P0122 TPS and P0107 MAP/MAF Codes

[dsonyx650]

Hello 60degV6 members,

I successfully replaced the broken camshaft in my '97 Pontiac GA 3.1L V6: see thread, "3.1L Sudden Power Loss and Won't Stay Running."

Currently, I've been driving the car a little more each day with no problems! Yesterday, I drove about 6 miles at highway speed, put the car in neutral to coast down a long hill, and about 45 seconds later, the engine suddenly died. The engine light came on and still comes on.

There was no fluctuation in rpm or any indication that something was wrong.

So I hooked up the OBDII sensor, and received the two above mentioned codes: P0122, and P0107.

According to the sensor:
P0122 means "Check Engine Code," Throttle / Pedal Position Sensor / Switch A Curcuit Low Input.
P0107 means Manifold Absolute Pressure / Barometric Pressure Cucuit Low Input.

According to Chilton manual:
P0122 means Throttle Positoin Sensor Low Voltage
P0107 means Mass Air Flow Sensor Curcuit Low Voltage.

Checked fuses - good.
Could these sensors have just died?

Thanks for the continued suggestions, Aaron

[pocket-rocket]

I've had vehicles throw a MAF sensor code when there was an intake gasket leak. That was mainly because there was air entering the engine that the MAF wasn't reading. Maybe you need a new TPS for the first code. Possibly someone has one sitting around that they could send you for the price of shipping, as I know some people on here have tons of spare parts sitting around. I have a spare one, but it's not the same part number and it looks nothing like the one your car calls for, or I would send it to you.

[talon2swords]

Well I'm definitely not an expert, but they both say low voltage or low input. Does that mean that not enough power is getting to both devices (computer malfunction, relay, etc.?), or that both devices themselves are faulty (coincedence), or that there is an actual problem somewhere else?

Anyway, really wanted to say that you keeping that old engine alive is interesting. Most folks would have given up and moved on. Keep up the posts! I personally think an engine should go at least 1/2 million miles, but that's just me. Maybe these 3.1l engines can be made into eternal "zombie" engines if all the defective parts are replaced.

[IsaacHayes]

Check the wiring harness, if you get 2 things like that and it dies it seems to me you may have a break in the wire or a short (cut insulation grounding out the wire) or something.

If it dies it means it lost MAP signal, so check that first. Low TPS wouldn't cause it to kill the engine like that. It's possible they share the same wiring harness so trace all the wires and inspect those would be the first thing I would do.

Zombie engine... LOL I like that. Low voltage means it's not getting the right signal back. They run off 5v and the amount of voltage back is the range of the sensor. Like the TPS is .5v at 0% throttle, and ~4.9v at 100% throttle. If it's getting 0volts then it means there is an issue and that's out of range, so likely the wire is broke or grounding out on something. Same with the MAP.

Check your wires carefully and report back.

[IsaacHayes]

Looking at the 1997 grand am wiring diagram bzopi posted in another thread, the MAP and TPS share the same 5v reference along with the A/C pressure sensor. So defiantly check your wiring it sounds like that 5v reference line is broke and that would cause low voltage reading on both of those sensors.