GM 2.5 Iron Duke TBI Swap

Has anyone here "borrowed" the TBI system from an Iron Duke and repurposed it to provide fuel and spark on another unrelated 4 cylinder engine? What advice/ instructions/ tips/ consolement would you have for someone considering such a plan? Any particular junkyard parts/ vehicles that are useful? Do you prefer the distributor or the DIS ignition- assuming the "recipient" engine already has an old points dizzy? Can the GM OBD-1 ECU accept alternative programming- and if so, what's the best way to go about it?

I have found some good info here on programming your own chips (or memcals) and EFI swap info here: http://www.gearhead-efi.com/Fuel-Injection/forum.php

So yes, the ECU can be reprogrammed, with a laptop, chip burner, chip(s) and the software. The above link has good info on it, as well as other sites out there.

As for vehicles, I would look for 80-90s GM 4-bangers, S10s would be a good choice along with Cavaliers and such. Not sure if any of the TBI engines has DIS from GM, can't think of any offhand so I don't know if they can run DIS or not.

Lada Nivas used the Cavalier EFI setup in the late 90s so they must be adaptable to some degree. You can find the Niva wiring diagrams on line for free.

tbi is an easy swap. why specifically do you want the iron duke version? what displacement/hp you working with? im actually retrofitting tbi into a 64 chevelle in the near future.

the tuning is easy. look for tunerpro rt, pick up a moates chip burner and some chips, and start playing. TBI is really easy. youll need a fuel return style system, but its internally regulated at the TBI as long as you dont feed it a E36 M3 ton of pressure. equal sized feed/retuyrn lines. you can lock out the distributor, convert to an computer HEW module and pcikup, and rock timing control. kn ock sensors are pretty insensitive, so do that as well.

michael

I have used a GM TBI setup on my megasquirted Volvo (B18), and coached a buddy of mine on putting one onto his Triumph. I used a GM coil, ignition module, temp sensors, and throttle body assembly...super simple. My Volvo uses a '75 240 B20 distributor that dropped right in to my '67 B18, which has a VR sensor that works natively with the GM 8 pin ignition module and looks bone stock. Super simple and works fine for me.

Most valuable advice I'd have from a generic sense (since you didn't give us much to go with) is that I used a single barrel (single injector) TBI. Due to my own mistake when i set up the injector parameters, I was using incorrect injector duty cycle timing and failed an injector when I was a long way from home. I didn't recognize it at the time, thought my MS was toast, and had it towed home. I have fixed my MS setup and haven't had a problem since, but I definitely carry spares, and for a while I wished I had more than a single point failure...as it is now, a failed injector driver, wire, or injector will down the car. After more thought, so would lots of other things like a single failed wire for the ignition circuit, a coil, or fuel pump, etc. Now I'm wiser and carry a spares for critical parts like coil, ignition module, fuel pump, injector, etc. that I couldn't fix with a rock and duct tape on the side of the road.

Bryce

Nashco wrote: I have used a GM TBI setup on my megasquirted Volvo (B18), and coached a buddy of mine on putting one onto his Triumph. I used a GM coil, ignition module, temp sensors, and throttle body assembly...super simple. My Volvo uses a '75 240 B20 distributor that dropped right in to my '67 B18, which has a VR sensor that works natively with the GM 8 pin ignition module and looks bone stock. Super simple and works fine for me. Most valuable advice I'd have from a generic sense (since you didn't give us much to go with) is that I used a single barrel (single injector) TBI. Due to my own mistake when i set up the injector parameters, I was using incorrect injector duty cycle timing and failed an injector when I was a long way from home. I didn't recognize it at the time, thought my MS was toast, and had it towed home. I have fixed my MS setup and haven't had a problem since, but I definitely carry spares, and for a while I wished I had more than a single point failure...as it is now, a failed injector driver, wire, or injector will down the car. After more thought, so would lots of other things like a single failed wire for the ignition circuit, a coil, or fuel pump, etc. Now I'm wiser and carry a spares for critical parts like coil, ignition module, fuel pump, injector, etc. that I couldn't fix with a rock and duct tape on the side of the road. Bryce

This is exactly what I want to do- except not megasquirt but a OEM controller. Volvo B18 with TBI. Everywhere I read on the internet about B18/B20 FI is people retrofitting the old D-jet systems...I want to go with something more modern, rather than trying to cludge the old open loop system. If you have more specifics about this setup I'd be grateful for them. Thank you!

