[Ray Green]

After replacing my water tubes, timing belt, and water pump ..... I get a "buck" in the engine every few minutes. It's very random as to when and at what speed, it does it. I scanned and got a code P1391 which upon searching other threads, I learned this could be related to CMP or CKP sensors. I've studied my Haynes manual but can't find where these sensors are on a 3.0L. I'm hoping it's as simple as I left a wire loose somewhere but you really don't take much wiring off to do this stuff on the 3.0L. It will sit and idle perfectly and runs great most of the time.

edit to add: I cleared the codes and looked for something I may have possibly left disconnected. Then, off for a low speed (under 50 mph) road test. At that speed, the bucking is more like a hesitation or a stutter. It did it several times in a 10 mile loop. It also completely died once and I never saw the oil light or anything come on. It immediately restarted and when I was about half a mile from home, the P1391 came back.

 

[Ray Green]

Thanks John. I'll certainly check that. I naturally want to blame something related to the work I just did although it could be something else. Does the crossover pipe have to come off to access/replace that sensor?

 

[Ray Green]

No, the pipe does not have to come off, but it does tend to hide the sensor a little.

I just went out and looked and couldn't see nor feel it. I didn't have the air box off so maybe that's why. I'll check thoroughly after work but I gotta go right now. I looked at NAPA online and the sensor they show has a pigtail. Advance doesn't even list one but they do sell shims. Remember, I have the 3-speed auto and not the 4OD.

As always, thanks for your help John!

 

[Ray Green]

I found the sensor and cleaned both ends of the plug with contact cleaner. I saw no damaged wires on the sensor and the plug was still intact in the harness/loom so I didn't break into it for now. I put a little dielectric grease in the plug and hooked it up. A road test of about 10 miles (50 mph or less) had one very small stumble and no SES light. I'll drive it to work tomorrow and if I have trouble, I'll replace the sensor. We have an auto parts store a couple hundred yards nown the street.

edit: I have to laugh, even though this isn't funny! I drove the van again to the local auto parts store to get spark plugs for our '02 Caravan 3.3L. The engine ran fine with no stutters but when I got home I found the radiator leaking! The right side tank above where the top hose connects has a big crack. I guess I shouldn't have twisted that hose out of the way when I pulled the front of the engine.

On another note, the plugs didn't cure the miss in my 3.3L. The wires all checked OK with an ohm meter and I didn't check the distributor cap yet. Also, under a load (such as uphill) the engine light flashes but as soon as you let off the gas it quits.