MSefi.com read only forum (Jan.15,2018)

I have a 79 cj7 with a 258 that is of course carbed.

The plan is to swipe a harness, intake, head and exhaust from a early 90s Jeep 4.0L as they will directly bolt onto that 258 block.

I have never done megasquirt so I have read through tons of info here last few days and searched for others doing this and found only a few threads.

What I believe I need is

Megasquirt 1 pcb 3.0 kit
Stimiluator
Tuning Cable
USB adapter

I would like to be able to control ignition and fuel with this setup so......

Since I have no OEM sensor onboard this engine my thought was to use an external crank sensor but I read in the info that a crank sensor is not sufficient and a cam sensor must be used. HESCO makes a bolt up crank sensor for this engine. Is there a way to get ignition control with this or is it not worth the headache.

Second I am a bit confused on the need for a wideband O2 sensor. I read in the info that OEM sensors are crap for tuning an engine. That would imply that I need to fork over another 200 for the wideband 02 Sensor kit. Is this really necessary? or will I be able to get a sufficient tune from the OEM part.

I am patiently trying to read through the tons of info here but it seems my jeeping compadres have not contributed much towards a writeup on how to do this. I will try to correct that and document and post up a detailed post on this. Thanks for your time and help in advance.

soonercj7 wrote:I have a 79 cj7 with a 258 that is of course carbed.

The plan is to swipe a harness, intake, head and exhaust from a early 90s Jeep 4.0L as they will directly bolt onto that 258 block.

I have never done megasquirt so I have read through tons of info here last few days and searched for others doing this and found only a few threads.

What I believe I need is

Megasquirt 1 pcb 3.0 kit
Stimiluator
Tuning Cable
USB adapter

I would like to be able to control ignition and fuel with this setup so......

Using an MS1 for ignition control requires MS1/Extra code, covered on a separate forum, MSExtra.com. MS2 can control the ignition with the standard code.

Since I have no OEM sensor onboard this engine my thought was to use an external crank sensor but I read in the info that a crank sensor is not sufficient and a cam sensor must be used. HESCO makes a bolt up crank sensor for this engine. Is there a way to get ignition control with this or is it not worth the headache.

You can run purely with a crank sensor (or purely with a distributor pickup), for MS2 standard code or MS1. You only need the crank / cam sensor combination for OEM Jeep ECUs. What's the trigger pattern on the HESCO trigger?

Second I am a bit confused on the need for a wideband O2 sensor. I read in the info that OEM sensors are crap for tuning an engine. That would imply that I need to fork over another 200 for the wideband 02 Sensor kit. Is this really necessary? or will I be able to get a sufficient tune from the OEM part.

I am patiently trying to read through the tons of info here but it seems my jeeping compadres have not contributed much towards a writeup on how to do this. I will try to correct that and document and post up a detailed post on this. Thanks for your time and help in advance.

Narrow band sensors are kind of like an on/off switch. They put out 0.8-1 volts above 14.7:1 and 0.1-0 volts below it. Useful if you're targeting 14.7:1, but targeting other air/fuel ratios is easier with a wideband. On a naturally aspirated motor, you could tune the thing for 14.7:1 across the map and then scale the tables to hit a richer air/fuel ratio at full throttle, but this can be a bit awkward.

One easy way ignition wise is to used wasted spark - for that you only need a crank position sensor. You could use EDIS, which does everything for you and only needs two connections to MS. Or drive the coils directly from MS - but for that you'll need Extra Code, and hardware mods/additions to MS.

thanks matt



there is a pic of the hesco wheel. Although looking at other peoples installs they appear to have changed occasionally. Hesco makes all the stuff to bolt up a 4.0 mpfi system on a 258 but they charge so much for all that stuff that if I was going that route I would just buy a full custom mpfi kit. That kit in the pic costst 350 alone. 250 for a fuel pressure regulator.

To top it off after more research I am reading that people are complaining about the hesco kits failing and having to occasionally cough up another 100 or more to replace parts. I will not be buying one.

I found a detailed explanation finally about the 02 sensor and can see that it makes sense. I am gonna go with that and the megasquirt 2 kit.

So I can just use something like a GM HEI and msquirt 2 to control the ignition with just the position sensor in the dist?

ty trakkies I will check into the wasted spark system, I saw some info on that and will read up on it.

I would use MS2 so you can control the IAC valve for cold starts/warm up. Depending on how comfortable you are with wiring you may want to use a relay board.

I think 79 has the duraspark distributor, in that case it is a VR sensor with a 6 tooth wheel. If you use the distributor I would upgrade it to the large Ford cap. Google search will get you all the parts you need for that. It is what I am using currently.

I pulled my parts from a Jeep XJ (easy to find in junk yards), just make sure it is 91 or later. Prior to that was the Bendix system, which is fine but I think parts might be easier to get for the OBD1 hardware. You can easily tell them apart by the throttle body, the bendix has three bolts holding it to the intake and the OBD1 has four. Also, the 91 to 94 head flows better, it is the 7120 casting. Later systems (OBD2) have a return-less fuel rail that I think would be harder to work with. However, they did have cam sensor that is basically the 4.0 distributor without the top, if you want a clean distributor-less system and still have oil pressure .



I would also pick up the 4.0 distributor and throttle cable. If you go with a crank signal you can get a single cam trigger from the 4.0 distributor (or later cam trigger as mentioned above) and it is physically the same as the 258 from the block down (4.0 on the left, 258 on right). The XJ throttle cable needs to be modified where it connects to the CJ pedal, that was easily done with a pop rivet. I used the shell of the pop rivet as the new stop and just crimped it on where I needed it. Been working for many years. Below is a comparison of the two distributors.



Take a close look at where all the exhaust tubes come together on your manifold, they tend to crack there.

I think HESCO sells dampers with the Bendix system pattern and the 91 up OBD1 (Chrysler I think) pattern. Sorry though, I don't know what they are.

And finally, I would recommend you get all your MS stuff from DIY Autotune, they are a great group to deal with. Oh, and don't forget to add in some funds for TunerStudio, it is a great program and you will want the full features.

Brian.

I think 79 has the duraspark distributor, in that case it is a VR sensor with a 6 tooth wheel. If you use the distributor I would upgrade it to the large Ford cap. Google search will get you all the parts you need for that. It is what I am using currently.

I would also pick up the 4.0 distributor and throttle cable. If you go with a crank signal you can get a single cam trigger from the 4.0 distributor (or later cam trigger as mentioned above) and it is physically the same as the 258 from the block down (4.0 on the left, 258 on right).

You are correct, I have that duraspark system with the small distributor.

Your 2 statements confuse me. You would go with the original dizzy upgraded with the ford parts or with the 4.0 dizzy?

Thanks alot for your post. I am going early next week to get the 4.0 parts. Just gonna grab everything, lol.

I have read that 95-99 (i believe that is the correct years) have a reinforcing rib on the exhaust to correct that cracking problem you mentioned. I will look for one of those.

I would also like to use one of the better 00-01 intake manifolds but the only info I have found from someone that actually tried it was that the intake interfered with the power steering pump mounting and he abandoned it and went back to the 91-95.



You can see why it (the far right one) is more better.

Yep,

I read up on that wasted spark stuff. I like it. I am gonna snag an EDIS-6 from the yard also. Deleting that distributor would be awesome.

Would the correct banks for the EDIS be 1 & 6, 5 & 2, 3 & 4 since the firing order is 1,5,3,6,2,4?

That trigger wheel is for the Jeep EFI from the mid '90s. Currently, only the MS3 (discussed on MSExtra.com) supports it. EDIS would require a Ford style 36-1 crank trigger.