300x and it's owner go "MAD" stay tuned.....

**mrcrsr** · 10-12-2013, 07:20 AM

gary, when you take the air temp sensor out like that it will set an alarm and code in the ecm, not sure if it will cause the engine to limit or not.

**Liberator*21** · 10-12-2013, 09:28 AM

Originally Posted by mrcrsr

gary, when you take the air temp sensor out like that it will set an alarm and code in the ecm, not sure if it will cause the engine to limit or not.

Charlie,

In theory.......
Sensor will still be in the manifold connected to the ECM under normal running...... "BUT", when I hit WOT it switches the resistance signal sent to the ECU as if the temps just dropped to freezing and when I let off of it goes back to normal operation reading the IAT Sensor.

**Dave Strong** · 10-12-2013, 06:00 PM

Originally Posted by Liberator*21

Dave,

Thanks for the suggestion, I'm kinda looking at it like this, I'm going to try everything I can without having to lay out some serious cash. As much as the thought of bigger injectors sounds right for WOT, it may really screw up the idle to mid range. It's very obvious that the issue here is lack of fuel since I've now got an abundance of air available. Under my current setup, I'm not that far away from getting it right as I'm running great till the motor hits a wall in the low 80's.

I got an email from a buddy and he recommended a "Piggy Back" controller system may help. All these ideas are great but there each about $500 a pop with no guarantee of success. What I'm doing is also a great learning experience for me as EFI is still relatively new to me and I'm learning on the fly and besides I'm having fun doing it. Boating days are becoming limited here as winter draws ever closer so I'll continue on my present path and then we'll see what next year has in store.

Just thinking crazy but what about another set of injectors that only kick in at high rpm, kinda like secondary's an a 4 barrel carb??
Seen that type of fuel enrichment used with superchagers and turbos on 4 stroke EFI's in the early
90's.

Dave

**opsdave** · 10-12-2013, 09:09 PM

I say keep it simple.... Once you figure out that you need xx% more fuel at wot send the ECU off to Simon and have it flashed and you're done. The injectors should be big enough to support the needs of that intake.

**Liberator*21** · 10-13-2013, 04:15 AM

Originally Posted by Dave Strong

Just thinking crazy but what about another set of injectors that only kick in at high rpm, kinda like secondary's an a 4 barrel carb??
Seen that type of fuel enrichment used with superchagers and turbos on 4 stroke EFI's in the early
90's.

Dave

Dave S,

Yep, that would work, but again I'm trying to use everything available that the motor has to offer using DIY technology with minimal impact to the motor. After all it's still a family boat at times and I don't want to depart to far from that usage either.

Originally Posted by opsdave

I say keep it simple.... Once you figure out that you need xx% more fuel at wot send the ECU off to Simon and have it flashed and you're done. The injectors should be big enough to support the needs of that intake.

Hey Dave,

Exactly.......Keep it as simple as possible. Your right on with the re-flash after I figure what it needs fuel wise. To send the ECU off now would be a gamble as I'm so close to getting it right. Last thing I want to do is throw an unknown % increase relating to fuel at the motor that may end up being to much and end up doing more harm than good. Baby steps is what I'm do'n...........lol.

**opsdave** · 10-13-2013, 04:44 AM

That was my exact thoughts Gary. Getting running well, then have it flashed. You're getting there!

**whipper** · 10-13-2013, 04:50 AM

As you say you cant reflash without getting her on a dyno like DBR,s to monitor every little detail you've done and were you need more or less. If you had her hooked up now to see what's going on inside exactly, the acu can be adjusted on the fly I think these days to get the best possible outcome with egt,s,air mass,fuel flow, hp, torque were and when then map to perfection. Then your tune could be saved so you always get the same results if you were to do this to other motors. I think the power head needs a trip to the docs to get hooked up at this point for the final tuning .

