Well, I couldn't let you all hog all the fun, so I'm in progress of rebuilding a Euro '82 500SEC engine, and have most of the parts ready to swap to MS as soon as I know the engine runs.
Little things like TPS and figuring out my solution to the air filter are still rattling around my head, but most of this seems to be coming together fairly smoothly so far.
(Having said that, I probably caused myself some unforeseen headaches, but hey, these things have to be done! )
I have to ask, though. What have those of you who have the engines running done about fuel pressure regulation?
Per the CIS troubleshooting manual I have, the '80 and beyond source pressure is listed as 5-5.2bar (~85psi) and all the Mega Manual warnings seem to point to never allowing the injectors to see anything above 70psi, and typical running pressure being between ~38-46, depending on the OEM.
If need be, I'm willing to go spend on a good aftermarket regulator, but I wasn't seeing any mention of these in the MB conversions I've looked at.
Thanks for any input!
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-Josh
'82 300SD 296k mi
'82 500SEC euro 153k mi (new project) It's alive! images Testing the 'cheap Benz' axiom, one bolt at a time!
I believe the stock regulator is tied in with the whole K-Jetronic which you will be removing. I used a Volvo fuel pressure regulator that was mentioned on the MegaSite quite a bit because it comes stock with barbed hose fittings on both ends making plumbing much easier. I started with a cheap e-bay adjustable regulator and found the adjustable feature to not really be of much use in tuning. It was big and heavy and needed a hard mount. The Volvo FPR was small and light and just rests supported by the fuel hoses. The FPR needed to be mounted backwards of how I thought it should be mounted when taking a first look at it. But I wasn't familiar with FPR's.
I have been getting around 12-13 back and forth from work lately. Always got single digits previously. I am still playing with my settings a bit. I have been playing with running lean 14.8 - 15 AFR and retarding the spark table to compensate for knocking.
Huh, I'd always thought your smaller displacement engine should get better mileage than the 5L in the 500SEC. What kind of gearing does your tranny have, and final ratio?
I'm not sure what mileage my 500 is getting, but it's only run through about half a tank, and now it needs brake work, exhaust work, and while I'm at it, I think I'm going to go ahead and do the MS conversion, so I'll never know just how bad the current mileage actually is.
On the topic of the conversion, I just picked up most of the plumbing I needed for the fuel system from a local hydraulics shop. Massively over rated fuel hose, rated up to 1500 psi working pressure...
The nice part about working with hydraulic shops is getting fittings that will hold up to just about anything, and look like they were intended to be in the engine bay from the beginning.
Instead of the bright red and blue aluminum AN fittings from the race shops, the steel JIC (same as AN, just meant for hydraulic use) are either the shiny silver of stainless, or a mild yellow of cadmium plated steel.
That being said, I think I paid as much for one of the fancy fittings in what appears to be stainless as I did for most of the rest of the plumbing combined! :P
Hello All.
I am currently in the process of installing a megasquirt conversion on my 1976 SLC. I have been reading Oughtsix’s conversion, and I have decided to follow his advice almost to the t, except for building my own MS computer. I do not feel confident that I will be able to do a good job welding, as I have tried it in the past, and it has never quite worked for me.
So far this is what I have done:
1. Removed Intake manifold. I had a severe issue with vacuum loss (traced to a nice hole in the pipe coming from the exhaust for the EGR, and the fact that the Air control valve was stuck in open), and needed to isolate the problem, so I decided to remove the intake to replace those pesky rubber spacers in between the upper and lower manifold. This also helped me to clean, and seal the intake in a much better fashion. I also used Eastwood’s Co. Alumablast to refinish the top of the intake, and it looks so much better.
2. Had the thermo-time switch rebored for the 3/8NPT pipe thread needed for the CLT. I also took off any of the CIS components (Warm Up Regulator, Idle Control Valve, and the Air Distributor).
3. Purchased 8 19 LB mustang injectors. Tested the injectors and they do not need to be machined down, and the fit is nice and tight.
