My dad and I have begun discussing some upgrades we want to do to our '73 Mercedes 450SL, which is currently equipped with a very rudimentary speed-density which operates on a very low pressure that we're not very pleased with in the least. I proposed replacing the old system with a modernized, Megasquirt-driven custom system, which he quickly came on board with.
What we're not sure of, though, is whether we should fit it with coil-near-plug sequential ignition and sequential injection available with an MS3X system, or whether an MS2 (or plain MS3) running EDIS-8 and batch-fire would be sufficient? From what I've read, sequential injection puts less strain on the fuel rails and pressure regulator, since the pressure in the fuel rail isn't so severely depleted with every injection event. There's also the added benefit in the case of not spraying fuel onto closed valves, offering slightly better emissions (hah) and fuel economy.
As for sequential ignition, the only difference I could find is that a coil has more time to recover between ignition events. Other than that it's added complexity and cost. But hey, it'd be cool (dad's rationalization).
However, sequential injection/ignition require both a crank and cam signal. We've talked about having a tone ring fitted to the harmonic balancer for the crank signal, but would it be possible to use the old breakerless ignition driver (think 40-year-old Pertronix kit) to provide the system with a usable cam position signal? (Yes, the advance mechanisms would be disabled.)
This or That
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0).
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
Re: This or That
If thinking about sequential injection, you'd do best to move to the MSExtra forum.
Dave P, London UK.
Rover V-8
MSII V3
EDIS
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Rover V-8
MSII V3
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Matt Cramer
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Re: This or That
On the other hand, the "less strain on the fuel system" is a bit more academic than something I've seen in the real world. The largest benefits I've seen from sequential are a leaner idle and better light throttle behavior.
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DonTZ125
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Re: This or That
Agreed. When it comes to fatigue, frequency is of much greater concern than magnitude (otherwise you're dealing with shock and plastic deformation, not fatigue!), and fuel rails tend to be so over-designed that fatigue is rarely an issue.
