Replacing Bosch jetronic with MegaSquirt EFI

[hbar]

Well, I f***** up. I forgot that ought6 said to reverse the order of the o-ring and spacer on the injector to make them seat properly in the heads. It's true; they DON'T seal properly, otherwise, as the o-ring gets pushed below the sealing surface. Now I need to order more pintle caps as it's impossible to remove them without destroying them. They're only .40 each on ebay but I'll have to wait until next week for them to arrive again.

DOH!

[bluefang]

i seemed to have had the last few days off and i have put together almost all of my fuel system, The O2 sensor was installed just after the bend right behind the front drivers side wheel. With the fuel rail i used the stock one form my 74' 450SLC and i got the injectors machined so that they have a barb on the end to attach the hose from the fuelrail to it. I am using a adjustable Monza fuel pressure regualtor placed in the return pipe of my system. All the fuel piping has been replaced, didnt have time to test it yesterday but i HOPE none of it leaks. With the ECU i have placed it pretty much where the old one was and i ran the wireing cable thru the gromet where the old one went thru. The Wireing harnes then goes to the relay board that is bolted, on stilts, to that side of the engine bay.
All i have left to do is test my fuel system for leaks, and then run wires to the sensors and the injectors, hopefuly something i ll get to complete today. I ll try to post pics later once i find a cable to connect my phone to my computer.

[oughtsix]

Sorry to hear that HBAR. I went through an extra set of hats also and I went through a few sets of O-Rings. I had several O-Rings split on me when shoving the injectors into the fuel rail. With your setup you might not have this problem but you might want to consider ordering some spares.

BlueFang - I used a battery charger to run my fuel pump while looking for leaks. I fried a fuel relay in the process so you would probabally want to remove the stock fuel wires from the pump before connecting up a charger if you deside to try this.

[bluefang]

Yeah i removed the wires from the pump, obviously original solid as a rock and rather hard to get to the bolts to remove the wires :-). But ofcourse i did a noob thing too and had the wires around the wrong way, no dmg but just wasnt getting any fuel. Also i had a faulty regulator so i am getting a new one tomorrow, all the fuel system joints look good didnt get any leaks when i got the pump going the right way, but didnt get up to a high enough presure cause the bolt to adjust the presure on my regulater sheared off O.o.

The wireing is all together cept i have to run a wire for the tach signal and the O2 sensor needs to be connected to the relay. Its almost all together....yahoooo

but alas i have to work on my old car cause its been sitting for a while and istn running properly which it kinda need too to be sold, so i prob wont get my merc up and running till the end of the weekend now :-(

[bluefang]

OK, all done, all my plumbing and electricals look like there working the way there ment to, but alas i am hopeless at tunning it to get it to idle properly. I can start it an then it dies after 3sec. Oughtsix can u plz post the settings ur car is running on :-( i just cant keep mine runing atm. Ty in advance

[bluefang]

All sorted out, got it to work and idle properly, now i just have to start data logging

[oughtsix]

I was on vacation last week. I will post my config file when I get home this evening.

CONGRATS!!!!!!!!!!!!!!!!!!!!

Here is a recent file:

MSQ file

[oughtsix]

BlueFang, how is your install going? Have you had a chance to work on it lately?

The MSQ I posted above is from May and I have been driving around on it for a few months now. It has been very stable for me. I have been driving this MSQ with no wideband O2 sensor. I finally got off my rear and sent my LC1 in to innovate. They had a replacement sitting on my door step in about a week. I reinstalled the WO2 this weekend and I am back to messing things up... Uh I mean tuning.

As reccomended by Jim on the MegaBoard i switched from two injections per cycle to 4 and it does make a signifigant difference at idle. I thought she was idling smoothly before but she is really smooth now.

I hope to post some pictures of my air intake soon. I am using an airbox out of a 92 Subaru Legacy which fits perfectly between the passenger side headlight and wheel well.

[LotusJeff]

Guys:

You all seem to be making great progress on your Megasquirt conversions. Well done!

As my user name implies, I don't own a Benz, but a Lotus Esprit circa 1986 with Bosch K-Jetronic CIS. Since so few of these cars were ever made, I haven't found one yet that has been converted to Megasquirt, so Ive been lurking around trying to find anybody else with K-Jetronic to Megasquirt experience.

Although the basic CIS system sounds simple enough, in my case what drives me crazy are the 20 electro-vacu-mechanical patches that have been applied to the system to make it work properly. I spend more time diagnosing and fixing things than actually driving the car.

So I've got about a million questions about how closely the Benz K-Jetronic looks to the Lotus K-Jetronic. Are your factory systems as complex as mine is. If so, it would encourage me even more to get all that aging stuff out of my car.

I look forward to hearing from you.

regards.... Jeff in the Boston area

[oughtsix]

Welcome LotusJeff.

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.