Chimaera rough idle confusion

[Tim_C]

I also have a problem that my central locking will not unlock from the key fob. It's slightly intermittent, but mostly does not work at the moment. I was reading the forum for potential answers and came across this...

https://www.pistonheads.com/gassing/topic.asp?h=0&...

"TBH I just disconnected the door switches and the locking & unlocking function returned .... clearly the central locking/alarm unit was creating a huge drain as the car's idle quality and drivability has greatly improved since I disconnected the door switches."

Surely this couldn't be the problem here too??

I think my son has a youtube channel, I'll see if I can get him to upload the video of the sparkrites.

[BritishTvr450]

The alarm on many cars creates a parasitic drain on the battery as displayed by lots of very modern cars a friend sells on his forecourt. If left alarmed for more than 3 weeks they drain the battery similar to TVR.
I used my TVR almost daily for a long time so never had battery issues.

A fully charged battery is essential on a Tvr and a drained battery indeed causes all sorts of issues around running the car.
Possibly a good idea to check continuity and making sure door switches etc are not corroded or stuck causing more drain.

[Belle427]

I struggle to believe that problem would cause the car to run rough.

[Loubaruch]

The central door locking depends on decent pulses being received from the alarm/immobilier perhaps if the alarm/immobiliser is on the blink it could possibly be causing the smooth running problems.

Edited by Loubaruch on Thursday 4th July 10:04

[PabloGee]

Also not an expert, but I have heard of failing immobilisers causing drivability issues, even to the point of cutting the engine out (though those situations could easily be a combination of things).

The point about being recommended to revert from Iridium plugs to B7ECS is one I would challenge from what I've understood.

I believe B7ECS were initially put into our engines by TVR, which would give that plug style and rating a place in our narrative; but when you look more closely at driving conditions and real world use, many people have found the BP6ES or BPR6ES to give smoother running. The idea is that the hotter and non recessed plugs burn the fuel more holistically in the cylinders.
The 'R' is of course about added resistance, which is mostly about radio/ECU interference, and it's worth understanding the target resistance in conjunction with the leads your using.

Sorry, more discursive than anything else...

[BritishTvr450]

Belle427 said:

I struggle to believe that problem would cause the car to run rough.

I thought it was a well known fact a weak or drained battery can cause poor running conditions on Tvr cars.
I was always told your battery needs to be in tip top condition to avoid such anomalies.
I’m happy to be corrected if you know better.

[Loubaruch]

Maybe starting but surely once the alternator kicks in the battery is just a passenger.

[BritishTvr450]

Ok. In the past it’s something that’s been mentioned.
Maybe it’s simply a good idea to have a battery showing 12.6 volts and well over 13 volts when charging.
My memory is sketchy at best but I’m sure I’ve read a new battery solved issues possibly relating to the Ecu but far from definitive.
I defer to the more knowledgable.

[miniman]

Can’t speak for TVR specifically but certainly BMWs, Jags and Land Rovers misbehave with assorted randomness when battery gets weak, even when the engine is running and charging.

[Loubaruch]

Yes but modern cars have quite different charging systems e.g. only charging when braking and on the overrun the batteries are also kept low in charge purposely.

[Tim_C]

The car is currently sat in the garage on trickle charge, so the battery is always fully charged at the moment.

[Tim_C]

This is the video of it running with the sparkrites in place. #6 is the one in the middle (thanks for the tip on uploading James/miniman):
https://youtube.com/shorts/XrRrVe3OnlM?si=3Q0_X4YB...

It does hit the problem a couple of times in the video where the spark drops along with the engine note, particulatry right at the end of the video and towards the middle.

[mk1fan]

PabloGee said:

Also not an expert, but I have heard of failing immobilisers causing drivability issues, even to the point of cutting the engine out (though those situations could easily be a combination of things).

The point about being recommended to revert from Iridium plugs to B7ECS is one I would challenge from what I've understood.

I believe B7ECS were initially put into our engines by TVR, which would give that plug style and rating a place in our narrative; but when you look more closely at driving conditions and real world use, many people have found the BP6ES or BPR6ES to give smoother running. The idea is that the hotter and non recessed plugs burn the fuel more holistically in the cylinders.
The 'R' is of course about added resistance, which is mostly about radio/ECU interference, and it's worth understanding the target resistance in conjunction with the leads your using.

Sorry, more discursive than anything else...

TVR had an 'ethos' that the cars were to be driven in a 'spirited' manner, go on trackdays etc .. So they fited a 'colder' (the 7 in NGK ranges) plug to perform better at the higher temps that these high revs produce (put very, very simply). The reality is though, that a lot of [RV8] TVR owners find the cars plenty quick enough just riding the torque of the engine with low rpms. In these circumstances, a 'hotter' plug (the 6 in NGK ranges) works better at the lower temps of low revs (again, very, very simply put). Indeed, I met a 500 Grief owner who would have benefited from a '5' plug

[miniman]

Tim_C said:

The car is currently sat in the garage on trickle charge, so the battery is always fully charged at the moment.

Mine was on CTEK conditioner all winter, was showing as fully charged on the CTEK but was dead and unable to start the car.

[blitzracing]

Looking at the posts in general, I don't think low 12v is a route cause. Also some early versions of RoverGauge wrongly displayed the voltage although that was fixed a long time ago plus you have lots of healthy sparks on the other cylinders.

Taking lots of steps backwards you have the same fault with the 123 ignition, so really that rules out the ignition system on all fronts,

Re run the video test with the plug out of the cylinder and see if it varies in the same manner. Id disconnect the injector for that cylinder when you do. Unignited fuel and air blasted through a plug hole with a spark near by will blow your wig off. Guess how I know. :-)

if its only with the plug in place I'd be looking at combustion chamber conditions, such as compression, or faulty injector. You can certainly flood an engine with too much fuel and knock the spark, so its compression test time or swap a couple of injectors over and see if the fault moves.