X5 4.4i - gearbox won't change back up after acceleration

[biggerdave]

New to the forum so hello all. My LPG converted 2000 4.4i has 96k mainly motorway miles and has started to hold onto lower gears especially after rapid acceleration (mainly in 4th but also in 3rd). Most of the time it resolves if put into Manual to force a change up and then back into Auto so a control/sensor problem maybe? Transmission oil hasn't been changed by the way (not good idea per one UK specialist?!) and I've tried the soft gearbox reset (no diff). Just wondering what I'm looking at before giving it to a BMW specialist - any suggestions for cause of problem and recommendation for good indy near North Yorskhire?

[RRPhil]

If the transmission fluid is overheating the transmission controller inhibits upshifts to keep the engine speed high and therefore the pump flow at a maximum. On the L322 this is extremely common and is usually caused by the bottom rows of the main radiator becoming blocked with sediment which strangles the cooling flow to the transmission cooler (though it doesn’t affect the engine temperature). It can be checked by undoing the radiator drain tap to see if any coolant pours out. I assume that the E53 is an identical setup (same engine and transmission as L322).

Phil

[bcredliner]

Two ways to do this. I suggest paying for a diagnosis and then post the results. That input will generate responses from those with similar problems and what the problem ended up being. Sorry, can't help you with a local Indy shop, Texas is big but still not close to you. If that is something you would rather not do, please post more about the circumstances---cold or up to temperature, always/sometimes, shifting normal otherwise or not, check for codes or not. Does it upshift normally under hard acceleration and the problem is the upshifting after? There are strong feeling on both sides of changing or not changing transmission oil. I change oil about every 50,000 mi. I have 107,000 mi. on a 2002 4.6 with all Dinan mods from the beginning, and, for the last 3,000 mi. a 150 shot of nitrous. Transmission is shifting the same as it did when I drove it off the showroom floor. That said, I don't think you will correct your problem with new fluid. My position is to change fluid is on a regular maintenance schedule rather after problems are showing and if you are having problems get a diagnosis and second opinion which you can get at least close to that here. As is, responses to your symtoms will range from a little duct tape will fix it to the problem will cost you more than both our X5s are worth.

[bcredliner]

Oh, WELCOME!!!