Misfire after extreme load

[AmuletOfNight]

But knowing what we know now, that it is a 4.6L, now the TPS is slightly out of spec. I'm thinking that the TPS is bad in this case? Because it should probably not be reading 1.21 volts.

[sly]

it should be closer to 1V when closed. It might be the TPS out of spec causing the issue. Usually that would throw a code though unless it's just below the PCM's programmed threshold. Have you read the codes at all to see if there's any stored codes?

[AmuletOfNight]

I have read the codes through the engine light (short a wire to the diagnostic port to ground), and nothing shows up, it comes up with a clean bill of health. So whatever is causing this is not out of spec enough to throw any codes.

[sly]

I would check everything for air leaks first... then if there are no leaks (fix the FPR vacuum line first) then if it's still being obnoxious, try replacing the TPS.

[AmuletOfNight]

I'll probably end up doing this today, just fire it up and start feeling around the vacuum hoses for any possible leaks, as well as probably finally get to redoing the fuel pressure regulator tubing...if that doesn't help, I'll replace the TPS, even though I don't want to (a bit short on cash right now). We'll see how everything works out, I'll let you guys know. Thank you for all the suggestions.

[sly]

If it is derivable, you can always put off the TPS swap until funds are happier. The unmetered air from the broken FPR line might be all the issue right there (kinda hope it is).

[AmuletOfNight]

Well I managed to scrape up some money to go get a TPS..Now the problem is actually REMOVING the f**king thing. The screws are SO tight and stuck in there that I have just about stripped them trying to get it out, and any rotation of the screw has resulted in a horrible grinding noise. I cannot even begin to understand why they are SO tight. I might have to drill these out...Does anyone know A) a good way to get these out, and B) the screws that go into those holes, since I'm going to have to replace these screws anyways.

[sly]

soak in PB Blaster or some other penetrating lube for a few hours (spray a little and let it soak in for a few hours) and then wiggle the screw back and forth about 1/8 turn as you increasingly loosen the screw (when you hit more resistance... go back a little and "wiggle" in place before loosening more). not sure of the thread of those screws though, once you have one in hand, you can probably find more at a hardware store.

[AmuletOfNight]

So that's not working, at all. PB blaster doesn't touch this. The screws are locked in there solid...we are going to drill the heads off the screws and then get some more screws from the store once we can get them out with vice grips. Can a vehicle run without its TPS for awhile? (A trip to the hardware store and back)

[miamibob]

As far as I know, doesn't the factory use a version of LOCTITE for these screws???

[AmuletOfNight]

Got the TPS off. I snapped the new one into place and turned on the ignition and I'm getting a wonderful 0.89 volts compared to the previous 1.21. Now time to run up to the hardware store and get a new thing of screws for this thing (since the old ones are ruined. Drilled them out, and still has to take vice grips to turn them).

[miamibob]

Progress!!!

[sly]

I really hope that sorts it. All this work needs to pay off.

[AmuletOfNight]

I swear, you guys are literally magic sometimes. How a faulty throttle position sensor can possibly cause a misfire, I don't know..But I just got back home, threadlocked some screws, threw the TPS in place, plugged it in, cleaned up, and started it up. Started up just fine. Took it out for a spin and she runs WONDERFUL! No more misfire! Hurrah!

[sly]

W00t!