ECU

[tom's dad]

Can any one advise regardin straight replacement of an ECU on a 4.3 grif. What vehicle is the original from. Is their some kind of identification reference Not sure whether I need one but I am collecting as much information as possible prior to investigating a total cut out of the engine whilst travelling home last night, with no prior symptoms.
All advise welcomed.

Cheers.

[GreenV8S]

tom's dad said:

Can any one advise regardin straight replacement of an ECU on a 4.3 grif. What vehicle is the original from. Is their some kind of identification reference Not sure whether I need one but I am collecting as much information as possible prior to investigating a total cut out of the engine whilst travelling home last night, with no prior symptoms.
All advise welcomed.

Cheers.

Its a Lucas 14 CUX hotwire as used on the Range Rover 3.9 V8, with a modified map. ECU failure would be a long way down the list of likely causes for that problem though, I expect you'll find the problem is something far more mundane.

[rev-erend]

Immobaliser or car alarm .. likely suspects..

Any number of loose / broken wires could cause this.. just take a careful look around.

[wixer]

Probably one of the fuel and ecu relays that are part of the wiring harness. Had an intermitent problem with my car where it was cutting out randomly and also breaking down to 6 cylinders. I changed them last week and so far no more problems. I did a bit of investigation into these relays and they are not happy dangling around on the harness, when they should be attached securely to a bracket or at least tied up securely.

[griffter]

As has been said, it's most likely an intermittent break in a supply circuit to the ecu or ignition. A break in the fuel pump supply would not cause a sudden cut out, but the car would go 'flat' first as the fuel pressure dropped.
Check the wiring to the ignition amplifier and the coil. Also worth checking the wiring to/from the ecu and in particular where any immobiliser is wired in.
I had a problem with very occasional complete cutting, but more frequent running on four cylinders, due to the immobiliser randomly and momentarily cutting the ecu supply circuit. I figured this was an ecu problem as the ecu was driving four injectors properly, and four at full load (overfuelling those four hence the cylinders weren't firing). Consequently I replaced the ecu by obtaining a 3.9 Lucas 'hotwire' 14CUX and replacing the fuelling chip with a TVR one. Then the probelm recurred - whereafter I found the immobiliser fault.

So that sort of answers your original question. TVR 4.3 ecus are rare and you could wait ages to find one. If it does turn out you need one, PM me and I'll try and help out.

[dnb]

It's fairly easy to convert a Land Rover 14CUX into any TVR one if you have a few EEPROM programming tools and the TVR ECU. I have these tools...

I suspect the problem in this case is related to the wiring (specially the 2 metal relays near the ECU) or the ignition system (amp or coil) and nothing to do with the ECU itself.

[Graham]

The two relays are the main power relay to the ecu, and the fuel pump relay. the main relay is controlled by the ignition switch, and the fp relay is controlled by the ecu.

as already said the ignition circuit on the lucas set up is totally separate, and it could be an earth problem on the ignition side.

G

[that daddy]

The only problem i know of on these ECU,s is the dropping of the feed to open the fuel pump relay,its normally temp related and when the motor cools service is resumed,it may run for 20 minutes it may run all day i have known of at least three failures of this kind(thought at first to be the standard tin relays fault)can be a pain to diagnous,can normally be detected on the fly.

[tom's dad]

Thanks all for your inputs.
Spent all day testing/isolating the various components of the ignition system to find that it was the wiring that was fluxd. One of the 2 white and black striped wires connected to the coil through one sheathed connector had corroded within the sheath. Excellent. Cost of repair 10p.
On reflection grif was running a little ruff at start up recently and I was going to replace the leads.
As a matter of intrest, I am keeping a record of wiring configurations and hope to enlarge the Heath bible wiring diagrams over time.

Thanks again.

[That Daddy]

tom's dad said:

Thanks all for your inputs.
Spent all day testing/isolating the various components of the ignition system to find that it was the wiring that was fluxd. One of the 2 white and black striped wires connected to the coil through one sheathed connector had corroded within the sheath. Excellent. Cost of repair 10p.
On reflection grif was running a little ruff at start up recently and I was going to replace the leads.
As a matter of intrest, I am keeping a record of wiring configurations and hope to enlarge the Heath bible wiring diagrams over time.

Thanks again.

Nice one well done,now you can easy.

[Pasco]

Spot on guys that's what makes this site bloody superb Cheep Fixes