Ok I'm lost

[ALEXO1US]

I have an auto tap and it gives me data but since I have no reference to compare I am lost.
This thing keeps stalling data from two sensors all over the map
First the tps is flakey it seems most of the time it sit at 0 but then it jumps to .4% angle but it's stalling at both.
The mass sensor also seems out although it was replaced two months ago which corrected the first time the stalling came.
But now for the part of the time it seems to get stuck and stops changing.
Is there some one out there that has a base line scan from AT they could send for comparison. Is it possible the mass could be screwed again so soon?
I’m sure the tps is screwed but this is a buddies car and I want be sure.
I changed the plugs out but the three on front were running lean the back three seemed fine.
All of the hard stuff is fine as far as mechanical goes.
This is a 97 grandprix SE with a 3.8
Error codes are
Code: Description:
P0102 Mass Air Flow Sensor Circuit Low Frequency
P0122 Throttle Position Sensor Circuit Low Voltage
P0171 Fuel Trim System Lean Bank 1
P1122 TP Sensor Circuit Intermittent Low Voltage
P1406 EGR Valve Pintle Position Circuit
--------: FREEZE FRAME DATA :--------
Generated by DTC code: P0102
Fuel System Status Bank 1: OL-1
Calculated Engine Load: 0.8 %
Engine Coolant Temperature: 187 °F
Short Term Fuel Trim Bank 1: -0.8 %
Long Term Fuel Trim Bank 1: 16.4 %
Manifold Absolute Pressure (MAP): 10.6 in Hg
Engine Speed: 854 RPM
Vehicle Speed: 0 MPH
Mass Air Flow Rate: 0.239 lb/min
Throttle Position Angle: 0 %
The mass is indicated where it seems to stick at but a ignition off and restart brings it back to life
I'm beginning to suspect a pcm issue but I have only work on my stuff chryco and i know them pretty well even if t didn't stall Would from the data I'm getting say this is one sick puppy.

Any thoughts would be of help
thanx

[BillBoost37]

Ok.. first thing to do is document and clear codes. Then see what comes back.

In diagnosing, you can turn the key to on and scan. Actuate the throttle and see how it reacts on screen. If it's not smooth with the throttle, replace the TPS.

The MAF, if you feel it's going bad, unplug it. The car will chug a bit for a while..but after a couple cycles it'll find it's way. You can run on an unplugged maf, unplugging is part of the test because it defaults to the tables.

Lean bank is probably because of the throttle and or maf causing calculations to be off.

[ALEXO1US]

Thanx I'm sure the TPS is done since it is jumpy doing that test you discribed.
But when I unhooked the MAF it did not make a difference.
I was just speaking with him and he said the thing ran great after he went out last night and today on the way to work.
I'm going to run out to a used car lot and see if I can get a baseline of a known good 3.8 around the same year.
I will also do a recheck of Vacuume lines using carbcleaner to see if I get any reactions
Thanx Alex

I should also say these codes came back twice and set again

[ALEXO1US]

UPdate
I just checked it out again and found that t fittling spit as was sugested we didn't have a replacement so I taped it up with electrical tape made it a bit better but I think it is still a problem will not know for sure until we get a new one. Is this a dealer item? Also when we let the throttle down slowly it seems not to stall but take foot off the gas fast and it stalls this could be the TPS since it according to the scanner it never get back to 0 it stays at .4.
another thing I notice is when it starts to go we get a big noise sounds like a hugh vacuume leak but it appears to be comming from the device below the intake tube going to the throttle body near the left side of the engine.
there is a vacuume line going there as well from that t fitting this maybe a dumb question but what the heck is that thing used for I suspect what it is or what it would be on my jeep but don't want to make myself sound dumber then normal. I wish we had a manual it would make my life alot better.
Anythoughts would help
Alex

[jakesq]

My first though (being in the service industry for ever) is you scan tool? may not be up to the task. I've seen some generic scan devices that have a very slow baud rate (too slow to be accurate) and can't accurately read live data. I would use a Snap on scanner or Tech 2 scanner and read the tps in milli volts during a throttle sweep and watch mz during maf testing along with grams and voltage. The one thing I saw in your scan data that was an eye opener was the +16.5 long term fuel trim. It's maxed out. But the suggestion to clear codes and record them and start fresh to see what pops back is a good idea.

Goos luck, Jake L.

[ALEXO1US]

I use Autotap so it not bad as long as you keep the pids down.
those lean numbers are an issue but with the big vacuum leak it is not surprising I have since did a temp fix on that T fitting so they should be better Having put the AT back on after the fix so Can't say what the numbers are will check again today and clear the codes again.
My biggest issue is I have no experience with the GP so I don't know what normal is.
I do know the TPS is funked so it needs replacing this was backed up by my multimeter data the MAF was replaced about 2-3 months ago to correct the issue then and it seem to have worked but now it seems to be done again as it works intermitantly.
Thanx for all your ideas and keep them coming
Alex

[ALEXO1US]

On a note this thing runs fine and all values seem fine until it reaches 205 degrees then it leans out and starts stalling I know it needs some cooling work as it is not running at optimal but what is it that could change after heat up?
This LIM/UIM issue that is talked about could this cheap plastic be cracked and after heat up opens up to cause a leak?
I'm going though in my mind I know if I keep plugging away at it I'll eventually find it.
I'm thinking there is something that changes at that temp but what I'm not sure.
He can drive it from here to the Airport in the morning and he said the temp stays just about 200 and all is well no stalling but if he gets into traffic it starts getting hotter and then the stalling starts. I did note the fans do not kick in until around 212 they stay on until about 200 then shut off again. Is this normal?
(The stalling will not stop until it allowed to cool down again for a few hrs)
At any rate please feel free to type up and give suggestions.
I suspect what ever it is it will be something small and stupid that will fix this. Yes the TPS needs to be replaced but if this was the cause it should be there all the time not just when hot.
Something changes when hot need to find out what that is.
The only issue is I keep burning my fingers.........
Thanx again
Alex

I was just thinking about the MAF readings I get when running OK it moves around changing values as it should but when hot it hangs but a turning off the ignition and restarts brings it back for a short time then it hangs again. Even when it seems to be working after it gets hot it still stalls.
Sorry for the long story but I'm trying to give as much info as possible

[RedZed]

Originally Posted by ALEXO1US

On a note this thing runs fine and all values seem fine until it reaches 205 degrees then it leans out and starts stalling.
I'm thinking there is something that changes at that temp but what I'm not sure.
He can drive it from here to the Airport in the morning and he said the temp stays just about 200 and all is well no stalling but if he gets into traffic it starts getting hotter and then the stalling starts. I did note the fans do not kick in until around 212 they stay on until about 200 then shut off again. Is this normal?
(The stalling will not stop until it allowed to cool down again for a few hrs)

Wow that sounds dead on to what my 99 Monte with 3.8 has been doing!
Wish I could be of assistance but I have yet to figure out the problem.

[n0dih]

Yup, AutoTap is a decent scantool, not buy far the caliber of HPT or EFILive's scantool, but decent. Make sure you are using v3.1 too.

Originally Posted by jakesq

My first though (being in the service industry for ever) is you scan tool? may not be up to the task. I've seen some generic scan devices that have a very slow baud rate (too slow to be accurate) and can't accurately read live data. I would use a Snap on scanner or Tech 2 scanner and read the tps in milli volts during a throttle sweep and watch mz during maf testing along with grams and voltage. The one thing I saw in your scan data that was an eye opener was the +16.5 long term fuel trim. It's maxed out. But the suggestion to clear codes and record them and start fresh to see what pops back is a good idea.

Goos luck, Jake L.