Building an LT5 engine harness from scratch. Any advice?

[shanker]

I chose an Autronic SM4 programmable ECU for my LT5 powered '62 corvette build. I purchased all new delco connectors for the injectors and all sensors.
My engine is a '92 and I have the factory GM service manual as a guide, but I'd like some more detailed wiring information for the connectors. I can't go by the factory wire colors, so I need detailed labels for each pin on each connector. Is there another book I can purchase? I've seen an LT5 engine controlled with this ECU so I know it's been done.

I may be in over my head on this one! Let me know your thoughts.

Thanks in advance.
~Brett

[HAWAIIZR-1]

It looks like a very nice project you have there and well done; always nice to hear when the LT5 is being represented.

You mentioned factory service manual and wondering if you also meant the Electrical Diagnosis Service Manual Supplement for your model year?

Another good source of electronic engine management is "How to understand, service, and modify Corvette (1982 throught 2001) Fuel Injection and Electronic Engine Management by Charles D. Probst" He also includes LT5 schematics in the book.

Kurt White from White Racing Products was kind enough to share this site for cross reference to GM connectors if this helps:

http://www.acdelcotechconnect.com/pi/wiring-connectors/gm/pigtails/

Aloha,

Craig

[shanker]

Thanks for the advice. I do have the supplement for the LT5 engine, and I'll pick up that other book.

From my research, it seems that the ignition coil packs fire two plugs at once. For example the number 1 and 6 cylinders share a coil pack; the no. 1 cylinder fires at 6 degrees BTDC compression, while the no. 6 cylinder is at the same spot in the exhaust stroke. Would both plugs actually spark at the same time?

[tccrab]

Thanks for the advice. I do have the supplement for the LT5 engine, and I'll pick up that other book.

From my research, it seems that the ignition coil packs fire two plugs at once. For example the number 1 and 6 cylinders share a coil pack; the no. 1 cylinder fires at 6 degrees BTDC compression, while the no. 6 cylinder is at the same spot in the exhaust stroke. Would both plugs actually spark at the same time?

It's called a "Wasted Spark Ignition System".
Here's a link or two:
http://www.gill.co.uk/products/digital_ignition/Introduction/8_wast_spark.asp
http://en.wikipedia.org/wiki/Wasted_spark

[-=Jeff=-]

If your New ECM will support the LS1 type CnP Coil on Plug, I would do that..

[phrogs]

I saw a build where someone put a LT5 in a 50s chevy and they had left out a few components and had to wire them in.

Not sure if he used an after market ECM or a stock one.
So I have no clue what you can get away with.

colors aside wouldn't the wiring tell you what you had to wire up no matter what?

I hate messing with wiring unless its plug and play I just have a hard time keeping the SMOKE in the wires.

[shanker]

I think I'll stick with the factory LT5 coil packs. they are in a hidden location and should be easy to wire.
I've received some ouside help with the wiring diagrams and I should be all set. I'll post pictures of my progress!

Thanks,

[phrogs]

do you have the secondary injector modules?

[shanker]

Yes I do. I won't be needing it though.

[ZZZZZR1]

Great pictures of that LT5!

I have a good friend who is installing an LT5 in a 1935 chevy.

I will forward this link to him.


:cheers:

David

[Pete]

Yes I do. I won't be needing it though.


Please keep us informed.

Let us know how you get away with the secondary modules and how you'll det the ignition to work.

Pete

[shanker]

Pete,
The ignition can be set up using 4 Bosch type ignition modules (one for each coil pack). They are small and inexpensive. The Autronic ECU has 4 ignition outputs which will tell each module when to charge and fire the respective coil packs. These 4 Bosch modules are small enough to mount under the intake.


The Autronic ECU can control 16 seperate injectors. I will be running the primary injectors full time, and the secondary injectors will be disabled at idle, and kick in at 1% throttle.

Of course, this is all easier said than done!

[Pete]

Pete,
The ignition can be set up using 4 Bosch type ignition modules (one for each coil pack). They are small and inexpensive. The Autronic ECU has 4 ignition outputs which will tell each module when to charge and fire the respective coil packs. These 4 Bosch modules are small enough to mount under the intake.


The Autronic ECU can control 16 seperate injectors. I will be running the primary injectors full time, and the secondary injectors will be disabled at idle, and kick in at 1% throttle.

Of course, this is all easier said than done!


Shanker you da man.

If you get it to work,could you get a complete package togather basicly plug and play i would be interested,let me know how much $$$.

This way i gaet rid of CCN BCM and the rest of the crap.

Those Bosch ignition modules a common part at part stores.

