TBI or MPFI?

[AbandonedBronco]

Hi all,

I have a 1981 Ford Bronco with a 4bbl carburetor on it. I enjoy tuning it, and love the power over stock, but no matter how much I tinker with it, I can never get it perfect. The better gas mileage I tune it to get, the less acceleration and more "stumbles" it has, etc. etc. etc.

The more I think about it, the more I love the idea of fuel injecting it and tweaking and tuning my own fuel and ignition curves with a computer that does what I tell it to.

On that note, the two options I have before me are keeping my 4bbl intake and installing a GM TBI, or pulling the stock EFI intake off of a 4.9 and using that. (I have no intention of using the stock EFI computer, just the intake, as I want to be able to use different cams and such, as well as tuning it myself.)
I'm planning on installing a MegaSquirt setup or the like.

The bonuses I can see to the TBI are:

Already have the intake.
Keeps a "stock" look (as much stock look as there is with a 4bbl on there).
Takes up much less space under the hood.
Ease of working on the engine, access to the valve cover, etc.
Simpler overall.

Bonuses to the EFI setup.

Better fuel distribution (a dedicated injector for each cylinder).
Better fuel atomization (air/fuel mixes at the cylinder instead of at the throttle body).


I don't care about peak power all that much, so if I can get to 180hp with the TBI and 200hp with the stock EFI setup, but I like the TBI more, 180hp is just fine with me.


Thoughts?

 

[bubba22349]

I have a stock 94 F150 with the 4.9 EFI before that also had a number of the Carbed 240 & 300's trucks. Worked with a number of Ford and GM TBI car's and trucks too they are quite good. But the winner to me is the 4.9 EFI setup it gives you the most bottom end torque for pulling and very good economy. Good luck in your build, I think you will be quite pleased with either system.

 

[garyt120r]

Get rid of TBI. It's not much better than a carb. MPFI is the way to go. SEFI even better for squeezing that last bit of MPG out of the combo.

 

[AbandonedBronco]

Thanks for the responses. My thought with the TBI is that, even though it's not much better than the carb, I can program it. I get pretty good gas mileage with my 600cfm (14-15 town/17-19 highway), so even if I just match that, I'll be happy. I'm mostly wanting the control, so I can get rid of the stumbles, lean spots, etc. as well as not having to worry about cold weather or elevation changes. So if a TBI is all I need, so be it.
However, I do like the idea of the MPFI a lot, and the low end it delivers, just not how much it fills the engine bay.

Decisions decisions. :roll:

 

[garyt120r]

Just throw on a modded efi head and intake. Get the ecu harness from a 3.8 car and get a moates quarterhorse or tweecer. You will have absolute control then.

 

[AbandonedBronco]

I've never heard of doing this before. Can you go into a little more detail? Is there splicing involved to put the wiring harness in? Then, use the 3.8 computer and control it with the Tweecer?

I just know a lot of people who've wanted to mod the EFI 4.9 and generally MegaSquirt is the only solution I've heard offered over the years.

 

[E4ODnut]

You can use almost any after market EFI system you want to on almost any engine. I started with a Haltech E6K on my 460, then went to Megasquirt for the 300. Now I run MS on all my Ford engines. The main reason I went to MS is because it had (and still does to a degree) open source firm ware which meant I could customize the program when I wanted. None of the others allow you to do this, but they are all becoming very versatile so for most people it's not an issue.

A very good system out there is Simple Digital Systems out of Calgary Alberta. They were one of the pioneers in the business and produce a very good product with support second to none. I would be using theirs if I could modify the firm ware.

I agree with the other posters in that if you are going to go to the effort of converting to EFI go multi port as opposed to throttle body. TB is better than a carb, but not a great deal if you have a well tuned carb.

The other nice thing about multi port for your 300 is that all the hardware required is available cheap at the scrap yards. Just bolt it on, add the control system of your choice and start tuning. If it's control you want you've got it in spades with programmable EFI.

I've been running my daily driver on MS now for about 8 years, well over 100,000 km of trouble free driving. If you decide to take the plunge I'd be glad to help in any way I can. Most of the people playing with programmable EFI are the go fast guys. Not many tuning stock engines for economy (especially a 300 six). It gets a bit lonely out here and I'd enjoy the company.

 

[bubba22349]

I've been running my daily driver on MS now for about 8 years, well over 100,000 km of trouble free driving. If you decide to take the plunge I'd be glad to help in any way I can. Most of the people playing with programmable EFI are the go fast guys. Not many tuning stock engines for economy (especially a 300 six). It gets a bit lonely out here and I'd enjoy the company.

