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Discussion Starter · #1 ·
I've been reading some articles on cleanmpg about installing an FAS switch on various cars. The one I particularly like involves wiring a switch directly into the fuel pump fuse. I've been attempting this on my CR-Z to no avail :cry: Has anyone attempted installing an FAS switch on their Z? any help I can get would be greatly appreciated
 

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for those that have no clue what a FAS switch is: FAS= Force Auto Stop, ie: a kill switch for the fuel pump to stop the motor.

considering our CRZ's have an automatic FAS switch, i haven't bothered to check into this mod.

to the OP, tell me what you are planning?
 

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Discussion Starter · #3 ·
I'd like to to be able kill the engine at high speeds (above 18mph) to maximize my mpg. I found this One Wire fuel injector shutoff w/ Fuse - CleanMPG Forums. My first attempt ended in failure. I realized it had to go through the fuel pump fuse (i don't know if there is a fuel injector fuse in the crz). I wired a racing safety switch to a fuse holder, so it's literally a plug in switch that can be removed for whatever reason. I know I need to put a fuse in the line (just for safety). I'll post pic eventually... is there any way to control the pre-existing auto stop in the Z?
 

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So I've done this on my Saturn SL2 by tapping into the fuel injector fuse. I feel like this is better because it maintains fuel pressure for faster restart. Plus in my Saturn, the injector fuse is only 10 amps which makes things kind of simpler. I simply got a 10 amp switch, some 18 guage (i think) paired wire and a fuse holder (to keep a fuse in the circuit). Connect it all together and it works fine. I have a simple flip switch, but a normally on momentary switch would be better. I've forgotten to turn my switch back on a couple of times, so a momentary one helps there. The switch really should be rated for the same number of amps as the injector fuse. I'm hoping there might be a way to tap into whatever causes the IMA system to go into auto stop. I don't have a CR-Z, but I'm thinking about getting one in a few months, so I'll probably play around with it then.
 

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Discussion Starter · #5 ·
unfortunately the CRZ doesn't have a fuel injector fuse. all I have to work with are the fuel pump fuse and ignition coil fuse. the latter doesn't work...so unless anybody can hack the ECU or knows which fuse is for the fuel injectors, we're SOL.
 

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Another option is finding the common wire going to each injector and splice a switch into that, though obviously that's a wee bit more permanent. Definitely don't mess with just cutting the ignition coil. If you do that, you will probably end up with fuel in the cylinders when the engine is stopped, which can apparently lead to bad things. Honestly, I think splicing directly into the injectors might be your best option. Cleanmpg has a few threads about doing it this way. Other than that, I can't really contribute, but hopefully I'll be able to figure something out in a few months. Sorry I couldn't help more.:blush:
 

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That's one mod I would entertain doing.

I think idle consumption of our 1.5L ICE is around 1GPH, so if one coasts about 10% of the time, then it's 1 gal/tank saved, or ~10% added to the MPG. That would bring me over the 50 mark. Time to join the research group :p
 

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Only if you are in gear.

I stopped coasting in gear and went from 41mpg to 46mpg. That regen in-gear coasting is not very efficient.

In some areas I can coast for a mile or so in neutral. Doing the same thing in 6th would bring me to a stall in about 200 yards.
but you need the regen to keep the battery charged.
 

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I put it in gear when I know I'll be coming to a stop or when I need to slow down on a steep hill - the battery stays adequately charged.

Regen efficiency is not very high, and 10% improvement in gas mileage confirms it pretty heftily.
good points. standing by to see where this goes.
 

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Discussion Starter · #14 ·
to keep update my current test of cutting off fuel via the fuel pump, I tested it this morning and it was a complete failure. Yes it killed the ICE but it also made every single warning light pop up. my next attempt will be to slice a switch directly into the fuel injectors. Anyone know how I could do this?

just to add to the battery thing. if you accelerate slowly, you use little to no assist. When you need to restart the ICE at speed, you bump start it, again using no power. provided you are easy on the gas and don't run too many accessories, your battery charge should last a while.
 

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I did a brief search on FAS for Insight 1 and 2 and both looked like a serious project. Guys ended up with 3-4 relay blocks that would do cut off a bunch of stuff at the same time, including injectors. Not sure it's worth the tempting $50-70/year with my mileage. I would definitely jump on it if it was closer to plug and play.

So in other words - check cleanmpg.com for FAS solutions on other Honda hybrids.
 

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That's one mod I would entertain doing.

I think idle consumption of our 1.5L ICE is around 1GPH, so if one coasts about 10% of the time, then it's 1 gal/tank saved, or ~10% added to the MPG. That would bring me over the 50 mark. Time to join the research group :p
Prob closer to .15gph when fully warmed up. My Civic with the R18 consumes .17gph at idle once warmed up. My Jeep CG with the 4.7L consumes closer to .65gph.
 

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Prob closer to .15gph when fully warmed up. My Civic with the R18 consumes .17gph at idle once warmed up. My Jeep CG with the 4.7L consumes closer to .65gph.
You are probably right, last time I ran my ScanGauge was about 4 years ago in a Toyota 1NZ and apparently I was an order of magnitude off in my head. 1% FE gain will not be worth the risk, then.
 

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I had a kill switch installed on my Del Sol, and could milk it that thing for about 45 MPG. That was just killing the engine in downhill coasting situations, and sitting at red lights, never could get into the pulse and glide myself. Of course I was getting 41 MPG to start with so it did help but in the end I found it to be to much of an extra hassle. I found over time and messing aroudn that I could get 43-44 MPG just taking it out of gear in the same situations.

I personally don't think it would be worth the effort in the CRZ there are many other techniques to work on that would probably yeild similar results. Going into nuetral of course is one, and while it doesn't kill the fuel completely as pointed out it is an effective way for someone to try to milk a couple extra MPGs out their car easily.

I myself like to let off the gas until I see it start to regenerate and then barely step back on the gas until it is neither assisting or regenerating. The car glides just like it is in nuetral, and the instantaneous meter stays maxed out at 100 MPGs. Once you get good at this you can milk it on even the slightest grades, without the extra hassle of pulling it in and out of gear. I have no idea whether this actually kills the fuel completely but seems to be rather effective so far in this car for me.

I guess I don't have much to add in regards to where to start in creating a kill switch for this car. I bet it is very technical. My Del Sol kill switch was a fuse, holder, some wires and a toggle switch. Don't think you can get away that easy on this car though.
 

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Now that you mention it, I'd modified my old Del Sol including a DC Sports header to the point where I had to readjust the fuel mix. I went the opposite direction (horsepower gain and rich fuel mix), where I installed a fuel-pressure riser in the fuel return line to raise the fuel system's design pressure. The fuel injection duration map would then put in more fuel for a given high throttle position / fuel pulse, so would the FAS kill performance by taking the threshold fuel pressure partially down. Since, the Del Sol's idle and low acceleration fuel mix was controlled by the oyxgen sensor, the feedback loop would control the the injector duration regardless of fuel pressure.
 
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