Calling all 4.6 upgraded users - 4.6 using 4.0 PCM?

[lanceslambos]

Ahh...the headaches and hassles of finding a shop that will actually do a Northstar engine swap! I called over 25 shops before I found one willing to take on the task, and several more calls around until I could get the price reasonable. The books all say that you have to drop the cradle and remove these out the bottom of the car. However Randy says it's unnecessary extra work & that he's done all of them out the top - so I looked around online. Sure enough if you remove the radiator, shroud and top plate cover, you can easily reach the wiring harness and bolts needed to do a top out job!

After talking to many shops I kept getting the same question or rather ran into an issue. If you're in the position to upgrade to a 4.6 & can actually find a shop to do it, don't make the mistake of telling them you are swapping a 4.0 for a 4.6! They will immediately decline the work. I don't understand what the big deal is (same block, same accessories, same wiring harness, etc.),just an extra 25 - 50 ponies & 45 - 50 ft.lb. of torque. But it got me thinking and I'd like someone to confirm this please. Will the 4.0 PCM/ECU work with the 4.6? I'm concerned with running lean due to the difference in size of the combustion chamber/ piston size. Furthermore, the engine I'm ordering is bored .30 over so it's more like a 4.8 / 300 cu. I'm sure of the exact cu. Would a stage 3 PCM/ECU tune do well? I ask because according to Jake, it is designed to run on regular as well as premium. Apparently the factory tune retards the ignition up to 7 degrees under WOT. I'm guessing it's a good thing if the stage 3 doesn't retard the ignition now,or maybe I'm thinking backwards and it could cause pre-ignition issues by running either rich or lean. I don't know - I miss the old school where a simple carb did the trick without the need for a brain!

In case you missed it - Will the 4.0 PCM/ECU run a 4.6 without issues?

[Paulaurora]

Ye most shops wont bother. If you were closer to Brooklyn NY my shop would do it.

[scottyaurorav8]

What does Jake say about a 4.0 pcm running a 4.6?

The aurora pcm will run the engine, allow you to drive away from the shop etc...but I wouldn't expect to get on it and run perfectly, it's not tuned for the 4.6. You would need a tune for efficiency. But will it run the engine, yes. If you have a tuned pcm it should run it better than a factory pcm though.... Just be careful. Last thing you need is to detonate the engine etc...

So bored .030 over on the 4.6. Did that require the engine to be sleeved? 4.8 sounds real cool. You are prob one of the few out there with that. I wonder if that sucker could make it to 5.0 lol

[Marc]

Mar 3, 2018 5:50:22 GMT -6 scottyaurorav8 said:

I wonder if that sucker could make it to 5.0 lol

According to en.wikipedia.org/wiki/Northstar_engine_series in a paragraph titled "Northstar Series"..............................

The block is believed to be capable of expansion up to 5.4 L, though no such engine has been produced.

[scottyaurorav8]

Wow....I can't believe no one ever attempted this. The thought of a 5.4 liter Northstar would intrigue me enough that if I were a machine shop, I'd definately delve into that. It be a beast for sure!

[tigger]

Mar 1, 2018 10:05:03 GMT -6 lanceslambos said:

the engine I'm ordering is bored .30 over so it's more like a 4.8 / 300 cu.

I hope you meant .030" over, that would put you at almost 4.7L. A .30" overbore (if it's even possible) would put you at around 5.4, but Marc did site a source, lol!


Anyway, I wouldn't sweat it just yet. The PCM calculates fuel delivery based on MAF, IAT, ECT, and MAP sensor readings, and then tweaks that based on O₂ sensor readings (fuel trim). If anything exceeds the parameters of the fuel table on your PCM, you'll get a light...

[sempar]

According to RockAuto, the AC Delco fuel injector part number is the same, so thats a plus. GM usually runs the PCM calibration at full throttle on the rich side ( to avoid pre-ignition and burned pistons / valves) so you might get lucky there. On the other hand, if the PCM can't compensate for a lean condition under those conditions, you could be in trouble. Might be a good idea to hook into the diagnostic link with a reader to make sure it doesn't go lean.

