High Idle after exhaust upgrade?

[Jstcruz]

Well, we figured out using the spray method that the intake plenium gasket is leaking. We are going to tackle this tomorow evening - rebuild everything from the lower intake plenium up with new gaskets and cleaning everything. I'll let you know how it goes.

Thanks again for the tip delexploder.

 

[delexploder]

Glad to help love the hood by the way :thumbsup I have had a similar idea for a few years and after seeing your cowl I think im gonna try

 

[Jstcruz]

Glad to help love the hood by the way :thumbsup I have had a similar idea for a few years and after seeing your cowl I think im gonna try

Thanks man

Well, last night me and a freind of mine took the intake down to the manifold -we also changed out my valve cover gaskets since it was down that far. The entire intake was carboned up and wet with gas, I assumed was from overcompensating for the lean condition. We cleaned everything real good and putt it all back to gether with new gaskets. It fired right up and idled down to about 850 rpm and idles smooth, it comes down quickly after revving it - which it used to hang and come down slowly. So this should be it! Also the exhaust wasnt so potent. I will not have a chance to drive it today but tomorow Im going back and forth on a 40 mile trip so I'll post how it does. Thanks guys for all of your input!

 

[Turdle]

I'm with the others. While installing the headers you must have bumped a vacuum line loose, could be the hvac vacuum lines got melted?

The brake booster can and will leak vacuum. Try plugging the line to it and see if the idle settles.

The pcv valve grommet can leak vacuum. possible the valve itself has come unseated

Finding a vacuum leak using a spray is hard with all the fan wash. You "could" take the fan off and run it for a while without overheating. This is where I would start.

Take the fan and shroud off. A cold engine will take a long time to get overheated at idle, so don't worry.

I use an unlit propane torch. With the engine running, Turn on the valve and point the torch nozzle right where you want it. A vacuum leak should suck in propane, causing the idle to change. Pay particular attention to the vacuum hoses under the upper plennum.

 

[Jstcruz]

Reviving my thread to chase problems with my truck Freeking yay!

After chasing a cel for EGR stuff, I have a lean bank 1 and 2 code again. I replaced the EGR selenoid and whatever that sensor is and now the p0171 and p0174 codes. I checked all the hoses again, sprayed half a can of carb cleaner over it... It idels pretty good and runs fine. Is it possable that the EGR valve can let in too much exhaust gas? When I tested it it seemed really easy to pull the diaphram up with vaccume.