Steven Kriss

Hi,

I have an Explorer 98 with a 4.6L and 136,000 miles. It idles a little rough at 600 rpm and gets about 330 miles per tank in city and 400 miles per tank Highway. However in the last year it has gone through 4 cat converters. Each one lasting from 300 to 500 miles before the "check engine" light comes on. I have changed the intake gaskets. It does not use any coolant or oil.

Need some recommendations?

stuford

did u ever change out the o2 sensors i think there are 2 or 3 of them just on the cats alone those could cause the engine light to go off

daveymisbehave

make sure your injectors aren't sticking. with that many miles I wouldn't be surprised. that would cause your rough idle and will make your engine run rich which will burn your cats out prematurely. Also make sure your fuel pressure regulator isn't bad. Bad idle and burning out cats prematurly all point to improper fuel mixture. You need to get a pressure gauge on it and do a leak down test to see what's going on. Also it wouldn't hurt to put a vacuum gauge on it. With that many miles your valves are probably starting to carbon up and might be leaking. That will cause poor performance and screw up the o2 readings. It's hard to say exactly but if you are burning out cats I would try to get it on a 5 gas analyzer and see how bad your emissions are. That is a great indicator to what your engine is doing fuel/air mixture-wise. Then go from there. 02 sensors don't just keep tripping. They do so for a reason. If the computer isn't liking what it's seeing it's going to throw a code. You can rule out bad o2s but hooking up a scantool and watching the cross counts. But I'm assuming that you're not dumb enough to replace 2 cats and not change the o2's. That's common sense.

Hope this helps