3.5 Update -- Malc -- You'll want to look at this!

[AndyM]

I finally made some time to focus on getting my 3.5 rebuild completed and my coupe back together. All of the manifold pieces, covers, oil pan, etc. were all stripped and painted with Endura. I also started to sort out the various fuel injection bits for the conversion I'm doing. Some of you may recall I'm converting it to a GM based ECU, but I'm trying to keep it as stock looking as possible (no bulky AFM or other crap). I'm very pleased with the results. It will take a very sharp eye to notice this is anything but stock D-Jet. So far, I've figured out how to mount a throttle position sensor, the coolant temp sensor, the intake air temp sensor and an idle air bypass valve. This info should be useful for anyone contemplating any type of aftermarket ECU. Here are a few pictures:

Overall view:

Here's the TPS mounted inside the stock D-Jet throttle body. This will be hidden under the stock D-Jet TPS cover:

Here's how the TPS mounts:

The Idle Air Control Valve in the stock warm-up valve location:

Finally, here's the Intake Air Sensor mounted in place of the stock cold-start injector:

I'm going to be running a stock L-Jet distributor which will trigger an MSD ignition box. That, in turn, will trigger the fuel injection. I'll be running fuel only to start out (just like stock D-Jet), but can add ignition control in later once I get the fuel curve programmed. Hopefully I'll have the motor in tonight, then its just a matter of making the wiring harness and getting it all wired up. I'll keep you guys posted.

 

[Malc]

KEEP ME POSTED :shock:

Nice job by the way. I need to look at how to do that in the UK with UK GM parts.... Humm V6 Vauxhall Vectra/Saab 95 springs to mind!
Oh dear, our Les isn't going to like more cars around the back of the shed!!!

I do have the factory ignition curves if you need them

Cheers
Malc

 

[andrey]

very cool GM ECUs are very nice!

 

[AndyM]

It should work out well. I'm using a '737 speed density ECU which only needs a map sensor. If that doesn't work out, I can always hide the smaller GM mass air flow sensor in the air cleaner box. Megasquirt is also fully compatible with all of this.

The hard part starts right after I get the engine in -- building the harness. I got original GM connectors and will build the harness from scratch with all of the proper terminals, crimps, etc. That way, I can run it right down through the frame rail to the stock location under the seat.

Malc -- the sensors are pretty much all standard GM from late 80's through early 90's with the exception of the TPS. That's off of a '92 Mustang 5.0. I don't know what you have available, but its easy and cheap to get this stuff new over here.

 

[Malc]

Thanks Andy,
I have been looking at a GM ECU (or ECM) either a 1227727 or 1227730 which uses a MAP sensor, THey I believe were fitted to a lot of GM cars with V6 engines starting in the 80's through the early 90's. correct?
I talked to the guy at:

www.customefis.com

The upshot is that you can keep the original distrubutor, however it's there just to distribute the spark not do advance and retard. So take the weights off and weld her up!!!!!

It sounds similar to early Motronic in many ways.....

The only down side of it that I could see was that a Lambda probe needs to be added to the exhaust, which could be tricky especially in RHD cars.

Cheers
Malc

 

[Philip Slate]

Malc, I'm sure when the time arrives and you need that Mustang TPS, if you ask for one on the board, you'll probably get a couple'a dozen of 'em.

 

[AndyM]

Malc -- I mis-typed above -- that's the one I'm using. The '727 and '730 are the same except one has a weatherproof case. I have both, but I'm using the non-weatherproof version since the connectors are much cheaper and easier to find. I got it confused with the '747 ECU I use on my Jeep.

I'm not pinning the distributor just yet. There are too many tuning parameters to worry about on initial start up, so I'm going to let the distributor handle the timing chores until everything gets sorted out. The ignition timing control on the ECU shouldn't care if its not actually triggering anything. Once its running, then I'll lock the advance and play around with the spark advance curves. Are the stock curves you mentioned in a format you can email? That would really help this process along when the time comes.

