LeSabre Running Rough Under Load

[gpayn]

Hi All,

My 1993 LeSabre has recently developed a problem under load in that it begins to miss on at least one cylinder when travelling along and then accelerating. There is little if any miss at idle, and no miss once at cruising speed unless under load like going up a hill or accelerating hard from start.

I have changed the spark plugs and this made no difference. I have also done a resistance test on the leads and they appear to be OK. Near new air filter installed. No fault codes coming up from the onboard computer through the DLC.

If I "kick down" and accelerate hard I get an inital rough patch then all cylinders come in fine, which leads me to think that it is something to do with either timing not advancing properly under mild load or perhaps fuel mixture under mild load?

Any suggestions appreciated...

[HotZ28]

If you have carbon core plug wires it is safe to say you have a broken wire or wires. After they have been used for sometime, they get brittle and just removing them to change plugs can break the carbon core. Once that happens, you begin to feel a surging or missing under load. Change the wires and also replace the fuel filter unless it has been replaced recently.

[imidazol97]

Originally Posted by HotZ28

also replace the fuel filter unless it has been replaced recently.

I second the fuel filter change. I waited till 120K to change on 98 LeSabre and I could hardly blow through the old one after I dried it. The new one I could have breathed through.

The fuel filter on 93 is under passenger side floorboard. Car must be up on ramps to access it.

[gpayn]

Originally Posted by imidazol97

I second the fuel filter change. I waited till 120K to change on 98 LeSabre and I could hardly blow through the old one after I dried it. The new one I could have breathed through.

The fuel filter on 93 is under passenger side floorboard. Car must be up on ramps to access it.

Hi there!

Thanks for the suggestion. I replaced the fuel filter about 2 months ago . . .

[gpayn]

Originally Posted by HotZ28

If you have carbon core plug wires it is safe to say you have a broken wire or wires. After they have been used for sometime, they get brittle and just removing them to change plugs can break the carbon core. Once that happens, you begin to feel a surging or missing under load. Change the wires and also replace the fuel filter unless it has been replaced recently.

Hi!

Thanks for the suggestions. I got a new spark plug lead today (single) and rotated it through all plugs and it made no difference at all -- still missing slightly, especially under load. I have also recently changed the fuel filter....

Perhaps time to try changing out the coils?

All the best,

GeoffP

[HotZ28]

Normally you will have more than one bad wire, especially if they are original! Put on a new set, they only cost about $30.00. Coils usually fail completely, not just enough to cause a miss or hesitation. You might also want to clean the throttle body with carb cleaner and run some injector cleaner and HEET through the gas tank. I would also check the 02 sensor with a live scan to see where they are. I have seen some water in the gas lately! I guess they are not making enough money off of clean gasoline, so they add some water to increase profits!!

[gpayn]

Hi All, Thought to drop a note to advise that the problem has been isolated and fixed. Turned out to be a faulty ignition coil (#3), so a bit of surfing got me a replacement from EBay Motors for $16 delivered and we are all running sweet again!