No expert in these matters, and probably my question has been raised before, but unable to find any discussion:
How practical, engineering and cost, would it be to "recycle" a complete modern fuel injection system from a dismantler yard, say from an Audi/VW engine, and implant its system into our engines, particularly for a good street car? This would include useful FI hardware system parts with software, and some after market hardware to complete a working system. Might it help be to select a donor engine's FI system with cc's that match our engines?

Dion had a really nice cis system from a VW.

People have adapted CIS from other vehicles to their Type IV before so I see no reason another FI wouldn't work.

I was looking at doing it Bosch LH2.2 or LH2.4 (later uses trigger wheel) from a Volvo and I know a few other people have looked into as well.

A few things to consider is how to tune or modify if the base fuel and ignition maps are too far off? What if the newer system uses knock sensors?

GM EFI

A co-worker here says to use the GM stuff from the Ecotech equipped cars. These can be reprogrammed using HPTuners (he has side business building and tuning GM cars)

Putting in a different FI system is like putting lipstick on a pig. Just get rid of the FI crap and go to tried and true carbs...MUCH simpler, easier, less expensive, the list goes on and on...remember, these cars are 40+ years old...

That's not the experience of many of us here who have owned and worked on these cars since they were new or nearly new. When it's operating as it should, the D-Jetronic FI system provides superior performance to any carb system on the same motor (assuming the motor isn't rebuild with larger displacement, high lift cam, bigger valves, etc.). Beyond performance, D-Jetronic also provides significantly better driveability, operating properly under a wide range of engine temperatures, load conditions, and air temperatures. FI injectors also provide vastly better fuel atomization, reducing emissions and improving economy. Lastly, the D-Jetronic system on the 914 is engineered to properly handle crankcase gases and fuel tank hydrocarbon emissions and reduce air pollution.

I worked with a group of about 10 other people around a decade ago to build on the work done by Bell Lab's engineer Frank Kerfoot, who drafted a full schematic of the D-Jetronic ECU. With this group, we reverse-engineered the D-Jetronic system in full and came up with diagnostic procedures and characteristics for all of the components. This includes troubleshooting guides and theory of operation documents. This work has been extended by many others here on 914 World, to provide rebuild kits for the MPS and the TPS, testing services, and new wiring harness products.

People who are interested in retaining their D-Jetronic system to maintain good operation and driveability, and keep the value of their 914 for resale high, are encouraged to review my D-Jetronic page (see my sig). If you plan to modify your engine for higher power, then carbs or other programmable aftermarket FI systems are recommended, as adaptation of the D-Jetronic system for modified engines can be complex.

OUCH! I just rolled my eyes so hard I hurt myself!

The FI vs. carbs discussion should go in its own thread. In fact, you can do a search and find about twenty different ones through the years, and add your two cents on to that.

This thread is about fitting a modern FI system onto a 914.

Yes, it can absolutely be done. Some will require you to fabricate parts, some will require a lot of creative adaptation of parts, most will require some electrical work and re-wiring. It is very unlikely that any will be completely right when you bolt them up, but there's at least a half-decent chance they will be as close to right as the original FI was, once you fiddle with things a bit.

That said, you get a whole lot more flexibility if you use something like Microsquirt to control a bunch of modern components. You don't have to live with anything that was designed for a different car, because you can tweak pretty much everything.

Of course, that means that you can tweak everything incorrectly as well. Probably more easily than making it all correct, since there are a lot more ways to be wrong than right. But it's a good learning experience, so...

--DD

Another thing to make clear is that for the unmodified 1.7 and 2.0 L motors, with stock pistons, valves, cam, etc., that to my knowledge, nobody who has fitted carbs or an aftermarket FI system has achieved better performance (i.e. improved torque or power).

As far as driveability is concerned, carbs will always be worse because they simply don't have the capability to react to all of the various engine conditions encountered in normal driving. It's possible that an aftermarket FI system could achieve better driveability than D-Jetronic, though such systems as active idle speed control and multipoint engine temperature measurement, improved load metering, etc., but that depends on the system implemented.

