1 hour makes all the difference
Discussion
Just spent an hour fitting some ACT Carbon trumpets to the Chim.
Easy job, even for me, once I'd spoken to Tim and realised I'd have to bend back the black 'mesh' below the windscreen to get the plenum released.
A quick drive out has proven the car is breathing and running much better, and slightly less 'popping and banging' from the exhaust leads me to believe it's not running as rich.
£300 well spent; utterly chuffed. Well worth putting on the list of things to do !
(and, for the record, I've no connection with ACT whatsoever, other than a satisfied customer !!)
Mike
Easy job, even for me, once I'd spoken to Tim and realised I'd have to bend back the black 'mesh' below the windscreen to get the plenum released.
A quick drive out has proven the car is breathing and running much better, and slightly less 'popping and banging' from the exhaust leads me to believe it's not running as rich.
£300 well spent; utterly chuffed. Well worth putting on the list of things to do !
(and, for the record, I've no connection with ACT whatsoever, other than a satisfied customer !!)
Mike
mgaut said:The thing you might have missed is that if you are flowing more air you will also flow more fuel - the air flow meter sees to that. Kind of how the "throttle" works - that's a restriction to the airflow just the same as the trumpets were, but its a variable one. You vary the air flow by pressing the pedal, the airflow meter adjusts the fuel flow to match.
so if it was running lean, and I've just helped it get better air in by improving the air flow, surely it should be running even leaner now ?
apologies if this is a dumb question and I've missed the bleedin' obvious
Mike
chassis 33 said:Popping and banging results from unbrunt fuel in the exhaust. This occurs when you decelerate. When decelerating the ECU prevents spark at the plugs resulting in unburned fuel entering the hot exhaust and igniting on the hot surfaces. If you take your foot all the way off the accelerator the ECU will also cut fuel off completely, only restoring it as the engine reaches tickover so popping and banging won't occur. If you want to produce popping and banging slightly depress the accelerator when decelerating.
pst...popping and banging means running lean, too lean for the spark to ignite the mixture, so it ignites in the exhaust when it explodes on the hot exhaust.
Regards
Iain
The popping and banging that Iain is commenting on is the type that happens when accelerating.
tvrbob said:
If you want to produce popping and banging slightly depress the accelerator when decelerating.
thanks Bob (and all); believe me I'm a past master at this (that long tunnel somewhere near Renne on the way back from Le Mans last year
) but it isn't doing that much now, which I thought was a good thing as per my original post. tvrbob said:
When decelerating the ECU prevents spark at the plugs resulting in unburned fuel entering the hot exhaust and igniting on the hot surfaces.
The only connection between the ignition circuit and the ECU is the feed that goes from the negative of the coil via a 6.8k resistor to pin 39, this gives a signal to the ECU that the engine is running. The ECU on hotwire engines has no control over the spark.
Popping and banging on acelleration means you have serious fuelling issues and the engine is dangerously lean.
Regards
Iain
chassis 33 said:I'm confused, this isn't the opinion I've gained from other discussions here. I wonder whether the Serp is different than your RV8 ECU.
The only connection between the ignition circuit and the ECU is the feed that goes from the negative of the coil via a 6.8k resistor to pin 39, this gives a signal to the ECU that the engine is running. The ECU on hotwire engines has no control over the spark.
Popping and banging on acelleration means you have serious fuelling issues and the engine is dangerously lean.
Regards
Iain
Take a look here http://homepages.nildram.co.uk/~eliot and also
www.rangie.com/articles_topic.php?id=167&cat=7&subCat=51
All the ECU controls is the fuel, the spark is controlled from the dizzy, the
signal is amplified in the ignition module and is fired by switching the
negative side of the coil, which is why the mounting bracket for the
ignition module has to be earthed.
The connection to pin 39 is so that the ECU knows that the engine is running and is the only way the ECU knows the engine is running, if not it switches off the fuel injectors and the fuel pump relay.
Regards
Iain
www.rangie.com/articles_topic.php?id=167&cat=7&subCat=51
All the ECU controls is the fuel, the spark is controlled from the dizzy, the
signal is amplified in the ignition module and is fired by switching the
negative side of the coil, which is why the mounting bracket for the
ignition module has to be earthed.
The connection to pin 39 is so that the ECU knows that the engine is running and is the only way the ECU knows the engine is running, if not it switches off the fuel injectors and the fuel pump relay.
Regards
Iain
Cider Andy said:
A serious question here, as I'm puzzled Iain: how can an engine run dangerously lean?
As the mixture leans out you get increased temperatures in your cylinders, this can lead to detonation, as the fuel explodes when it comes in contact with the exhaust valve (which doesn't benefit from the cooling effect of the fuel passing it, unlike inlet valve. Detonation if left unchecked can cause accelerated wear of bearings due to the shock loadings.
The other thing that can happen is that the piston can literally melt like in this picture
and then things start getting expensive. There's loads of examples if you Google for "piston" "lean" "melt"! But I must stress, you have to really mistreat your engine for things to get that bad!
Regards
Iain
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