltage and continuity on all the wires that have anything to do with the path involving the code and they are all fine. I've tested from the pcm terminals to the connector ends of the tps, iac, and fuel tank pressure sensor. I have replaced the pcm, tps twice, and the throttle body. Nothing helps. Any ideas of any sort at all let me know, this has been like this for 7 months an I don't know what to do
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Teching In
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Symptoms are the idle increases on its own slowly to 1500rpm, and it dies if it's in drive stopped with the brake on. No other codes, just p0122. I put my friends pcm and tps from a 2002 Silverado with 5.3 4x4. All I got was a generator code. No p0122. So that would kinda make sense. Is it possible to have something wrong with the tune that it would instantly trip it?
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Teching In
Joined: Mar 2016
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From: Nebraska, The Good Life.
Actually, you CAN tune out the MAF blending in that manner. I had to do something similar on my Dad's A/A intercooled Whippled Silverado because there was no way to avoid turbulent airflow to the MAF at low load (no real straight areas of charge pipe post-intercooler). Since the 4.8 still wasn't maxing the MAF at mild boost, we didn't want to lose the redundant airflow readings for high load situations.
How can you tune MAF blending like that? You can set the switch point from MAF to SD but it's a one time thing. Stock is 4000. Above 4000 is all MAF. Below 4000 is MAF/VE blend. If you set it higher you just up the blend. Lower and you just run MAF only longer. Not sure how you run MAF at idle and VE/MAF high RPM. You can do Open Loop at idle and CL above say 1200RPM. That's how I setup my car.
As far as the OPs question... did you try another TPS as a check? Just cuz the wiring is right doesn't mean the TPS isn't going out. But get your tuner to up the low error and see if it helps.
As far as the OPs question... did you try another TPS as a check? Just cuz the wiring is right doesn't mean the TPS isn't going out. But get your tuner to up the low error and see if it helps.
How can you tune MAF blending like that? You can set the switch point from MAF to SD but it's a one time thing. Stock is 4000. Above 4000 is all MAF. Below 4000 is MAF/VE blend. If you set it higher you just up the blend. Lower and you just run MAF only longer. Not sure how you run MAF at idle and VE/MAF high RPM. You can do Open Loop at idle and CL above say 1200RPM. That's how I setup my car.
As far as the OPs question... did you try another TPS as a check? Just cuz the wiring is right doesn't mean the TPS isn't going out. But get your tuner to up the low error and see if it helps.
As far as the OPs question... did you try another TPS as a check? Just cuz the wiring is right doesn't mean the TPS isn't going out. But get your tuner to up the low error and see if it helps.
in agreement with gametech. Sometimes it is preferred to use the VE under low speed, transients whenever the MAF is located in a "bend", then leave the MAF to calculate "steady" state aircharge, and additionally provide a "load" value, as MAF directly relates to engine load, VE tables do not.
That is an ENORMOUS problem. I have no idea if it is your only one, but tuning out your TPS on a cable throttle setup will never work well. Show your tuner, and if he doesn't immediately recognize it as an accidental problem, run away. It could have been an oversight, but things aren't looking favorable for your tuner right now.
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Well I think that answers one of my questions. On the other hand, does anyone have any more advice on the this p0122 code? It makes absolutely no sense, I've went through the flow chart so many times and everything checks out perfect. Or is the way those settings are going to trip it instantly?
to start,
that p0121 max and min are wrong. max should be 100. min should be 0.
theyre both at 105 kpa right now.
second of all, your low threshold and high threshold is wrong. Return it to the setting i previously posted, the image with the blue circle.
Your issues should be gone after that.
Get a new tuner.
that p0121 max and min are wrong. max should be 100. min should be 0.
theyre both at 105 kpa right now.
second of all, your low threshold and high threshold is wrong. Return it to the setting i previously posted, the image with the blue circle.
Your issues should be gone after that.
Get a new tuner.