ECU Failure? Or something else.

Mogwyth · Post by **Mogwyth** » Sun Jan 23, 2011 10:48 pm

What are the symptoms of a failed ECU?

I have a Discovery II with a recon 4.6 on it's original 4.0 ECU, it ran fine for 1200 miles and then developed a hesitancy around 1750 revs under low acceleration and fuel consumption gradually fell away. Initially there were no fault codes and we found a damaged wire that appeared to solve it but it was back within 50 miles, this time it threw up Lambda faults so we replaced. This made no difference to the running and no further faults came up on my local garages diagnostics. After much head scratching we took it for a second opinion at an LR specialist who have Testbook, which revealed no faults. Basically it's just not going closed loop and is running open loop all the time.

Cheers

Bill

kiwicar · Post by **kiwicar** » Mon Jan 24, 2011 5:01 pm

Hi
How old are the Cats? just they can fail, and they don't show up as a sensor fault.
Mike

ChrisJC · Post by **ChrisJC** » Mon Jan 24, 2011 5:04 pm

Can you borrow an ECU, and get it 'testbooked' to not fall foul of the immobiliser?

Chris.

Mogwyth · Post by **Mogwyth** » Mon Jan 24, 2011 6:23 pm

Cheers guys,

Cats no idea but at least 2 years that's how long I have had it.

Mine has had the immobiliser deactivated (got an after-market one) so we are going to try an put mine into the garage's V8.

DEVONMAN · Post by **DEVONMAN** » Mon Jan 24, 2011 8:28 pm

It could be the coolant temp sensor telling the ECU that the engine is cold even when it's warmed up.
Worth checking the sensor's resistance when cold and hot.

Also less likely, but ditto for the air intake sensor.

Regards Denis

Mogwyth · Post by **Mogwyth** » Sat Jan 29, 2011 1:36 pm

All sensors have been individually checked and appear to be functioning correctly.

We tried swapping ECUs but despite mine having the factory immobiliser deactivated, neither ECU will run the other vehicle, which is puzzling.

We have compared the ECU readouts between two motors and everything is near enough identical, really puzzled.

DEVONMAN · Post by **DEVONMAN** » Sat Jan 29, 2011 1:58 pm

Mogwyth wrote:All sensors have been individually checked and appear to be functioning correctly.

We tried swapping ECUs but despite mine having the factory immobiliser deactivated, neither ECU will run the other vehicle, which is puzzling.

We have compared the ECU readouts between two motors and everything is near enough identical, really puzzled.

If the electrics are all ok then maybe as "kiwicar" said earlier, the cats could be the problem. I note you are running a 4.0 ECU on the 4.6.
I've read that the ECU can automatically adjust for the bigger engine but I have never been convinced about this.
Is it possible the mixture has been incorrect and the Cats have suffered after the 1200 miles.
This is just a thought so shoot me down if it's nonsence.

Cheers Denis

Mogwyth · Post by **Mogwyth** » Sat Jan 29, 2011 3:46 pm

Surely if the cats have gone, the power delivery problem would be at all revs? and power overall doesn't seem effected, if I plant my foot to the floor she takes off like scalded cat.

What are the symptoms for failed cats any way to test them?

DEVONMAN · Post by **DEVONMAN** » Sat Jan 29, 2011 4:39 pm

Mogwyth wrote:Surely if the cats have gone, the power delivery problem would be at all revs? and power overall doesn't seem effected, if I plant my foot to the floor she takes off like scalded cat.

What are the symptoms for failed cats any way to test them?

Didn't realise it took off like a scalded cat so new scratching of grey matter now required. Could be something as simple as a dodgy injector.

Regards Denis

Mogwyth · Post by **Mogwyth** » Wed Mar 02, 2011 10:57 pm

Back again.

Right the ECU went of to Lynx Automotive for repair which is where it's been for the best part of 4 weeks, they are proving a pain in the arse, not really telling us anything just keep saying it's a complex repair maybe next week, not very happy. Anyone know anything about them?

Thinking of telling them to stick it and buying another ECU but new ones are a £1000 can anyone recommend a source of secondhand/refurbished ones?

ChrisJC · Post by **ChrisJC** » Thu Mar 03, 2011 8:01 am

eBay:
http://cgi.ebay.co.uk/Landrover-Discove ... 19c3839ba6

(although it says 3.5L, Disco2's were all 4.0L !!)

Or call some 4x4 breakers, I would think there's plenty about, just there isn't enough call for them to make it worthwhile advertising them on their own.

Chris.

Mogwyth · Post by **Mogwyth** » Fri Mar 18, 2011 1:33 pm

A word of warning, I would advise anyone needing ECU work done to avoid Lynx, I have just listened to a telephone conversation between them and my garage and basically their customer service is none existent, it will be done when it's done and we are idiots for trying run a 4.6 engine with a 4.0 ECU.

They are claiming this is what has damaged the ECU

And anyone who says they are the same ECU doesn't know what they are talking about, I assume he includes the LR workshop manual in that and an acquaintance of mine who is running the same setup!

Mogwyth · Post by **Mogwyth** » Sun Apr 24, 2011 12:11 pm

Never got mine back from Lynx so we managed to source a new one for £170, didn't solve the problem, please see my new thread.