1997 Chrysler LHS Rough Idle

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MEMBER
1997 CHRYSLER LHS
6 CYL
FWD
AUTOMATIC
120,500 MILES

'97 Chrysler LHS 3.5L V6 120,500 miles.

When at a dead stop in drive or reverse, it idles rather rough (even throwing up a low oil pressure light a few times), around 600-650 RPMs. The problem is almost completely eliminated in neutral or park, but there is still a noticeable lack of a smooth idle.

It also has a bit of hesitation (feels as if you are pulling the slack out of a weighted rope) when starting out from a stop.

I checked the upper intake manifold for by spraying carb cleaner at each intake, but it produced no effects at all.

I regularly run injector/fuel system cleaner through the engine every 2,000 to 3,000 miles. I recently ran SeaFoam through it to see if that would help the idle, but I got nil.

There is no CEL and the only code is a number 12 (battery disconnected).

1 Reply

CH112063

MECHANIC
1,320 POSTS

You may have one but the store at this website has the vbest and cheapest fuel pressure gauge for one quarter of the price I paid for the same one 10 years ago. Test this. It should be no less then 50, more like 55. Also try running an oil additive in it, for cleaning the combustion chambers, this happens, and cause a rough idle under any slight load. Part number is 04318001. Also be sure there are no TCM codes out of the transmission, we had a hell of a time with this huge batch of bum torque converters made in China. Also try a stall test, if its under 1750 the stator in the torque converter could be bad and there is no way to check it. All in the order I mentioned. Re-check codes with a DRBIII if you get a chance. The MAP sensor may be bad, the throttle body may need servicing also. Hope it works out. Let me know, ok?