What is this?

Joined
Aug 16, 2004
Messages
266
Location
Sitka,AK
I can't find my FSM, I think I left it at work. Do you guys know what this is and how much deflection the plunger inside is supposed to have?
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My truck was running great yesterday and today runs like crap. Idles fine but as soon as you give it gas it sputters and excellerates very slowly... Super gutless and thirsty. I sprayed starting fluid over all of the vacuum lines as it was running but didn't notice any RPM change.
I've read some of the "hesitation" threads so don't hate, I checked my TPS and it looks brand new and is super springy. I think i musta replaced it a few years ago.

Any more ideas? Stuck EGR? I don't know which one it is.
 
Joined
Feb 9, 2004
Messages
2,109
Location
Buffalo Grove, IL
That is the ISV or IAC valve. Idle Air Control or Idle Speed Valve -- common terms for the same valve. If your truck idles fine it is probably working correctly.

Check your fuel pressure if you are having trouble with higher RPMS off idle.
 
Joined
Aug 16, 2004
Messages
266
Location
Sitka,AK
I just bought a tps, and that didn't fix it. $160 fail. Do you know if that valve is supposed to be completely closed when removed? When I take mine off it there is some gap around the edges of the plunger, and it only depresses maybe 1/8" or less.
I guess I'll have to check my fuel pressure. Do you know what the psi is supposed to be before the fuel rail?
 
Joined
Aug 16, 2004
Messages
266
Location
Sitka,AK
Also, as I move the tps back and forth, there are basically 2 rpm ranges. It sits at 700 for about 1/3 of the slot, and then it jumps up to about 1300 rpm for the last 2/3 of the slot. It was doing that with the 'old' one, that's what made me think it was the problem.
 
Joined
Feb 9, 2004
Messages
2,109
Location
Buffalo Grove, IL
The TPS is basically a sensor that tells the computer what position the throttle is in. Either idle, or off-idle for the most part. I changed mine out because it was sticking quite a bit and the idle was high due to the TPS sticking.

Test the TPS by means of the Factory Service Manual procedure to see if it is within spec.

The IAC .. it isn't relevant how much the plunger is out when it is removed or when the vehicle is not running. It is controlled by the computer to allow the appropriate amount of air into the throttle body when the truck is at idle. It does have a range it moves in, but you can only really test it or see if it works properly by following the test procedure in the FSM.
 
Joined
Oct 4, 2009
Messages
33
Location
Greenville, SC
Clean it...

I was having a similar problem a while back and removed and cleaned the EGR tube this is inside the intake. This cured my hesitation, sputter, shutdown problems. Clean it, if nothing else it will eliminate this as a problem.
 
Joined
Aug 16, 2004
Messages
266
Location
Sitka,AK
Ok, I'll do that. I assume it's attached to the egr, but behind it, going into the intake?

I think it's fuel metering, because it's getting even worse mpg than normal.
 

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