Hi, ive no idea why the engine stalls, hopefully compatible lambdas are fitted and the electrical connections are okay ? Replacing the exhaust won't stall your engine. As u say u had it fitted the question is what else has been touched ?
But with the high idle speed that is possibly due the engine is breathing better after fitting the Y pipe etc, and so the EFI ECU recognised this, as it does.
Its something that I had on initial start after I fitted a Janspeed CAT back system, the revs went up to 2500-3000 for two minutes, then dropped back down to 1000 and then onto its usual 650-700 rpm as it normally does on a cold start, so the ECU readjusted and sorted itself out, that was 12 years ago and never missed a beat since.
So if you can get your engine to run longer, at least a couple of minutes the high idle speed will drop.
I believe the 14CUX ecu uses unique lambda sensors which work the opposite way to most others.
I’ve seen universal sensors used on these and cause heaps of running issues.
Did you fit them or were they done by a garage?
Also I would check that no vacuum pipes have been knocked off the intake plenum during the exhaust installation especially the brake servo pipe
The air filter would be well and truly blocked if it was stopping the engine, black all over.I had them fitted at a garage initially, then I removed and refitted myself as I was unsure if they fitted correctly. But they're for a disco 1 not universal fitting.
I have checked all vacuum pipes they look to be good.
Should I change the plugs/filters?
Check both prop shafts - UJ bearings are possible causes. Also check the transfer box output bearings.UPDATE. I've got the car idling at around 780rpm. But when I drive it the underside of the car seems to vibrate and shudder, there's no silky smooth ooomph. It's not a wheel bearing vibration as they were replaced in August for MOT. Could I be needing a transmission fluid change?
UPDATE: ALL SORTED.Aaaahhhhh, one of them tricky technical problems then! I won't tell if you don't. Glad you got it sorted.
Good luck with the vibration/shudder, I guess that won't necessarily be as easy to sort. Chin up keep smiling and all that!