Dodge SRT-4, HOM toys option, and WI injector placement

[turbojack]

1) is rear window defrost

2) push to activate auto IC spray hold down to manually spray

3) got me on that one had to go look at the car. Never really noticed. It does nothing, and I dont know what it is. I'll need to figure that out since it now bugs me that I dont really know.

4) DAB settings. In the picture it's on 3 (0, 1, 2, 3) it's a thumb wheel type of switch

5) HOM switch activation. Push once to activate (turns on red LED)

additonal questions:

1) the location of the red (HOM) and blue (IC sprayer) are up to the owner/installer of the toys option I put mine just under the boost gauge pod (which now is occupied by the DDS3).

2 &3) the toys switches are supplied in a panel (as in the picture) that directly replaces a cubby hole panel for cigs or glases etc... no drilling for the toys panel, but to install the LED lights you need to drill holes, again location of lights is up to installer/owner.

Ps. I was planning on posting pictures of all the components (incl DDS3 in the former boost gauge pod), how do I do this?

[Roverdose]

are you going to run into det (knocking) when turning the boost up on the std ecu mapping?

what boost are you running now? what will you be turning it up to? and when are you planning to inject the water?

if the ecu is expecting race gas, it will be from tickover to top revs. if you inject water too late the hom may have been turned off already.

Drew

[Richard L]

Originally Posted by turbojack

The info I have are from documents in PDF format. Here's the links to the documents:

http://www.dodge-srt4.com/howto.shtml
(Mopar Stage 2 Turbo Toys Instructions)
(page 4 has wiring diagram for the toys)

http://www.dodge-srt4.com/tech.shtml
(PL Body Service Manual)
(pg 8W 30-26 has wastegate wiring info)

I've been hearing from other SRT-4 owners that also looked at what I'm trying to do. A couple are trying to do the same thing (HOM activation) with diff parts and components and ideas. For example, heres a copy of a comment from another SRT-4 owner after he had read about my Aquamist WI & HOM activation plans that I posted on the SRT-4 forums:

"Very nice. I take it that the yellow line is a momentary ground. Hard to tell. This was the problem I ran into. The ECU does not like constant ground. Very interesting."

I then replied with:

"I think I understand what you mean. The ECU needs to be able to override this. The DDS3 after making checks will activate the switch with a pulse. Even if the DDS3 say's things are good, the ECU can still say no."

To which he replied:

"What I had problems with was that pin C14 (white wire on HO Switch) need a 1 second pulse to ground to activate HOM one to deactivate... re-set so fourth. So with the varables in mind how do I educate my controler as to what state HOM is in. Ground side of the blinky red diode is good before the resistor. But no... There was a reson the red LED was a bad idea on either side. I can't remember what I found but I think it was voltage leaking from the ECU... Anyway
I started playing with the photocell side of a 12V Bolinger fiber optic tranciever. It knew when the light was out. It knew when it was on, and even better it knew when it was blinking... Then I lost intrest.
Please post what you come up with. I havn't abandoned my little bag of radioshake parts yet.
What is real nice is the use of a flowmeter rather that a pressure switch to see if fluid is moving."

So from reading peoples comments I'm a little lost.... taking everything perceived away and starting at square one.

From what I understand how HOM should work (NO WI, or DDS3):
You add race gas and then you hit the HOM switch and then run the car. The PCM/ECU sees the HOM has been activated and switches to an enhanced timing MAP or it just plain allows more timing based on HOM switch activation (more power). While in HOM mode the PCM lights up a Red LED to inform the driver of HOM activation. IF the driver activates HOM without race gas the red LED still lights up but... if after getting into the gas pedal the PCM receives a signal from the knock sensor that is not within the defined threshold of the HOM map it reverts to the base map (or reduced timing) and flashes the red LED informing the driver, hey you hit the HOM switch but you don?t have race gas in the tank, not going to allow this, possible engine damage.

The ideal scenario with WI:
The DDS3 makes the WI checks and activates HOM via sending a signal to the PCM just as if the switch was hit. The PCM activates the HOM map and lights up the red led. The DDS3 see that WI is still working fine. The driver gets into the gas pedal and because the WI has been setup and tuned correctly the red LED stay lit and the car has more power.

The problem scenario with WI #1):
The DDS3 makes the WI checks and activates HOM via sending a signal to the PCM just as if the switch was hit. The PCM activates the HOM map and lights up the red LED. The driver gets into the gas pedal and because the WI has NOT been tuned correctly the PCM reverts back to the non HOM map and blinks the red LED. The DDS3 does not care about the blinking red LED and continues to work even if HOM light blinks. The driver sees the HOM LED blinking and notices that the DDS3 is fine and realizes the tune is off. This IS NOT A WI failure problem it?s a tuning problem. To me this is how it should be.

