hennigm4

So, my vents go from vent to defrost only when under load, I know its some type of vacuum leak, I have checked all the hoses in the engine compartment they all appear good. Just wondering what else to check? It will not do this at any RPM just sitting, only when accelerating or going up hill etc.

Any suggestions? Vacume leaks are horrible in these jeeps.

Thanks,

Mike

VTJeep

i know you can test vac lines by spraying carb cleaner at connection points to see if it ups the idle.. if so you have found a bad vac line

freegdr

there should be a check valve somewhere in the line so it stays under vacuum while driving looks like this not sealing replace it see what happens

TrekkerJmm

Look under the passenger side bumper for a little "Football" it holds vacuum to the vents when accelerating. Follow it to the motor and see if it leaking...Tj

freegdr

this is the vacuumb\ ballif the check valve before this in the vacuum line from motor is not holdin vacuum in it will escape when under a load a motor only creates vavuum at conctant rpm when you acceleratye it will draw the vacuum out of ball thus allowing vents to change to defrost

hennigm4

Football thing ok, I replaced those lines last year, fixed it then. This seems new and it seems to coincide with hard start when warm, with smelly cat, and running rich.

Where else could a vac leak come from that may cause the other symptoms?

I have replace, EGR, IAC, TPS, O2, waiting on MAP to arrive.

Pulled all plugs, they all look the same, slightly black, wires good, cleaned dist contact in the cap. Fuel pres steady at 31-32 psi.

Im stumped if the map doesn't fix it.

Bad manifold seal?? Headgasket??

I would hate to let the dealer find it, but may have to.

Mike

freegdr

doesit have a check valve in it i replaced mine and it fixed it for me

hennigm4

Check valve was replaced this summer.

Thanks,
Mike

freegdr

did you check it now its just a cheap pc of plastic