Hello, I have a '04 3.0 Sport with now 102K miles. It has developed the occasional jerking / stutter and it's usually when I am pulling into traffic. It is like the motor just shuts off for an instant then comes back on in a half second. The car has a new huge battery, front plugs, filters and oil changes. Code reader says lean condition bank 1 and CEL comes on when the jerking occurs. Some times it is lean bank 2., sometimes some specific cylinders. I have read all the posts from people with similar conditions and the suggested cure always seems to be change coils, plugs, battery cables or clean grounds. I have cleaned numerous grounds suggested which were not dirty or rusty. I change the negative battery cable several years ago. And they look good. I do not think the problem is electrical but rather a fuel delivery problem with the metering going lean at a part throttle condition. It may occur when the engine is warming but not fully hot but this is only a maybe. It runs great under full throttle and idles fine but I occasionally I perceive a slight dip in RPM on idle. But rarely. Several of you seem to know this car well and perhaps could advise about where to look for a problem with the fuel injection or metering. Also at 102K miles perhaps the fuel pump is cutting out intermittently. How many miles are they typically lasting? I have a new fuel pump but hate to cut the floor up if this is not the problem.
Any suggestions and help appreciated.
Thanks

 

Question as I just basically just went thru this. When it acts crazy is it usually around the 2200-2800 rpm range and almost always does it the most when in high gear ? Not always in high gear but more like 95% of the time it’s when it does it.

 

Hi TonyJ1977,
The rpm range sounds about right but may not always be in 4th gear as I am often accelerating into traffic when it bucks.

 

pinnacleranch, replace the rear plugs and then lets see what you have. The rear plugs are the ones that normally cause the symptoms that you are seeing. After that, I would be looking at what we call "The Big 3" (ie, IMT o-rings, PCV hose, and the brake booster vacuum line). With the age of your car, these are all possibilities.

If you are thinking it is the fuel pump, then I have a test for you. This is a 2 part test that will need some time inbetween the tests. Both tests will start after letting the car sit overnight (atleast for say 5 hours). The first test is to simply take the ignition and roll it straight to START as quickly as possible and then noting how long it takes for the car to start. However you want to measure this is up to you. The second time starting it, roll the key to the RUN position (not START), pause for about 3 seconds, then finally roll the key to the START position. Again, measure the time that it takes for the car to start. If you notice a difference in time of say a second or two (possibly more), then odds are, your fuel pump is starting to go. Otherwise, you are most likely looking at a plug issue. Not uncommon for a car with your mileage to start developing an oil leak that slowly fills up the plug wells, leading to misfires.

 

Thermo,
I will try the fuel pump tests tomorrow and check or replace the other items this week and report back. I did check the red tube into the fuel rail and thought it was not pushed in quite all the way. The tape around the end was coming loose. So corrected that.

 

As thermo said also change the rear plugs and also don’t just choose any double platinum plugs either. Go with the Bosch fine wire double platinum plugs. I was using the auto light double platinum and they ran fine for about a month and then I went with the denso double platinum plugs and they made it about 6 months and now that I’ve switched to the Bosch fine wire double platinum plugs the car has never ran more smoothly and that bucking has gone totally away. Our cars are very very picky about the plugs.

 

I know how it can be hard to believe that it can be the plugs when it runs so good at lower and higher rpms but really tho these cars are picky picky when it comes to certain things. All of the plugs that I’ve tried before when pulled back out still looked new when removed and I even took one of the sets and put them in my truck and the truck runs perfectly with them so it’s not a “bad” plug it’s just that the car doesn’t like them. And just to make a little fun out of the subject that bucking and jerking is the cat trying to cough up that fur ball lol

 

Hi Guys,
Sorry to not get back sooner, it has snowed here 9 inches so I have been driving my truck instead of the cat. I did do the fuel pump tests as Thermo suggested and the car after sitting overnight started up in about 1 second. After sitting it still started quickly so the check valve in the pump is good and the pump probably is too. I did clean the PCV valve and look at suggested areas for a vacuum leak. I did find the small red hose someone suggested that goes to the fuel rail and manifold seemed to have pulled out some and was held in place with tape which was peeling away so I replaced the tape and made sure it was tight. I also thought I could hear a slight vacuum leak but sprayed starter fluid around all the suspected possible areas with no change in idle. The two large control valves into the manifold that are sealed with O rings were suspect so I wrapped some tape around them to see if it made any difference. So far the car has not bucked again but hasn't been driven much due to the snowfall. I will report if any new events happen.

 

Not one, but THREE "Super Tips" in one post.
(and one pretty darn good shot in the dark there, pinnacleranch!)

I love this place.

 

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