I've been tuning my 3800 with HP Tuners for almost a year now, and I'm realizing how limited the P04 PCM is. The problem I'm having in my research is finding a compatible ECU replacement. Something like the Holley HP ECU looks promising, stating it's compatible with 6 cylinder engines and GM sensors. While also having the much needed features for a boosted application like 1-5 bar MAP sensor, traction control, injector drivers, using stock knock sensors, etc. I won't be switching to an aftermarket ECU for a while, but I want to start doing my research. I just don't really know where/how to start.

 

Hard part is going to be finding someone who's actually done it.

The only ones I've ever seen done on a 3800 are cheapo Megaquirt setups. Ive never seen it done with a nice full feature standalone.

Would be really cool to do for a max effort setup:
-Swap to a DBW TB
-Swap to a good modern ignition system
-Built in ability to multifuel- either true ethanol flex, meth injection, or even a dual inejctor pump/race gas setup
-Launch control, boost by speed, legitimate traction control


I'd love to do that in my monte some day. My big hangup is emissions as it would be an instant fail around here without an OBD port. Swapping back and forth to stock sounds like a giant pain too.

 

What about Zippy/Greg? Didnt he do the Holley youre talking about?

 

Now that you mention it, I think you're right.

I don't really remember hearing much feedback though after he put it in TBH. Hopefully he'll chime in here.

Id be interested to know if he thought it was worth it- I know they're pretty expensive to buy + the time to install and tune in. Im most curious as to how well the traction control / boost by speed works as that could be a real gamechanger for a high hp FWD setup, especially for anything that sees real street time.

 

As far as the Holley brand of ECUs go, I believe there's only two options, the dominator (~2200$) and the HP (~1400$). Both of those ECUs are compatible with 4, 6, and 8 cylinder engines. They can both drive over 12 injectors, which is plenty even for a dual injector setup. They can both drive 2 wire ignition coils with an add on module. (Are 3800 coils considered two wire coils? The bottom of the coil only has the two inputs, which plug into the ICM.) They can both do progressive water/meth control if using Holley solenoids. The only major differences I'm seeing are the number of additional inputs you have available. 83 in total for the dominator, including 4 speed sensor inputs which I'd love to use. A disadvantage for the HP is that it doesn't appear to support drive by wire.

I'd really like to hear from the person that may have put a Holley ECU on a 3800, if anyone knows how to get in touch with them.

A side note on emissions. My 2000 is going to be emissions exempt here in a few years. So as far as I'm aware, there's no requirement in Texas for looking into the ECU with the OBDII port after the vehicle becomes emissions exempt, just a safety inspection.

 

Overall, wiring a harness for one of these ECUs looks fairly simple. The route I'm planning to do is an unterminated harness, so I can wire in all the factory 3800 sensors, but adding an EV1 injector sub harness. The only thing I'm lost on is the ignition side of things. Specifically the cam/crank sensors, and doing the actual ignition coils.

 

I'm slowly starting to figure out the install. I'm pretty sure the cam position sensor is magnetic, and it's a 3 wire sensor. However, I can't seem to find what type of sensor the crankshaft position sensor is. I know it's a four pin connector, and if it's a ferrous type sensor, then the Holley part # 558-431 which is a ferrous crank/magnetic cam harness should be plug and play assuming the sensors are supported. The one thing I can't figure out though is how to wire the ignition coils. I don't know whether the new ECU would connect to the factory ICM, or directly to the coil packs. Would you then consider the factory coil packs a 2 wire coil since they're being connected to the new ECU?

 

Id think the stock coils are 2 wire - theres only 2 terminals on each.

TBH though, I wouldnt bother using an aftermarket pcm that has to still use the stock ICM, thats the worst part of the whole ignition system.

I'd probably at least go to LS coils too to get it a touch more modern than the 80s waste spark. At least then you're not wasting some spark energy firing the gap on an empty cylinder.

 

The Holley Dominator is capable of full ignition control, I just didn't know if you could connect the 3800 coils directly to the ECU or if you had to go through the stock ICM. I'm not finding any way to do a 2 wire coil setup anyway. And btw, I'm using Holley's "EFI Selection Chart" which guides you through the process of building your harness for a new Dominator or HP ECU. Since you recommended ditching the stock coils, what about going with Holley's smart coil kit? There would be one coil per cylinder, and they're designed to plug directly into the ECU so they benefit from all the ignition control features. The only things I'm uncertain about, is if you can use full length spark plug wires with those since technically they're coil near plug. Also, if it would work with a 6 cylinder. The ECU is compatible with 6 cylinder engines and you can set your own firing order, so I couldn't see why not.

 

TBH, I've got no idea, youre way over my head on the standalone stuff. I was just saying it would seem like a real waste to spend all this money to be stuck with the stock ICM.

Looks like a nice setup, but jeez - $675 for coils on sale? There's no way to make junkyard LS coils work? I wonder what these do better than JY LS coils? Just thinking people do 1k++ whp on them.

I don't see why not, LS people have done it before - especially for the people going for the retro look that put the coils on the firewall or frame.

Any reason you wouldn't just mount the coils on or above the valve covers though- LS style? Certainly a lot less to fail with only a few inches of high voltage vs a few feet.