Mopar EFI

[Pharaohabq]

Now I did search and I didn't bring up anything on this subject, and I know Jeep Engines are too heavy and though torque-y But, I was thinking, "What ways can we improve MPG on out L28 engines either NA or T?"

 

Well A while back I swapped my AMC Jeep 4.2L Crappy carb setup to basically the Mopar EFI kit. The Mopar Multiport EFI is more efficient than stock L28 Bosch system. I built my own using junkyard/Ebay parts here's a link off my ProjectJeep Site:

 

http://www.projectjeep.com/Projects/EFI.html

 

The EFI improved my Jeep milage from about 13MPG to closer to 18 or 20MPG.

 

Okay, I know there's a lot of differences between the AMC 4.2 and the Nissan L28, but the Mopar MPI System is still a possibility, since the EFI works also with the 2.3L AMC engine too. Basically as I understand it, the Jeep Computer will try to figure the correct mixture regardless of engine size. (Yes I know I could do Megasquirt, but this is pre-setup though the fuel maps may need tweaking)

 

The Mopar EFI has a few main components, Manifold, injectors, ECU, O2 sensor, temp, MAP sensor, TP Sensor, Distrib sensor and CPS sensor. Some also use a Speed sensor. I'm talking the ODB1 version (pre 96, mostly 94') the ODBII stuff is a little more of a pain.

 

I am not going to go into the how of all this unless its more feasable through our discussions. But I'd like to talk more of the similarities between the Bosch System, and the Mopar EFI.

 

Of course, Both Bosch and Mopar EFI have manifolds, and very similar injectors (plugs look the same anyway) The Bosch system doesn't have a MAP Sensor or a CPS (crank position sensor) because Bosch uses the Air Flow Meter(AFM) I don't know about the TPS or what kind of Distrib ignition timing Bosch uses, so these may be an issue. Both Bosch and Mopar use Fuel return lines back to the Fuel tank for the overpressure off the Fuel regulator. (though Mopar also can use a non-return system w/ a later Fuel pump, which works well in my Jeep)

 

Ideally, a Mopar AMC Manifold could be adapted to fit an L28, but I'm sure there'd be fit and position spacing issues which would open it's own can of worms so to speak. So I'd assume then we'd need to use a stock L28 Manifold. Putting the MAP on an L28 is Simple, just plug a hose in.

 

The throttle body may be a bit different. We don't need the MAF anymore, So we can remove that, but the Throttle body, or more importantly the Throttle Position Sensor (TPS) which mounts to the side of the throttle body may be hard to fit to a stock L28. We'd likely need to get a throttle body off a Jeep or another compatible GM car. (likely need to see what other vehicles used the same TPS and aquire the largest one it's compatible with. )

 

The O2 sensor may need to be changed to a newer type, but it'll just screw into the Exhaust manifold somewhere down the line. (might have to install a threaded boss for this, any Exhaust shop can do it, or supply parts.) the Temp sensor can be put anywhere in the water cooling system. Though, Jeeps require 195 degrees thermostat, the 180 degree that an L28 takes shouldn't make a difference. Leaving the stock one in place will ensure your temp gauges still work.

 

Next is the two harder parts to figure. The Distrib position sensor, and the CPS. The Crank Position Sensor (CPS) on a Jeep, is what allows the computer to know where the crank is positioned, and on what cycle the engines cylinders are on. Basically these are the two most important sensors since the engine will not start w/o them.

 

Now how Mopar got around not mounting the CPS next to a toothed flywheel was to make a Harmonic Balancer that had teeth that could be "read" by the CPS, mounted next to it on the engine front. I don't know how compatable a Mopar Performance Harmonic balancer would be, but it may be possible to modify a stock balancer with the correct notches (it's a pain, was why I bought one for my jeep) but it could work. Hopefully the crank on an L28 could take a heavier Mopar Balancer, but we'd have to test fit one to see. I don't think the extra weight on a Mopar balancer would affect the engine performance much if any.

 

Lastly the Distrib sensor, I know that's not the right name, it's a cam sensor or something. In anycase it just tells the computer when to make the spark for the plugs, handles ignition timing and all that so it's pretty easy. but how to make one work on an L28. I'll need to look into the S130 Distrib sensor and see how it works. I know you can buy just the Sensor that goes in an Mopar Distributor, but I'm not sure the similarities.

 

So what do you think?

 

Phar:icon32:

[Mike kZ]

Give it a shot!

[Pharaohabq]

Anyone else got anything to say? Anyone done this? looking for input here...

 

thanks,

 

Phar

[RTz]

The Mopar Multiport EFI is more efficient than stock L28 Bosch system.

 

Why?

 

What kind of MPG are you looking for? An S30 with LJet can pretty easily get 28mpg (hwy), 30+ if you work at it.

 

 

Anyone else got anything to say? Anyone done this? looking for input here...

 

The hurdles you must overcome to make your idea work would take more effort, and likely money, than an aftermarket EMS. And, I'm betting, less fruitful. In my opinion you're going about it the hard way.

[Pharaohabq]

Why?

 

What kind of MPG are you looking for? An S30 with LJet can pretty easily get 28mpg (hwy), 30+ if you work at it.

 

 

 

 

The hurdles you must overcome to make your idea work would take more effort, and likely money, than an aftermarket EMS. And, I'm betting, less fruitful. In my opinion you're going about it the hard way.

 

I was thinking I should be able to get ~22-25 in town, and 30+ on the highway. I dunno.. It's hard to say just what it would work out to, right now my S30 gets 18City and about 23 on the highway. granted my S30 needs some work.

 

Maybe trying the hard way, Which aftermarket EFI were you thinking? Megasquirt? Looks like Megasquirt is pulsed in banks rather than firing the individual injectors like the mopar EFi does.

 

Phar

[RTz]

I was thinking I should be able to get ~22-25 in town, and 30+ on the highway.

 

Stock Ljet can meet that goal.

 

 

Maybe trying the hard way, Which aftermarket EFI were you thinking? Megasquirt?

 

I didn't have a specific brand in mind, but Megasquirt will do.

 

Looks like Megasquirt is pulsed in banks

 

Yes, batch-fired.

 

firing the individual injectors

 

Yes, Sequential.

 

Jeep Computer will try to figure the correct mixture regardless of engine size.

 

 

I get the idea that two things are attracting you to the Mopar... Closed loop and Sequential injection.

 

Sequential injection will only help incrementally. Its not the end-all be-all in EFI. Don't put all your eggs in that basket. For example, there is a member here with a 280zxt, running 7.4:1 CR (not exactly ideal for MPG), getting 30 MPG (hwy) with a sequential (aftermarket) system. Here's the kicker... he's never timed his injectors to the valve events. He has no idea how far off the events may be. So, did he get lucky, or is it just not that significant?

 

Closed loop is the mixture trimming I believe you are referring to. Keeping it simple... this is only happening under cruise conditions and the target is 14.7:1 AFR. While 14.7 is the best compromise for emission's, it is not normally where peak MPG is going to be found. Leaner, much leaner in some cases, will usually net better MPG. One could say... the idea you're holding on to, is actually working against your goals.

 

Disclaimer: I've made some assumptions about the Mopar EFI based on what you've given us. If your information is wrong, then so is mine.