Has anyone used TBI with a megasquirt setup? I have an 84 Blazer with the factory carbed 305 that I want to megasquirt, but I am unsure as to whether go with a TBI or a multi-port setup.

Any feedback would be appreciated

 

Megasquirt…..that’s a sticky subject. For a DIY project it’s pretty darn neat, I just don’t think it’s on par with stock GM code and hardware quite yet, and it’s definitely not on par with the new code and EBL board being released by Rbob.

Main problems I see:

1. No check engine codes
2. No limp home mode, GM stuff can get you home with several sensors dead in the water
3. Parts availability, can’t get a megasquirt at local parts store
4. Rather ruff code, doesn’t have a lot of the smoothing and transitional routines that GM used.
5. Price and/or assembly time
6. Not emissions compliant, which it doesn’t look like it matters to you.

Advantages:

1. DIY appeal factor
2. More performance oriented features, like N2O control and higher RPM tables, and rev limiters, although this is all added in the EBL
3. Will do MPI or TBI, again there are strong hints that MPI will be no problem with the EBL
4. Open source code with lotsa people working on it, could be some very cool stuff out in the coming years.
5. Faster data logging than stock GM ecm, once again fixed by the EBL board.
6. No need for separate tuning equipment

What’s best for you all depends on where you want to go with your project and how much time and money you want to spend. If your goal is to just FI your stock 305, then go with a TBI setup. You can get a complete setup for less than 150$ and you could probably get away with a stock chip if your motor doesn’t have much done to it. TBI will support 400+ HP with a 454 TB and big injectors, unless you plan on making more power I don’t think the advantages of a MPI system will outweigh the cheapness and simplicity of TBI. Megasquirt is a cool little deal, but I wouldn’t run one for the simple fact that you will most likely toast an ECM in the middle of nowhere some time in your life, and being able to bum a ride to the parts store for an ECM to fix your car on the side of the road is priceless. It happened to me when some wires shorted out on the firewall, I was back on the road in a half hour, if I would have had a MS I would have had to tow it and be down for a week or two until I got a replacement.

 

Sounds good to me. I was thinking multi port would be the way to go, but for reliability and the fact I don't plan on rodding the blazer as it will be my college vehicle, TBI is my best choice for its simplicity.

I have a complete tbi setup (harness and all), but I liked the DIY appeal and the fact I can mess with it on my laptop.

 

You’re not going to gain anything with a MPI system on a stock 305. TBI will be cheap and easy to work on. It sounds like you’re more interested in the tuning aspect of the hobby anyway. TBI will let you concentrate on learning to tune instead of chasing wires and a complicated MPI systems around.

If this thing has to be pretty reliable, you really need to just go with TBI. Just pick up an 85$ burner from Mr. Moates and some flash chips and you’re in business. With GM stuff you can kinda sneak into your equipment instead of having to buy it all at once. Get a cable and the burner and get started, then later on get a WB then maybe pickup an emulator so you can tune on the fly. On a college budget being able to spend the money when you have it and hold on to it when it’s scarce is really handy. You also have to remember this equipment will work on most any GM vehicle. You can tune your buddy’s cars for beer money. Not that I would have done anything like that. Actually since my car is down and I’m not going to get it running until later this summer I’m tuning in exchange for a hot rod to drive for a while. My buddy has me tuning his stealth rammed camaro and my brother is inheriting my TBI system for his vortec headed 350. Between the two I should have some fun this summer. I usually data log to and from work and burn 2 chips a day. I can get a car in pretty good shape in a week or two of this. Although I have them convinced it will take at least 3 or 4 weeks and 2 trips to the track.

 

I've been reading on megasquirt and I am not understanding what the problem is with it.
Loggin on the go and autmoatically adjusting the VE table sound like heaven to me.
You wont need 2 weeks to get your car running. Also, you don't have to mess with the computer every time you change the chip.
It can be also wired to where you can go back to stock settings in a matter of minutes. I always have my stuff wired like that just in case.

I really see megasquirt as a great product.
So far I have not read why its bad, only that its not good.

Tell us specifics.

Also, i wanna ask About Rbobs system, dewey316 mentioned it to me>?

Hows that work???

Thanks.

 

You're right, I am more interested in the tuning aspect of it more than anything. I'm also tired of having it carbed. With mornings here in ND in the winter that are sometimes -20*, TBI is the way to go.

I am definately after performance, but I would like it to be reliable when I start college next fall. The best mileage that I have been able to pull off with the qjet 305 is 15.7 mpg. Keep in mind this is with a 5,000 lb 4x4 chevy blazer. I know that I don't stand to gain a TON of fuel mileage with the TBI, I do expect to gain 1-2 mpg with it at the most.

What is the 'WB' that you speak of, along with the emulator for tuning on the fly. I didn't know that could be done with TBI. Can you fill me in on it?

Also, what is Rbobs system all about?

