Help running problem baffling me

[matthg40]

Evening all I have a strange problem with my 40.the car ticks over perfect and sounds fine when running but one thing I have noticed some times it sounds like it wants to cut out and sometimes does.also when u rev the car and the revs drop it's cuts out I have no ideas. I've checked timin that's perfect it's had new coil pack battery starter motor alternator so I'm ruling out electric problem any one got any ideas if so please help many thanks matt

[PeteG40]

please can you be more explicit in your topics than 'help' please.

[matthg40]

Sorry dad

[cheys03]

I wouldn't rule out electrical problems just because you've bought new bits. I learnt this myself recently. I had a problem where the engine would stall or almost stall when the headlights were on and the engine was warm - when the ECU is tweaking the afr using the lambda sensor. When it tweaked it slightly lean the revs would drop, the output from the alternator would also drop momentarily and so the fuel pump would pass less fuel. This made the mix leaner still and hence it would stall if the ECU didn't richen the mix fast enough.
My immediate reaction was to upgrade the alternator to a 90A model, after all I've added a lot of electrics lately. Didn't solve it. Then I added a rectifying diode to the alternator regulator earth reference in order to make it output 0.6v more. Helped, but didn't solve it. So, I had a think and broke out the multimeter.

I spent yesterday morning running a big thick cable to the in-line fuel pump because it was only seeing 12.3-12.5v of the available 14v when the engine was running due to poor cabling. In the afternoon I beefed up the engine earth strap which was costing ~0.7v. Now all is dandy and engine idle is very strong even with the headlights.

Sorry for the long-winded lecture, but what I'm getting at is that you can't be sure that you've ruled out a whole area of diagnostics until you've done some diagnosing!

[matthg40]

Ah that was an interesting read thank you for that mate it's so wierd because Its not constant like u say I could still be a fault with the wiring loom so what basics would you check then thanks for your help mate