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Discussion Starter #1 (Edited)
This write-up will describe how I changed the "old" Bosch K-Jet fuel system on my 280SL -85 to a modern EFI-system and it will probably also work on the older Bosch D-Jet system.

I will try to cover as much as possible regarding our engines when it comes to different options and installations but in the end, anyone planning to build and installing a MegaSquirt EFI system will require that you do some homework.

IMO.. It's the best you can do for your car...

First of all I want to say that I have stolen some texts from other sources and pages which describes things better than I ever could so it's possible you recognize some parts of the write-up.

I will not explain in detail everything I've done to mount everything or manufactured since it quite straight forward and a picture says more then 1000 words. Hopefully I will keep this thread living and share future events regarding the rebuild.

A little glossary.

EFI: Electronic Fuel Injection.
MS: The MegaSquirt EFI system
ECU: Electronic Control Unit (the brain in the EFI system).
AFR: (The Air:Fuel Ratio (AFR) is the amount of parts of Air to one part of Fuel in the mixture. E.G. an AFR of 15.9 is 15.9 parts of Air to 1 part of fuel. An AFR of 14.7 is stoichiometric, which is the most efficient mixture for a petrol engine, so it produces the minimum emissions. Best power is produced around 13-12.5AFR. A lower AFR means more fuel (Richer), a higher AFR means less fuel (Leaner)).
TPS: Throttle Position Sensor.
CLT: Coolant Temp Sensor.
IAT: Intake Air Temp. sensor.
MAP: Manifold Air Pressure sensor which measures the absolute pressure in the intake manifold (included and mounted on the MS board).
VR sensor (Variable Reluctor sensor): Trigger sensor for detecting crankshaft position .
FP: Fuel Pump.
FPR: Fuel Pressure Regulator (needs to get correct pressure for injectors)
Triggerwheel: Toothed wheel mounted on crank-pulley to detect TDC

Some info regarding MegaSquirt (from MegaSquirt Wiki).
MegaSquirt is the registered trademark of an aftermarket electronic fuel injection (EFI) controller designed to be used with a wide range of spark-ignition internal combustion engines (i.e., not diesel engines.) It is a complete standalone fuel injection controller with software and hardware, developed by Bruce Bowling and Al Grippo, developers that work on the US East Coast. The software for the platform is open for modification (for use on Bowling and Grippo hardware only). The hardware provides for only fuel, ignition and idle air control in most cases, keeping the cost low (though there are user configurable outputs in most cases for other functions). The hardware is open in that the schematics are available for troubleshooting and educational purposes, but not for copying. The product is aimed at the DIY market as in most cases MegaSquirt requires assembly and tuning by the user.

The assembled controller takes input from several sensors in order to manage the fuel injectors, including a throttle position sensor (TPS), exhaust gas oxygen sensor (EGO or O2 sensor), MAP sensor, tach signal (or crank position sensor), intake air temperature sensor (IAT), and a coolant temperature sensor (CLT). The latter two sensors themselves are usually the General Motors type, although you can recalibrate the controller to use other sensors including Ford and Bosch.

My comment:
There are different versions of the MS ECU (MS1, MS2 and MS3) due to the evolution, faster, more functions etc. I used the MS2 since it's the most common one but MS3 are the latest one and will probably get more and more users which gives better support in the end.
There are also different software depending on how one will use it but for us r107 owners I think the MS2's "extra code" software (I think version 3.11 is the latest), is the best one since it can easily be configured to handle our needs.

Why then?
The K-Jet system in my car worked very well without any problems. Since I had a late model (1985) I also had an oxygen-sensor (lambda) and a catalytic converter mounted on my car. Before the installation of the new fuel system I changed the old narrowband oxygen-sensor to a new wideband oxygen sensor and an Air/Fuel Ratio (AFR) gauge. I could monitor the actual fuel-mix while driving and the Bosch K-Jet worked over all expectations. Lean fuel mix (above 14.7) while cruising and richer mix (below 14.7) when accelerating, just as it should.

BUT there was something "old" over the engines character since I could feel a little "lag" in the engines response. I was looking for a little more modern character in the engine, and it has happened a lot during the last 30 years when it comes to optimizing the engine's fuel and ignition control. And don't forget what it cost to repair those old systems. The best part is that I can easily restore it to original again without any problem since I didn't make any damage to the original parts.