A friend of mine had recommended a DIS system off a 88-91 Cavalier, not sure what engine that had. I don't have much preference between DIS and dizzy, as long as it's cheap, easy to get parts for, somewhat programmable, and of course, works.

What intake manifold did you use? I have a Weber 2bbl carb intake (twin SUs on the B18 now) - would that fit the throttle body? How about O2 sensors, knock, intake air temp, etc?

the 87 and later motors are distributorless, at least in the Celebrities... i haven't really looked at the one in the yard that i drove a couple of years ago to see what they did for a cam/crank sensor- i'm thinking they used something in the distributor hole to do that since they had to still drive the oil pump, but they might have added new bosses to the block for those sensors, too.. i can't see why they wouldn't have gone to DIS across the board in all 2.5 applications- Grand Am, S10, etc..

I think they used a crank sensor, might have to drill the harmonic balancer and mount a sensor- the sensor for the Iron Duke is like 15 bucks at Rock auto. I also got a closeout special for a Cavalier TB for 13 bucks. What the heck. Bought it, we'll see if I can get it mated up to the old Redblock and go from there.

O2 sensor: Use a single wire, just like the stock setup. Buy a spark plug anti-fouler from the parts store, cut it in half, weld it on the downpipe as close as you can to the manifold. You can buy an O2 bung for a few bucks more that will look nicer and save you a few minutes, but where's the fun in that?

Knock sensor: I didn't use one. Knock sensors are tuned with a special filter specific to that engine to reduce the impact of unrelated engine noises. I would highly recommend avoiding one that you can't actively monitor and adjust.

Intake air temp: I used the GM air filter housing, which has the air temp sensor integrated into it.

Coolant temp sensor: I had a hole near the front of the engine, passenger side, that I tapped slightly larger to the pipe thread matching the GM sensor I used.

Ignition: If you use a setup from a car with a distributor, such as an earlier Iron Duke (pre-87???) then it uses a VR sensor inside the distributor that plugs into the ignition module inside the distributor. If you get the '75 240 distributor I mentioned above, it bolts right in and has a VR sensor that is compatible with the GM ignition module. I think you'll need to lock out the vacuum advance and then wire the Volvo timing sensor to the GM ignition module. That leaves you with all GM parts (coil, ignition module, ECM) except the actually distributor assembly. Personally, I think this sounds way easier than setting up a crank trigger. It also keeps the engine bay looking closer to stock if that matters to you.

Intake: I cut my intake and exhaust manifold casting into two pieces, reused the exhaust portion, and made my own tubular intake. This was basically just for fun, as I had scraps for all the parts to make it in my shop and wanted to build something. I have a pair of Weber manifolds I've got since then and planned to use, but never did. I expect the Weber manifold will work just fine. Obviously, the throttle linkage needs some crafty adaptation going from the old rod linkage to the GM cable style.

Fuel: I used a fuel pump from an 80's Ford truck/van. External pump with nice dampers, easy to repurpose and common as dirt. I ran new fuel lines. I added a fitting to the filler neck for the fuel return. If you don't have any sort of surge tank, like me, you WILL have air in the line with aggressive driving (or when you're really low). My wagon is a cruiser, fine by me.

The reason I went with the megasquirt is so that I could adjust it easily and I also had one around.

Bryce

Dusterbd13 wrote: tbi is an easy swap. why specifically do you want the iron duke version?

If it removes one more of those characterless boat anchors from the road, don't complain! Horrible engines, and I hope he can put the parts to good use.

Got some more advice last night from my friend. I think the GM ECM will be the way to go- solder in the chip adaptor and tune on-the-fly with a laptop, then burn it to a chip once I've found a tune that works. He's not using the Iron Duke, but the GM 122 engine- the 1.8 to 2.2 liter engine used in the Cavaliers. Similar concept, though. TBI.

