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I need a tune for 05' GTO to write out a P0121 code

Predator support for GM gas vehicles

Moderators: mikel, 06MonteSS, Vas@Diablosport, JonDiablosport


Posts: 25
I have a an 05' GTO and was looking for some help to change MAP values to fix a p0121 code, thanks!

it's a v9r03 revision predator, for a 2005 GTO.

Thanks, again!

Post Tue Aug 11, 2009 3:33 pm

Posts: 45076
Location: DiabloSport World Headquarters

Are you running a blower?
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Post Tue Aug 11, 2009 3:36 pm

Posts: 25
No?

Post Tue Aug 11, 2009 3:39 pm

Posts: 45076
Location: DiabloSport World Headquarters

That code seems to be pointing to an issue somewhere.
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Post Tue Aug 11, 2009 3:40 pm

Posts: 25
Not sure why your asking, but I was looking for some answers for this code and found out on HPtuners site that you could change MAP settings to 'fix' this problem...

Post Tue Aug 11, 2009 3:43 pm

Posts: 25
"The curse of the P0121 Code...
This code is infamous for giving people with larger cams fits...everything from traction control troubles, to shift point issues to just the good ole' P0121 code showing up for seemingly no reason making people scramble to purchase new Throttle Position sensors, adjust their set screws, etc, etc.

Before I go any further have a gander at the DTC information provided by LS2.com"

http://www.ls2.com/boggs/dtcs/DTC%20P0121.htm

Post Tue Aug 11, 2009 3:48 pm

Posts: 45076
Location: DiabloSport World Headquarters

OK, fo you have a big cam or something?

I'm just trying to figure out what happened to cause this code in YOUR car....
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Post Tue Aug 11, 2009 3:50 pm

Posts: 25
well, it started after a TB port...but this code isn't just about a "big cam", I've seen others with this same problem after TB ports or if they have done any other intake, air flow up-grades...plus I've done 'resets' of the TB and not had any codes for a day or two. I've done all the other things like checking connectors, loose or frayed wires, checked for other codes, cleaned the TB and checked for misaligned TB blade....and so on....

Post Tue Aug 11, 2009 4:00 pm

Posts: 25
"To outline a few key points

Quote:
The MAP is greater than 65 kPa

Quote:
The predicted throttle angle does not match the actual throttle angle

Quote:
All conditions present for 20 seconds

Now, that 65kpa map figure comes into play in nearly every LS1 Car/Truck because its the max map setting in most of the calibrations for the sanity test as shown here


Under normal circumbstances a stock cammed A4 will probably idle at around 35-40 map. When switching to a larger cam with more overlap your map readings could go up to as high as 70 or more kpa map which is way outside of the normal boundries. On a stock cammed car you'd probably need to be at around 30% tps to hit that same map number which is where that predicted throttle angle quote comes into play.

Now onto the last quote the 20 second timeframe. This will Usually come into play more often than not at idle with large cammed vehicles because many times your steady state map will be within the map sanity guidelines so there is a good possibity you might not see this code pop up immediatly.

There are a few ways you can cure this issue
a. Do as suggested in the help file which is to just set the min to 0 & max to 100
b. Adjust them to YOUR liking so you'll be within a reasonable limit. This will help determine if there IS a real issue with your TPS sensor later down the line.

So there you have it, as good an explanation I can come up with for that bastard code. So the next time you go WOT in your auto LS1 with a large cam & you go from 1st to 4th by 40mph or just a nagging p0121 code for no obvious reason you now have the info needed to fend it off. "

Post Tue Aug 11, 2009 4:00 pm

Posts: 45076
Location: DiabloSport World Headquarters

So, if you reset the TB this code does not appear for several days?

That would lead me to think it is related to Throttle Position maybe?

What do they say is the 'fix'?
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Post Tue Aug 11, 2009 4:08 pm

Posts: 15670
Location: CT

all kinds of good info here:

http://www.gearchatter.com/viewtopic11756.php


you may need a new MAP sensor....

"A skewed MAP sensor may cause this DTC to set. If the TP sensor is operating
properly, and if this DTC continues to set, test the MAP sensor for proper operation."
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2014 Camaro SS - 2SS, RS pkg., short-throw shifter, NPP perf. exhaust, BMR strut-tower brace, Cold Air Inductions cold air intake

Post Tue Aug 11, 2009 4:18 pm

Posts: 25
Yes, this is a TB/Throttle position issue.

"Quote:
The MAP is greater than 65 kPa

"Quote:
The predicted throttle angle does not match the actual throttle angle

Quote:
All conditions present for 20 seconds

Now, that 65kpa map figure comes into play in nearly every LS1 Car/Truck because its the max map setting in most of the calibrations for the sanity test as shown here"

Now there is a screen shot of a HPtuner screen showing the values of MAP range and where you might adjust this...but here's the link to the page.

http://www.ls1.com/forums/showthread.ph ... ight=p0121

And here's the link to HPtuners for p0121

http://www.hptuners.com/forum/showthrea ... ight=p0121

Post Tue Aug 11, 2009 4:45 pm

Posts: 964
So bascially your saying that the ported throttle body is now leaking more air than it should, causing the throttle position sensor to think it open when its not and it cant close any more so it throws the code P0121. All this for how many horses?
Only one thing to say about my "Diablew" Tune!
" Just Friggin Wicked"
Now with TCM support...

Post Thu Aug 13, 2009 2:07 am

Posts: 25
OK, back for a second plea for help....tried a new MAP sensor, wasn't needed...same code...so can I get some help???
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Post Thu Aug 13, 2009 6:16 pm

Posts: 99
I had this same problem with a BBK 80mm TB. you're basically screwed. I went back to stock TB and had no problems. cjfast I believe you are correct, it needs a MAP readjustment somehow. I heard of a trick with a temp sensor that used a resistor that could trick the MAF to think it was always a cool temp therefore giving you more fuel for power. Maybe you can figure a way for the TB sensor or MAP. good luck. There more than one way to skin a cat. If you like the ported TB "feel" on you car, then go for it.
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