Cameron58

99 Jeep Cherokee Sport, 4.0

problems : error codes 505 and 123, after engine runs for about five minutes it revs itself up to between 3 and 4 on the gauge and stays there.

The throttle body has been cleaned with carb cleaner. IAC valve, throttle body sensor, and MAP sensor have been replaced.

I used a smoke machine to test my engine for vacuum leaks. The only thing I found is smoke seeping out of the space between the two parts of the throttle body indicated by an arrow.. This is a pic of a new throttle body. I used it to help indicate the location of the leak.

The gasket is in good shape. The smoke is not coming from under the throttle body, from hoses, or from connectors.

So, where is the smoke escaping from, and what do I do to fix this? Is it time for a new throttle body? Thanks.

dave1123

I'd say you have a loose intake manifold. As the engine warms up the gasket gets soft and the weight of the manifold allows it to sag and open vacuum leaks on the head. I doubt the throttle shaft being worn would allow the engine to run normally until it heats up, then cause the problem. With the engine cold, check the torque in the manifold bolts.

Cameron58

Thanks for the response. I'll give this a try. Do you know the correct torque for these bolts? Or, is there a technical reference online with this information?

dave1123

My book says 24 lbft.

XjJunky

23 or 24 foot pounds, but they must be tightened in a certain order

sergiorod1987

A few years later, did you get this issue resolved? Did torquing your bolts fix your issue? I have the same issue with the smoke test, my throttle body is leaking in the same area you noted.

cruiser54

Make sure the bolts haven't loosened up. They got loose anyway because the factory torque spec was too low.