Technical Engine noise at high RPM and light load

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Technical Engine noise at high RPM and light load

As it somehow ran out of fuel today (seems the tank has a filling issue and when I thought it was full, it has only a gallon or so in it), I put v-power in. It now revs through the noise which is quite a bit quieter now and bounces off the limiter, boots to 50 in 2nd in a hurry.

I'n confident it's a pre-ignition issue given that over-fuelling and higher octane fuel have improved the situation. I'm going to get new plugs in it and replace the crank sensor just for the hell of it.
I used to get a bit of pinking on my 899 Cinq under full load at low-medium revs when it was using 95RON.
I'm sure the ignition timing was a little too advanced.
The crank sensor is adjustable but the screws are tiny and old so I left that alone and ran it on Tesco 99RON instead and it ran very well on that.
 
I used to get a bit of pinking on my 899 Cinq under full load at low-medium revs when it was using 95RON.
I'm sure the ignition timing was a little too advanced.
The crank sensor is adjustable but the screws are tiny and old so I left that alone and ran it on Tesco 99RON instead and it ran very well on that.


Mine has issues at higher revs under lower load. New crank sensor to go on tonight. See how that goes.
 
You can move/refashion the bracket on the 899

D

Seems an extreme solution!

May give problems if I eventually sort the issue out and the timing is too retarded to run the engine. Access to the sensor is not that easy, there's an engine mount in the way.
 
Seems an extreme solution!

May give problems if I eventually sort the issue out and the timing is too retarded to run the engine. Access to the sensor is not that easy, there's an engine mount in the way.
As said, the bracket the crank sensor is on IS adjustable.

Edit:
In the attached pic, I’ve circled the adjustment screws in red.
 

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As said, the bracket the crank sensor is on IS adjustable.

Edit:
In the attached pic, I’ve circled the adjustment screws in red.

Mines different to that. The bracket is part of the timing cover. Definitely no adjustment available. The sensor goes straight through the casting.
 
Is yours a 999 rather than an 899?

D

It's an ohv spi, starter on the right hand side (looking from front) with inlet manifold in the head.

I have had a thought. The only times it knocks are when there will be a decreasing manifold pressure. Is there supposed to be a small cannister in line with the map sensor to smooth out the pressure fluctuations? I'm possibly going to buy another map sensor cheap from Amazon, it'll either do the same, be worse or improve things.
 
It's an ohv spi, starter on the right hand side (looking from front) with inlet manifold in the head.

I have had a thought. The only times it knocks are when there will be a decreasing manifold pressure. Is there supposed to be a small cannister in line with the map sensor to smooth out the pressure fluctuations? I'm possibly going to buy another map sensor cheap from Amazon, it'll either do the same, be worse or improve things.
It should connect straight to its port on the throttle-body.

I know you’ve said yours is connected to the manifold, so different to my Cinq 899.
And with your crank sensor mounting being different too there is the possibility it isn’t a Cinq 899 engine.
I wouldn’t have thought the Sei version was much different either.
 
It should connect straight to its port on the throttle-body.

I know you’ve said yours is connected to the manifold, so different to my Cinq 899.
And with your crank sensor mounting being different too there is the possibility it isn’t a Cinq 899 engine.
I wouldn’t have thought the Sei version was much different either.

It came out of a Cinq, but whether that's what it left the factory in I have no idea. The ECU that was in the car has 500 on it so it's at least a Cinq ECU.

It does have leaky stem seals, wouldnt have thought they would cause it though, if I rev it past 4k when cold it knocks. Not enough time for a coked up head to develop hot spots. I'm going to pull the map sensor and change the plugs, see if there's any difference.
 
Just been out with laptop keeping an eye on timings. I'd say About 55 degrees timing advance when it's clattering. If I hold it at 30 in 2nd for a bit (knocking) then floor it, it's fine.
 
More updates.

Cleared faults as there was a few from working on the electrics and unplugging things, 4 faults returned after a drive cycle. Injector, both coils and evap valve. Coils were active faults, other 2 were stored and none were requested the warning lamp. Evap has been replaced with a resistor and doesnt return a fault immediately after clearing unlike before I fitted the resistor.

Pulling the map sensor doesn't change the problem, and it cuts out when hot, takes full throttle to restart it, although I removed the map and it started right back up.
 
I've possibly worked it out.

Changed the plugs today, 2 and 3 were black with soot. The 1.1 ECU that ran it without knocking has less advanced ignition timing. When it cuts out with (I assume) heat, it restarts as if it's firing on 2 cylinders and requires full throttle to get going again.

I think a coil is failing and firing early, it's the only thing that's only related to cylinders 2 and 3 and can cause heat related stalling on a (fairly) cool engine and early firing along with sooty plugs.
 
Are the heat ratings the same (correct) on all your plugs?

And are the gaps right?
 
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Are you using an MPI ECU on an spi car?

Only other option if it is not faulty management is very high compression, skimmed too far maybe.

Do you have a compression guage?
 
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Its an 1108 SPI ECU from a Seicento. Plugs were the correct ones, although I've gone one hotter to help with the carbon deposits from leaky stem seals. The head will be coming off over Christmas to do the gasket and seals.

It's most likely to be a failed 2/3 coil, Expecting one to arrive within the next few hours, if it's not that then I don't know what to look at next.

I'll be making a set of HT leads today and hopefully the new coil will solve the issue :)
 
New coil did bugger all, 1.1 ECU is making it knock now too.

I give up with trying to solve it. I'm just throwing money at parts that don't need replacing.
 
I was starting to wander if it could be an issue with trigger phasing,

But people on here seem to swap 899-1.1 etc ECU from ohv to ohc engines without issue so the trigger must line up the same at tdc.

Can you adjust the air gap on the trigger?
 
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