Up and down idle after intake manifold gasket replacement

[bottomline2000]

Do you have a DBW or DBC throttle body? Just wondering why you throttle position sensor says 0.

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[Fixture]

Bottomline2000, its just the stock 2002 TB.

Is there a way to test the TPS? if so what voltage/ohms should I be looking for?

Jonathan

 

[bottomline2000]

Bottomline2000, its just the stock 2002 TB.

Is there a way to test the TPS? if so what voltage/ohms should I be looking for?

Jonathan

I mean is it an electronic or cable driven throttle body. You should not be showing 0% tps at idle. Even at idle it should be slightly open. I'm going to edit this with a screenshot from my EFI Live catalog at idle. Mine is modified so my idle rpm may be higher than yours but the % is still relative. Mine is dbw..drive by wire or an electronic tb and it's stock.



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[Fixture]

Mine is dbw. 2 cables attach to the passenger side. Not electric.

I will hookup my laptop tomorrow and get a reading cold and when the idle warms up and it's steady at 450rpm.

 

[bottomline2000]

Mine is dbw. 2 cables attach to the passenger side. Not electric.

Then you should be able to probe it with a voltmeter to confirm proper output. The carb cleaner may have contamination a connection.

The carb cleaner may have fouled a connection.

If this test ok, I would put the original front 2 O2 sensors back in and give that a shot. The rear 2 only show the condition of your cats and don't impact performance.

EDIT: After thinking about it the computer is in open loop when cold so I don't t think the O2 sensors should be able to cause this at first start up..

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[SnowDrifter]

Any updates on this?

 

[Fixture]

Nothing yet. I ran my diagnostics and my TPS still reads 0 even when warm. I havent tested it yet. I am just going to get a new one. I am also going to do a smoke test to rule out completely a vacuum / air leak. I also an wondering if I did get a bad IAC like others have said. Will post what I find asap. 4 cars and no time for them all! ugh.

 

[JoeM5952]

Try taking a reading from the wiring on the TPS and see what you get. Run the throttle up and down smoothly and see if you have any dead spots on the wiper. It is a potentiometer and can fail over the years.

https://www.silveradosierra.com/vortec-5-3l-v8/bad-tps-t577009.html#p5724961

 

[SnowDrifter]

Posting here as a self reminder to check my TPS readings. IIRC there's an absolute and compensated reading. Will look into it tomorrow and post back

 

[Fixture]

Ok all. I finally got around to replacing the TPS and the IAC again. The TPS seems to be fine, but the new IAC has a metal head on it. I put in on, but the idle will not drop below 1700 rpm. My problem must be not getting a good IAC. Here is a picture of what I took off the car first (left) the one I just took off (middle) and the new one (right). I am going to have to try another one for now. Also I am getting my knock sensor errors again for 1 and 2! I just replaced them 3 months ago. I am done with this truck. ugh