Like how my 94 drives so much that want to do an EFI 300 / auto trans swap into a 56 F350. Was hunting for 96 F250 or 350 2X4 with single wheels to use as a donor, had planed to use all stock parts package including the factory harness and computer. E4ODnut I would be interested in hearing more about your combo of parts.

 

[E4ODnut]

Bubba,
It's pretty simple really. The whole thing is stock except for the controllers. I use my own version of Megasquirt for the engine and my own custom controller for the E4OD.

The only reason I use my own version of Megasquirt for the engine is because when I started this MS was fuel only. I had to adapt the Megasquirtnspark code to work with the Ford TFI ignition. The reason I did this is because I wanted some redundancy in case I screwed up badly I could go back to Ford EEC-IV control easily. Now, with the later versions of MS there is no need for custom code, but because I like what I have, understand it, and can modify it if I need to, I stick with what I've got. MS2 is very good. MS3 is even better but they are both written in languages that I'm not fluent in, so again, I stick to what I've got.

Similar story with the E4OD. At the time there was no option for a custom controller for the E4OD. Carl Baumann marketed one, but it didn't have some features that I wanted so I had to build my own. Now, I believe Carl's does everything and more than mine can do. There is also a transmission controller that will work with MS which might also work with the E4OD.

It's a hellova lot easier to buy a system than design and build one!

The thing with any programmable system is that the results are really all about tuning. The tuning software for MS has come a long way in the time that I've been involved in it. The original "Megatune" was good, but the latest version of "Tuner Studio" is just so much better. It's just natural evolution.

TS even has an "autotune" feature that some people swear by. It might work well indeed, but I am from the old school and prefer to do things manually because it give me complete control. Having said that, every tuner has their own style and preferences. There is no "wrong" way if you can achieve the desired results.

If anyone is serious about Megasquirt I'd strongly recommend contacting Matt Cramer at DIY Autotune. They are a dealer for MS and almost all things involved in programmable EFI. Matt and his business partner Jerry have published a very good book on programmable EFI systems. A must read for anyone getting just into the sport, if I can call it that. I believe they have kits now that will almost "plug and play" Megasquirt into the EEC-IV harness.

Matt is especially good. He's a regular contributor on the various MS forums and is very knowledgeable. We correspond frequently privately, just about general technical things.

 

[bubba22349]

Thanks E4ODnut, I kind like the building part of it too. In the past have built and repaired PC's though the only code I wrote was in the old basic. I am glad to hear the MS will work with all the stock parts and that they have better code versions now. Thanks again

 

[MPGmustang]

I vote TBI, like you keep saying, it's simpler, easier to learn, less clutter, and you can still control it.

I myself went tbi on my 200ci, mostly because it's the easiest, but because there is less fuel connections, less wires all around, the benifit for me was the simplicity of fuel injection. nothing else. I'm using a OBD1 computer and gm 2bbl TBI, it's not 'tuned' yet for peak but at least it's running and working for now, just waiting on a new chip from Affordable Fuel Injection.

I liked installing the TBI as it's simple, everything was very straight forward. I didn't have to worry about much except the fuel lines. I am even thinking of putting one in my 66 bronco just for the ease.

 

[E4ODnut]

GPMustang,
If you have an engine that has never had factory Speed Density MPFI then I would have to agree with you in that the initial installation would be easier to go SD TBI, but that's all. As far as tuning goes, there is no difference. They both take a lot of effort, but a well tuned SD MPFI will always be a bit better than a well tuned SD TBI. Same as, a well tuned SD TBI will always be a bit better than a well tuned carb and conventional distributor.

In the case of the 300, Ford has already done all the hardware engineering for you and this hardware is readily available at almost any wrecking yard absolutely dirt cheap.

Why not take advantage of the superior technology and go SD MPFI?

 

[AbandonedBronco]

Thanks for all the feedback everyone!

Yeah, the more I think about it, the better MPFI simple is. Tuneability, precision, power, economy, etc. Plus, there are plenty of parts in the JY for next to nothing. About the only thing I don't like about it, as said, is just how much room it takes up. I love how quickly I can get to everything on my carb'd engine without having to pull a bunch of stuff out of the way.

I can see why you like the programmability, E4ODnut. I write a lot of my own programs for various different things, so I imagine it'd be nice to be able to tweak the code behind the system to tell you exactly what you want to know, as well as do extra stuff.

