I'm open for whatever suggestions. I just want this rig ready for squaw... i wasn't too worried about it 4 months ago, but now i am since its 2 weeks and counting.

 

Right, well, consider this. That's a vacuum throttle opener, not a coolant throttle opener. The coolant lines are for the ISCV(Idle Speed Control Valve). A problem with acceleration isn't going to be caused by either. You also had a vacuum leak that you solved by replacing the TB.
Throttle cable you mean? How do you stretch a TB? Anyways he's checked that...supposedly.
Something's up with the TPS circuit, and it ain't the TPS. They aren't going to "burn up" over and over for any other reason. The wires, connectors, pins, or inside the ECU(which could be fried). Other than that...vacuum leaking...unmetered air going into engine at the TB...too much of it in proportion to throttle application...revs uncontrollably raising as a result.

 

We're not even sure the throttle position sensors were tested before they were replaced. Just sayin.

 

Hey Mak, I'd almost think you know as much about this as Jerry's shop.
Just a thot; might be wrong, but pretty sure the TPS wires run back to the ECU; I'd check the FSM for connectors, (unplugging those are a pain) make a loop-back, and check the resistance (bet FSM has a proceedure for that) of the harness. Brittle wire jacket on an old twisted Cu wire jacket? Recipe for intermittent connectivity perhaps. Granted doesn't explain the consistent nature of no/full throttle.

Just sayin...

 

Hey Thanks Mudhippy thats what its called Idle speed control Valve
Mak thats your problem im willing to bet on it

the hot coolant closes it and the cold coolant opens it .. its not working right .. all kinds of junk gets in there and messes with it . mine was really messed up and was staying open more than it was supposed to when it was supposed to be closed.

 

So lets back track a little bit. what you're telling me is that the Throttle Valve is monitored by coolant? and if its malfunctioning it can fry the TPS?

 

Just got a call from them. They're gonna let me have it over the weekend and drive it stereo-less... They think maybe the stereo is surging through the vehicle, and shorting out the TPS. The guy that works on my truck checked the harness from the ECU all the way to the TPS and its giving perfect readings. I told him to check the Throttle valve, and he told he did already and is functioning correctly. he also stated that if it was the throttl valve, it would have a fluctuating idle, ( which it doesn't ). I also asked him why the TPS would be getting fried now but it wasn't when I had power loss. he says, i thought about that as well, and doesn't make sense. He says maybe the powerloss was shadowing the initial issue. ( again, makes no sense )

So just a run through of what I just said.

The harness from the TPS to the ECU is perfect. and the TPS is adjusted perfectly.
They're going to give me the runner for the weekend, or until it has issues again with the stereo disconnected from the battery. If it still has issues with the TPS, the last resort is that the ECU plug is fried and will need a new one.

Does any of this make sense, or am i being thrown more bull crap?

 

I call bull. Did they tell you why they think the stereo is causing the throttle position sensors to fail? The stereo is in no way connected to the throttle position sensor circuit with the exception of chassis ground.

And if you said throttle valve he probably thought you meant the main butterfly valve in the throttle body, not the idle speed control valve.

 

exactly what I said. The stereo was completely rewired on its own circuit when I had it professionally installed years ago. ( that way I wasn't using the stock wiring ) He thinks maybe the ground is dirty or messed up and its surging through and grounding out on the TPS.... But whatever, he's gonna let me drive it around for the weekend. I guess driving it around till it has issues wont hurt right? all they're doing is disconnecting it from the battery, so if its the stereo, it wont blow the TPS in theory.

So i'll try their method out. ( wont hurt ) if they're wrong. Then I dont know. But if its not the stereo, it'll still blow either way.

 

It's not possible for the stereo to 'ground out' on the throttle position sensor. I would take it back and tell them to pull their heads out of their asses and figure it out. Otherwise find a shop that knows what they're doing. They're messing with you at this point.

 

exactly. I'll drive it around for a few days, it'll blow the TPS again, they'll have to replace it again, and then back to the drawing board.... again. I'll even show them what i think is wrong with it when I go to pick it up today.

 

Mak's right - he doesn't have anything to lose or any better suggestions on what to try just yet.

This will just buy him some time to do some more research for other causes and if/when it still happens...he can just tell the shop, "I told you so."

Fink

 

I guess as long as they're not charging him for throttle position sensors then ya...just hate to see people get yanked around like this.

 

I already made it clear to them that im not spending another dime on this vehicle in repairs. They've replaced the TPS' under warranty. ( the whole vehicle is under warranty for 36k miles on all top end work they've done ) So they better hope its not the ECU, because those suckers aren't cheap brand new, and I wont settle for anything less if im not paying for it

just out of curiousity, could it be the VAFM? its been replaced before and its under warranty. but would it cause an issue such as this? I know the VAFM and TPS work in conjunction with eachother, so maybe its not even a fuel issue? it could be an air issue?

 

Certainly possible...but I guess if the shop thinks your stereo is killing throttle position sensors anything's possible right?

Anyway if you have an ohmmeter you could always check it yourself.

 

Would the VAFM cause the TPS to fry though?

I have one, yeah. I'll fiddle with it a bit this weekend ( i cant fiddle with it too much though because it'll void the warranty. )

 

I don't have a wiring schematic handy to look at right now (working) but I don't think so. The testing procedures are in the FSM...nice & easy stuff.

http://personal.utulsa.edu/~nathan-b...92volumeai.pdf
http://personal.utulsa.edu/~nathan-b...93throttle.pdf

Edit - from what I can tell, the TPS and VAFM are separated by the ECM, meaning that the VAFM would likely damage the ECM before it got to the TPS (assuming it's even possible of course). If you have the time I'd suggest checking resistance values at the ECM as well as in the ECM itself. The more troubleshooting you do yourself, the more confirmed data you know you have. If you haven't noticed I'm not too quick to trust a shop.

 

If you look in engine/troubleshoot in the FSM, a bad VAFM Circuit can poor driveablilty, assuming the TPS wasn't fried this whole time.

 

so its been 4 days since they disconnected the stereo. and i've had no issues...

They called me up asking how she's running and I said great, no issues what so ever.

So I felt the need to doubt it more, I decided to dig into this a little deeper. I called Audio express ( who originally installed the stereo 6-7 years ago ) and they said yes, its definitely possible. The TPS is a low voltage point and if a high powered stereo isn't grounded correctly, it will "surge" through a lower voltage point. He said its also possible that a it could have wires crossed through it ( but the mechanic checked the harness and its fine ) He said its very simple to check the ground to the stereo, we usually ground them to the chassis.

So... basically it comes down to the mechanic that did my top end, didn't have a clue what he was fiddling with and probably left the stereo ungrounded and/or grounded to the wrong place, correct? I seriously cant believe this is even a possibility...

 

6-7 days now and the TPS is still fine, the truck is still running great. and theres still no stereo... think the issue has been found :o