Thread: Flashing check engine light Discovery 3S 4.0 V6

Double post

Originally Posted by Tombie

That will likely bite you on the arse...

You’ll need to then fit emulators to the post Cat sensor input lines or it will go into limp mode.

I replaced them with aftermarket cats, not no cats at all.

Also, you don't get limp mode with no cats, just codes.

Edit

And fiddling with the downstream sensors is not a good idea either, they are also used for fuel trims.

Get some vgood aftermarket cats and problem solved.

so the fuel trim is adjusted by o2 sensors after the exhaust gas has been through the converters?

hmmm..

Originally Posted by Cambo@oldjaguar

Get some vgood aftermarket cats and problem solved.

Not sure if the forum allows this but I've had a look around and cant find a supplier for quality aftermarket cats. The dealer prices are eye watering.

Originally Posted by Pedro_The_Swift

so the fuel trim is adjusted by o2 sensors after the exhaust gas has been through the converters?

hmmm..

Yep, it's a thing with newer petrol engines on Jags and Land Rovers, other makes too.

Originally Posted by Julian B

Not sure if the forum allows this but I've had a look around and cant find a supplier for quality aftermarket cats. The dealer prices are eye watering.

Any half-decent exhaust shop would be able to supply them, just cut the old ones out, weld the new ones in.

A standard type, not a "sports" one with a low cell count. $500 each fitted would be ballpark.

Ended up taking the car to a trusted independent.
Replaced O2 sensors and fault remains.
Camera scope down hole, cat is perfect.
Ignition all working, now new plugs and leads, and fault remains.

Ongoing misfire codes. No hardware codes.

Noise on right bank the boys are thinking timing chain stretch and misfiring because of this. They have seen it before.

Anyone heard of this?

I would cut the cat out, weld in a temporary section of pipe and see how it runs.

I'm two for two on my own cars with misfires under load caused by choked cats, and on the 2nd car the cats "looked good" from a visual inspection.

Not to mention the numerous other cars I've seen with the same problem.

How much is it gonna cost to cut out the cat and weld in a temporary pipe, vs pulling the engine down to check the cam timing and chains?

Isn't the timing chain for the right bank at the back of the engine?

Have a look at YouTube on replacing 4.0 Explorer timing chains.

There is one in Spanish AFAIR which shows how to do it , but there are lots of special tools required to do it properly.

There must be a Ford specialist somewhere who has all the gear.

The 4.0 l started as a 3.0 Essex v6 and had the OHC heads grafted on so some chains are on the front of the engine and some on the back.
A job not to be undertaken lightly.
On the plus side a full long engine was when I looked a couple of years ago only about USD2500 from a USA Ford dealer . It may be cheaper to buy a new engine than renew the timing chains.LOL
Regards Philip A
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