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2011 Range Rover sport supercharged. truck has 140k miles on it. Had a rough idle and a few random misfires on cold startup. Also the rpms were surging at a consistent speed but was only every so slightly but can def feel and hear it. Always drove great. Very little hesitation, still had its power. I just had a intake valve cleaning done,(walnut blasting) and all new spark plugs. I had replaced injectors and timing chain in past and for now the misfires are gone and also it took care of rough idle. I still have engine surging ever so slightly. Mechanic wants to replace transmission and says that will solve case. Any thoughts on this? Also i deleted cats and straight piped. Sounds amazing. Any other mods for performance as well does anyone know about. Thanks in advance.
 

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2010-2012 Range Rover Sport
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I don't think that transmission should affect rpm surge, look what else is on. AC pump?, if worn and sluggish/binding to turn, engine may be compensating bigger load and it looks like it surging, same could be applied to the alternator, if bearings are failing and it is on/off harder to turn, it may appear as surges but likely AC then anything else easy to check - just turn it off.
Deleted CATs? yakies. I already feel bad for every driver that follows you in the traffic and being poisoned with that plentiful exhaust. I would not do that to a fellow driver just to get few Db deeper sound and free up 10 more horse powers on already insane 510hp beast of the engine. I am at 90K and just ordered new CAts so I my RRS would be less smelly to me and others.
 

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2006-2009 Range Rover Sport
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Arh the ole I dunno what the problem is so I will replace parts until the problem is fixed, even though some are not related and charge the owner for all parts.

By all means tell your mechanic to replace the transmission but if the problem is not fixed the mechanic has to pay for the new transmission and labour - I bet he declines and does some actual diagnostic.

Surging could be almost anything - does reading the codes show up anything?
 

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Arh the ole I dunno what the problem is so I will replace parts until the problem is fixed, even though some are not related and charge the owner for all parts.

By all means tell your mechanic to replace the transmission but if the problem is not fixed the mechanic has to pay for the new transmission and labour - I bet he declines and does some actual diagnostic.

Surging could be almost anything - does reading the codes show up anything?
I absolutely love the way you think. as of now I have no codes that come up. I cleaned the maf sensors and going to see if that does anything. Walnut blasting intake valves that were completing carbed up didn’t help the surge but took away random misfire at startup and rough idle. Have you ever changed your transmission oil and filter. I heard it’s a sealed transmission
 

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Mechanic wants to replace transmission and says that will solve case. Any thoughts on this?
It sounds like your mechanic believes it’s the torque converter having issues staying in lockup at steady speed. Don’t ask me why but ZF thought it would be a good idea to allow lockup in gears 2-6, not just 6th for interstate cruising. This wears out the lockup clutch much faster as there are exponentially more transitions in city driving than on the interstate.

Is it worth replacing the trans?


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2006-2009 Range Rover Sport
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No it is not a sealed transmission - I have changed the sump on my 6 speed to a metal pan and replaced the filter. A home mechanic can do it and replace the fluid on a regular basis but a good transmission place can do it all for you - about $1000 (including a metal pan and oil) here in Aust so I would assume $750 in your money but local members on here could advise you on this.

Lets just assume it is transmission related - I agree most likely torque converter related but also degradation in the gearbox. So before replacing your transmission I would change the transmission fluid (mega flush not just a drain and refill) and then put some tubes of Dr Tranny in. If the problem goes away then that was clearly the issue but dont get too happy as it may very well come back - Dr Tranny delays the inevitable but maybe for a long time - but at least you would know.

However while I don't have a handle on the actual problem, the transmission is a start by and by the sounds of things it needs a service anyway.
 
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