As far as emissions go, carbs are again the worst solution, as most carb systems can't handle fuel tank or crankcase emissions, and the poor atomization at low venturi speeds leads to high CO emissions. Aftermarket FI systems with lambda control can reduce emissions as compared to D-Jetronic.

One thing that's often thrown out there is cost, with the claim that going to carbs is cheaper than fixing the D-Jet system. With rebuild kits available for the TPS and the MPS, as well as the classifieds here, a D-Jet system can be fixed up relatively cheaply. New carbs, especially twin IDF's, aren't cheap. And if you do save some money, you'll probably lose more in the resale value of your car, because carb cars sell for less and can be difficult to impossible to pass emissions in some states.

One advantage of an aftermarket FI system over a stock D-Jet is the ability to increase performance thru increased displacement, compression and a higher performance cam. You can make theses changes, have significantly increased performance and still maintain good drive ability.

Agreed, I mentioned this earlier in this thread. The main issue is that modified engines have significantly different volumetric efficiency (VE) curves. While it's relatively straightforward to adjust the main mixture setting of a D-Jetronic system, changing the VE curve is complicated. Inside the ECU, the VE curve correction is handled by the daughter card that sits above the main PCB. Depending on which ECU is being used, the VE correction circuit consists of 3, 4, or 5 waveform generators that are OR'ed together using diodes. To modify a D-Jetronic ECU for a different VE curve would require characterizing the engine on a driven workstand to extract the actual VE curve, then modifying the DTL waveform generator circuits to duplicate the extracted VE curve. Bosch did all this crap for the many applications that D-Jetronic was used for and build a ton of different ECU's, specific to each engine configuration.

Clearly, nobody wants to do this. The simplest way to go is to use carbs and change the jetting and emulsion tubes to best fit the VE curve of the built motor. With a big box of jets and tubes and experienced engine guy can do this with good results. You can also get starting points from people who have built similar engines, helping you only to need to do fine tuning to get it just right. However, with carbs, it will always be a compromise fit as their configuration is fixed and they cannot provide the control across the whole running range for an optimal VE fit. Plus, you take on all the other baggage you get with carbs (i.e. driveability issues, emissions, etc.).

Aftermarket FI systems are the best solution for modified engines. These systems use mapping to provide an accurate VE correction across the engine speed range, and are extremely easy to tweak. Add in spark management, lambda control, and idle stabilization, and you can make just about any engine mod work, and end up with a driveable, powerful setup. Personally, I've never done one, but there are gobs of people here on 914World who have put just about every system you can imagine on our 4-bangers, they can provide a world of information and help on the process.

One last consideration is the how the FI system monitors load, which is how it sets the basic fuel mixture. D-Jetronic (D for "Druck" which is German for "pressure", i.e. manifold pressure) uses the pressure level in the intake manifold to monitor load, which is accomplished through the Rube Goldberg designed "manifold pressure sensor" , which is tightly integrated with a monostable multivibrator circuit in the ECU.

Aftermarket systems blissfully replace this mechanical nightmare of a pressure sensor with a solid-state sensor, but they're still subject to the same problems of load measurement that any speed-pressure based FI system has. Bosch went through several iterations before coming up with the system that's in use in most systems today, the mass-flow air sensor, based on a heated platinum wire in combination with a thermistor. This system measures exactly what you want, which is the mass flow rate of air into the engine, making it very simple to calculate the required amount of fuel for optimal performance at a specific engine speed, load, temperature, and throttle position.

When considering an aftermarket FI system, be aware of how it does load measurement. Also be aware of compromises implied by the type of sensing used (e.g. multiple or single throttle body designs).

As a thought exercise in the past, I kinda figured out how to "update" the D-Jet system to a modern FI.

Take a junk D-Jet "Computer" and remove everything but the edge card connector used to hook to the wiring harness. Install a MegaSquirt in the case. Put the programming jack on the bottom where it is not visible.

