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working on an stalling issue

A

alexo1us

New member
Have 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
 


Sounds like every sensor in your throttle body is bad or there is bad wiring...also the bank 1 thingy means you have a vacuum leak somewhere...
 
bluegtp91 said:
Sounds like every sensor in your throttle body is bad or there is bad wiring...also the bank 1 thingy means you have a vacuum leak somewhere...
Click to expand...

I suspected a vacume leak as well but looked for one for awhile couldn find one> But there is crapload of places for one to hide since it is the front three are burning lean any ideas on where to look.
I just want be sure before I tell him to buy another mass sensor.
the tps i already to him to get one.
The vacume system is hard to follow any have a diagram for routing?
thanx again
 
bluegtp91 said:
Check the "T" Fittings around the LIM...those are always the first to go...
Click to expand...

Thanx I will have a hard look today I will try that spray carb cleaner trick to see what happens.
interesting note.I was just talking with him to meet up for further checking
He said it ran fine bath last night and today for his trip to work about 40 miles. which we couldn't even keep it running at one point with out the two foot process.
Thanx again
 
Update
I just checked it out again and found that t fitting spit as was suggested 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 huge vacuume leak but it appears to be coming 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 a lot better.
Any thoughts would help
Alex
 


furher info this thing run fine at 190 or lower after that the stalling starts up again. after we taped up the t fitting it ran better as discribed above but still stalls Ihave read about lim issues would they be more evident at higher temps . he said it been running hotter now then before I asked him if has been over heated he said no.
the carb cleaner didn't reveal anymore vacuume issues. I suggested he get a TPS which i know has a problem and take it from there.
bottom line is maintainence has not been ongoing combining issues to make a mess.

thanx again
keep the suggestions comming it helps the thought processes
 
I have been troubleshooting a similar issue to yours. Same car, 97 GrandPrix SE with 3.8. The car stalls out when letting off the gas too fast. I replaced the TPS which didn't help the problem. Then replaced the Idle Air Control Valve. This made a big difference, but didn't totally clear it up. It will still stall about 10% of the time (when trying to make it stall). I also cleaned the MAF with some precision electronics cleaner.
While changing those valves, I noticed the soft rubber vacuum T that fits on the throttle body is cracked. This T connects hard plactic vacuum lines to the fuel injector regulator? to the throttle body and then goes down to something? I've hit up all the chain autoparts places, but no one carries this T. Looking like a dealer part.
 
Thanx for the note
I decided it was best to take a break from for a few days heading up to the bone yard to see what I can find.
that t was cracked on this one to use rubber tape to wrap it helped a lot but i know it needs a new one (dealer item).
I asked about oil change he said changed it self meaning it goes though a lot oil
with running hotter and oil usage I'm beging to suspect a intake gasket issue.
or even a cracked manifold.
But i never worked on a 3800 before so it's all trial and error.
Good luck on yours please post your resolve when you find it
 
I recently had the same problem with the car stalling out when letting off the gas, right after I had replaced the PCM. After spending hours trying to figure it out, it boiled down to a crack that had developed on the back side of the air intake after the air sensor but before the throttle body. Make sure you have everything buttoned up and sealed there, it appears that this sensor is very sensitive. I hope your problem was easy to fix as mine??? Good luck!
 


all i know is when you start boostin it should be in the 100 area. i think idle should be about 30-40.
 
update
ok I'm starting to be glad I do not own one of these haven't done anythiing to it yet.
Today he came out of work to find the fan on high keys in his pocket.
he got here I was just getting ready to pull the wire off the fan motor when it stopped on its own.
heres the kick now everything works as it should no stalling no running hot even the tach has stopped its little bouncing thing.
I would bet the AT will show normal values on the TPS and MAF.
Could a bad fan motor cause this?
 
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