4.6iS Acceleration Not Consistent

[cribasp]

I own a 2002 4.6iS and am experiencing something odd at times while accelerating. At times the throttle is very responsive throughout the full range of the accelerator pedal travel as it should be. At other times the pedal has a "dead spot" from about 1/3 of the way depressed to the point where it hits passing gear (where it seems to wake up and hauls butt). Dealer can't find anything in the fault codes and can't help unless the Check Engine light comes on and stays on.

Has anyone experienced similar problems with their X-5?. Any help or suggestions would be greatly appreciated. Thanks in advance!

[jmh]

Originally Posted by cribasp

I own a 2002 4.6iS and am experiencing something odd at times while accelerating. At times the throttle is very responsive throughout the full range of the accelerator pedal travel as it should be. At other times the pedal has a "dead spot" from about 1/3 of the way depressed to the point where it hits passing gear (where it seems to wake up and hauls butt). Dealer can't find anything in the fault codes and can't help unless the Check Engine light comes on and stays on.

Has anyone experienced similar problems with their X-5?. Any help or suggestions would be greatly appreciated. Thanks in advance!

If the symptom is simillar to the feeling of a sleeping clutch (ie the revs increase but you don't pick up speed proportionaly) you might be experiencing a bad torque converter. This is a common issue on 4.6's (I've seen half a dozen by now), this defect will not throw any fault codes or the like.

- Jan

[JV]

Originally Posted by jmh

If the symptom is simillar to the feeling of a sleeping clutch (ie the revs increase but you don't pick up speed proportionaly) you might be experiencing a bad torque converter. This is a common issue on 4.6's (I've seen half a dozen by now), this defect will not throw any fault codes or the like.

- Jan

I was gonna say the same thing as Jan did. Take note of the difference in sounds when this happens, and note if there's any more/less engine roar when you accelerate as well.

JV

[cribasp]

That for the reply. When it happens the engine rev's don't climb as the accelerator is pressed. I'm not a mechanic but it's almost like the throttle position just stops moving in the middle part of the pedal travel until passing gear is activated. It will act like this for days at a time and then act normal for a period. I can't find a trend to when it happens (cold temps, first startup, etc.). I'm stumped, but for what this cost I would like consistent performance. At times, merging on the highway has been more exciting than it should have.

[JV]

Originally Posted by cribasp

That for the reply. When it happens the engine rev's don't climb as the accelerator is pressed. I'm not a mechanic but it's almost like the throttle position just stops moving in the middle part of the pedal travel until passing gear is activated. It will act like this for days at a time and then act normal for a period. I can't find a trend to when it happens (cold temps, first startup, etc.). I'm stumped, but for what this cost I would like consistent performance. At times, merging on the highway has been more exciting than it should have.

Has your dealer checked your intake and throttle body and throttle control?

JV

[cribasp]

I don't believe they did anthing other than check the fault codes because it wasn't acting up when I took it in for normal service (oil change etc). I live a hundred or so miles from the dealer and was just hoping something would show while they had the vehicle for normal service. The only thing they did other than normal work was something about a new recommended seal on the dip stick. I was hoping that was a cause of a leak (I've heard that there have been problems with vacuum leaks?) but the problem has returned sinced this replacement.

Do you know of a place where factory notices to dealers about X-5's are available to the public?

Thanks again,

Steve

[JV]

Search around through the forums for TSB (Technical Service Bulletin)or on the front page at www.xoutpost.com.

www.Alldata.com is also a great resource for such info.

JV

[rgnbull1227]

this ounds like something I expeience on my 4.8. Whether I am shifting manually or using the auto mode, when I accelerate it actually sounds as if it downshifted, but has not. I was told this was normal in the new engine as the valves adjusted. Does any other 4.8 drivers know what I am talking about? That when you accelerate, it sounds as if it downshifted but its still in the same gear.