**mrcrsr** · 10-13-2013, 07:49 AM

you can't use an acu on a 300x, it is a motorola engine. a reflash is 650$ and probably won't be rite the first time, i couldn't imagine trying to set up a fuel curve without have the engine here to tune. the price of the wolf looks better every time! i can tell you on steve's engine if the iat sensor is disconnected it will set an alarm, on the last bit of tuning we did to get wot and midrange correct we got the fuel pressure down to 39 psi(his has a modified 300x computer done by mercury) and the curve up top was fat. anyway, the motor wouldn't cold start so we unplugged the iat to fire it when cold, and it set an alarm every time. a cheap route would be to use a microsqirt or megasquirt computer, feed it the tach signal and have it fire an additional injector or 2 into the plenum at the problem rpm points. another way that may be better is to use an msd rpm switch, and intercept a coolant temp sensor, at a particular rpm the switch triggers, use a relay and use both terminals, 87 and 87a, install a resistor on the one terminal that is triggered thru the relay. that way the relay when unpowered(or untriggered) uses the cts as normal, when relay is triggered it is intercepting the cts signal and modifying it, as the cts has more effect then the air temp sensor. select your resistors by using the ddt and trying different resistors tied into the cts wiring until you come up w/ a range of say 70 degrees up to 100 degrees, that way you have an idea of what each one will do.

**Liberator*21** · 10-13-2013, 08:39 AM

Charlie,

Thank you for the additional info.....

!!!!!

Here's where I'm at currently. Added a micro switch that will take the IAT from normal temps readings to 32 degrees @ WOT. As seen by the clip below in the garage, temps is 72 degrees, IAT reading is 10200k Ohms, when I go to WOT, change sent to the PCM is now 32800k ohms (32 degrees in air temp). we'll see if it helps the big end any. I shouldn't get any alarms as the IAT is being read all the time, just the output signal changes.

**R.grover** · 10-15-2013, 02:57 AM

gary the project seems to be slowly workn out for you. dose any one no of any second hand mad efi units for sale?

**Liberator*21** · 10-15-2013, 04:17 AM

Originally Posted by R.grover

gary the project seems to be slowly workn out for you. dose any one no of any second hand mad efi units for sale?

Rick,

I replied to your PM, call me today, 12 noon your time/7 PM my time. As for another MAD Intake being available, there's not many out there in the used parts market. Took awhile for me to find this one, just gotta keep put'n the word out there your look'n and check the parts board weekly.

I went out yesterday with the modified IAT design I did, and it did help the top end a little in speed and additional RPM's, so that alone is worth money in the bank, it positively confirms the need for more fuel at WOT which I knew all along, but had to confirm by real numbers. Working on another approach to added fuel at WOT now, more to follow as I get into it. My time to play is growing short as o'l man winter is on my door step knocking on the door, I'm try'n to put him off as long as I can but it's getting harder and harder everyday.......

**R.grover** · 10-22-2013, 03:48 AM

all the bugs sorted now mate? was good to talk to you on the fone the other day mate

**Liberator*21** · 10-22-2013, 04:16 AM

Originally Posted by R.grover

all the bugs sorted now mate? was good to talk to you on the fone the other day mate

Rick,

Great talking to you as well and I wish you the best in all your projects. O'l man winter has opened the door here in my neck of the woods so on water testing will be coming to a close for now....

. I am continuing to work technical issues on paper and in the shop. Looking at a piggy back fuel delivery system to provide additional fuel only at WOT as that's where I'm still lacking. I'm looking at adding 3 injectors to my current system, one in each horn, as for controlling the system I'm looking at a SDS EM1, triggered by either RPM sensor or micro switch. Have to redesign all the throttle/TPS linkage as the 3 added injectors will interfere in that area since it's all mounted on that side, so I'm basically starting over again.

To make things even worse, my o'l P4 H/T Dell Workstation took a dump on me so I can't do any CAD layout work till my new system arrives, I just decided to spring for a new HP Workstation w/I7 Quad Core processor and move into the latest technology for workstations. That was obviously a huge hit to my pocket book that wasn't planned for, but never the less needed.......lol.