4. I took the old CIS Air intake, and sealed the CIS portions, and took out any moving parts… Including the Fuel Distributor…. Painted it with Eastwood Detail Gray, and drilled and tapped out a nice hole for the IAT... Figured that it would look really nice on the outside of that monster.
5. Removed all the accelerator linkages, stripped them, cleaned them, painted them with Eastwood black, and reassembled them. Now they have nice and smooth movements, and are not binding.
6. Bought the idle control box, and a 1992 Jeep IAC valve and tapped out two m6 bolts on the side, and I am using the bracket that used to belong to the WUG for it. Now need to get the right combination of hoses to connect it to the air distributor, and the (now inert) CIS intake. This should work as I am taking nice clean filtered air from the CIS, and through the air regulator am going to the intake manifold after the throttle body. BTW, the reason that I kept the original huge CIS intake was to keep the even bigger Air cleaner on top of it. I will eventually add a cold air intake, but more like the 560’s version that still has the large air cleaner… The reason for this is to have a large filter that allows more air in and gets dirtier less. (And still keep some semblance of originality).
7. Bought new bolts. As I had cap head hex bolts, I chose to replace them, as they tend to stretch and lose some of their strength after repeated torqueing.
8. Bought the Relay panel, the CLT, and the IAT from DIY autotune.
9. Cleaned the V of the engine block, and painted with temp. resistant black.
The idea is that anything that gets touched/removed is cleaned, and if needed stripped, painted, and reconditioned if possible, or replaced.
The plan as of today is to get some parts in (replacing the heater hoses that run UNDERNEATH the intake manifold) before dropping in the reconditioned manifold.
After the intake manifold is in, the injectors with new seals will be put in the car, and the electrical will start. I have decided to use the negative post of the coil for tach input, and wire the fuel pump from the relay board for safety reasons (the 76 had the safety switch on top of the CIS housing, and that got deleted as it would not be used, or useful.).
I will post some pictures of the work so far, and would appreciate any comments, and recommendations. I have found oughtsix’s site extremely helpful, but any other ideas would be greatly appreciated…. And no, there is not talking to me about keeping the CIS, as these systems are not well supported, or understood… They might have been state of the art in 1976, but…. Now, they are just a pain.
I do have a couple of questions though. I still need to find a nice power lead that is on both at run and at crank. I was thinking of using the lead coming from the old fuel pump relay, but are there any other ones closer to the engine compartment? If not, it is not a huge issue, as I need to run cables to the engine anyway.
Any progress anyone? I fooled around for a week on my 380SEC to get the CIS working properly (rebuilding the fuel distributor on my own). Recently I spent more than a week to get my 380SL working properly but it just does not want to cooperate. I think I have pretty much decided to convert first my 380SL and then my 380SEC. I have a spare engine (with a broken cylinder) to experiment on. (Hi to all the computer professionals, here is another EE turned CS guy!)
Anyway, no one really answered the gas mileage question. The original gas milae is 14 to 17, I would think that a good modification (especially with the UEGO) and better portioning of fuel should bump this up to the very low twenties. Anyone seeing that? (Or are your feet too heavy after the conversion )
Did anyone keep the original idle air control valve (as it is neither a PWM solenoid nor a stepper)?
Also, Where did you all mount the toothed wheel and its pickup for the ignition?
Umm i have MSII controlling fuel atm and i would say yes a definite improvement in mileage, i have a very heavy lead foot, kinda bad really, and i manage about 20mpg even with the lead foot, but thats with the car leaned out about as far as it will go, like 15.8afr cruise, cut off when decelerating, as lean as the car will go with out changing the advance etc(still stock) will soon do the sparks mod too, that will make even more improvement.
BUT.... i dont run it normally as a leaned out car, i usually have it set up for max power 12.5afr etc when the peddles on the floor, and lean all other times which works pretty well.
I decided to do away with the original Air Intake Valve, as mine was quite stuck, so I bought the housing from DIY autotune, and used the bracket that is being used by the WUG to hold it. I still have not configured the car, as I was finishing the fuel rails, and getting the Wife's 124 on the road, but will keep on working on it over the weekend.
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Linear Mode