Still undecided about distributor vs. DIS. I like that the dizzy looks more stock, but I feel like the DIS will give better spark control- no moving parts to wear out. Hmm.

the difference will be marginal until its coil on plug. the gm ecm of the era wont control that, or cop. reason i was asking abouit the iron duke stuff is that it will be severely fuel/air/hp limited. pretty much anything over 100hp or 5000 rpm it wsill choke it and be a bitch to tune. the 2.8 tbi system will support right up to 150, and the 4.3 will do 200. north of that its small block stuff, or big block.

A Volvo B18 will be just fine with the GM TBI setup. Similar horsepower limitations.

For what it's worth, the Volvo dizzy with GM ignition module and coil definitely still has moving parts, but I'd argue the only "wear" item you need to be concerned about are the cap and rotor, which are super cheap (and easy to get) and I think we'd all consider those pretty reliable. There's no points, and you lock down all of the advance mechanisms inside the distributor so that the ECM does adjustments based on MAP, temps, TPS, etc. All things considered, both the DIS and the distributor (with VR sensor, GM ignition module, GM coil) method will be FAR more reliable than the old mechanical/vacuum advance and points style and both are essentially no-maintenance. Sure, cap and rotor when you do spark plug wires, but that's quick and infrequent.

Bryce

Interesting . . .

I've got the TBI setup from my '88 s10 iron duke sitting in a box somewhere in hopes that one day I have a use for it... my thoughts have always been to use a megasquirt and use the stock ignition system on whatever engine it is (vac advanced)... had thoughts of using it on a yugo...

Some good information here. I'm thinking about using one for a later phase on my Corolla challenger if I don't try out a carb box.

Sealing TBI for SC'ing

Very interesting stuff.

I've been doing some snooping around the Moates website and it looks like MOST of the TBI systems use a G2 chip, which in order to do any ECM tuning requires soldering in a chip adaptor. I'm pretty clumsy with a soldering tool (hence why I've shied away from DIY M/S) but apparently the 94/95 GM 8 cylinder trucks used TBI with a G1 (Memcal) chip adaptor- which can be used with the Cavalier 4 coil pack DIS and one or two TBs.

My last hurdle (on paper, anyway) is figuring out the VSS (Vehicle Speed Sensor), although on the Corvair TB setup I'm using loosely as a guide, he uses either an in-line speedo cable sensor or a hall effect (I think) sensor on the driveshaft/ axle shaft/ wheel. Then of course there's the wiring harness.

BTW, my friend's website for Corvair EFI, if anyone's interested. Lots of good info here:

http://www.corvair-efi.com/

Bryce, do you think the ECM in question would talk to the electronic volvo dizzy, or since I'm already thinking DIS (and have a model using DIS to go by) should I just continue along that route? I really don't have any preference one way or the other, and looks are not a major concern.

Unless you want the car to drive like a Cavalier, the VSS isn't really necessary. On manual transmission ECMs you probably wouldn't even notice, on auto ECMs you'd have a stumble or possibly even stall coming down from cruising speed to a stop with a manual transmission. It's quite easy to add a sensor after the fact if you decide the stumble/stall is not acceptable for you.

The wiring harness, well, everybody's a little different there. I used a MS catered harness from DIY autotune...even if you're not using a MS, these things are really slick:

http://www.diyautotune.com/catalog/megasquirt-wiring-bundle-1239-long-p-101.html

Of course, if you were using a MS, there are pre-terminated versions available.

Any of the GM TBI ECMs will work just fine with the Volvo distributor because you're using ALL GM components except for one sensor, and that sensor doesn't even directly show up for the ECM (it is hooked up to the ignition module directly). The VR sensor (timing sensor inside the distributor) replaces the GM VR sensor and works just fine with the GM ignition module. In GM distributors, the ignition module was located inside the distributor and has a short pigtail that plugs into the sensor on the distributor shaft. With the Volvo distributor, you'll locate the GM ignition module and coil wherever it suits your fancy and then splice the Volvo VR sensor in exactly the same as the GM one previously was. A picture is worth 1000 words...but I don't have a picture of my setup handy, at the moment.

