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Question -
Roland,
I have a 95 LHS currently has 100,000 miles, I am trying to figure out what may be causing my rough idle. I am not recieving check engine codes, however I see a lot of people have had to replace their intake gaskets. In your opinion is this fairly easy to do, what should I watch for, and is it a good idea since the gaskets are pretty inexpensive? Thanks for your time
John
Answer -
Hi John,
There is a pretty long list of things that you have to remove before getting to the manifold gasket for change out so I would not try that unless you concluded that it was leaking for sure. Often if there is a small leak the O2 sensor will compensate for it in contrast to the years when we only had carburetor fuel supplies when roughness was often due to such a leak, and as the result there may be slightly increased idle speed rather than roughness.
In my experience the more common reason for rough idle without codes is a slightly ajar egr valve due to a sticky valve stem or buildup of crud in the opening. So look for the valve in the exhaust return tube between the exhaust manifold and the intake and observe the motion of the stem as you rev the engine to 2500 rpm and back to idle. The stem has a slot into which you can insert a screw driver tip and lever it open (against spring tension) and closed. Feel to make sure that the valve stem bottoms when you allow it to be closed by the spring. Spray the stem where it enters the valve body with solvent if it seems to be sticking.
The possibility of an intake manifold leak can often be detected by use of a spray can of carburetor cleaner with a straw on the tip. With the engine idling try very short bursts of spray around the perimeter of the manifold (so at to not use enough at any moment to catch fire) with particular attention to the corners and fittings to the manifold and listen for a change in the idle after each burst which would be a clue to a leak at that point.
If you find the leak and need to replace the gasket, let me know which engine you have. I have the Chrysler '94 LHS manual and can xerox and postal mail you the pages that tell how to get to the gasket to change it. You might also want to check the attaching screws that should be torqued to 18-20 foot pounds, depending upon which engine you have in case the leak is due to a loose screw.
Roland
Roland,
I have to say youre pretty good. So far I have found one line from the transducer ( I I believe thats what it is) completely off at the EGR, and the EGR is very dirty. I was curious if there is a cleaner to use on the EGR, and I cant seem where to find where this hose orginally pluged into on the EGR. If you look at the transducer there is a electrical connection w/the part number 4287 634 (it appears to be a sensor of some sort) the hose connects right under this electrical plug. there is another hose connected directly to this 4287 634 but that is still connected to the EGR.
Thanks you so far have saved me a lot of time and knuckle busters.
John
AnswerHi John,
If you will look on the underside of the hood at the emission control label it will show you where the egr hoses are connected. One comes from the intake manifold to the electrical transducer, and two go from there to the body of the valve. Let me know if you have trouble finding the nipple that the detached hose connects to, nonetheless.
Aside from cleaning the stem with solvent where it enters the valve body there is no other cleaner. You can remove the valve and clean out crud with a wire brush or braided wire if you believe the valve is hanging up inside rather than around the stem of the valve. But you may have solved the problem already.
Roland