Some things that I think are worth knowing when making the decision.
The relay board is optional, and as the name implies, holds the EFI related relays as well as fuses. It also provides you with a single spot to wire in all of your sensors, injectors, and fuel pump.
Really save some time when installing the system. And gives you ONE grounding point for the whole installation which will prevent electrical interference.

MS can also control start and stop of an electrical Fan (via a relay), it's possible to set up exactly when to stop, start, hysteresis etc in the software.

It can control different types of idle "steppper motors.(upper left corner in picture)

If one replaces the ignition system, Megasquirt has a 12V square wave tacho signal out of the box. The only thing to do is to remove the cord from the Bosch system and replace it with the one from the relay board. Works perfect without any modifications.

If the relay-board are used, there is a FP-relay which gives a +12V to control the FP. I just removed the old FP relay and connected the FP-relay output to the empty FP-relay socket's FP power source.
Otherwise one must connect the MS's FP-output to a new relay for controlling the FP.

I could mount everything on the engine except the injectors and drive it for a while to see that everything worked as it should. Then I just removed the K-Jet system and mounted the Fuel rail and connected the injectors.

So what do I need then.
There are many "3d" party fuel system vendors but the reason why I selected Megasquirt EFI system is the vast community supporting it, the price and if it's correctly assembled and mounted, it will work without any problem for a long time. I know amateurs who had put it in their old Volvo's without any knowledge about fuel injection system and have had it running without problems until the car was too old and too broke to repair, then they just moved it to their next car... still running.

1. If one only wants to replace the fuel system.
The cost for new parts (assembled kit inside the parentheses).

MegaSquirt-II(ver.3.0) EFI System 260(420)$.
MegaSquirt Relay Board 64(88)$ (optional but makes it easier to install).
Cable for connecting MS ECU to Relay Board 75$.
GM Coolant Air Temp Sensor 17.75$.
GM Intake Air Temp Sensor 17.75$.
Throttle Position sensor (from a Volvo 850) 50$
Fuel rail (I paid 150$, ready to use for my 6cyl, V8 K-jet needs 2 shorter ones and D-Jet can probably use the original one).
6 to 8 Injectors (suppose you can find standard Bosch injectors like mines in any scrap yard and I have heard that injectors from Ford Mustang will fit without any modification).
FPR (Fuel Pressure Regulator) I found a used on, did cost 100$

MegaSquirt Simulator w/ Wheel Simulator 59(88)$. If one wants to test the system before mounting or just troubleshooting, the MS simulator is a good investment.
Wideband Oxygen sensor: 199$. Not necessary but make it a lot more easy to tune in the EFI system since you can see exactly how lean or rich the is engine running. When the engine is tuned in the sensor can be removed so maybe one can borrow the equipment for tuning.

2. If one wants to replace the ignition system
36-1 Trigger Wheel 25$.
3 Bosch BIP373 coil driver transistor 8$ each (V8 needs 4 drivers).
There are a ready module "QuadSpark Four Channel Ignition Module" if you don't want to build it yourself but it cost 89$ instead of 4x8$ (BIP373 coil drivers).
IGN-6 Six-Tower Coil Pack 75$.
Trigger sensor (from a mecedes Vito I think) 50$.

I took the easy road and bough myself a spare motor, then I could use the spare top and intake manifold to experiment and measure on.

Picture 1 shows the MS ECU, Relay board and the 3 Ignition transistor drivers attached to the Relay boards back chassis which controls 2 ignition coils each on my 6 cylinder engine. Ignition 6-Coil Pack to the right.

Picture 2 shows MS ECU, the cable between MS ECU and Relay board. You can see the simulator connected instead of the relay board and also the optional display where each value can be displayed and altered e.g. if it's mounted in the car.

Picture 3 shows the standard MS installation where the trigger signal for injectors is taken from the ignition coil, best choise if only replacing the fuel system .

Picture 4 shows the standard MS installation where the trigger signal for injectors is taken from a toothed wheel which is mandatory if one want to control the ignition.

Picture 5 shows the AFR gauge mounted in the center air outlet, really shows how well the fuel system performs.
 