In either case, it's a matter of preference if you use an electronic ignition with distributor or DIS. I had all of the GM junk around for the dizzy version and my experience is that the DIS components are a little less common. Every parts store in the nation has a GM 8 pin ignition module on hand, but a Cavalier DIS ignition module isn't as prevalent. Also, I am a sucker for parts bin swaps and stockish looking engine bays, so the '75 distributor seemed more fun to me. I also think it was easier to adapt than the DIS because I didn't need a precise (or imprecise and adjustable) crank sensor bracket. As I said, it's a matter of preference.

Oh yeah, one more word of warning. Some of the later DIS setups are hard to get a tachometer signal from. With ECMs setup for TBI, I don't think you'll run into this problem, but just something to check before you commit to a direction if you have a tach and want it to work with a DIS setup. Make sure the DIS you choose has a tach output.

Bryce

Oh yeah, and another DIY Autotune plug...I haven't tried it, but I've been thinking the latest MicroSquirt would be a great candidate for a simple, single TBI setup like I'm using on my Volvo (single low impedance injector):

http://www.diyautotune.com/catalog/microsquirt-engine-management-system-839-wiring-harness-p-509.html

It has lots of advantages for a simple system on an old car, like we're discussing. It's completely sealed, pre-assembled, cheap, small (easy to hide), and works with all of the standard GM parts. It's limited in features, so you're not going to have tons of room for growth. As far as I can tell, the only real limitation compared to the GM ECM or MS2 is that it can't control the GM (4 wire, stepper style) idle air control valve. FWIW, I have been running without IAC for a few years on my Volvo and it's really not that bad except in very cold temperatures.

Just more food for thought for others considering this same path.

Bryce

The dizzy does have the advantage of not needing to craft a tone wheel for the crank sensor. I see that Rock auto sells the dizzy tone wheel and electronic pickup for the dizzy. Those parts run about $30, vs. $130 for the whole dizzy. I wonder if I could simply swap those parts into a B18 distributor? They look very similar otherwise. And I have boxes of old B18 and B20 dizzies.

Then lock down the timing so the mechanical doesn't do anything...the ECU and ignition module will modulate the timing. Won't even matter if the dizzy shaft is worn out, as most are.

Another thing...the 94/95 GM TBI ECM on the V8 pickups worked with a dizzy anyway...so this should be drop in. Wiring schematics look pretty easy, even for a carb guy like myself.

I'll check out the microsquirt, too. Looks interesting.

I'd recommend getting a whole (used) distributor from car-part.com if you're considering the '75 240 B18 distributor. I think I paid less than $50 shipped for mine.

Of course, if you wanted to try modifying what you've got with the GM VR sensor parts, that's always possible. If you gave the GM and Volvo distributors a few shots of tequila and left them in a dark shop, there's no telling what might happen.

Bryce

tbi wiring is silly simple.

i'm parting out a 94 v8 chevy truck if you want to be lazy and not source one locally.

Nashco wrote: I'd recommend getting a whole (used) distributor from car-part.com if you're considering the '75 240 B18 distributor. I think I paid less than $50 shipped for mine. Of course, if you wanted to try modifying what you've got with the GM VR sensor parts, that's always possible. If you gave the GM and Volvo distributors a few shots of tequila and left them in a dark shop, there's no telling what might happen. Bryce

Isn't that what happened between Volvo and Ford a few years back?

The reluctor and pickup from the '75 242 dizzy look like they'll slip right on to the old B18 diz shaft. $40 shipped to my door for the parts. So now I'll have a dizzy to play with and modify and a TB to mount on a weber intake. That ought to keep me busy for a little while.

My friend has some tested good used G1 TB ECMs he'll part with for $50 each...then I'll need to round up an ignition module and all the sensors, make the wiring harnesses, and get the emulator so I can tune with my laptop on the fly.

Wow. Baby steps, to be sure, but it feels more manageable this way. Fuel Injection! Hah! Who'd a ever thunk I'd ever be intentionally putting Fuel Injection in a car?

By the way, Bryce, what kind of fuel economy numbers are you putting down, if you keep track?