Brendan

 

1st post here, I think. I got some thoughts on Megsquirt that might help. My cars aren't 3rd gen's, but are powered by sb chev's. 1954 ***** CJ3B w/ 76' 262 sbc, total stock engine and 1972 Porsche 914 w/ 355 sbc, 12.5/1 Comp. AFR 210cc heads, etc.. I'm changing both to Megasquirt. The Jeep from Rochester 2GC card to 1990 Suburban TBI intake and 220 TBI w/ 305 injectors. The Porsche from Holley 900 4Di, installed in 1995 to 1988 Suburban 454 220 TBI on Edelbrock Vic Jr. intake.

For Megasquirt, 262 is using MS 2.2 circuit board, no flyback dampers using resistors instead. The CPU is MSII w/ ignition and idle air control. The board is assembled and tested w/ simulator just waiting to finish intake install, fuel tank return line and pump. The 355 is using MS 3.0 board w/ flyback circuit and MS II CPU for ignition and IAC. Board not assembled yet. Just got the 454 TBI for $35 on ebay and am rebuilding this week. Using stock 90lb injectors with 35psi to increase the lb/hr to get closer to the holley 4-80lb injectors.

This is all fairly easy and very inexpensive to do w/ GM TBI's as the TBI has most of the sensors and other two (water and intake air sensors) are easy to find in wrecking yards for cheap or maybe free. The TBI's, intakes sensors, wiring connectors are all over the place in wrecking yards for cheap or at Autozone for more cash. TPI or MPI gets a bit more involved, as you probably know. Just about everything you need to know is at www.megasquirt.info

The WB you mentioned is a wide band oxygen sensor. Not really necessary or recommended for a newbie. If installed as the only O2 sensor by someone new to DIY EFI, it can potentially drive the VE tables into detonation if mis-calibrated or in a way rich condition by leaning out too much. Stick with a cheap 4-wire O2 sensor at first.

Both engines were converted for driveability, mileage and in the Jeep's case to keep the engine running at any angle. The complete conversions are way cheap, 355 for about $500 total and the 262 for $400. Most parts were bought using FleaBay, www.car-part.com and local PickaPart wrecking yard.

Hope this helps.

 

WB stands for wide band. A stock O2 sensor is a narrow band sensor in that it only see's 14.7 to 1 air fuel ratio. It just flips back and fourth across .45 volts when your near 14.7 The ecm monitors this and adjust fuel accordingly. A wide band can read afr's from 10 to 1 all the way to 20 to 1. This allows you tune your wide open throttle without any guess work, unlike with a stock o2 sensor your pretty much tuning by ear and plug cuts like the old days. With megasquirt and with Rbobs new EBL board you can have the ecm use the WB to self tune itself much like it does with the stock NB sensor. A wb is one of the most powerfull tools you can have for tuning. It removes alot of the guess work involved.

Moates has devoloped some very cool hardware called the autoprom and the ostrich. The autoprom is an emulator and burner all in one package and the ostrich is just an emulater you can use if you already have a burner. An emulator allows you to make changes on the fly without pulling over to burn a new chip and physically swapping them. Very cool and very fast. Megasquirt does this much the same way. The power of having the autoprom is that you can hook it up to any ecm and tune away, when your done you just burn a chip and stick it in your ecm and move on.

The second piece of hardware I speak of is the EBL board and Ultimate TBI code. Our TBI ecm's log at an excruciatingly slow rate of 1 frame per second. This keeps you from being able to see alot of what goes on at WOT and during transitional situations like pump shot. I've always used the logger included with my zietronix WB to get around this, but it's a pain to switch back and forth. Some smart individuals developed a lockers setup that tapped into a factory edge card in our ecms to monitor every single parameter in the ecm real time. The second part of the equation is the code. With TBI half the code is on the removable chip that we program the other half is in the on board rom hardwired into the ecm. The trick is to go "romless" and run all the code in one bigger chip this allows you to redo the code and reprogram the ecm to do anything you want using source code. The EBL board is basically a lockers setup and romless setup rolled all into one. The best part is that Rbob developed his own ultimate TBI code that fixed all the problems with TBI. There is a 10 page thread in the DIY board that describes what all has been changed in the code, but basically the code puts our 15 year old ecm's right up there with some of the high end stand alone ecm's available. There has even been talk that with slight hardware changes it should run a MPI setup with no problems.

All these neat things cost money, a burner cost 85$, a ostrich is around 200$ an autoprom is roughly 350$. The EBL board is more than a burner and less than the autoprom. PM Rbob for a quote and check out www.moates.net for the rest. A WB will run anywhere between 200 and 350.

Looking at those prices it makes the megasquirt look very attractive, but you have to remember you'll be able to program most any GM vehicle with this equipment. If your planning on sticking with this hobby for a while then DIY tuning is the way to go. Megasquirt has it's nich, but it doesn't have the millions of dollars GM spent in sofware development behind it's code. Your just not going to get the tunablilty that GM stuff offers from it. At the same time GM code can pretty intense, but when mastered you can do some pretty amazing things with it.

I guess my suggestion is that if your in this hobby to further your knowledge and challenge yourself go DIY, if you just need to get a wild setup running well enough to have some fun with it and oem reliability isn't a factor along with a minimal learning curve MS might be better for you.

Sorry for the novel, just way too much stuff to keep it simple.