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Discussion Starter #2
This is how I did it..

TPS.
The MegaSquirt controller uses the throttle position sensor (TPS) to determine for example... when the engine is at or near full throttle (to shut off feedback from the O2 sensor), when the engine throttle is opening or closing rapidly and needing an accel/decel enrichment. It also cut off fuel when decelerating.

First I visited the nearest scrap yard and bought a TPS .
Usually the TPS is mounted on the "butterfly" valve's shaft directly on the throttle house but since I didn't want to buy a new throttle house I decided to mount it somewhere on the linkage to the throttle instead.
Since I couldn't mount it on the throttle house I had to find a other place which rotated 90 degrees, the same as the throttle valve. I found a linkage which moves around a fixed shaft which I will use. Before I could mount the TPS on the linkage I had to make some fabrication.

I started to grind down the plastic bushing, by doing this the shaft is exposed so it can be used by the TPS. It was also necessary to cut a new "track" for the locking clip which holds the linkage in place, I used a "Dremel" tool and a small cutting disc to do this. I connected 5v and measured at WOT (Wide Open Throttle) and when it's closed, you also see that the TPS moves instead of the shaft it's mounted on. Fortunately, the TPS did not reach any of its end positions since the linkage didn't really move 90 degrees. The accuracy is enough since I will set both end positions in MS's tuning program.

It did take some fabrication and I'm not sure yet if it's a good construction or not since the cords from the TPS will move every time I hit the pedal and the linkage moves. It's not really a big problem since I will mainly use the MAP sensor which measures the absolute pressure in the intake manifold, for all calculations in MegaSquirt. So time will tell, I can always buy another throttle house with a TPS mounted on it.
 

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Discussion Starter #3
Sensors

CLT in an empty "slot" beside the original coolant sensor.
IAC sensor in the spare engine's fuel distributer house which stripped from everything and sealed. Now I could use the same air filter as before without any modifications.

A vacuum hose to the MAP-sensor (located on the MegaSquirt ECU). Now all inputs to the MegaSquirt system are in place
 

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Discussion Starter #4
Injectors

I've turned down a "standard Bosch injector" (0280 150 792) to exactly the same diameter as the stock plastic injector holder. In that way both the stock injector and the new one are identical in size and will use the same seal (o-ring) as original. I also had some spacers made which places the seal in the same position as on the stock one.

I used 2 o-rings on each injector just to be safe, I don't want any leakage. You can see how nice the new injectors fit, notice the spacer which put the seal in a correct place.
When ordering the fuel rail the distance between the injectors must be correct.

The measurement for a Mercedes M110 fuel injector distance in mm

I----93,5----I----93,5----I----93,5----I----93,5----I----93,5----I
I----------------------------- 467.5 mm ------------------------I

The picture shows the distance between injectors on a 450 engine, but do some extra measurement just to be sure.

I had no problem removing the old K-Jet in one piece since the rubber seal on the injectors where dry and hard, I just pulled it right off. The right side of the fuel rail is connected to the original fuel-hose/line and the left side has a banjo-coupling which I took from the spare motor. The fuel return then goes via the FPR back to the fuel tank. The FPR is adjusted to 3bar since this is the flow rate my injectors are specified at and the engines calculated fuel requirement.
 

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Discussion Starter #5 (Edited)
Relay board

I mounted the Relay board on the left side in the motor bay which is connected via a cable to the ECU mounted under the steering wheel. Though the Relay/Power Board is not required, it is a convenience and reduces the chance of miss-wiring during the installation. The relay board provides a central place for all of the required relays, fuse protection, and external wiring for the MS ECU.

I used one power block for 12 V directly from battery and the other gets 12V when ignition turns on via the relay below them on the picture. I used the brown cable which used to supply the old ignition coil to +12V, to draw my new 12V ignition relay.

I decided not to use the original Fuel Pump relay and uses MS Relay board's FP relay instead.
I removed the FP relay under the glove box. You can see the thick red cord(5'th from left) at the Relay board which goes to the old Fuel Pump relay socket (Picture no.3).

