Damn Saturn L200. P0105 and P1640
 

I still haven't been able to find the diagnostic flow charts for the P1640 code, and the P0105 is showing up, which is MAP/BARO CKT Malfunction, basically saying that there's something wrong w/ the MAP, but the system isn't sure what.

I replaced a TPS that only showed NOT or WOT, and a huge dead spot in between, and that didn't fix the problem.

The TPS at closed throttle still reads 18-20%.. And it's not technically adjustable, although I probably will adjust it anyway, by slotting out the holes for the screws.

Coming down the hill in 1st gear, engine braking at 4k RPM, I get around 8 inches of vacuum coming from the MAP sensor... I know this is wrong, it should be damn near 30 inches. I've tested for vacuum leaks, but it's kind of hard to test correctly when you can't test under load... The voltage input is fine, signal output is fine, and I haven't checked the ground for continuity back to the PCM yet, but I will check that as well.

It doesn't feel like it's actually braking though... the car still feels like it's trying to accelerate, or like it's keeping about 1/4 throttle. I know that MAP codes show up for things that aren't directly related to the MAP sensor, so I'm checking other stuff as well, such as the IACV and TPS settings.

Anyone know how to adjust the IACV?

I posted over on Saturn Fans, but they're not much help...

The IACV should not be adjustable.
It sounds as if yours , or your throttle, is stuck partway open.
Have you taken the throttle body off and inspected it yet?
You may find the throttle hung open by some carbon or other foreign material.
You definitely need to check for a hung throttle plate before you adjust the TPS.
Is yours fly by wire, or conventional?
I had a Fly by wire Toyota the other day with a similar issue (always over idle, MAP code) that just needed the Throttle body cleaned up.

Backstory - I just replaced this engine.

So yeah, I've checked/cleaned the TB, removed and replaced the IACV 3 times, changed the TPS (and it needs to be adjusted now) and the throttle plate is adjusted to the point where it is just barely not contacting the throttle bore.

On some cars, you can adjust the IACV's counts, but on others, you can't. I haven't found a feature with my scan tool that will let me do it, but some you can also just unscrew a little bit and reinstall. It's quite unfortunate that I don't have an airflow meter or a way to tell how far open the IACV is at idle. The car normally idles high, so maybe I just need a new IACV.

Frankly, I'm going to adjust the TPS anyway, because I'd rather have it set to 0 at NOT than 18-20%. Right now, it goes to 100% just before it's actually open 100%, so I'm actually going further than the pot will read.

There's a little bit of slop in the screw holes, so I'll try adjusting with that first, but if it doesn't come within spec, I'll slot the holes and adjust further.