HIGH IDLE ISSUE AND INTERMITTANT SHIFTING CAUSE IAC, TPS?

1999 Buick Century

Tiny

saturntech9

December, 4, 2012 AT 8:34 PM

Its not a cat have you replaced the coolant temp sensor yet?It could explain the symptoms.

Tiny

dennislvaughn

December, 11, 2012 AT 4:19 PM

Ok finally got to changing the cts. How long will it take for the ECM to learn this part, or is there no learning? It still idles erratic at start, but settles quickly. I'm thinking the hose I ordered is not good.

Tiny

saturntech9

December, 12, 2012 AT 1:14 AM

Try unhooking the negative battery cable for about a min then hook it back up and see how it runs?

Tiny

dlvaughn1963

December, 12, 2012 AT 7:30 AM

Well I'm convinced the issue I s the pcv tube. Do you remember that tube I replaced three months ago? It looks like the hose I got from autozone. So I've ordered the hose from a gm parts store. Will let you know how it turns out.

Tiny

saturntech9

December, 12, 2012 AT 4:31 PM

Whats wrong with the tube is it bad again?

Tiny

dlvaughn1963

December, 12, 2012 AT 9:21 PM

It's not holding a seal where it goes into the valve cover

Tiny

saturntech9

December, 13, 2012 AT 6:17 AM

Have you tried putting on a hose clamp to see if it takes care of the problem?

Tiny

dlvaughn1963

December, 14, 2012 AT 3:28 PM

Can't be clamped. I think the aftermarket hoses do not have the right dimensions for the hole the tube "t" goes in. The oem plug part is rubber and has a better fit. The aftermarket hose has a plastic "finned" plug that does not offer a tight enough fit for the hole, so there must be a grommet needed if you use the aftermarket hose. The problem with trying this, is you would have to take the throttle body off, and remove a clamp to do all this. Then I'd need a gasket and other things. I've ordered another hose, but this one is supposed to be oem. I will see when it gets here on Monday.

Tiny

saturntech9

December, 15, 2012 AT 7:06 AM

Sounds good keep me posted.

Tiny

dlvaughn1963

December, 18, 2012 AT 4:13 AM

Well replaced the line and as always the initial start sounds good, then the random misfiring starts up. It seems that anytime something is replaced, it changes but not really fixed. It seem that when I replace a part, the engine goes thru a high rev that seem to cycle for about four accelerations. I attribute this to the engine computer relearning for idle mixtures. Of course when the engine goes though the rough idle cycles with the misfires, the intake air sounds like its being blocked or rerouted. I'm wondering if my mass airflow sensor is bad. Cause when I unplug it and let the engine run, it seems to settle to normal. I did get to replace the coolant temp sensor but that has not changed anything. I'm almost running out of options.

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