The problem scenario with WI #2):
The DDS3 makes the WI checks and activates HOM via sending a signal to the PCM just as if the switch was hit. The PCM activates the HOM map and lights up the red LED. The driver gets into the gas pedal?shortly after the DDS3 sees WI failure?dumps boost and stops WI. Because WI fails PCM sees knock sensor reading above threshold ?.reverts MAP?red LED blinks. Driver either first sees DDS3 warnings or red LED either way doesn?t really matter since both systems have fail safes not dependant on driver action. Because the driver sees the DDS3 has found a failure in the WI he knows to look into the WI system. Again, to me this is how it should be.

The problem scenario, with WI #3):
The DDS3 makes the WI checks and something fails. Because of WI failure DDS3 never activates HOM, and PCM never lights up the red LED because the DDS3 never activated HOM. Again, to me this is how it should be.


OK, now why does the DDS3 need to know if PCM makes the red LED blink? If the DDS3 does not see a problem with WI, WI functions as designed. Just because the PCM say?s?hey you got no race gas in the tank, why does the DDS3 need to know, why should it care? The DDS3 does have control over a boost solenoid and will allow raised boost, this raised boost level will not be so much so, that without HOM working it will be dangerous. I always intended to tune the car first without any dependencies of WI for safety. The PCM will revert map regardless of whether WI works or not, IF it sees a knock threshold above HOM values.

I?m thinking that if the DDS3 can activate the HOM switch (turn on) then the DDS3?s HOM turn off capabilities is not necessary because the PCM takes care of that based on knock threshold values in the PCM. To me this is a fail safe that does not need to be messed with or enhanced in any manner.

IMO the answer is having the DDS3 just send a momentary pulse to the PCM. This pulse would be a mimic of the pulse of the switch when activated by hand. I must first say, that maybe I just don?t understand some basic electronics and this is not possible without also tying into the red LED so as to complete some type of circuit. I see the HOM activation by the DDS3 as a turn it on and forget it type of thing. Let the PCM via the Knock sensor say keep HOM on or turn it off because some parameter has not been successfully met. If I can, I would like for the DDS3 to turn HOM on and not care if red LED blinks. The proper function and control of the red LED by the PCM can be one of my tuning tools for WI.

Thanks
Jack

These are excellent information and ideas that will help me in my wring scheme. I am taking every point on board and have suggested the following strategy as a starter.

If the aim of WI is to replace race fuel, then the whole project should be simple. Based on that assumption, I suugest:

1) Detect teh HOM mode by monitoring the red led - when the WI sees the "low" signal from wire terminal #C14, it can switch on the water injection - may be some interfacing circuitry, but put that aside for the time being.

2) If knock presists after depression of gas paddle after WI is mapped, the HOM mode will drop out and so does the WI - until bigger jet is used or a new map is created.

3) If WI fails, the above will also automatically cancel the HOM by the ECU.

What do you think?

[Richard L]

Originally Posted by turbojack

1) is rear window defrost

2) push to activate auto IC spray hold down to manually spray

3) got me on that one had to go look at the car. Never really noticed. It does nothing, and I dont know what it is. I'll need to figure that out since it now bugs me that I dont really know.

4) DAB settings. In the picture it's on 3 (0, 1, 2, 3) it's a thumb wheel type of switch

5) HOM switch activation. Push once to activate (turns on red LED)

additonal questions:

1) the location of the red (HOM) and blue (IC sprayer) are up to the owner/installer of the toys option I put mine just under the boost gauge pod (which now is occupied by the DDS3).

2 &3) the toys switches are supplied in a panel (as in the picture) that directly replaces a cubby hole panel for cigs or glases etc... no drilling for the toys panel, but to install the LED lights you need to drill holes, again location of lights is up to installer/owner.

Ps. I was planning on posting pictures of all the components (incl DDS3 in the former boost gauge pod), how do I do this?

You need to store your pictures on a public accessable site first then you
post the url of that site between [img]url[/img] quotes.

You can email me the pictures: richard@aquamist.co.uk, I should be able to do the rest.

I have one more question, looking at the wiring diagram, can the wire such as the c14 accessable from the back of the panel?

[turbojack]

Quote:
"1) Detect teh HOM mode by monitoring the red led - when the WI sees the "low" signal from wire terminal #C14, it can switch on the water injection - may be some interfacing circuitry, but put that aside for the time being. "

Answer:
If I understand this correctly and the low signal is what makes the red LED blink the WI would be injected when the red light blinks. When the red light blinks, the the PCM has diababled HOM, too late for WI at this point. I think that when the DDS3 first sees a signal going from the HOM switch to the PCM it's time to turn on the WI is better.

