Terrol

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

7pane

What does the pcm show when you look at the live data? I am suspicious of the pcm being incorrectly pinned or the pin broken/corroded

Terrol

Thanks for the reply, live data is the same, I have access to a good snap on scanner, .61 idle-4.60 wot moves through the range just fine.

7pane

Then it would almost have to be a software issue. Are you seeing any other symptoms other than the code? Have you tried using stock software just to check the code?

Terrol

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?

Terrol

My tuner said its speed density at idle and mid cruise right now. He said we could go full speed density, but he doesn't want to tune around a problem. And I don't blame him

subeone

iTrader: (5)

modify that table. OR modify the idle adjuster screw, disconnect tps, put key in ACC position, count 10 seconds, put key in off position, connect TPS sensor, good to go.

Terrol

Ok, so that has to be it? I'm not sure if my scanner will do that. I don't have hp tuners. Just have a guy that dyno tunes put a tune on it for me.

2xLS1

iTrader: (25)

If your tuner actually told you that you need to find another tuner.

7pane

​​​​​​​This is it

Terrol

Hp tuners the way to go for tuning software?

gametech

iTrader: (1)

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.

JakeFusion

iTrader: (7)

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.

Terrol

Thanks for the replies. Yes I've tries several different tps sensors all to no avail. I'll see what he can do about adjusting that low error.

gametech

iTrader: (1)

There are multiple steady state transition tables, as well as VE coefficient tables. By setting conditions that won't ever allow steady state, you won't go into MAF only, and by heavily biasing unsteady state toward VE, you pretty much can eliminate MAF influence in areas you don't want it. You can change far more than just the all MAF switchpoint. As for how you would run all MAF at idle, I guess you could do the reverse of what I am talking about, but I can't imagine anyone wanting to.

subeone

iTrader: (5)

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.

Terrol

All right guys bringing this back up, this is what the Tuner has programmed right now, so is this the problem or are we looking at something else?

gametech

iTrader: (1)

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.

Terrol

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?

subeone

iTrader: (5)

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.