Hello Everyone. I am new to the forum and recently got a 2005 Jaguar XJ8L with 179k miles.

I really need help. The person I got it from said the car was sitting for a few years and said it needs transmission fluid top off. The car was making a sort of humming sound when accelerating even a little bit hard. So I did a transmission service had the fluid drained and filled and pan changed. In the drain around 2 quarts came out and when filling it around 8 quarts went back in. I used pentosin ATF6.

The car has lights for ABS, DSC OFF and Transmission Fault. The shop said the front passenger speed sensor is bad.

The shop that did the trans service and engine oil change said there are a lot of codes in the car and erased them all. After erasing codes when he started the car the car was misfiring very bad and he turned it off and turned it on again and it was very smooth.

I drove the car after the transmission service and the trans was slipping a little bit. then it seemed to become fine and I think the car went in limp mode and wouldnt go past 2nd gear. The randomly the car would barely pick up speed and the rpms would just go up without the car moving and a hmmm or humming / maybe grinding noise would come when accelerating. Luckily I had an OBD scanner and had it plugged in while driving the car and I cleared the engine codes and it went back to normal. No humming no slipping and full power and smooth shifts. Then if I stepped on the gas even a little it would go to limp mode again and start slipping and humming on acceleration and I would clear the engine codes and it would go back to normal and again it would go in limp mode and if I cleared the engine code it would be back to normal again.

I am very confused because it seems like the transmission is bad from the noise and slipping but when the engine codes are cleared it acts completely fine. If the transmission was internally bad shouldn't it always slip and make noises. There is also a loud grinding noise at idle also when the car is in drive gear which goes away when putting the car in neutral.

Not sure if its a transmission computer related thing or the transmission is actually bad. I just hope the transmission does not have to be rebuilt or replaced because it will cost thousands.

If anyone has experience or can provide direction on what to do that would be great! I am located in Houston TX.

 

The rear wheel speed sensors are the ones the abs dsc speed controle speedometer and transmission rely on.
25€ a piece. Also have a look at the reluctor rings below the rear speed sensors . Brass brush and brake cleaner if they are dirty. . They can also swell because of rust underneath them. Thin shimm might help.
Then the transmission has its ground cable , might be helping to clean up the connections.
I only use the zf 6 lifeguard original fluyd together with a whole kit Zf 1068.298.062 pan filter magnets screws but I also changed the interior rubber parts .
bridge seal ,4 tubes and connector sleeve. ZF 1068.298.090. Rubber parts do not like the transmission oil. Fissures in the bridge seal to the mechatronic make it lose oil pressure up to (750millibar )wich is necessary for the adjustment to the different clutches . If those are exchanged system is sealed again and pressure adjustment gains a little. Especially on early cars
If there was only 2 quarts drained ( should be 4 quarts without removing pan) ( 6-7 quarts with removing pan) might be damaged inside). Most
probably cheaper to swap tranny .
I would give it a try with the rear speed sensors , clean up reluctor rings and another drain of oil through the drain hole . Refill with new oil (4 quarts.) Till it comes out the fillet hole. Close filler hole then start engine , car leveled ,foot on the brake constantly, go through all positions of the gear lever like 10- 20 each one after the other and back into P. Let engine run get underneath car open filler hole again( beware of the exhaut temp) and continue till it runs out at 40-50 celsius OIL temperature oil still dribbling out then close filler hole torque . Watch oillevel procedure for zf6hp26. On youtube

 

Sorry missed some words at the emdd. Let engine run open filler hole and continue filling up tranny till it runs out. When that oil has the necessary 40-50 celsius then the level is correct. Close filler

 

Car has to be LEVEL when you do that, not just jacked up at the front do you can reach it. Filler hole a a difficult reach, with minimal clearance from the exhaust, and as stated, the engine has to be running to do this.

It's entirely possible the transmission is wrecked, if it had been running any time at all with one quarter of he required fluid volume...

 

Filler ( open that one first) hole can be opened with a short 90 degrees allen /hex key . Located about 2 inches above pan right side of car near the exhaust tube.

 

I had a first gen xj8 that would constantly go into limp mode - I had an OBD permanently in place to reset, so I could continue driving. After a few months the OBD reset stopped working and the car wouldn't stay out of limp mode for more than a mile or so. In my case it was a transmission shifter module on the side of the tranny - the contacts were bad so even though the car was in D mechanically the tranny couldn't get electronic confirmation - so that would trigger the limp - replaced the module with one from a salvage yard solved the problem. the tell tale sign for mine was the PRND lights would go out when shifted into D or R. Not sure if the second gen has the same set up ???