So new problem
going down the motorway when I got above 4000 rpm my engine management light started flashing, let the revs drop and it stopped, got above 4000 again it started flashing again.
Plugged in my code reader, got random / multiple cylinder misfire detected.


It has.
new Magnacore kv85 leads
new NGK iridium spark plugs
new crank sensor
I have also visually checked wires


so all the things that I have looked up point to ^ so suggestions needed, also freeze frame data attached.
Thanks

You can check fuel supply

Runs fine so wouldn't think fuel has anything to do with it.

Which ECU does the car have? (Micro ECU or box on the wing ECU?) Alternatively, what year is the car?

I'd start by removing everything that obscures your view of the leads. Start the car up in the dark, look for blue flashes.

Check that the new plugs are R type.

New plugs and leads suggests (I'm assuming you had no problem prior to that) an issue there. Alternatively, coils.

The Micro ECU is notoriously carp -- in the Punto 2 guides/FAQs there's a series of tests for the ECU itself.

Mines 2001 mpi will look at the ECU when I have finished work
Plugs are a couple of months old and have been fine coils and leads have been fitted for a month

According to woj.... where the Short Term Fuel Trim is concerned "the ECUs normally accept values in the range of -25% to 25% to be OK". So -46.1% would seem to be way off!
First step is to follow fingers suggestion -dark night & head under bonnet. That's with the car stationary of course

Try the phonic wheel re-learn.

Indeed 46% short term fuel trim is excessive, so is 18% long term, but the problem is not here I believe. After crank sensor change you really ought to do the re-learn procedure. Start, warm up properly, rev it up to 6000 rpm and let it drop down to idle, three or four times.

I'm guessing this is a micro ECU.
No flashing or sparks going on.
Will do the re learn as I have change the crank sensor twice in a week after the first ones wire got ripped out by the alternator.

Let it warm up till the fan kicked in, revved it up to 6000 and straight of to idle three times then turned it off, will leave it 5 mins then off down the motorway

They don't have knock sensors do they?

I think the engine is detecting knock and is adding more fuel to stop this, hence random multiple misfire and excessive fuel trims.?

Neilix05 said:

Let it warm up till the fan kicked in, revved it up to 6000 and straight of to idle three times then turned it off, will leave it 5 mins then off down the motorway

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You might have to turn off the ignition and straight back on again from my bad memory? You might need a few attempts....

GrandeGuy said:

They don't have knock sensors do they?

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Yes they do if Mpi.

If it has swap to Vpower or high octane to see if it goes, if yes maybe new sensor, or decoke needed, if turbo charged you should be running high octane any way . .

Turbo one day but not at the moment . just got back and didn't do it again. Have done a dechoke on the way back. No knock noticed at anytime. So will keep a good eye on it.

Will give a tank of high octane next time I fill up as have literally jut filled the tank

Would lambda or cat have any effect on this?

Ecu's learn and adapt for slow changes with the engine. The more modern ones are so geared towards emissions that they get upset from the slightest change. If the light is off now then don't worry.

Not normally, the lambda controls how much fuel goes in, things that cause knock, ignition control devices, excessive compression, thermostat (running too hot causes preignition) **big one is wrong plug rating**, if the plugs are running too hot they glow, this ignites the fuel before the spark gets a chance too.

As regards to the compression one, people can skim the head too far this leads to pre ignition/detonation/knock.