Programmable Engine Management using stock Bosch wiring - Alfa Romeo Bulletin Board & Forums
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post #1 of 64 (permalink) Old 10-28-2009, 04:14 PM Thread Starter
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Programmable Engine Management using stock Bosch wiring

I wanted to know which systems out there, if any, allow you to keep your Bosch wiring in place. I've seen reference to Megasquirt plugging into the harness on the L-Jet maybe. Does it work for the Motronic 4.1 specifically the Twin Spark? Do any of the others have an interface to the harness?

I wanted to explore one of these options on my TS. As is it is currently stock. I am not interested in removing the harness to the injectors and various sensors. I wouldn't mind adding a sensor or two - MAP , IAT, etc and rolling up the AFM pigtail and tucking it out of view, but that's as much as I want to do to the existing system.

I haven't found any discussion on it so far.

Thanks,

Stefano
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post #2 of 64 (permalink) Old 10-28-2009, 07:58 PM
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FWIW, I think you'll find that adapting to the stock harness isn't the bigger issue.
Find a means of connecting X aftermarket system to the stock ECU plug and you're in. (an old blown stock ECU can be scaved for it's connection block for example)

The real problem is the sensors, senders and injectors themselves as some systems will work with Bosch stuff, some won't, or won't with the specific ranges found in the car. (as in 'be prepared to change over to some other type, like prolly Chevy')

Then there's high impendance vs low impedance injector driver issue. (do you want to tap in a driver box to match the aftermarket system to the injectors, or change the injectors to match the aftermarket box?)


I took the easy way out:

SDS with it's harness and sensors, then as I have no AC, tucked the whole of the stock engine harness that was related to the EFI back through the firewall where it resides in a bundle behind the glovebox. (I didn't want to cut it up as it may at some point be returned to use)




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post #3 of 64 (permalink) Old 10-28-2009, 11:11 PM
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A lot of aftermarket systems like a variable voltage TPS, so that may be an issue. Some can quite easily do acceleration enrichment via MAP sensor change. Probably worth looking/asking about your intended system if you don't want to change from the switch style TPS.

As per Tifosi's post, an old system could be butchered for a plug, but I'll make the sujestion that you come up with a way of glue or potting in epoxy the back of the old ECU plug once all the wire are attached and known to be correct. The last thing you want is some random failure that is a result of moving ECU pins or broken wires.
I had some dodgy pin contacts in 1 of my cars and it was no end of frustration for me. Especially as it was so intermitant and effected multiple pins.

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post #4 of 64 (permalink) Old 10-28-2009, 11:28 PM
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Another option is the AEM - Fuel / Ignition Controller (F/IC). From what I read on their forum, the FI/C-8 is the 1 to use as it has more features. The important part is that it can do an Airflow meter output signal (a variable voltage output map based on a rev/load scale) to make the factory computer think the AFM is still there. It intercepts the original injector signal allowing more or less injector open time. The only problem I see is that it doesn't allow additional ignition advance, it's only capable of standard or retarding the ignition timing.

Add the advantage of not having to start the programming from scratch, doesn't effect the cold/hot start programming or variable cam timing.

I use the Trust E-Manage Ultimate (very similar product) on my MR2 for basically for the reasons above, but I haven't used it yet to simulate the AFM output signal so I can ditch the AFM and over 1 metre of plumbing with heaps(!) of bends (been to lazey ).
But it is deffinately a capable little thing that has a very effective auto-tune feature (via feadback from a wideband AFR meter).
Multiple correction maps (inlet air temp., coolant temp., road speed) dual maps for fuel and ignition. I used 1 of the spare outputs to switch on an intercooler fan at low engine speeds and low loads (car moving slow or stationary, intercooler in the worlds worst place). The fan switches off when cruising and switches on again when on boost.

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Last edited by Duk; 10-28-2009 at 11:38 PM.
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post #5 of 64 (permalink) Old 10-29-2009, 03:43 AM
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Take a look here to see what one guy from the Alfagtv6.com web site did with the MegaSquirt:

Untitled Document

I'm doing something very similar. I'm in the tuning stages right now. Using stock sensors and put in a potentiometer type throttle position sensor from a junkyard Saab with an adapter bracket I fabbed. I hollowed out a junk stock ECU box and wired the MS into the connector from that so it connects to the stock ECU harness in the passenger footwell.

