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post #1 of (permalink) Old 12-30-2002, 08:15 PM Thread Starter
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258 Homemade Fuel Injection using Megasquirt DONE!

Finally had a clear day to finish the install of my megasquirt fuel injection system on my jeep.

For those not familiar with Megasquirt, check out the websites:


and Yahoo group for messages:


The weather here in Winnipeg is cold now, and I am really impressed with the way this system is running. It started as soon as the system got fuel, and ran perfectly right off the bat, using the fuel curve (actually VE table) for a 350 chevy scaled down to a 258 and set for the GM tbi unit I am using that I got off a 305 chevy.

Instant starts and very crisp throttle response. Roads are bad right now and all testing had to be done in 4wd. I used a stock 258 intake manifold that I ground out the plenum just about to 1/8 inch of the edges to mate up with the Gm tbi and not have any "funnel" to the adapter. I mad e the adapter from 2 1/4" thick aluminum.

The incredibly crisp throttle response makes me feel like horsepower has increased. I'll have to wait till the roads are better to get more insight into that. Best test will be cruising down the highway for power.

The system cost me $110.00 for the ECU kit, I think around $50.00 for the relay and power distribution kit, $35.00 for the "stimulator" (to test the unit), $20.00 for the tbi at a junkyard, including all sensors and wiring harness (and a rear view mirror), $150.00 for the fuel pump, $14.00 for a piece of aluminum to make the adapter and at least $100.00 for hose, wire, heat shrink tubing, etc. So I'm in to this for around $500.00.

The software to tune the ecu is free, and this project is the brainchild of Bruce Bowling and Allan Grippo who developed the Megasquirt system that is cheap to build, fully tunable, and adapts to multiport or TBI.

More megasquirt kits should be available in the new year, but several months from now. They made up about 500 or so kits and they were done as a group buy. This is megasquirt's second version and biggest distribution yet. Guys are megasquirting everything from kit cars, pinzgauers, racecars to boats.

The kit uses an 02 sensor, if desired, and I will start tuning soon to get the best mixture and fuel economy. I'm just amazed how well it's running without any tuning at all. I simply used the VE table for a 350 chevy, lowered the upper rpm limit slightly, and set the fuel volume for a 258 engine using 2 40 lb/hr injectors squirting in an alternating fashion.

My only beef with the project is the noisey Carter fuel pump. Emits a real howl from beneath the jeep. Maybe I should have avoided the BBD manufacturing company that got me started into all this tinkering to begin with!

Anyhow, this is a good alternative for those who want to build as much of the system as possible, and who would like to be able to tune all aspects of the fuel injection system.

Best wishes and a Happy New Year to you all.

Tim Martin
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post #2 of (permalink) Old 12-30-2002, 09:34 PM
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Re: 258 Homemade Fuel Injection using Megasquirt DONE!

Cool, thanks for the update. I glanced through their website from one of your old post. I liked what I saw and the ease of adjustability plus I like being a little differant then the other guy.

Keep us updated on this I'm very interested in hearing how it works out for you.
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post #3 of (permalink) Old 12-31-2002, 12:29 AM
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Re: 258 Homemade Fuel Injection using Megasquirt DONE!

1. Congratulations.
2. Share the experience.
3. Let others know that if you can do it... so can they.
4. Let us know:
a. Any power increase.
b. Any MPG increase.
c. Amount of time for the install.
d. Amount of miles it takes for a "payback" of fuel savings to cover the EFI costs.
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post #4 of (permalink) Old 12-31-2002, 01:40 PM
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Re: 258 Homemade Fuel Injection using Megasquirt DONE!

Hey Tim,

I am real interested in doing this. Can you give us details on how you did this?
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post #5 of (permalink) Old 12-31-2002, 02:21 PM
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Re: 258 Homemade Fuel Injection using Megasquirt DONE!

this judging by the picture could be done on my motor

I absoulutly dispise a carburator. my jeep appears to get 10 mpg

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post #6 of (permalink) Old 12-31-2002, 03:37 PM
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Re: 258 Homemade Fuel Injection using Megasquirt D

Ahh ...FI within the $$$ reach of mortal humankind [img]images/graemlins/shocked.gif[/img]!!!

