Transmission problems. 2000 SSEi

[Sether]

Yesterday and earlier today my car drove fine no problems there, but I drove my car to work later today and my transmission started really acting up, all of a sudden if I put my foot slightly more on the pedal to gain some speed it would drop into 3rd gear but it would do that much earlier then it would normally, and then if I went down even a little more it would drop to 2nd gear with maybe a 1/4 or 1/3 throttle total. It did it the whole way to work and it was very worrying and annoying. I also noticed that my boost gauge was reading about 1-2.5 psi of boost even at idle which is really different as it normally sits around -3 or -4 at an idle or no throttle. It wasnt like that yesterday and I feel like that's a hell of a coincidence to happen at the same time. I did add 1 pint of trans fluid before it started acting up as I checked it and it was 1 pint low. Just figured I'd mention that. I have no clue on what to do or check. Any guidance would be lovley. It's a 2000 Pontiac Bonneville ssei. I wonder how the drive home will be, I did hear a shop in my town does free transmission inspections.

Also I forgot to mention my tranny does have a transgo shift kit and has gotten a clean filter and fluid about 4 months ago. It did have a good amount of clutch dust, like that magnet inside the pan was caked.

[nos4blood70]

Check for leaks, no slippage at all? Any check engine lights?

[Goostoff]

You could just need a simple tune up. No vac at an idle could also indicate an intake gasket leaking as well. Dont be so quick to blame the transmission. I get people all the time come in with odd shifting problems thinking they need a transmission and it turns out to just be a bad coil or just old plug wires

[Sether]

Check for leaks, no slippage at all? Any check engine lights?

So it did throw a code the night I posted this and its got to do with the TPS code po102 I believe. Though I switched it out with the old TPS sensor I used to use on my old throttle body, and the same problem seemed to happen immediately after i started driving on the highway but not at all when I was driving around town. I've down some testing with torque pro and I ran the throttle position both before and during the malfunction and the actual throttle percentage seemed a little higher then what I was actually doing but the throttle archs seemed perfectly normal even when early downshifting. The graph looks no different when it was malfunctioning when I was accelerating than when I was doing the same before it would start malfunctioning. But I did learn that when my boost gauge is giving a 1 or 2 positive boost pressure when at idle and low throttle its actually a false reading and torque shows that it was at normal operating pressure during that whole time. So I really didnt learn much, besides that the actual sensor doesnt seem to be the problem.

[MKMike]

P0102 is not a TPS code; it's a code for the MAF sensor which will make your transmission and engine do very strange things.

The MAF sensor is a crucial part that tells the transmission when to shift, influences when the spark plugs spark and how much gas the engine needs.
When it goes bad, gas mileage suffers, the car runs poorly and the transmission may not shift right.
You can try cleaning up the sensor with MAF sensor cleaning spray because it leaves no dirt-collecting residue and won't melt the plastic.
If the sensor electronics went bad, you'll have to replace it.
Buy a Hitachi MAF0047 or a good used one from a junkyard (clean it with some MAF sensor cleaner).
While many aftermarket parts are junk, Hitachi made the original part and still makes the replacement part in Japan, not China.

If you can turn a screwdriver and unplug a wiring connector, you can replace the MAF sensor yourself , saving the cost of labor and saving money on the part.

Here is an example of how the MAF sensor failing or being dirty can cause transmission issues [url]http://www.tripleedgeperformance.com/Harsh-Shift-P1811.html

[Sether]

[quote="MKMike"]P0102 is not a TPS code; it's a code for the MAF sensor which will make your transmission and engine do very strange things.

Sorry for the trouble, the code was a Po121 Its diffiently a TPS related problem that I cannot figure out. BTW Forgot to mention I ended up replacing my TPS with another I had, same problem and my throttle numbers from a scanner looked all normal.

[maxi426]

Could be a problem with the connector or wiring. The refresh rate on the scanner may not be fast enough to catch it. Does your scanner do graphing? Monitor the TPS reading while wiggling things, and pushing around lightly on the harness

[Sether]

Could be a problem with the connector or wiring. The refresh rate on the scanner may not be fast enough to catch it. Does your scanner do graphing? Monitor the TPS reading while wiggling things, and pushing around lightly on the harness

So I tried that, and at idle it would read about .4% throttle at idle and then every few seconds it would spike to about 0%, maybe im reading the graph wrong and it was running at 4% at idle, I dont know but it kept spiking to 0. not sure if thats normal or not. Didnt give any trouble at idle. My wiring harness was below my throttle body and very close to the crosspipe and almost touching my EGR so it could of been getting really hot, I forgot to move it above the TB after installing my Intercooler. So its back up there, if that doesnt help it atleast gives me peace of mind that those wires arnt getting that hot.