It does work with the original FP relay as long as there is a a tacho signal precent either from the original ignition or a tacho signal from MS ( see "Regarding the tacho signal" below)
 

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Discussion Starter #6 (Edited)
Fuel rail.

After I had removed the complete Bosch K-Jet system I cleaned things up a little.

I reused the adapter from the spare fuel distributer so I could use the original fuel hose on the fule rail, the fuel-return goes via the FPR (Fuel Pressure Regulator) back to the fuel-tank.

It could be a good idea to test the fuel rail and injectors before mounting, I connected the fuel lines, fixated the injectors to the fuel rail then wired the FP and used the injector test in the MS Software. No leaks and the spray pattern were perfect.

Attached the fuel rail brackets, injectors and fuel rail.
Made the wiring by soldering injector 1-3-5 and 2-4-6 together since they are fired together. Used shrink-tube to isolate and protected it all using electrical tape.

Connected the 6 injectors to the Relay board, I used 3 parallel small +12V cords instead of one large since I could use 3 connectors on the relay board (if one gets loose two are still connected).

You can see the complete fuel installation on the last picture, from fuel rail -> FPR -> to fuel tank
 

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Discussion Starter #7 (Edited)
Oxygen (Lambda) sensor.

To be able to use "close loop"and optimize the fuel injected into the engine, the Megaquirt FI system needs a wideband oxygen sensor to be used to give feedback to the MS ECU about the amount of CO in the exhaust gas. I bought a sensor from Innovate which also has a gauge showing either the Lambda or the AFR (air/fuel ratio)-value which I mounted in the center ventilation output on the car.

Since my car alredy had a narrowband oxygen sensor controlling a "frequency-valve" which helped the WUR to adjust the control pressure in the K-Jet fuel distributer, I can put the new sensor where the old one where mounted.

What is a lambda meter?
A lambda meter measures the air/fuel ratio using an oxygen sensor in the exhaust gas. It is important when tuning to measure and adjust the air/fuel ratio in order for the engine to run correctly.

Lambda vs Air/Fuel ratio
The air/fuel mixture is expressed either as the ratio of air to fuel vapor or as a lambda value. The lambda value is derived from the stoichiometric air/fuel ratio, which is the chemically correct ratio of air to fuel for complete combustion to take place. The stoichiometric ratio is 14.7:1 when expressed as an air/fuel ratio, or 1 when expressed as a lambda value. A richer mixture will have a lower air/fuel ratio and lower lambda value. e.g. an air/fuel ratio of 12.5:1 equals a lambda value of 0.85, and is a typical value for a naturally aspirated engine under full load.

Tuning mixture
The optimum mixture varies with engine type, engine load and speed, operating conditions and operator preference.

In general it is best to tune the mixture close to stoichiometric up to moderate engine loads for engines using catalytic converters and running in closed loop. This will keep the long term mixture adjustment from altering the mixture at points in the fuel tables where the ECU is not running in closed loop.

From moderate load to atmospheric pressure the mixture can be made progressively richer for increased power, cooler running and less chance of damaging the engine. Usually the air/fuel ratio which produces maximum power is from 12.5:1 - 13.5:1, but this varies with engine type. At cruise, lean mixture above 14.7 up to 15.5 will save fuel.
 

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Discussion Starter #8 (Edited)
Regarding the tacho signal when converting to Megasquirt (If ignition is replaced otherwise MS take the trigger signal from original ignition coil).

When the ignition is turned on, the fuel pump starts for a couple of seconds to build up the fuel pressure and then stops again, if the car starts as it should the Fuel Pump relay detects the tacho signal (engine is running) and starts the fuel pump. This to prevent the fuel pump to deliver any fuel when the engine isn't running, don't want any fuel if you have crashed the car, would you?

The original tacho signal is fetched from the Bosch ignition system (at least on my car from 1985) and are used both for Fuel Pump relay to detect that the engine is running and tachometer. If one removes the original Bosch ignition, one must replace the tacho signal also otherwise the fuel pump will never start due to missing tacho signal to the Fuel Pump relay.

The good news is that Megasquirt has a 12V sqare wave tacho signal out of the box. The only thing to do is to remove the cord from the Bosch system and replace it with the one from the relay board. Works perfect without any modifications.