Also is the Autronics ECU tuneable with a laptop?

Pete

[DaveK]

Also is the Autronics ECU tuneable with a laptop?

It appears to be, they have tuning software available on their website.

http://www.autronic.com.au/

Dave

[shanker]

my Autronic SM4 unit is fully tune-able with a lap-top. it can log data from track time, and has a number of really cool features that I probably won't use on this project, like turbo anti-lag that spools your turbochargers up fast when you mat the gas out of a corner.
it's also equipped with "flat shift". This allows you to change gears without lifting off the throttle while a secondary rev-limiter keeps the engine at the ideal RPM. This is accomplished with a simple pressure switch on the clutch linkage, like a brake light switch.
The Autronic units are also unique in that they have an auto-tune function that uses the input from all the engine's sensors to tune itself while you operate the engin over all the RPM and load ranges. once the engine is self-tuned you can make the minor changes that you want.

It's also significantly cheaper thsn FAST or Motronic etc.

[todesengel]

my Autronic SM4 unit is fully tune-able with a lap-top. it can log data from track time, and has a number of really cool features that I probably won't use on this project, like turbo anti-lag that spools your turbochargers up fast when you mat the gas out of a corner.
it's also equipped with "flat shift". This allows you to change gears without lifting off the throttle while a secondary rev-limiter keeps the engine at the ideal RPM. This is accomplished with a simple pressure switch on the clutch linkage, like a brake light switch.
The Autronic units are also unique in that they have an auto-tune function that uses the input from all the engine's sensors to tune itself while you operate the engin over all the RPM and load ranges. once the engine is self-tuned you can make the minor changes that you want.

It's also significantly cheaper thsn FAST or Motronic etc.

Have you thought about how you were going to read the crank and cam positions? I am not versed on the autotronic but most standalones will not read the 8+1 configuration on the lt5 crankshaft. Some also will not read the cps setup on the lt5 as well. Do you plan to run an external trigger wheel? I am welding the 9th tooth on the crank (the one that is not evenly spaced) closed so that it does not trigger the sensor.

Interested to see how your project lines out as I am doing something similar with mine, with exception to running a haltech p2000 platinum in place of the autoronics unit.

Does the Autotronics control your fp as well?

I am also running sequential ignition, as well as timed fuel injection. Pros/cons are debatable, and up to the individual to choose their own path imho.

Secondary injectors are going the way of the dodo and being replaced with meth injectors in their place. larger primaries will take care of the fuel.

Your harness build question perplexes me a bit. You have inputs/outputs and primary functions of the engine that must be taken care of. Your ecm should have a pigtail of sorts, labeled for each one of these functions. It is a simple matter of joining your sensors to the proper leads provided on your ecm. I may be oversimplifying the obvious, perhaps you could give more detail to your particular situation with the wiring.

It should be interesting to see how my zr1 registry labeled unimpressive system compares against your autotronics unit. If I can be of any help to you feel free to pm, I may not have the answer but I will try the best I can.

[ZR1@gmx.com]

I have a new 93-95 Wiring harness FS if that would help!

[XfireZ51]

Can you tell us more about how Autotronics interfaces with the DIS module?
And if youbdon't need the secondary injector module, is the Autotronics driving each injector separately?

[shanker]

This project has been moving forward, but mostly in the chassis & body department. I haven't touched the engine wiring yet except for purchasing all the necessary connector pigtails & getting wiring diagrams. I was originally looking for pinouts on each of the LT5's sensors, but I have that info now. Part of the reason I chose the Autronic Engine management is because I've seen it control the LT5 engine and it can use almost all of the stock sensor inputs. Crank & cam position sensors are usable with my autronic unit as far as I know.
I'm using an AEM brand CDI 4 channel ignition to fire my factory coil packs. I haven't heard anything bad about the "wasted spark" setup. I planned to use an external regulator & set fuel pressure at a constant.

todesengel: Using only 8 injectors sounds like a great idea! I'll PM you about which ones you're using, and what you use in place of the secondaries to fill the holes. I don't really need meth injection but I do need something in place of those injectors. Maybe just leave them in place without wiring them? I was told by a GM ZR1 engineer that I could run the FP at 55psi and I'd be happy with the results. the stock injectors are 22.8lbs/hr @45psi

I was planning to run all 16 injectors, and have the secondaries kick in at anything above 1% throttle. I was told this would give a good idle and performance. Basically I would wire primary & secondary injectors together, but use a relay for the power output to the secondaries. Both injectors for each cylinder would fire in unison above 1% throttle.

I am no expert and I have no real experience with the LT5 engine so if anyone has advice for me I will certainly appreciate it.