Intermittent fault with wiring to ECU

[taylormj4]

Hi Folks,
Recently, whilst the engine was running, I lifted up the ECU just to tidy up the wiring / get the floating relays back in place so I could replace the vertical carpet section, and I noticed that when I lifted the ECU, the engine started running rough and the revs dropped like it was going to stall. When I lowered the ECU back to its usual position, back to normal.

This was repeatable.
So suggests either the connector to the ECU is not making good contact or the wiring loom into the connector has a cracked wire.
Has anyone experienced this before?

If it's the loom, I suspect that's going to be a right pain in the bum to identify and repair.

[Belle427]

Unplug it first and see if there is any green corrosion on the connections, wont hurt to give it all a good lashing of electrical cleaner too especially the wiring connector itself.

[taylormj4]

Many thanks again Belle247. You still got your TVR?

[Belle427]

No Im without at the moment, thinking of coming back in the future though.

[taylormj4]

Belle427 said:

No Im without at the moment, thinking of coming back in the future though.

Good man. Chimaera again or something different?

[Belle427]

No idea to be honest, Im a V8 man at heart but I do really like the T350. A little over my budget but maybe one day.

[taylormj4]

Update:
This seemingly now resolved. More road tests needed to confirm, but no issues out on a run today

See other thread on how this was resolved:
https://www.pistonheads.com/gassing/topic.asp?h=0&...

[PabloGee]

That's brilliant.
Well done, really satisfying.

[Sardonicus]

From my personal experience I would want to find this int connection be it loose termination or broken wire within the loom these problems seldom go away permanently just saying, IMO its just a running rough or breakdown waiting to happen... again, and yes I do this st for a living so I would keep wobbling that loom till I tracked the issue its your help in hand right there seldom gets better than this for diagnosis

[taylormj4]

Sardonicus said:

From my personal experience I would want to find this int connection be it loose termination or broken wire within the loom these problems seldom go away permanently just saying, IMO its just a running rough or breakdown waiting to happen... again, and yes I do this st for a living so I would keep wobbling that loom till I tracked the issue its your help in hand right there seldom gets better than this for diagnosis

Hi Sardonicus, know what you mean. I think I have found the problem in the connector. High and intermittent resistance readings due to surface tarnishing, then low readings after cleaning. Following cleaning and reassembly, I can't make the engine misfire by moving the loom around like I could do. What I meant by more road-testing required was, I'm pretty sure I've fixed one issue but there may have been others.
Have a look at my other thread, linked above.

[Sardonicus]

taylormj4 said:

Sardonicus said:

From my personal experience I would want to find this int connection be it loose termination or broken wire within the loom these problems seldom go away permanently just saying, IMO its just a running rough or breakdown waiting to happen... again, and yes I do this st for a living so I would keep wobbling that loom till I tracked the issue its your help in hand right there seldom gets better than this for diagnosis

Hi Sardonicus, know what you mean. I think I have found the problem in the connector. High and intermittent resistance readings due to surface tarnishing, then low readings after cleaning. Following cleaning and reassembly, I can't make the engine misfire by moving the loom around like I could do. What I meant by more road-testing required was, I'm pretty sure I've fixed one issue but there may have been others.
Have a look at my other thread, linked above.

Good call proper job