You are correct that this set-up will be similar to early Motronic -- with the important exception that it doesn't need that big, clunky looking AFM. It also only needs the VR sensor in the L-Jet dizzy to fire the ECU through an ignition module (I'm using an MSD -- but a stock GM module will work too). Its also much easier to tune and there's a ton of support for the GM ECUs. I got an emulator from Moates.net which will allow me to tune "on the fly" with my laptop. As for the lambda sensor, if you use a three-wire sensor with a heater in it, you can mount it just about anywhere downstream on the exhaust (but not too far down or you'll have a delayed response).

Phil's right -- when the time comes, I'm sure there are more than a few of us (myself included) that would nab some sensors the next time we're trolling the yards. I'm sure you can make other sensors work, this is just the combo that I figured out. It still should be easier than reinventing the wheel. If you or anyone else is interested in parts sources for any of this (like the IAC mount, harness, tuning hardware/software, etc.) or the very limited (and easy) modifications to mount everything, let me know and I'll try to assemble a list -- after I confirm that it all works, of course. :lol:

 

[Malc]

Yes I have the official curves in the BMW workshop manual.
I can scan/ email or copy / post either way not a problem
Might be nice to get a letter in the mail that isn't a bill :wink:

I am still in Houston ,but going home tomorrow so can you wait till next week?

Cheers
Malc

 

[baldo]

Andy,
Excellent work. I'm very interested to see how it works out. Keep us posted. I purchased a 75 csi about 4 months ago and although the stock d-jet runs well as can be expected now, something like this may be in my future.
Thanks for the post,
Charlie 75csi

 

[Bill Cutler]

Have done much the same thing with my CSi.
Here in Australia there are lots of aftermarket, fully programmable engine management systems available, ranging from Motec (well known in international racing circles) to Autronic, Haltech, and the one I used, Wolf.
See http://www.wolfems.com.au
These systems, the Wolf in particular, take inputs of engine speed, throttle position, and manifold vacuum to determine a full range of fuelling settings. The sensors are much the same as Andy has used, and coincidentally I have arrived at the same installation positions - again leaving the engine bay very stock looking!
The Wolf unit has fuel and ignition maps reading 16 different load points at 125 rpm intervals, so it can be tuned immensely accurately, so this kind of set up is always going to give you much more flexibility in how you tune the car i.e. for performance ( more aggressive maps) or economy...
The Wolf kit cost me AUS$1300, chicken feed in UK pounds or USD, and will cost me another $200 for half a day on a rolling road dyno.
I reckon this is way better value than trying to re-invent the wheel by cobbling together parts from other cars, and hoping they all work together...
Just my thoughts on it.............[/img]

 

[Malc]

Bill,
The Wolf system sounds pretty good, and a reasonable price. Could you let me know how you set it up, wiring etc
Thanks
Malc

 

[AndyM]

Bill -- that sounds like a good system. How does it run? Did you get dyno results? It could be completely unfounded, but my biggest concern using any aftermarket ECU is with the reliability and ease of replacement. I don't want to get stuck somewhere with a broken custom ECU with no replacement available for weeks -- and no easy way to get it tuned exactly the same way. With the GM stuff, I can get a good used ECU for $25 just about anywhere. All I would need to do is swap the custom-programmed memcal (chip) and be on my way again. That's really the only reason I didn't install the Megasquirt I built a few years ago. It would also be extremely easy to duplicate this system once I get it all set up.

I believe the GM ECU will do everything most aftermarket systems will do. They all pretty much use the same GM based sensors. It is also fully programmable using similar input variables using Tunerpro, Tunercat, GMPCM (or any of the other readily available tuning programs). It will also "block learn" off of the O2 sensor to self-tune within certain parameters -- or you can disable the block learn and run a richer mixture without O2 feedback. Other benefits include detailed warm-up sequence, full idle control, knock sensing (which I won't be using) and a "lean-cruise" mode (if you use a speed sensor) for increased mileage on the highway. I also like the fact that any garage can plug in a scanner and check all of the sensors, inputs, etc. There's a bit of a learning curve for all of this, but its not that bad. Check out http://tunerpro.markmansur.com/ for some info on the tuning parameters. I think you'll be surprised. Even better -- the hardware and software costs half as much as the Wolf -- even in USD.