Bl**dy, pi**ing, so**ing intermittant LT fault

Hi all - LSE's (4.2 V8 - no lpg) been behaving itself very well recently, but to punish me for saying so it's developed a really annoying fault.

It'll start from cold and run perfectly, takes me where I want to go, switch it off; come back 5 mins later and it won't start. Cranks but no spark, no fuel injection. This has happened a few times, and I've jiggled, cleaned, replugged LT connections in various order, and it will suddenly come back, with no consistencey as to which wire has been moved.

Once it starts it's fine, never misfires, hesitates, or stalls. It'll run perfectly for several days, then suddenly not start.

Just been and tried the Rave ignition LT diagnostic tests with the following results.

TEST 2
1) Batt volts - 11.99v. I know it's a little low but it's been cranking while I've been trying. Batt only 9months old.

2&3) Batt -ve to coil neg & pos - both 11.87v - within range

3) amp earth to earth - 0v. - within range

TEST 3

Ign off - Batt +ve to coil -ve - it's 11.99v - should be 0v
Ign on - Batt +ve to coil -ve - 11.99v - should still be 0v EDIT just been to check and ign on - it's 0.17v

This seems to be the problem but rave doesn't offer any diagnosis.

There's continuity between the coil neg and the amp plug. Coil is new - replaced trying to solve this.

Before I take the dizzy out for the rest of the tests, can anyone suggest what's the problem - pleeaase?

TIA - Alastair

Check the ECU temp sensor. Battery should be at 12.6 volts unloaded. Get it shunt tested.

My previous 3.9 had a hissy fit a few weeks after I bought it, and similar to yourself, checked all connections, replaced Coil, Dizzy cap, rotor arm, all the LT wiring, the Plug leads, had the dizzy out and cleaned and reset the bob weights, Changed the Vacuum advance/retard unit, had the thing on an osciliscope to check injection timings and pulses.....etc etc etc....

The only thing I didn't change was the ignition amplifier on the dizzy.....it never crossed my mind....so I changed it and then for the remaining 2.5 years I had it before some C**t stole it, it never missed a beat, never failed to start and never let me down....

Some motor factors can test the ignition amp.....the plae I went to said they would test it for £5 and if it was duff and I bought a new one from them, the test was free....

Maybe worth a shot

amp,they are cheap and easy to fit , you can do it with the dizzy in so worth doing that first

Thanks for the thoughts - I can't help thinking it's a simple loose connection or short.
The fact that when it runs it's absolutly fine, smooth & quiet, makes me think it's a 'simple' LT fault.

With the ignition off there's battery voltage at the batt pos to coil neg, and when ign is on it drops to 0.2v ish, when according to rave it should be zero on both, - this is with the ign amp unplugged - which makes me inclined to discount the amp.
Something somewhere is feeding power to the coil with the ignition off.

Where does the thicker all white wire from the amp plug terminate?

Thx again - Alastair

Changed the ignition amp module a week ago and - touching wood - it hasn't played up again.

Thanks for all the suggestions - as usual, excellent help.

A Merry Christmas to all.

Alastair

I am in smugmode

fett said:

I am in smugmode

Click to expand...

Then I'm in 'Super Smug Mode'...as I said it first

ur assuming I would bother to read your posts