idling and shifting issues

[Shaun]

So my swaps been done for a couple months now, and I'm starting to come across some issues. The first is, whenever I start the truck cold, it idles at about 1100-1200 rpms. Which I guess isn't a huge problem since it smoothes out after a minute to around 400-600. But I literally can pull out of my driveway in the morning and it will hit almost 40 mph without even touching the pedal. Usually by the time I get to the first stop sign down the street, it calms down. Now my other problem is that sometimes, not every time I drive the truck, it will start shifting funny. Once it's been running for 30 minutes +/-, and it's good and warmed up. Like if I'm on the highway, in moderate traffic, out of nowhere it will downshift. And it won't up shift again, unless I punch it a little then let off the gas. And on city streets, it will shift hard into second....then the shift into third is waaaayyy past the normal shift point. It kinda sounds cool though, like a throaty mustang in the upper rpms. Today it happened when I was about 3/4 of the way home, then it seemed to start shifting fairly normal again a couple miles down the road, but the idle was up way higher than usual. By the time I got home and put it in park, it was idling around 1100 in drive, and 1600 in park. Now, when doing the swap I put a brand new TPS, IAC, and MAP sensor, so I'm thinking none of that should be the issue. When my pcm was sent out for a flash/vats removal and mild tune, he also had to switch the OS on it, since I was switching to DBC. Any body have a clue what the issue could be? I'm thinking all of the problems are somehow related to the pcm or the tune he did. Someone please shed some light on this. I'm so frustrated with this truck, I'm almost ready to call it quits and sell it.

 

[Scrufdog]

Anytime you have problems with both idle/fuel and shifting happen at the same time its usually the TPS. Check it for proper operation with a voltage gauge or data logger, both hot and cold.

 

[Shaun]

The thing about that, is it was acting like that when I finished the swap. So I replaced the existing one with a brand new one. Same thing. Unless there's a short in the wire somewhere...

 

[Scrufdog]

a lot of aftermarket TPS sensors suck. Get a test meter on the thing to make sure it has a smooth transition from 0 at idle to 4.5 or 5v at full throttle

 

[Shaun]

had a tune done today. seems (so far) like thats fixed the problem. i'll know for sure in a day or so. Tuner said there was a lot of weird stuff (a lot of "cold start" settings and what not) in there that he wouldnt have done. i guess all tuners are different. but since this guy lives/works a couple miles away (south florida), and the previous tune was performed in Michigan, that this one should be more suited for driving around down here.

 

[Shaun]

So, in trying to fix this problem, so far I've replaced the tps sensor again (2nd brand new tps), checked and retightened all grounds and power source connections, had it checked out and tuned by a professional, who said he wasn't seeing any error codes or anything, and he drove it around for like 25+ minutes (of course it didn't act up while he had it), replaced the alternator because the volt gauge doesn't really sit where I think it should. Probably in the 12v range if I was a betting man. I also upgraded to the 145 amp alternator. Battery charges fine. Everything seems to be working fine. No loss of power in any of the electronics (power windows, radio, headlights or anything)... And since the problem goes away after I turn the engine off and then back on, I went to AutoZone last time the problem happened, and their scan tool said low tps voltage. That was before replacing the tps again for the second time. So my question is......W T F ?! What is the problem here?! It's getting to the point where this is an everyday thing. What could be causing the low alt voltage, and supposedly low tps voltage? Could they be related, but seemingly not affecting anything else? HHHHEEEEEELLLLLLLLLPPPPPPPP

 

[Shaun]

Haven't had issues since last Thursday. Today they're happening again. Anybody got any clue? Thought I had the problem fixed, but I guess not. I'm about to stick this thing on autotrader and craigslist

 

[Shaun]

Ok, so after putting a second iac, the high idle has gone away. The intermittent shifting in and out issues are still present. Went out today and got a pretty decent scanner with live data. It also lets you record data, so you can drive and then view what happened at the moment the "fault" occurs. I haven't done this yet. But there is a code P0717. Turbine input shaft speed sensor, circuit "A" no voltage. Is this the speed sensor on the side of the tranny? Cause those are only like 20 bucks at AutoZone. Or am I looking at something internal? Even though there's still an issue, I'm overwhelmed with relief that I've finally (i hope) narrowed down the problem. Any input is hugely appreciated

 

[Scrufdog]

Turbine input should be at the front of the tranny, close to the engine. Detects the rotationof the input side of the torque converter. would definately cause shift problems.

 

[Shaun]

So I'm looking at a tear down...right? Is there any sort of test with a multi meter I could do, or anything to confirm before I try to tackle this?