Take the MAP sensor off the MegaSquirt board, and relocate it inside the MPS housing. Hook the hose on the MAP sensor to the inside of the Manifold connection hose boss. Wire it up to use the factory connector.

Take apart the TPS and install a small modern TPS in it.

Take the trigger points out and replace them with a small toothed wheel for cam speed reference.

Don't hook up the O2 sensor portion of the MegaSquirt. Run it in open look all the time. You lose some efficiency, but you maintain the appearance of stock.

Gut the factory Aux air regulator, and install an IAC into it from the bottom. Hide the wires under the intake manifold.

Make sure to build a D-jet appearing harness with extra wires for the ground returns. The MegaSquirt requires that you have a proper ground return to it.

I don't remember off the top of my head if you would need to add resistors in the injector circuit or not.


If this were done right, the engine would look like a stock D-Jet system. But it would start and run like modern FI.

For a little more money, buy a commercial aftermarket FI that incorporates Ignition programming. Then the distributor would only be used for the high tension distribution. It becomes "pointless"

Clay, I like that, "stealth modern" FI!

While I don't mind Megasquirt as I've used it a few times, the OP was asking about using EFI controllers installed by OEM's on cars found in the wreckers and with 10s of thousands or more installs. (I did find a burnt Megasqurit once at the wreckers, car fire and no idea what caused the fire)

Subarus also have the ability to be reprogrammed fairly easy I believe and the software and hardware needed is cheaper than the stuff I posted earlier.

I'm sure there a quite a few fuel and spark systems you can grab from the wreckers and install and get the car running and possibly it might run half way decent.

Of course it's going to be a compromise in the as-is installed state. Without dyno testing or data logging that you can use to perform mods to optimize the system, you might as well stick with what you have.

Want a more modern system on a stock D-jet 914?
Install a L-jet off of a 1.8 914.

Bolts right up to 2.0 runners by giving the 3/4 tubes a little tweak and a couple sheet metal screws to fasten the air cleaner mount.
Didn't notice any power difference from a D-jet 2.0, no gain, but more important no loss.
Nice clean install that looks factory.




I did the gutted D-jet box trick, looked stealth, but what a PITA to work on.
And BTW good luck plugging the cable into that jack.

I'll defer to the wisdom of this board and attempt to get my FI system sorted out. The only time the car seems to run right is when you're accelerating above 2800 rpms. It "bucks" badly between 2400-2800 rpms, to the point where I have to short shift to keep it manageable. With the replacement of the fuel pump, at least it'll start now. I replaced the plugs, wires, dist cap, rotor, coil, and circuit board in the TPS housing, but didn't check the points gap or timing. Hopefully, the shop that installed the fuel pump will get it sorted out without costing me another arm and a leg.

I'm following this thread, will be interesting to see what later year FI systems can be retrofitted onto these 914s, without too much trouble (that being the key phrase). All this talk of opening up the ECU, disguising wires, installing sensors, add'l circuits, etc. makes my head hurt. Plug and Play is what I'm all about, nothing that involves hooking up a multi-meter or laptop!

There is the problem. The 914 is not a mainstream car like a Chevy. Therefore you won't find the "Plug and Play" stuff you are looking for. Any aftermarket/replacement system you pick will require time and the use of a multi-meter to get it working. If you go with carbs, they will require lots of tuning to make and keep them working right. (I have run D-Jet, L-Jet and Carbs on a 4 cylinder 914)

If you really want "Plug and Play", get a new injection harness from Bowlsby, get a rebuilt pressure sensor and TPS, get new injectors and bolt it all on. No meter required, just money.

This is about as close to plug-and-play as you'll get for an FI system that will work on just about any VW air-cooled configuration (sorry, you will need a laptop). And so affordable, too! Only $1200 more for the turbo version! Make sure to watch the video.

http://www.cbperformance.com/product-p/7075.htm

Whoops, meant to edit this, not repost it, sorry.