My 1980 K-Jetronic had many goodies to meet new EPA standards including a warmup enrichment vacuum circuit, Lambda feedback enrichment circuit as well as vacuum advance and retard of ignition. Megasquirt has been great in eleminating all of these vacuum based potential problem areas. All of that junk is gone now and the motor is truely computer controlled. My car will actually drive smoothly with a bad power door vacuum solenoid. The new fuel plumbing consists of 8 injectors, two fuel rails, a fuel pressure regulator and some fuel line. I swear that with the old K-jetronic system if I sneazed in the cabin it would cause the engine to stumble
I have been driving my Mercedes for a couple of months now and I am still amazed that it starts EXACTLY the same every time I turn the key. Hot or cold it doesn't mater. I figure it is starting at about 3/4 of a second of cranking. Just minimally longer than it takes my 2003 Maxima to start but always exactly at the same amount of cranking.
She has been idleing better and more stable than she has since I owned her. This last weekend I changed my settings from 2 injections per cycle to 4 injections per cycle and she is even more rock steady at idle.
Acceleration is silky smooth without any flat spots. The throttle response is instantanious compared to the K-Jetronic. When you look at what has to take place when accelerating with k-jetronic it make a lot of sense.
1) Push on accelerator and open the throttle body.
2) A vacuum is created causing more air to enter the intake.
3) More air rushes in over the CIS measuring plate causing it to lower.
4) The fuel distributor opens to allow more fuel into the intake.
All of these take time and the mass of the measuring plate creates momentum. Add these up they make a big lag in throttle response. Add on top of this the imprecise nature of a mechanical control system. With megasquirt the properly metered fuel is injected near simutaniously with the opening of the throttle body and the arival of air in the intake.
The simplicity of the Megasquirt fuel circuit is so basic that diagnostics are almost eliminated once your car is tuned. I must admit that one of megasquirts down sides is that it does promote tinkering. Even though my engine runs so much smoother that with K-Jetronic it is hard not to try to get that last little bit of fine tuning. When I can sit in the air conditioned (Theoritically) cabin and make tuning adjustments with a couple clicks of the touchpad it is hard to resist.
I have talked little about the computerized ignition advance of MegaSquirt but this in itself is a major improvement over the vacuum based advance.
The process of installation has been such an education that I feel I have a much better understanding of how the fuel system is supposed to work and how to make changes and what I can expect the outcome to be.