For those attempting this, what is the approximate cost of the entire modification? I have K-Jet with aftermarket Lambda on my 79 280ce M110(european import)and it is starting to show its age. I really don't want to start dumping hundreds of dollars on OE parts and still have fuel issues. I am also very interested in hearing about performance/mileage improvements.
The cost of the Megasquirt unit itself is minimal, about $400 prebuilt and tested for you but the "miscellaneous" parts such as sensors, fuel injectors, wiring etc.. can be cheap if you already have them or can get them used, to many hundreds of dollars more if you need to purchase them.
I've got about $1000 invested already and will probably spend a few hundred dollars more by the time it's done, but I'm doing the "full" conversion to a crank sensor Distributorless Ignition system.
A frugal person could probably do the entire fuel only conversion for less than $500 finished.
My father has been ill and I went to visit him this weekend so I have made no progress on my install but I have started to put together a website. Here is a link to my INCOMPLETE bill of materials to help you with some idea on cost.
[url=http://www.hitechengineering.net/DNN/MegaSquirted450slc/tabid/54/Default.aspx[/url]
I will continue to update my website as time permits.
I was able to spend some time on my install this weekend. I got everything back together and wired everything with the relay board. I pulled out a lot of stock ignition wiring and cleaned things up. I spent a good hour trying to get her started back up and it would run for 15 seconds then die. This frustraited me for a while then I remembered having the same problem when I initially got her running.
TIP: If you are using the stock fuel relay it will not energize unless the system detects the engine is running. I.e. No Tach = No fuel = No go!
When you turn the ignition key the fuel relay energizes the fuel pump for a moment then turns off power to the pump. When the fuel relay circuit detects the engine is running it energizes the fuel pump again. The green/yellow wire from the bosch ignition box needs to be connected the the green wire and green/yellow wire from the diagnostic connector.
The stock fuel pump relay circuit works very well and everything is already wired in with the proper fuses etc. The only thing you have to make sure of is that you feed a tach signal to one wire in the engine bay. This can be a tach signal from the stock Bosch ignition, the Ignition out line from Megasquirt or the tach out from the MSD. Either way it saved a lot of wiring using the stock fuel relay and has proven to be reliable. I just needed to refresh my memory from over a year ago about the tach signal. The Tach signal also feeds the instrument cluster tachometer.
I pulled the majority of the stock ignition wiring to straighten things up. I am running a MSD6AL for ignition. This made the stock ceramic low resistance resistors mounted on the driverside fender surperflous. The MSD drives the coil directly and does not need any external resistance. Under the mounting point for the resistors on the driver side fender there is a 2 post terminal strip. On one of the posts is a green/yellow wire and a green wire. I believe the green/yellow is the tach signal for the dash tachometer. I believe the green wire is the tach signal for the fuel relay circuit. I believe the green/yellow wire from the Bosch ignition box was originally connected here. I just needed to reconnect it after my cleanup.
The fuel relay circuit is completely independent of the K-Jetronic CPU. I have my K-Jetronic module completely removed and the fuel relay circuit still functions as it should. My theory is that the tach signal detection is actually within the fuel pump relay itself but it has been quite a while since I looked at this schematic.
I am considering removing the bosch ignition box altogether to further simplify things. This would leave megasquirt reading the tach signal directly from the distributor (VR I believe). But for right now the Bosch box is doing a good job of conditioning the signal and with the MSD driving the coil (or megasquirt directly) there is really no load on the bosch box. By my thinking this means it should last a long time as the power transistors are switching a very small fraction of the current they were designed for.
Any way it is nice to have the old girl back on the road again! I drove her to work for the first time in about two years. She was running over a year ago and running well a few months ago but the rats nest wiring was pretty bad. Installing the MegaSquirt relay board made a huge difference in the cleanliness of the install. I also feel much much better about the reliability as everything is well laid out and tight.
I hope to post some pictures and commentary about the wiring on my website later on this week. I will also post some gas mileage figures as they start adding up here in this forum.
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