Can anyone tell me why my jag engine sometimes
surges and hesitates repeatedly at around 50 miles per hour?

I had the throttle cleaned but it didn't help.

Thanks for any imput!

Rick --

Submitted by dougdwyer1@com… on Sat, 01/09/2010 - 10:57

Ignition coil failures are common on that model...but you'll have to figure out which one of the six to replace.

Also, 50 mph@steady throttle is right about where the torque converter would lock-up....which feels like another gear change. If the system was having difficulty deciding to lock-up or release it could bounce between the two and it might feel like a misfire.

I would advise getting a scan tool which can display live data so you can check for any trouble codes and monitor the engine management system while the problem is actually occuring.

Cheers
DD

Submitted by SC38-21185J on Sat, 01/09/2010 - 09:18

Could be any number of things. I would change plugs, cap and rotor for starters, then fuel pump. Replace any in-line fuel filters. You might have a slug of bad gas? A good tune-up by a qualified mechanic might be in order. Look for any disconnected vacuum lines at the carbs and distributor.