Crankshaft Sensor Problem?

[bkopper]

Having a problem with my 98 Grand Cherokee Laredo 4.0 liter/automatic. First time I drive the car each day it starts and runs fine. After first stop, it will start Okay and after reaching around 20-25 mph, the engine begins to "pop" (backfire), the car begins to buck, and it seems like it is running on 4 cylinders. After a couple of hundred feet riding a bucking bronco, things automatically straighten out and the car takes off like a jet! If I don't stop again, it will run fine for hours. Car has 134,000 mi., new plugs, cap/rotor and oxy sensor. Have cleaned battery posts, body grounds, and checked and replaced all rubber vacuum hoses. Seems to be worse in damp, rainy weather. Gets 23 mpg and runs good. Occasionally seems like transmission is sluggish when shifting into first.

No Codes being set. Jeep dealer didn't have a clue and said without a code they couldn't be of help. Several local auto repair shops have said it doesn't sound like a fuel pump/filter problem.

I think I might have a crankshaft sensor problem BUT THE CAR DOES NOT STALL AT A STOP OR WHILE UNDERWAY! ANY IDEAS? All suggestions will be appreciated.

I don't look forward to replacing the sensor since I know how hard it is to work in close quarters with 2 feet of extension, a swivel and a socket! Never thought about starting bolt from top engine compartment.

[dksob81]

Originally Posted by bkopper

Having a problem with my 98 Grand Cherokee Laredo 4.0 liter/automatic. First time I drive the car each day it starts and runs fine. After first stop, it will start Okay and after reaching around 20-25 mph, the engine begins to "pop" (backfire), the car begins to buck, and it seems like it is running on 4 cylinders. After a couple of hundred feet riding a bucking bronco, things automatically straighten out and the car takes off like a jet! If I don't stop again, it will run fine for hours. Car has 134,000 mi., new plugs, cap/rotor and oxy sensor. Have cleaned battery posts, body grounds, and checked and replaced all rubber vacuum hoses. Seems to be worse in damp, rainy weather. Gets 23 mpg and runs good. Occasionally seems like transmission is sluggish when shifting into first.

No Codes being set. Jeep dealer didn't have a clue and said without a code they couldn't be of help. Several local auto repair shops have said it doesn't sound like a fuel pump/filter problem.

I think I might have a crankshaft sensor problem BUT THE CAR DOES NOT STALL AT A STOP OR WHILE UNDERWAY! ANY IDEAS? All suggestions will be appreciated.

I don't look forward to replacing the sensor since I know how hard it is to work in close quarters with 2 feet of extension, a swivel and a socket! Never thought about starting bolt from top engine compartment.

If it is worse in damp weather, ussually this is because moisture is getting in under the distributor cap. Check to make sure the cap is tight and no crack in the cap or distributor.