🔧 BUILD Twincharged 3800 Malibu

[Turbocharged400sbc]

Don't even have to do that iirc, makes it easier to see iirc

 

[ASlowV6]

Okay, cool. At least I’m not a complete idiot. That’s not to say I’m not a partial idiot who accidentally put it in the wrong location. Clips are tight. I can barely rotate it with a pair of needle nose, but it doesn’t seem like it’s going anywhere.

Cam sensor is getting steady 12v on pins A and C, and B has steady ground. Did a pretty good wiggle test and everything seems okay. Terminals seem nice and tight.

 

[Turbocharged400sbc]

Does the sensor trigger with a magnetic fairy wand?

 

[ASlowV6]

Nope

 

[Turbocharged400sbc]

Wait pin A has 12v on it while plugged in?

It should only rise with magnet iirc
Maybe it's bad.

You have a scope to backprobe for at sensor signal?

 

[ASlowV6]

I was confusing myself by thinking the same thing. Apparently the Holley puts out 12v on the signal and it is supposed to drop out where is sees the magnet. It is configured as single pulse, digital falling in the tune.

 

[Turbocharged400sbc]

So it's not dropping. You have spare cmp?

 

[Turbocharged400sbc]

I kinda think the odd ckp waveform falling off is acting like the pcm waking up and then dropping to off, then cycling back on like the pcm is losing voltage during cranking

 

[ASlowV6]

Running to the junkyard now to grab a pocketful

 

[Turbocharged400sbc]

Check voltage drop across everything while cranking.

 

[Turbocharged400sbc]

Signal out from pcm to cmp should be a dropping 5v waveform though?

Crap I'll have to dig out my Modis later

 

[ASlowV6]

Cranking the heater up to 75 so the wife might be willing to come out and give me a hand later

 

[ASlowV6]

That’s what I was gathering as well. From what I can tell from Holley LS guys I don’t need it to drop to 0, I just need to see it go from 12v to 6ish.

At this point I’m just going to put a new sensor in and see what happens before I dig any deeper.

 

[ASlowV6]

New cam sensor and it starts! She is definitely not the happiest sounding car on earth, but it fuckin runs!

 

[v6buicks]

 

[sktchy]

I kept trying to tell people cam sensor is critical on stock pcm but apparently just as much so with a Holley. Neato.

 

[Turbocharged400sbc]

Holley probably not default batch fire like we are.

Even with the old C³I ignition and ecu we start as batch fire under 400rpm where we switch to sequential once TDC is determined via cmp.

My wagon drives just fine mostly without a magnet in the gear (ln3 "vin c" issue)
Starts perfectly fine roughly half the time when it guesses TDC correctly

Thankfully wasted spark and injector wall wetting counter injectors and ignition firing 360*off

 

[ASlowV6]

There is an option to run no cam sensor. I guess I’d assume that makes it batch fire, but I’m not sure.

It dies after about twenty seconds. I’ll dig into reading some live data tomorrow. For now I’m just going to let myself be excited that it finally runs again lol

 

[bs009]

This box comes unchecked by default so I would check that if you haven't. I'm sure fueling is going to need a lot of learning initially

Really glad you got it working!

 

[ASlowV6]

Good to know! In your experience does the fueling correct itself pretty well?

 

[v6buicks]

I have no input, but I really wish I was switching to Holley right now instead of hot rodding my stock stuff. Just the universal support alone would be amazing.

Just curious. Would there be any benefit to switching to a hall effect sensor and trigger wheel with more teeth? I saw someone complaining about that on another forum which is the only reason I even questioned. If so, it would be slick if someone came up with a replacement wheel for stock sensors and balancers.

 

[sktchy]

Good to know! In your experience does the fueling correct itself pretty well?

Holley closed loop has as much swing as you let it have. I'd suggest leaving it at 100% to start and then using your logs to see how much it's off. Then once it gets the error roped in drop it to like 10 so you know if somethins wrong. Otherwise it'll try and dial in a problem real quick.

 

[ASlowV6]

Ah that’s a good point. From how long it takes to fire I’m thinking it probably needs more cranking fuel to begin with.

As far as a higher resolution reluctor, I honestly have no idea. I’d imagine there is some benefit, otherwise why would stock stuff be using 58 tooth? That’s way beyond my current understanding tho.

 

[sktchy]

If it fires leave the crank trigger alone for now and start looking at other things. Fuel error or vac leaks, start unplugging injectors and coils. The Holley should be super responsive as long as everything's working right

 

[bs009]

The Holley's self-learning on the fueling is like the stock PCM on steroids, it's has what is basically a short term fuel learn and a long term. If it sees a part of the fuel map that needs constant adjustment it will update the learn table and you can just apply it to the base map and go again. It learns so quick that a lot of people are saying you don't even need a flex fuel sensor but I'm using one anyway. As long as your base fuel map is pretty smooth it should be able to dial things in pretty much perfectly for fueling.

For cranking it's going to need about 2 revolutions before it will fire because it has to wait for the cam signal, but if it's sitting there kinda half-firing you'll probably want to make a few changes. I feel like mine is relatively dialed in on my GP at this point but I do want to work on the cold startup to see if I can make it behave more like my truck does haha. Also keep in mind that if you're running E85 it will need even more cranking fuel when it's cold.
This is what mine looks like in my GP and I haven't had a day yet where it didn't fire up right away.

About the crank trigger, there's a lot of people running V8's using the MSD flying magnet setup which is only 4 crank triggers and they're seeming to have no problem with the low resolution from it. I think the idle timing has to suffer a little bit if you ask me but it works pretty well otherwise.

Just curious. Would there be any benefit to switching to a hall effect sensor and trigger wheel with more teeth? I saw someone complaining about that on another forum which is the only reason I even questioned. If so, it would be slick if someone came up with a replacement wheel for stock sensors and balancers.

Funny you should mention this because I've been working on making something like that myself the last few weeks lol
This is an early design that has a couple kinks but I think I'm getting close to something I could sell if people are interested.

If this works out you wouldn't need a cam sensor to get the engine to fire if you use batch injection I believe since it has a missing tooth. Both are supported by the Holley and then with our cranks if there's an issue and you want to go back to the 3x signal you'd still be able to do that.