You can see the purple cord connected to the green/yellow cord on the original "connector" which is the tacho signal going to the original fuel relay and tachometer, the red (not used on the connector) cord is the 12V supply to the old Bosch system.
 

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Discussion Starter #9 (Edited)
Conclution of first real drive after the swap.

What a difference, never seen that needle move so fast when I hit that pedal. First of all, the idle... it's so rock steady... In "P" it stays on 800 +/-20 rpm and when putting it in drive it slows down to about 600 rpm without any hesitation. The sound from the engine is also different, more smooth and it responses direct on any throttle-change, before there were a little lag.

I spend 50$ to registrate the Tuning software for MegaSquirt and to enable the auto tune-feature. Made a ruff estimation of the Air/Fuel need and created a map(picture). Vertical axle is the Load(Throttle opening) and Horizontal the rpm...

Acceleration = rich mixture(below AFR 14.7:1 green area).
Cruising = Lean mixture(above AFR 14.7:1 red/brown area).

At normal cruising I usually have a load between 40 to 50 and 2500rpm , so my Air/Fuel-ratio stays over the optimal lambda 1 (AFR14.7:1), a little lean when cruising...
At idle (600-800rpm) I stay between AFR 13.7 to 14.7, a little rich when idling...

The software then use this AFR-map as target and the wideband-lambda sensor to tune in/correct the necessary amount of fuel in the actual fuel map.

Took the car for a ride, started the auto-tuning and It just got better and better while driving. Of course it needs more fine tuning but the car runs better than ever before although I had a well working K-Jet system before. When everything is tuned in, the sensor can of course be removed.
 

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Discussion Starter #10
Ignition

If one only wants to replace the ignition system, its a little overkill to use MegaSquirt since it’s mainly made for controlling the fuel injection and the ignition control come as a bonus. There are many 3’rd party dedicated ignition systems which do exactly what my setup does probably for a better price if one only want to modernize the ignition system

MegaSquirt can handle many different types of ignition e.g. it can drive the original (single) ignition coil directly “out of the box” without any modification since there are one high current ignition driver circuit built in but the trigger wheel must be used to detect TDC position. By using the complete setup of sensors, the ignition advance/retard can be dynamically modified due to coolant temp (for easy start), idle, altitude, Intake air temperature etc.

In my case, I’m doing a EDIS6 Wasted Spark setup which do exactly what Ford’s Edis “Wasted Spark” system do except that I don’t need Ford’s Control unit to ignite the coils in the Coil Pack. Since there only is one high current ignition driver circuit built in I had to buy 3 new ones to drive the 6 Coil Pack (instead of using Ford EDIS ECU which contains similar circuits).

If one doesn’t want to use any extra high current ignition drivers as I did just get Fords EDIS ECU and Coil Pack from nearest scrapyard and let Megasquirt control the Ford EDIS ECU using only 2 wires, one to get the trigger wheel sensor signal to Megasquirt ECU and one to tell the Ford EDIS ECU to ignite the spark(in this case the trigger wheel sensor must be connected to the EDIS system instead of the MS system (thats the extra wire to MS from EDIS).

In the software I selected
• Wasted spark as ignition system
• number of cylinders
• number of teeth’s on my trigger wheel and automatically 3 output are assigned (accessible on the relay board) which I use to enable my 3 high current ignition driver circuit which I mounted in the Relay box for easy wiring (see picture).

When replacing the ignition, the only challenge was how to attach the trigger wheel and sensor. I first had an aluminum adapter made which proved to be too weak (due to poor design since it didn’t fill the whole pulleys inside void and using countersunk screws.), the holes for the screws got bigger and bigger somehow and the whole adapter could be rotated a little inside the pulley. Instead a steel adapter was made which is mounted together with the “flywheel”, needed 6 new longer bolts for that.

The Megasquirt ECU will control the ignition by using 3 "coil driver transistors" witch fire 2 spark-plugs at time (Wasted Spark) via a 6 Coil Pack. The "coil driver transistors" are mounted at the Relay Board's aluminum chassis and the signals are taken from the circuit board.

The Coil Pack costs about 450kr (75$) and the transistors about 50kr (8.5$) each. The Coil Pack can probably be found much cheaper at nearest junkyard...