Quote:
2) If knock presists after depression of gas paddle after WI is mapped, the HOM mode will drop out and so does the WI - until bigger jet is used or a new map is created.

Answer:
I see no reason to stop water injection if if PCM sees knock. The PCM will bypass HOM if it sees knock, but WI can still run. IMO the DDS3 uses info to control WI components. The PCM uses info to control fuel, AND disable HOM if knock threshold is exceded (I have just way over simplified what the PCM actually does but please except this for the sake of reading this). I was just thinking about using the DDS3 to activate the HOM switch, it will have no control over it other then turning it on, after this DDS3 is done with HOM. The PCM still controls whether it will stay activated based on knock values.

Above should also answer #3 in same post

Quote:
I have one more question, looking at the wiring diagram, can the wire such as the c14 accessable from the back of the panel?

Answer:
yes

[turbojack]

Originally Posted by Roverdose

are you going to run into det (knocking) when turning the boost up on the std ecu mapping?

what boost are you running now? what will you be turning it up to? and when are you planning to inject the water?

if the ecu is expecting race gas, it will be from tickover to top revs. if you inject water too late the hom may have been turned off already.

Drew

Several SRT-4 are already upping the boost without water and without the HOM. Without stage II or with stage II the boost can be raised (factory stock settings bypased by the owner), however the PCM will still retard timing when knock present.

I'm using the factory supplied adjustment instructions for Stage II on the factory supplied stage II wastegate actuator. This yields for me about 16.5 -19.0 (conditions apply). Right now I dont plan on upping the boost since at this point I'm trying to concentrate on HOM without race gas. As far as when I plan on injecting water, the actual WI tune will be handled by same people who market the piggyback I'm using. They have a fair amount of experiance of using the piggy back to control the HSV plus they have a very good working knowledge of the SRT-4. So I dont know at this point yet.

Because whether the HOM working or not is dependent on what the knock sensor sees and then feeds to the PCM, I think the key will be to find out when the car is near MBT since if I've read correctly this is where knock will be most prevalent. While road tuning and watching info via a ODBDII scanner I might be able to start a basic tune fairly close and then tune thu expermenting and datalogging till I can get the HOM light to stay lit. if it blinks I know the tune is off.
[/quote]

[Richard L]

Originally Posted by turbojack

Quote:

Answer:
If I understand this correctly and the low signal is what makes the red LED blink the WI would be injected when the red light blinks. When the red light blinks, the the PCM has diababled HOM, too late for WI at this point. I think that when the DDS3 first sees a signal going from the HOM switch to the PCM it's time to turn on the WI is better.

Looking at the wiring MOPAR wiring diagram, the +ve end of the red led is wired directly to a steady +12V via a resistor.

In order for the led to light up (HOM is ON), the c14 junction has to go "low". When the led blinks, the c14 junction will go "high, "low", "high", "low" etc.

My logic tell me that when c14 goes low, it is at the "HOM" mode.

The function of the HOM switch is not important as it is momentary so I cannot determine what state it is in after it was pressed until the red confirms it. It can also cancel the HOM mode after a momentary "press".

Am I on the right track?

[turbojack]

I think your right on the money. However understand YOU are better then I in reading and interpreting a wiring diagram, and understanding what the symbols actually mean (I have to look them up in a internet glossary).

[Roverdose]

i see, so you can press the hom switch and get a few revs going before it turns itself off?

Drew

[Richard L]

Originally Posted by turbojack

I think your right on the money. However understand YOU are better then I in reading and interpreting a wiring diagram, and understanding what the symbols actually mean (I have to look them up in a internet glossary).

We need to decide at some point how water injection will play its part.
I suggest the follwoing list of priority (order of importance):

1) Replacing high octane fuel at "HOM" mode
2) What action to take under water fault conditions
3) Actively disable the HOM mode or allow the ECU to switch off the HOM
4) Lower the boost pressure to wastegate setting by the DDS3

Question:
The rate of injection is determined by the PSI-FI and how can we tell the PSI-FI that we are in HOM mode?

At present the DDS3 will not know when the water should be injected so it cannot flag a logical fault under these conditions - it will only report that water is flowing or not. We can put an interface circuit to tell the DDS3 and PSI-FI at the exactly the same time that HOM mode is activated.

Is there a spare input on the PSI-FI to that effect? Once we have extablished this, we can sail forward.