Hesitation on light throttle
 

2002 4.4.

As the title says, I have an issue with a missfire / hesitation on light throttle openings. It manifests itself after a few miles from start up and only seems present on very light throttle openings, mostly after slowing down from a reasonable speed and then applying throttle again.
To date I have renewed the plugs and coils, cats and the PCV system. I have smoke tested the inlet to check for air leaks and done a compression test on all cylinders. Air flow readings have been checked against a known good MAF. I am now running out of ideas and welcome any input. Its also worth mentioning its a duel fuel car running a sequential LPG system, the problem is present on both fuels.

Iam starting to think perhaps the throttle body itself ????

Stop throwing money at it . I'd take it to a reputable Indy and have them hook it up to GT1 software and see what's causing your hesitation?

Good Luck and keep us posted, please!

Thanks , i did, who diagnosed a head gasket blown and wanted me to hand over £1500 to fix. After pressing him on how he got to this diagnosis he said it was his best guess.......

Sounds like the notorious torque converter lock/unlock failure. Many of us here have had it, particularly with the 4.4 and 4.6. It manifests itself very much like a misfire about every 2 seconds under light acceleration. If it appears to go away in Sport mode or with the cruise control on, it's the torque converter. Both of these scenarios essentially lock up the TC so it doesn't keep unlocking. Search TC failure and symptoms on this site....there's a bunch of info. Brace for a TC replacement. I just drive in sport mode now and it's fine but a TC or full trans replacement is on the horizon. Best of luck.

Now that sounds interesting. But would the tc throw up a mil lamp with missfires ? This is what happens if I don't drive through it.

I get no codes so if you're getting a code, maybe it's something different although I have heard of mil lamps for TC issues if it senses a heavily worn TC or a valvebody solenoid failure in the trans. The 'misfire' feeling from a worn TC happens consistently every 2 seconds under light acceleration from about 40mph to 60mph. When the TC goes from unlock to lockup it causes a slight load on the engine and makes it feel like a rythmic misfire. If your X5 is doing that, I can almost assure it's a TC which is a very common wear item on the X5s, especially if your at or over 100k miles. Try the cruise control and the sport mode and see if the throttle hesitations/oscillations go away under the same driving conditions. Please report back. It's always good to have more data points for other Xoutposters

Thanks for the tips guys. I have to admit that it does sound like a TC issue now Ive read up a bit, but mine seems to have some differences to what people have been describing. The "Miss fire" only last for a second or two if you keep gently accelerating. It becomes more prominent if there is a load on, ie my trailer. The gearbox changes are as smooth as silk up and down with no clonking. Going up a gentle incline with the trailer on and getting the speed just right I managed to get some faults registered which where all " missfire on cylinder x" and multiple missfires. so I am sure its an engine problem rather than trans. Ive ordered up some new O2 sensors as the existing ones look original and Ive got 130k miles on her now, so we will see if they have any effect.

Sure you've thought of it, but fuel filter?

Then again, just re-read you've got the same problem with the LPG system. Next.

Well guys, the more testing Ive done thanks to the pointers on here (thanks guys) It looks more and more like the TC. To this end Ive booked her in with an auto trans specialist for a diagnostic. I will keep you all posted.

I Don't know but this is what happened to me....

I would ask.. are all coil packs brand new? or were they just checked? I know you said they were new but your description is identical to the way I would describe the problem i had.

First post here. Totally just bought a 2005 X5 3.0i 78,000 miles 3 weeks ago and it did exactly what you describe.

between this and the others I can tell you (only from what ive read not from experience) there are about 5 other causes of this LOL. Ive read and read and read and read and read... you get the point. search search search.

misfire cylinder 3. did the water test everything acted normal when unplugging coil. traded places with coil pack 2 and 3. Misfire on cylinder 2 now.

replaced all 6 coil packs haven't thrown a code in a 100+ miles. Car acceleration and I'll even go as far as to say shifting is smoother WAY smoother. night and day difference from the first drive after I put the coils in.

had the original black and grey bosch coils in there 78,000 miles. Ive heard people say a coil is either good or its bad which is not true and I'm convinced that these coils were deteriorated causing small? misfire (s) how's that sound? anyways they were junk in the car and still not throwing codes. the wife drives the car she doesn't throw codes I drive and im throwing codes. the problem got worse after I replaced the original spark plugs with dealership oem plugs FYI.

ya I had the leak on the boot no I haven't replaced the ccv/oil separator system yet ya i checked the DISA and the flattened out oring bugs me. am i sold on the vanos actually making a difference if i replace it?? sheesh i dont know. could there be some other little shutter or something slight im still fixated on that im determined to find out what thats all about.. I think so lol

Just to update this thread. Just got the car back from the transmission specialist who had confirmed the torque convertor was on its way out. I had the whole box overhauled due to the millage - 133K, and she is as smooth as silk now. Thanks to the guys on here who pointed me in this direction, without you I would have still been chasing that miss fire ! Not that I didnt have one cause I did, caused buy me buying cheap coils to try and cure a miss that wasnt there !