Very simple function, the coil has a permanent 12+ connected to one side and the other side of the coil are grounded via the "coil driver transistor" when it's time to fire. This will replace the distributor, old transistorized ignition box and coil.
 

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Discussion Starter #11 (Edited)
This is just to give a little hint and "know how" regarding the Tuning Software

Tuner Studio is a freeware but have some limitations compared to the registered version. It can be downloaded from Welcome to EFI Analytics! | tunerstudio.com , it's a very small program to download and install if anyone just want to check it out.

I started from a default project and just filled in my injectors flow rate (244.9 CC at 3bar) calculated the "Required Fuel" which are used when setting up the values in the VE-table.

Used the standard "Control Algorithm" to "Speed Density" which means that all calculations are based on the MAP-value (Manifold Air Pressure) instead of the throttle position.

For ignition I have used a toothed wheel and here comes the nice part of the ignition configuration.
By selecting Wasted spark in combination with D14 (actually output for led 14 on the MS cabinet), MS will automatically assign output D14, D15 and D16 for Ignition to my 6 Coil pack via 3 Bosch BIP373 coil driver transistors mounted on the back of the Relay board . I also have to fill in the Dwell time (charging time for each coil). In the Trigger wheel setup I have to enter number of tooth's and how many degrees the sensor is mounted before TDC which is 50 deg. in my case.

I don't use the Idle control outputs, instead I have used the "PM2 FIdle output to control my electrical fan. As shown in picture it starts when the temperature reaches 88 deg C with a little hysteresis to avoid toggle on and off AND RPM is above 300rpm (don't want fan to use any current when cranking the engine).

The Warm-up Enrichment is the extra fuel added to the ordinary fuel when the engine is cold. At most I add 40% more fuel and decreasing it to 0 % at 72.3deg C.

There are also After Start Enrichment which gives a specified extra % fuel for e.g. a specified number of ignition events or trigger pulses (Taper cycles) which helps the engine to stabilizes the idle directly after the engine starts.

I use a Fuel cut off when the engine is over 1500rpm AND the Throttle Position Sensor is below 5% opened, this save fuel ...

Everythingabout the configuration above is very straight forward, there is an endless amount of information on the web for almost any engines and applications but when it comes to the fuel and Ignition maps it gets more fuzzy...

As usual I did it the easy way, I measured my ignition curve using a stroboscope lamp before switching the ignition and used that to create a decent ignition map which works very well in my opinion (see picture) there are certainly more to be done on it but it works very well as it is.

I mesured:
10 deg / at Idle (800rpm)
28 deg / 1500rpm
44 deg / 4500rpm
Since it's possible to fine tune the fuel and ignition those values are very ruff but work as a start map.

The AFR table is made by me and the VE table is auto tuned from the projects default map.

The VE-map is where the actual amount of fuel at every rpm and load are stated and it's impossible for me to know the values here. The default map which comes with the project is said to work on almost any car and it did work on my engine quite well, maybe run a little rich but that's better then to lean.

Again I took the easy road by using the wideband oxygen sensor which tells exactly how the Air/fuel mixture is. By setting up the AFR map (which automatically interpolate between the cells ) I can use the auto-tune function in the registered version of Tuner Studio.

I do know that during cruising I should have a lean fuel mix and at accelerating I need a richer fuel mix. As you can see on my AFR map, at 600 rpm (idling with gear in D or R) I have a little richer fuel mix to avoid stalling. The red part is when I'm cruising and the upper row is at WOT (wide open throttle). At WOT almost every naturally aspired engine lays around AFR = 13 at max torque and AFR = 12.5 at max HP and this map works perfect.

The VE table is a result of the auto tuning calculations based on the Req. Fuel and the AFR table. For each cell the auto tuning reads the AFR and changes the VE table's value until the actual AFR value from the oxygen hits the value in the AFR table's cell.

Overall I must say that there hasn't been any problem doing the configuration since all optional settings in the program must be manually enabled so when starting only the basic configuration dialogues are enabled.
 

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Discussion Starter #12 (Edited)
Idle and Cold start

The cold start equipment on Bosch K-Jet consists of two things as far as I know, the cold start injector valve and the auxiliary air regulator. The injector is mounted at the intake manifold and supply some extra fuel during startup.

