y8s Hydra Nemesis Parallel Install Thread
 

I'm going to be doing this because I want to pass OBDII plug-in tests.

Don't come in here and tell me why I shouldn't do it. That's not this thread.

I'll start with a list of ECU functions and their pins and if they should be ported back over to the stock ECU.

I already have the male and female harness connectors and pins. I can wire them all up like a boomslang and intercept what's needed and send it off to the hydra.

Most of what I'm looking for is answers to questions that come up about sharing sensors, piggybacking signals, etc.

Next post starts the hard dataz.

Matt

Stock ECU functions
 

These are basically just pasted from my Hydra pinout spreadsheet.

Definitely going to the stock ECU:

Need to be Shared with Stock ECU:

OK So I plan to have the stock ECU do the following functions (you can find them above)

• A/C
• Check Engine (MIL)
• Purge Control
• Fuel Pump Relay
• Idle Control
• A/C Control
• All stock gauges
• Use the Stock O2 sensors

I'm NOT sure the stock ECU will care if the hydra will do these:

• Knock Sensor (believe stock ecu doesn't care)
• VVT
• VTCS (pretty sure it's OK since it's passive)
• Fake out the MAF sensor (have kinda done this before--just need a spare output)

Also:
It's a pretty easy task to piggyback a digital signal since they're just pulses, right? Finding bias resistor values or making a voltage follower for the stock water temp sensor will be kind of a pain since the hydra may have an internal bias resistor. Might be easier to just put in a second sensor.

Definately put in a second coolant sensor. Much easier and less headache.

The VVT is questionable, as the stock ECU will constantly be trying to put that cam in a certain spot buy the HYDRA will put it elsewhere. The stock ECU will never win. That could cause a CEL, but I dunno. Is there a CEL for VVT related problems?

Knock sensor won't matter I do believe. I unplugged mine for a while and the stock ECU never cared.

The MAF sensor you are on your own. That has to be given a signal. If you can fake it out then I guess you'll be fine, but there is a potenital for CEL from this if your fake out plan isn't just right.

Someone needs to build a circuit to show the "A-OK" code for passing OBD2. I know, it's probably not legal, but... It would be simpler. :)

Also2: where are you gonna put the Hydra? Right next to the stock ECU? I did that with MS2 and hated it. Now that I'm standalone Mine is velcro'd to the carpet behind the passengers seat. Easy to get to and no mess under the dash. You might consider remote mounting it.

If you just unplug it, it detects that it's stuck.

Also, when my knocksense went haywire, stock ecu returned P1609 Powertrain Control Module (ECM CPU) Knock Sensor Circuit or something like that. Not sure if Hydra will do the same. But this says there is a KS MIL

Very interesting thread. I wish I could keep the stock ECU running the idle control and A/C. Especially since the wideband with the Hydra doesn't do so well at tuning the idle controls. Good luck.

subscribed! Very interested in doing this as well!

Several, in fact. If the Hydra is controlling VVT, then the ECU will happily throw P0011 and P0012 for timing over-advance and timing over-retard, based upon the fact that it cannot control the cam properly. Additionally, it will throw P0010 simply because the oil control valve is disconnected, as it will detect an OCV undercurrent condition and assume a wiring fault.

Likewise, you've for P1512 and P1518 for VTCS valve stuck (vacuum switch not changing in response to solenoid command) plus P1569 and P1570 for VTCS solenoid undervoltage / overvoltage (solenoid fault).

In other words, leave the damn things connected to the stock ECU.

P0327 and P0328 are knock sensor overvoltage / undervoltage faults. Not sure who you didn't see a problem, as they are both listed as MIL faults.

It is quite specifically illegal, unfortunately. And it's Federal, not California law.

thanks joe. I hadn't yet looked at the list of fault codes.

AH wait, now I remember. Tec3 used its own knock sensor.

FYI to all, I did run the Tec3 in parallel. It only ran fuel and spark.

I think the thing that's going to suck is if I can't run VVT externally, I will have to fool the ECU twofold...

1. The AFM needs an input signal somewhat proportional to load and rpm.
2. The AFM and RPM signals drive the VVT settings.

So you can see that if I want to control VVT in parallel with no CEL, I'm going to have to do it in a roundabout way. But I can (sorta?) do it.

oh yah, also...

if I do end up with a parallel install and can't successfully get the hydra to do all of the things it is awesome at... it might become a liability.

ms ftw.

While I agree, it's not really a fair comparison. These problems are endemic of any parallel install (regardless of which ECU is being used) and are a good illustration of the problems and shortcomings which one often experiences with such a configuration.

And for that:
http://alt1040.com/wp-content/upload...tter-whale.png

Assuming that Hydra has the ability to squirt out an analog voltage in proportion to two variables (RPM and MAP), just follow the link in my sig and repeat the process for your Hyrda.

Why are you so dead-set against letting the ECU run the VVT system? You're never going to be able to control VVT directly without throwing codes.

I'm not dead set on direct control. It's just easier to know what the cam is advanced to when I put "+6 degrees" in a box and not "airflow duty cycle 33% at 2 psi and 3400 rpm"

Indeed. Presently, Hydra is calling that a "coming soon" feature, and I suppose it'd be a neat thing to see. I just have this nagging suspicion that it will take a lot of highly focused dyno time to come up with a cam map that beats the factory map, turbo or not.

For standalones, it's easy- pretty much anything is "better than nothing." But since you're already condemning yourself to a life of parallel operation, why make it even harder than it has to be? Get the MAF-substitution map built and let the ECU do its thing.

an alternative is a quick harness swap to a less-than-ideal situation to keep the CEL happy and then switch back for max control and power.

If you let the factory ECU control VVT, and if VVT advance at different RPMs is a function of airlow, you can therefore modify VVT by diddling your AFM cheat signal. Problem is, other things would be affected too, like EGR.

The other way of doing this is to build a box that fakes the cam sensor signal phase angle by an amount specified by a Hydra output. If the box puts a lag in the signal, the ECU will compensate and advance the cam....

right. I mentioned that above and how much it would suck.

basically I'd have to pull on my left ear to advance timing and rub the shift knob to retard it.

Ya don't like my box?
BTW said box is way easier to design if you only need to advance the timing over factory. Would that be the case?

I suppose if stock is optimal, it doesn't matter. Considering the effect was largely RPM based and not boost based...

i just have to find your black box and recall the wiring colors :)