We could be looking at the first "Mr. Fusion" [img]images/graemlins/laugh.gif[/img] [img]images/graemlins/cool.gif[/img]
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post #7 of (permalink) Old 12-31-2002, 04:52 PM
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Re: 258 Homemade Fuel Injection using Megasquirt D

how much is just the MS control unit kit?

I saw a reference to the first group being $110?
is it in that ballpark still?

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post #8 of (permalink) Old 12-31-2002, 08:00 PM
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Re: 258 Homemade Fuel Injection using Megasquirt D

Thanx for the info man. I'm looking into a cost effective TBI system for my Ford and this may be the ticket. Thanx! [img]images/graemlins/smile.gif[/img]
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post #9 of (permalink) Old 01-01-2003, 02:26 PM
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Re: 258 Homemade Fuel Injection using Megasquirt D

I already have the MS and stim kit, and plan on putting it on my 258 w/4.0 head at some point. Glad to see someone has a running system!!!
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post #10 of (permalink) Old 01-01-2003, 06:12 PM Thread Starter
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Re: 258 Homemade Fuel Injection using Megasquirt DONE!

Back from the lake, spent New Years Eve out there.

The ECU or controller was $110.00 for a kit that included all parts to build the ECU, including the case. Another kit containing a case, relays, fuse holders and terminal strips was purchased and this second unit, the power and relay kit sits in the engine compartment, the ecu under your dash to avoid extreme heat.

It's sketchy as to exactly when another group buy will be occurring. They have some boards and the main chip available and will have them up for sale soon. The small parts, like the resisters, capacitors, etc can be easily obtained on your own. If you want one, you had better was the Yahoo group closely to get in on the few that are left.

I've done some tuning since the initial setup, and a significant amount of driving on it. So far, it runs flawless. The oxygen sensor shows that I'm slightly rich, but the exhaust doesn't smell that way. O2 sensors are very sensitive to rich and lean deviations from stoichiometric mixture (14.7 to 1 afr). I read up on the tuning software while away, and am eager to do some more testing on the road, using the 02 sensor for feedback.. I can't imagine that it could possibly run better, but there is some fuel savings in tuning it more closely.

I took a buddy out for a ride and he is very impressed, the power and throttle response got him. He wants to build a Megasquirt for his drag cars. I just can't get over how it starts with just a turn of the key, no fiddling with a choke, and will drive away with very little warmup and run perfectly. The tbi must atomise fuel much better. I did a few full throttle runs, but it's hard to find good roads right now to go far, and it pulls nicely. Probably no horsepower improvement over the Motorcraft 2100 carb. If there is, it's likely marginal. The jury's out on that conclusion, as a dyno is really the only way to know for sure, as I've never measured my 0-60 time or 1/4 mile to have a valid measurement of power. The big improvement is in the throttle response. At any speed I can give it half or 3/4 or full throttle and get instant wheel spinning response.

This setup would be ideal for a later conversion to a V8, as the tbi would be usable for up to a 350 cube motor. The same tbi, but different sized injectors are used on the 4.3, 305 and 350 chevy. I had no troube finding the tbi at a pick a part yard, and there may have been more, including 350 tbi's with larger injectors, but I didn't care, as the 258 is what I need to make run with it. I grabbed the wiring harness and sensors, as that cost nothing extra. I pulled the harness apart, cut out all the plug ends I needed, and used solder and heat shrink tubing to lengthen them to my new harness length.

I plan to do a detailed writeup, and have taken pictures all along. I just don't know how to "publish" it to fellow jeepers. If I do it up on Word, with pictures and text, can someone get it from me by email, and post it on their website?

I won't do the writeup till I fine tune the VE table (that's the table that determines fuel and air and various rpms and MAP levels).

I was worried that it would be hard to tune this system, but it turns out that it is running great right out of the box, and tuning is not required to make it driveable. Or even to make it run excellantly. I would like to know that my Air / Fuel ratio is optimal for that blend of emissions, fuel economy and power. Also, the engine life should be longer if it burns clean.

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