I've been doing some research on line about the MegaSquirt system and it seems that, all said and done, I'd be looking at around $800 for the whole system? Is that an overestimation?
I'd most likely go with the MegaSquirt II setup since I'd very much like to be able to control my own ignition timing. Can the MS control the stock feedback carb distributor? That'd be pretty nice since I have one in the garage that I pulled out of my '84 when I converted it to DuraSpark II.

Driving to work this morning when it was 50 out and having it lag and bog at every takeoff reminded me why I get so frustrated with my carb. If it's running well today, it doesn't mean it will be tomorrow.

 

[E4ODnut]

AB,
I'm just heading out the door for a week or so, don't know if I'll have internet connection or not. Will talk when I get back, if not sooner.

 

[E4ODnut]

AB,
Our trip got postponed for at least a day. Sea conditions are too sloppy out there for me today.

MS can be configured to use almost any kind of trigger source. You can use your old distributor, but in my opinion you'd be a lot better off to get the stock TFI distributor and E-core coil when you get the rest of your EFI hardware from the scrap yard. I'm assuming that the distributor would be a bolt in, but I don't know that for sure. The nice thing about the TFI distributor is that it contains the hall effect trigger and the TFI driver for the coil all in one package. Also because of the larger diameter cap, you don't have to be concerned with rotor phasing which can be an issue with some small diameter distributors.

I suspect that MS2 will do everything that you need it to and your cost estimates sound realistic. I'd strongly suggest contacting Matt at DIY Autotune and discuss your project with him. He will be able to best advise you on you to proceed.

 

[AbandonedBronco]

Out to sea, huh? That sounds intriguing? What do you do?

I had planned on going with a TFI distributor. I have one from my '84 (feedback) but I imagine one from an EFI would be better. The feedback one is the small cap, unlike my DSII.

I'd planned on getting a hold of Matt at DIY, but haven't yet. I'll be out of town for the weekend, backpacking.

 

[E4ODnut]

AB,
What do I do? I'm a semi-retired electrician. The only reason that I'm not fully retired is that I have too many expensive habits, a boat being the worst of them. We just came back from a boating holiday somewhat extended by the need to hide from some rough weather conditions in the Strait of Georgia.

Let me know what Matt can advise you on.

Regards,
Robert

 

[AbandonedBronco]

Glad you made it back safely. Rough weather out on the water is not something I'd like to deal with.
Boats are fun though, just got back from a weekend camping boat trip myself. Loaded up our camping gear in our aluminum fishing boat and cruised out across the lake and found a spot along the far shore in the trees. Pretty fun. Then, my brother has a 70s speedboat with a Olds 455 V8 in it. It does like to get up and move.

As for the EFI conversion, if I were to go with the MPFI, what all would I need off of an EFI 300? Upper/lower intake obviously. Fuel rail and injectors. Throttle body. What else? I'm not looking to use the stock computer/setup. Just the components to use with my own MegaSquirt.

 

[E4ODnut]

AB,
Because I started with a factory stock EFI engine I can't draw on experience on the list, but here goes anyway.

I'd say just unbolt the lower manifold and all things attached to it for starters. This will give you the lower and upper manifolds, throttle body, fuel rails, injectors, fuel pressure regulator, air filter assembly and inlet air temp sensor. You should probably use the exhaust manifold too, but I don't think it would be critical if you don't. Come to think of it, you may have to use it because of fit to the EFI intake. If you use the stock down pipes you have a ready made bung for your wide band O2 sensor, which is absolutely essential for tuning. You'll also need the stock coolant temperature sensor. I don't recall where it's located off hand but I can find out. You'll also need the TFI distributor with TFI module and the E-core coil. Megasquirt has a built in MAP sensor, so you won't need the Ford one, they work on different principals anyway. It would be best if you can use the EFI in tank fuel pump and fuel lines. You can use an external pump but it's easier and better to go all stock Ford stuff.
Also get the complete engine wiring harness. I believe DIY Autotune offer an adapter that will allow you to plug Megasquirt into the stock Ford EECIV 64 pin plug, check with Matt on that. I had to build my own because they weren't available when I did my conversion. Believe me, it's a lot more cost effective to buy one if you can.

I believe that the EFI heads have a somewhat different combustion chamber design for faster burning. All that probably means is that your final tuning may be a bit different than mine. Others may be able to add some more information about that.

Unless you know for sure that the components came of a good running engine, it would probably be a good idea to get the injectors tested and cleaned (refurbished?) at a reputable injector shop. It's cheap and then you know you've got good injectors to start with.

That's all I can think of for the moment.