patooyee

Does anyone do this? It is somewhat popular on LS engines for hot rodders who don't care about all the advantages of electronic fuel injection. Most of them use an MSD box to control ignition when they do this. But on a motor with cam phasing (like an LE5) you would either have to disable phasing or use the stock ECM to control it. If you were using the stock ECM I don't see why you couldn't also use it to control ignition just as it would in stock form. I imagine one would then just disable all fuel-related error codes and move on with life knowing that half the ECM functions aren't going to be in use.

So I guess in summary, I already know how to run a carbureted Ecotec with an MSD. My question is if anyone has done it using the stock ECM?

Please don't get into the why's, logic, reasoning, etc. of why one shouldn't, etc. I'm aware of all of that. This is just a curiosity of how if one wanted to ...

ItalianJoe1

iTrader: (10)

That's an interesting question...

A lot of the VVT tables are airflow related but I think you could make it work... i'm not sure that if you locked it into open loop and just left the injector drivers firing into space, it wouldn't work and give you full VVT control. There's a lot of diagnostic stuff in the PCM that has to pass before it allows cam phasing though.

Sharkey

iTrader: (1)

in the case of a vvt engine i would disable vvt completely, as in swap in some non vvt cams and solid cam gears, and block off any oil passages that are used for the vvt system. its going to be the only way to get it running correctly.

however, yes you could in theory run the vvt with the factory ecm, and control the ignition with it as well. however you will need to run both cam sensors, crank sensor, map sensor and possibly even the maf sensor to make it work. i know its not what you want to hear, but your a high pressure fuel pump away from it running the way the factory intended it.

patooyee

I'm not really "wanting" to hear anything specific other than what it would take. It's just an option that I am considering.

The answer would be obvious and simple if there was no VVT.

But ultimately the VVT is just two signals going to two actuators. There are aftermarket standalone VVT controllers. It's all just circuitry and programming. The only question is really, "Has the e67 been hacked enough by HPT to run VVT without fuel management or not?"

I think the question could fairly easily be answered by someone with a running VVT car. Just throw it in open loop and see if they can get it working, right?

I have no experience with VVT admittedly. Is it a huge gain? Am I obsessing over nothing? It seems like, if one could get it working, anything helps, right? It would seem like, especially on a turbo engine, VVT could be advantageous since you could increase overlap and take advantage of more cylinder filling under pressure instead of worrying about having to suck it in.

patooyee

OK, just posting what I see under camshaft timing in HPT:

• There is a low, med, and high barometric pressure threshold with a table for each and for each camshaft, 6 tables total. The tables don't differ very much. So you would either need to run the MAP or possibly default all these tables to the same values? Tables are cylinder airmass vs. RPM. Would that be airmass based on MAF sensor, calculated based on MAP sensor, or both depending on open vs. closed loop?
• There is a DoD table for each cam. I don't think these engines used Dod though.
• Intake Cam Position Minimum: The Intake camshaft position minimum when spark reduction overlap requested. - These tables are zero'ed out for both cams.
• ECT correction factor tables for each - these are set at 1:1 on intake and are one of .1, .25, .625, .75, or 1 on the exhaust.
• There is an enable condition delay table for each cam, seconds vs. ECT. No big deal there.
• Low & high oil temp enable and disable values, no big deal.
• Low RPM enable, disable, high rpm enable, disable. Not rocket science there.

That's it. I'm going to try to do some research on fail modes for VVT next ...

patooyee

What Alldata has to say about it, I'm too tired to think about this in depth right now.

CMP ACTUATOR SYSTEM OPERATION

The camshaft position (CMP) actuator system is controlled by the control module. The control module sends a pulse width modulated 12-volt signal to each CMP actuator solenoid to control the amount of engine oil flow to a camshaft actuator passage. There are 2 different passages for oil to flow through, a passage for camshaft advance and a passage for camshaft retard. The camshaft actuator is attached to each camshaft and is hydraulically operated to change the angle of each camshaft relative to crankshaft position (CKP). Engine oil pressure (EOP), viscosity, temperature, and engine oil level can affect camshaft actuator performance. The control module calculates the optimum camshaft position through the following inputs:

• Engine speed
• Manifold absolute pressure (MAP)
• Throttle position indicated angle
• CKP
• CMP
• Engine load
• Barometric pressure (BARO)

A locking pin keeps the CMP actuators in the parked position to avoid valve train noise upon engine start-up. The parked position is 0 degrees of camshaft actuation. The locking pin will release the actuator after the EOP is sufficient to overcome the locking pin spring pressure. The exhaust CMP actuators also have return springs. The return springs are necessary to assist the CMP actuators to return to the parked position due to the rotational inertia of the valve train components upon engine shutdown. The control module uses the following inputs before assuming control of the CMP actuator:

• Engine coolant temperature (ECT)
  
• Closed loop fuel control - I'm thinking that this means that VVT only operates while in Closed Loop?
• Engine oil temperature (EOT)
• EOP
• Engine oil level
• CMP actuator solenoid circuit state
• Ignition 1 signal voltage
• BARO

ItalianJoe1

iTrader: (10)

It is definitely functional at WOT/Open loop, makes a difference in the spool time on the turbo LE5 I've tuned.

I don't see how you couldn't make it work really. I'm sure if you wanted to be 100% you could set very specific steps to the tables vs. RPM, then lock the car in open loop/fail the MAF and see if the cam sensors still show the changes.

patooyee

Huh ... I guess I need to ask about this on HPT forum then.

here's the thread if anyone cares to follow: http://www.hptuners.com/forum/showth...550#post430550

ItalianJoe1

iTrader: (10)

I would do it but I don't have access to an LE5 to experiment. HPT forum would be a great idea, much more open minded guys and more actual tuners. Most people on here have never seen HPT, and even less actually know what they are doing with it.