I think this is how it works on the other K-Jet system equipped engines too. If there is some kind of "Idle motor" or simular I'm quite sure MS can handle it since there are lots of options to select amoung for controlling the idle (see picture). The Relay board has 4 outputs for this which can be configured from the Tuning Software.

The auxiliary air regulator is mounted under/behind my intake manifold. When the engine is cold it’s wide open and provides extra air via the “idle screw house/tube” then to the air cleaner, it closes gradually when the engine gets warmer. The rubber hose to the auxiliary air regulator can be seen going down under the idle adjustment screw in the picture.

Since MS has a warm-up enrichment curve where one can for each temperature set exactly the amount of fuel added to the normal fuel map, the original cold start injector can be disconnected.

I have left the auxiliary air regulator as it is since it was hard to reach and too disconnect. The engine probably gets a little too much air when it's cold but it’s probably compensated by the cold start enrichment.

Since I used a other "Fuel distributer house", the original rubber hose from the Idle Screw house didn't fit, instead I used a rubber hose to connect the idle air intake to the air cleaner( see arrows in picture).

I haven’t had any problem during cold start so far. For every day it gets colder outside I do a test start and tune the cold start enrichment.

The Idle must of course be tuned when the engine is warm. I just turned the Idle screw until the idle stayed at 800 rpm.
 

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VERY cool, I'll be keeping an eye on this project. I have a K-Jet engine outside of my car and think Megasquirt EFI would be way more efficient than the constant spray of the CIS.
 

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Discussion Starter #16
Thougt I could edit older posts, they are to old maby...
Anyway, the spring is coming to south of Sweden so I have started to consolidate what I have done so far and I noticed that I have forgot to mention one little thing which could help anyone who's planning to do something like this and planning to find a suitable Fuel Pressure Regulator (FPR).

When I turn on the ignition, MegaSquirt gives a priming puls for a couple of seconds to build up fuel-pressure, this pressure should be held for at least a couple of minutes. If the engine isn't started the Fuel pump stops again and doesn't start until it gets a signal that the engine is cranking.

Unfortunatlly the Malpassi FPR I bought and used doesn't hold the pressure as I thought, seems to be some kind of bypass or just leaking. I thought that it was only mine but now I know that they all work like that.

So if I just turn on the ignition without starting the car, the fuel pressure drops almost immediately, as soon as the engine starts cranking the fuelpump starts again but (could) give 1-2 seconds of unnecassery cranking while the fuel pressure builds up again.

I have now finally found a FPR which says holding fuel pressure for at least 20 min and also works as a damper : "SX Performance 15404 -6 AN Fuel Pressure Regulator" , you can check it out for yourself...

I will soon order one from the US and see if it works better than the one I use right now.

ps. Since my odometer and trip counter now works I will start messuring the fuel consumption which is very interesting IMO.
 

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Nice
I like the 2 wire on off idle valve(not pwm), just for ease, it can be triggered by a switch to save an output on a non dd




Sent from my Autoguide iPhone app
 

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There should be a setting to prime the pump when the box fires up, and options on prime pulse and such, that should cure ur for issue, If u turn the key in and give it a sec for the prime pulse



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Discussion Starter #19
I don't understand what you mean, please explain...

My (very small) problem is that the pressure drops immediately after the priming pulse ends, no matter the length of it.

So if I dont start the engine immediately, the engine must up to 300 rpm before the fuelpump starts again and build pressure in the fuel system. I could lower the limit to 200 rpm but still the pressure should still be there from the initial priming pulse.

Almost all modern fuel systems have a priming puls to build up the pressure in the fuel system (even the old K-Jet) and then holding the pressure.

If I turn on the ignition just to listen to the radio for 5 minutes and then when I finally turn the key to the last positon to start the engine, the pressure build up from that single priming pulse should be there.

I know I can manipulate the priming pulse length depending on temperature but still, the pressure should remain for a while and not immediately drop to zero.
 

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I hear ya, u need a fpr, if it's adjustable I would try and bump the fuel pressure up a bit and see if it will hold (and drop req fuel)

I have never seen a proper working fpr that wouldn't hold a prime

Your install is looking good, next is boost


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