P1494 & P0302 --- My Resolution

Was getting a P1494 (leak detection pump) and a P0302 (#2 cylinder misfire) Did a little searching on the forum and discovered that a P1494 would come up if the pump was bad, or the pump was not getting proper vacuum. The P0302 at the same time had me confused. Oothers have had the same problem (both codes) but never posted any final results.

I had just replaced the master cylinder and apparently knocked off the vacuum hose for the LDP from the intake manifold. Looked at the little rubber elbow that goes from the plastic "hard line" to the intake manifold and it was shot. Used a piece of 1/4" fuel line hose in its place. Now here's my take on things: The fitting for the LDP vacuum line is between the #2 and #3 cylinders on the intake manifold. I'm guessing the vacuum leak was significant enough to cause the #2 cylinder to misfire (and of course the LDP to not work, since it was getting no vacuum).
I replaced the plugs as well since I was under there, although none of them looked like they needed it...

Maybe this will save someone else some diagnosis time....

I had the same error code (P1494)... read your post and that was my problem. Thanks for the pre-emptive posting!

Where/what is the LDP? I'm getting the error now, and I've noticed the vacuum lines/elbows on the manifold are dry rotted pretty good, probably the source?

LDP is the Leak detection pump for the evap emission system on all obd2 vehicles. Used to test for fuel vapor leaks.

I replaced that elbow and left the battery unhooked for about 10 mins. No more MIL. I guess we'll see if the fix sticks over the next few days...

Thanks!

PS: I was hoping it'd fix my cruise...but no go. I still need to replace the brake switch.

I had the p1494 code and sure enough it was the elbow piece on the manifold.