John

[plato442]

Yes it will. My 4.0 pcm ran the 4.6 engine just fine, until I got a tuned pcm To swap.

[AmunRoo]

Mar 5, 2018 8:14:00 GMT -6 plato442 said:

Yes it will. My 4.0 pcm ran the 4.6 engine just fine, until I got a tuned pcm To swap.

What year STS radiator did you get?  did you see the temps drop at all? I'm guessing it was plug and play...

[RCA1186]

According to old posts I've seen the PCM should compensate and run it. I don't know if that means it will be running right or not. FWIW Ion (madtuner) said he wouldn't trust running a 4.6 on the 4.0 tune if I'm remembering right.

[AmunRoo]

Anyone know anything about the STS radiator? Is it bigger than stock? Is it beneficial or is it just more coolant to cool off? There isn't much in the way of cooling system mods for this car that I've seen.

[RCA1186]

This is a quote taken from the aurora upgrade sticky

speedneon said:

-WHAT ABOUT THE DISPLACEMENT DIFFERENCE, WONT IT RUN LEAN?

aurorabrain said:

speedneon said:

yeah i am fine, brain says that the stock ecm will trim the fuel back to normal.

The fuel pressure and injector size is the same for both engines. All the electronics are the same. The PCM will see more airflow and should adjust to compensate because it's looking to maintain a programmed A/F ratio. If not we can fake it out by upping the fuel pressure or changing to a slightly larger injector. I don't see a problem at all, but i guess we'll have to find out.

This has proven to be of no issue. The classic pcm runs the engine flawlessly, neither rich or lean.

[rocketaurora]

Can you bore a 4.0 out to 5.0?

[rocketaurora]

I would love to have a 305 5.0 in my aurora then I would just need a custom intake so I can supercharge it damn sneeze valve

[Marc]

May 17, 2018 11:02:41 GMT -6 rocketaurora said:

Can you bore a 4.0 out to 5.0?

It could be done. According to en.wikipedia.org/wiki/Northstar_engine_series it is possible that the N* could be enlarged to 5.4L.
Scroll down to "Northstar Series" to see that.

[RCA1186]

That would scare me haha

[plato442]

Apr 9, 2018 17:11:51 GMT -6 AmunRoo said:

Mar 5, 2018 8:14:00 GMT -6 plato442 said:

Yes it will. My 4.0 pcm ran the 4.6 engine just fine, until I got a tuned pcm To swap.

What year STS radiator did you get?  did you see the temps drop at all? I'm guessing it was plug and play...

It is a slightly larger radiator. It falls right into place however, BUT I think I added some foam shins between it and the AC core. I didn’t really see temps drop, however it is slightly more volume to keep it cool. Radiator was from an 01 STS same year of the engine donor.

[Pat]

Great information in this thread.  Surely the 4.6 swap into an Aurora has to be one of the easiest to accomplish.  I wonder, will the Aurora intake manifold cover fit the 4.6 so it looks stock?

[Randy T.]

PCM runs the 4.6 perfect. Torque management, like with the 4.0, is the fun killer. Any Aurora stuff will fit on the 4.6, I had an Aurora front cam cover on my first 4.6. For 1st gen, 95 radiators are bigger and fit in the 96 to 99 no problem. Even when you buy them new aftermarket, the 95 radiator will be bigger.

[plato442]

Jan 31, 2019 8:25:13 GMT -6 Pat said:

Great information in this thread.  Surely the 4.6 swap into an Aurora has to be one of the easiest to accomplish.  I wonder, will the Aurora intake manifold cover fit the 4.6 so it looks stock?

I don’t know if I’d say easiest to accomplish, however it’s pretty straight forward. Looking back I wish I would’ve gone with larger cams