Interface on '94 ECU (OBD-I?) - Defender Source
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  #1  
Old October 6th, 2005, 12:11 PM
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Jason Herring
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Interface on '94 ECU (OBD-I?)

Does anyone know if the ECU on the '94 D90 is OBD-I compliant, or something else? I was thinking of hooking up a scanning tool to the ECU if possible to read the ECU output on a PC, but I haven't been able to find any interface spec.

Has anyone done this on the early D90's?
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  #2  
Old October 6th, 2005, 02:01 PM
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The vehicle has a code rearer box to display fault codes, the hookup and diagnostic interface is unique to Land Rover. You need either the factory tool from Lucas, testbook, or one of the aftermarket diagnostic systems such as the Rovacom to view data in real time.
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Old October 6th, 2005, 03:00 PM
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Right. But... no one has reverse-engineered this? There are alot of projects out there which have reverse-engineered various engine's ECU protocols and allowed viewing in real-time. This was before it got alot easier with OBD-II.
I was wondering if anyone had heard of a project/software for Land Rovers....
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Old October 6th, 2005, 08:00 PM
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With the RovacomLite costing as little as it does, it seems hardly worth the effort to spend the time reverse engineering it.
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Old October 7th, 2005, 03:43 AM
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Well, I want to integrate this functionality into a Car PC project I'm installing in my D90 - so a stand-alone app isn't desireable. It's not about the $$.

I was going to use http://www.dashpc.com but I might use a different package as that one is very poorly documented.

For OBD-II there are open-sourced scan tools available & some Car PC projects include this.
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Old October 7th, 2005, 01:03 PM
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Yes, 94 system is OBD-I compliant.

It's more widely known as the Lucas Hot-Wire EFI system. However, I don't know if this system offers any diagnostic output that you can view real-time. That's one of the many reasons I'm going to be swapping to a different ECU, probably MegaSquirt now that I have experience with it.

-Hans
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  #7  
Old October 7th, 2005, 01:10 PM
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Hey Hans, how is Megasquirt? I've looked at that system and thought about replacing my Holley Pro-Jection TBI (on a different truck) with it as I've had some problems with the Holley unit. I hadn't really thought about swapping out the D90 ECU - but if you have success with it, I might go that route... I'll be very interested to hear about any progress you make with it.
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Old October 7th, 2005, 02:14 PM
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Megasquirt absolutely ROCKS..... at least in my CJ-7 so far. Getting the initial settings and tuning calibrated is time consuming, but it gives tremendous tuning ability as well as real-time data viewing and logging as well as on-the-fly adjustment of the fuel map. It's also a near exact replacement for the Hot-Wire system, and you can use most of your existing sensors. (you do have to replace the O2 sensors, with the cheaper and more common versions). The tuning software out there is also really nicely done too.

The biggest advantages for me over the hotwire system is that you can use normal O2 sensors instead of the rare and unusual titania sensors in the Defender. You can eliminate that $500 Mass Air sensor completely, and also remove about 5 feet of intake tubing if you want to make a REAL cold-air intake setup. No $300 chip from RPI to adjust the fuel map. And the newest version even lets you keep the intake stepper motor fully functional. I plan on using it in mine with the later THOR intake manifold which supposedly is a real HP jump. I also plan on totally replacing the wiring harness at the same time, that way I can sell the old system on E-bay as a complete drop-in for somebody that wants to inject an old buick or series truck.

The drawbacks.....it ain't exactly CARB approved. No check engine light. It's also something that most mechanics just aren't going to understand fully, so you are stuck doing any repairs yourself.

A lot of guys have used the MS system to replace the Holly ECU's with good results. What kind of truck is it in?

-Hans
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  #9  
Old October 10th, 2005, 06:50 PM
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I've got two Jeep J-10 pickups - one is a general-use truck, the other a baja racer. Both have built 401's. I have a carb on the baja, and the TBI Holley unit on the plain Jane J-10. The race truck engine is tired & the other truck has a fairly fresh engine. I want to swap engines and install the TBI unit in the baja truck at the time of the swap - I've had alot of fuel slosh problems with the carb setup on trails. The other truck will then officially demoted to 'beater' status.

I've been having some trouble with the Holley unit - for reasons I can't understand, the engine starts loading up on fuel during compression braking - this starts immediately when I let off the gas and if decelerating for awhile causes the engine to start to burp and once in awhile backfire. I can watch the O2 sensor in realtime (with the Holley software - pretty good in it's day IMO) indicate the EG is getting super-rich... I have done everything I can think of to stop this situation, but so far, nothing has worked out. I didn't do this in years past. I think the Holly ECU may be flakey - it's under-hood mounted (exposed to heat and moisture), which is against the mfg's recommendation, but I had no choice - the cabling simply wasn't long enough to go anywhere else.

Anyway, it's lasted a good number of years - since 1996. I would not mind a more elegant solution.

I had been considering megasquirt for awhile for this project. I would want to use my existing components, which I think I can with the MS setup. I've toyed with the idea of going MPI - but I'm not sure if I want to go through the extra headache. It might be kindof cool to have one of the only MPI 401 AMC V8's in the world, though but I'd like to know how much real power this is going to give me over my TBI setup, which I'm happy with.

If this works out well, I might consider doing something like this for the Defender... if I don't go diesel, that is.

What is the "Thor" intake manifold? Is that the factory manifold on the 4.0 or the 4.6? I have the option to pick up a complete 4.0 in good condition but needing a rebuild fairly cheap.

I have to say I'm pretty disappointed at how little horsepower comes out of the 3.9L V8, combined with how crappy the gas mileage is. I'd live with one issue or the other, but not both.
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  #10  
Old October 10th, 2005, 10:00 PM
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Thats one thing I have heard about the Holley system. The Megasquirt can adjust the deceleration fuel amounts. You can definitely use the Megasquirt in place of the Holley ECU, I'm using mine with a Jeep 4.0 Multiport manifold kludged onto a 4.2. The main problem with the Holley is that the programming is very generic and not tunable enough.... IIRC it's based on the GM computer. OR, you can always go with the new Edelbrock MPI setup for the Jeep.

The 'Thor' Manifold is that funky banana looking thing on newer 4.6's, supposedly has better low-end torque. I also plan on, eventually, doing a stroke job with a buick 300 crank to bring the 3.9 to 4.8.

-Hans
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  #11  
Old October 11th, 2005, 10:06 PM
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Is this the newer manifold? Will this bolt onto my existing 3.9 without major mods??
http://cgi.ebay.com/ebaymotors/LANDR...QQcmdZViewItem

I think I would avoid the 3.9 block if I was going to go through the trouble you are talking about - the 4.0 block has a much stronger bottom end w/ cross-bolted mains. Can you stroke a 4.0 similarly?
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