Fried ECU

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daftpooly

daftpooly

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Monkey 'angin country
After much head scratching, consternation and tinkering I've eventually come to the conclusion that my Disco 3.9 V8 ECU has been fried:mad:. There are plenty of ECU repair companies hawking their wares on t'net, have any of you guys had any positive/poor experiences and could recommend/steer clear of a particular company?:confused:

I'm posting this on the V8 and Discovery freds :D
 
daftpooly said:
After much head scratching, consternation and tinkering I've eventually come to the conclusion that my Disco 3.9 V8 ECU has been fried:mad:. There are plenty of ECU repair companies hawking their wares on t'net, have any of you guys had any positive/poor experiences and could recommend/steer clear of a particular company?:confused:

I'm posting this on the V8 and Discovery freds :D
Click to expand...

What makes you say that your ECU is fried? What are the symptoms? It's not a common fault with them.:confused:
 
I'm breaking a 95 3.9 V8 disco, the ECU is in working order as the car is a right off but run. If you want to come to some deal on it give me a PM your number, I'm sure it will be cheaper than having yours repaired.
What makes you think that its the ECU I've not heard of them going often, have you been welding on your disco with the battery connected?
Have you check that the wiring loom is in good order?
 
I've changed all engine electrical components and sought advice from my indie garage, another non LR garage and the following is from the carelect website.

A common ECU problem we see is loss of 1 (or both) injector banks (usually following work in engine compartment) This failure is relatively easy to diagnose (check for injector pulses).

The car gets to 1600 revs then it's like a switch being turned off, no misfire, no hesitation, it doesn't cut out, it just drops back to tickover then picks up cleanly again straight away.:mad::mad::mad::mad::mad::mad:

I'm hopefully borrowing an ECU tonight to absolutely confirm my theory.
 
daftpooly said:
I've changed all engine electrical components and sought advice from my indie garage, another non LR garage and the following is from the carelect website.

A common ECU problem we see is loss of 1 (or both) injector banks (usually following work in engine compartment) This failure is relatively easy to diagnose (check for injector pulses).

The car gets to 1600 revs then it's like a switch being turned off, no misfire, no hesitation, it doesn't cut out, it just drops back to tickover then picks up cleanly again straight away.:mad::mad::mad::mad::mad::mad:

I'm hopefully borrowing an ECU tonight to absolutely confirm my theory.
Click to expand...

If you lost all yer injectors your landy wouldn't run. If you lost half of them it'd misfire like a bitch.

Does it do it when cold? when hot? Only after a long run? right from start up?
 
Andy/Ratty thanks very much for your direction guys.

To answer the questions and provide a bit more feedback the tank was put back in at the weekend, it was removed for boot floor replacement, flushed at that point, new filter, new fuel lines, new fuel pressure regulator, new injectors, fresh fuel, there are no leaks or splits on any of the hoses or manifolds. It's had new Lucas module, dizzy cap, rotor arm, quality leads and plugs.

It just gets to 1600 revs then drops back to tickover when in gear, regardless of whether it's cold or hot and regardless of road speed. It doesn't misfire, stutter, backfire anything it just drops to tickover. As soon as it drops it picks up cleanly immediately. It's almost as if there's somebody just switching it off but the engine doesn't cut out.

The only diagnosis is that the ECU is cutting the pulse to the injectors for whatever reason. The battery was disconnected when the welding was done in the boot, the only 'event' during the engine rebuild was one occassion when the alternator was being removed the battery hadn't been disconnected which resulted in a nice big spark:doh:
 
Fixed it:) Well temporarily at least until I fix it properly. I eventually realised that the ECU had gone into limp home mode and after finding the following a penny dropped:rolleyes:

eightinavee said:
Are you using the oxygen sensors in the downpipes that the LSE would have had ? If not this is what is causing the rich mixture.You have 2 choices,first is to change the tune resistor in the efi harness - it about 12" from the ecu plug in the loom.Or you could fit the oxy sensors in the downpipes and connect them up.(Technically the better option.)
Click to expand...

I ditched the cats during the re-build but kept the lambdas. The mistake I've made is that the bosses are too deep:doh::doh::doh: so the lambda isn't protruding into the exhaust flow enough and is telling the ECU there's a fault and kicking in the limp home mode.

Temp repair was to remove the tune resistor and replace with a 22p 470Ohm resistor from Maplin. I've even created a little plug and socket set to enable an easy swap for the permanent solution:D The permanent solution is to take the downpipe back off remove the bosses and weld on new bosses half the depth, put the old 3900Ohm tune resistor back in and that should be it:confused:
 
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