I want to get into prom burning and i have decided that i need to swap my 88 305 oddball ecu for a 747 from a truck. My question is, do i need sensors specific to that computer? Or will my existing sensors work? The computer is coming with the stock 305 tbi truck chip which i have been told is an AKMJ. What do the letters stand for?

thanks

 

All the GM sensors I've seen are interchangeable- but let's see if anyone can post what's not.

The letters AKMJ are the Broadcast Code (BCC). They are just a way of identifying which memcal it is.

John

 

So is that the one for a 305 tbi truck then? Thanks for the help guys, sorry for all the newb questions. I have heard that the 350 knock sensor is different than the 305 one, but i am not sure if that is because of the computer or just the engine differences (larger displacement perhaps).

Thanks,
Mike

 

I believe the TPS sensors from TBI to TPI pivot backwards in relationship to each other. And in some applications the IAC wires are flipped. And then there is the connector issues on swapping newer series to old, and small distributor cap to large. Then there are a few different MAF sensors.

 

thanks for the info, my question more specifically is can i just plug in this new 747 computer to my 88 305 tbi wiring harness and go? Or do i need to change sensors, or even the harness? You guys are really helping me out, thanks again.

Mike

 

I'll give your a probably, but you need to verify things with a wiring diagram, to be absolety sure. As far as sensors go in that deal, they are the same. A quick check should show the only difference being the Air temp sensor, ie the 747 doesn't use one.

 

I wonder why it doesn't need air temp? Isn't that how the engine adjusts the fuel ratio in conjunction with the o2 sensor?

Mike

 

You could just upgrade to the 8746, it aleady has the IAT. There really is very little reason to go to the 7747 over the 8746 unless you plan on taking full advantage of the vol eff table expansion patch. The 8746 patchs currently out in the public are the code 43 and the rev limiter.

 

so it would be better to use the 746 instead then? Would i have problems with using the 747 over the 746? Like i said i am a newb...sorry for all the questions. I'm actually kind of waiting to burn until the prominator comes out, since that seems like it would be the easiest way to go about it. Would either of these computers be able to drop right in with the stock chip and run a tbi system until i get further into burning and can really tune my application?

Thanks again guys :hail:

 

Tell me more about the vol eff table expansion patch for the 7747. I would like to have more granularity in tuning my motor.

Do I need to go romless to use it?
Where can I find it?

One other question, can a romless 7747 be made into a 8746 or vice versa? It seems that they use the same hardware schematic.

Just Wondering,
Greg...

 

I take it this is going into the '88 Bird. . . I second Jon as to using the 1228746 ECM over the '7747. The '746 is designed for car use whereas the '747 is designed for truck use. The '747 has been more popular due to the hac that became available many moons ago.

Couple of differences: the '746 has better idle control, no PE delays, highway mode lean cruise, VATS (if desired), canister purge, and the two nifty patches. There is also a hac & ecu file available for both.

RBob.

 

Good question. The TBI vehicles use an intake manifold with a large water jacket. The whole doggone manifold for that matter has water from the coolant system in it. They also come with a thermostatically controlled air intake system.

Between the two the IAT isn't required. As for the use of the IAT on the '746, it is setup to enrich the mixture as the intake air temperature climbs. This in effect cools the engine down. The table range for this functionality is 48° C to 110° C. Quite warm for intake air. The thermvac switch regulates the intake air in the range of 33° C through 55°C.

The IAT does affect the SA in various areas such as knock retard attack rate, launch mode SA and transient SA.

RBob.