Once I've got thing running how I like I'm going to lose the AFM and then eventually get the spark control working on it.

Kevin

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post #6 of 64 (permalink) Old 10-29-2009, 04:22 PM
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something to consider with the MS system, you can now get one with built in support to use either low or high impedance injectors, you now longer have to add inline resistors to accomodate stock Alfa injectors. I'm in the midst of building my 35 pin adapter to go from the L-JET harnass to the MS. You can use all of your current temp sensor, you will have to change the TPS as mentioned above. The biggest issue I've had so far was figuiring out a way to keep the VVT functional....

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post #7 of 64 (permalink) Old 10-30-2009, 04:15 AM
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True, I don't have one of those on the Verde to worry about!

Kevin

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post #8 of 64 (permalink) Old 10-30-2009, 06:50 AM
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Quote:
Originally Posted by GuyC View Post
The biggest issue I've had so far was figuiring out a way to keep the VVT functional....
RPM switch perhaps?




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post #9 of 64 (permalink) Old 10-30-2009, 12:22 PM
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Tifosi you pretty much nailed it, what I've set up in software ( the MS is not yet installed ) is for the vvt to be triggered at about 1800 rpm, the issue was figuiring which wires were available in the harness to use for this.

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post #10 of 64 (permalink) Old 10-30-2009, 01:12 PM
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As near as I can trace, the wires for the VVT are:

1) -ive goes to the sleeve over the wire that goes to pin #1 on the ECU (grounded isolation sleeve basically)

2) The fused wire goes to the coil +

3) 3rd wire goes to terminal 51 on the TPS (high throttle deflection contact) which in turn goes to ECU plug terminal #18 once activated. (also has a direct tie-in to ECU plug terminal #3 regardless of TPS being activated or not)


Or am I like a day late and a dollar short on the info?




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Last edited by Tifosi; 10-30-2009 at 01:15 PM.
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post #11 of 64 (permalink) Old 10-30-2009, 04:27 PM
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Yes you are a day late....

I knew what the stock setup was, but the MS requires a pot style tps so that

eliminates it as an on/off switch for the vvt. There are / were several wires

available that used to feed the ignition ecu that are now available to use.

When I complete the install I will post a thread on it

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post #12 of 64 (permalink) Old 11-03-2009, 08:42 AM Thread Starter
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Thanks for the discussion guys. I didn't know about the TPS. It's only a switch? Hmmm.

Certainly takes some work, I see. Rewiring the whole thing may not be as much work as I thought, when compared to wiring up a gutted ECU. Since my Motronic TS is in a US spec Alfetta, having it look stock is the final goal. I may just jump right in and get my Spica throttle bodies mounted up to a TS manifold and go for a whole rewire and programmable of my choice.

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post #13 of 64 (permalink) Old 11-03-2009, 09:33 AM
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I installed a TPS from a SAAB that is a pot, requires an adapter to be fabbed but no big deal. I also have a Porsche 944 Turbo TPS that is a direct bolt on, the only problem there is that the connector is 6 pin instead of 3 so the stock wiring harness connector won't fit it.

I can get part #'s and pics if you are interested.

Kevin

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post #14 of 64 (permalink) Old 11-03-2009, 09:39 AM Thread Starter
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I think I'll go straight to modifying some Spica throttle bodies, thanks. Anyone know of a TPS that will work on the Spica throttles?

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post #15 of 64 (permalink) Old 11-04-2009, 07:05 AM
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Quote:
Originally Posted by iachella View Post
I think I'll go straight to modifying some Spica throttle bodies, thanks. Anyone know of a TPS that will work on the Spica throttles?
There's less fabrication work for a generic TPS on a Bosch Manifold vs. one for a SPICA. You have to weld on a boss to screw into, and put in a small plate onto the shaft. Not easy.

Less work to adapt a larger GTV6 throttle to a Spider and find a close enough TPS.

I wish it were otherwise, too.
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