I was just wondering what resistors you guys that have dsm 450cc injectors and starting problems are using?

Most use 10 watt 10 ohm resistors. Why? Honda resistor boxes are 6 ohm.

I used 10 watt 10 ohm resistors on a MS powered car and it wouldn't start. The priming and idling pulses were not getting past the resistors. I checked out the MS forum and learned that for my setup 4-6 ohm resisters would be ideal. I replaced the 10 ohm resistors with 4.7 ohm and it made a world of difference. Starts and idles perfect.

I realize honda ecus and MS are different but where did the 10 ohm come from?
Just wondering if this could benefit any of you.

 

huh. thanks for the input. perhaps that is causing my "putting" at idle. i'll hav to give it a shot, but i just blew my motor, so it will have to wait a week or so.

 

This is good info.
Glad that you shared it.

Anyone else try this ?

I guess ill buy the 4.7's.

 

Pull the top cover off of the ECU. With the vehicle running for at least 5 minutes touch the injector drivers (the small rectangular black chips in the upper left corner, if the ECU connectors are on the left). If they are cool or just warm to the touch, you are fine. If they are too hot to touch, I recommend upping the resistance to 6 or 7 ohms. This could vary with the resistance of the injectors.

devnull, what is the resistance of your set of 450cc injectors?

 

does that mean it is better to use a honda resister box since it's at 6ohm? I have a honda resister box, but not sure if i should use the resister box or cut the lines and put in resisters.

 

I used to use those stupid Radioshack 10 ohm resistors. They kept coming loose or breaking (connectors) off even after we soldered the thing on.

it was hard to start and puttered a bit at idle. Switched to a honda oem resistor box and...... the difference was night and day.

it idles perfect now, but it's still hard to start from time to time. Sometimes it starts on the first crank, and sometimes it takes a few more.

Honda oem resistor box

 

The resistance on my dsm 450cc is 2.3 ohms. Measuring the temp with your finger can't be to accurate. I wouldn't use anything higher than six. Honda used 6 ohms to run low impedance injectors. The only reason to up the resistance is if you get some injectors with really low resistance.

Though I admit I don't know what the resistance of the oem low impedance injectors is but I would guess it is ~2.5.

The higher you go (more resistance) the more pulses get blocked. With the 10 ohm resistors in I had to add a **** load more fuel in the maps to get it to idle (this is a dyno tuned map that idles fine with high impedance injectors). The more fuel I added the more pulses got through so it compensated. But it made the car run like ****.

Once I changed the resisters the car behaves as though it has high impedance injectors. In other words normal.

 

that is great info im gonna try it tomaro if everything goes as planned and let you know how it turns out

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by devnull &raquo;</TD></TR><TR><TD CLASS="quote">
The higher you go (more resistance) the more pulses get blocked. With the 10 ohm resistors in I had to add a **** load more fuel in the maps to get it to idle (this is a dyno tuned map that idles fine with high impedance injectors). The more fuel I added the more pulses got through so it compensated. But it made the car run like ****.
</TD></TR></TABLE>

Thats not exactly true. The fueling problem is caused by limiting the current flow to the injector thereby causing it to open much slower.

 

how about roscher 880's?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stizzit &raquo;</TD></TR><TR><TD CLASS="quote">Thats not exactly true. The fueling problem is caused by limiting the current flow to the injector thereby causing it to open much slower. </TD></TR></TABLE>

Yeah the limited current flow caused by resisters over 6 ohm.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by devnull &raquo;</TD></TR><TR><TD CLASS="quote">I was just wondering what resistors you guys that have dsm 450cc injectors and starting problems are using?

Most use 10 watt 10 ohm resistors. Why? Honda resistor boxes are 6 ohm.

I used 10 watt 10 ohm resistors on a MS powered car and it wouldn't start. The priming and idling pulses were not getting past the resistors. I checked out the MS forum and learned that for my setup 4-6 ohm resisters would be ideal. I replaced the 10 ohm resistors with 4.7 ohm and it made a world of difference. Starts and idles perfect.

I realize honda ecus and MS are different but where did the 10 ohm come from?
Just wondering if this could benefit any of you.</TD></TR></TABLE>

MS ?
-PHiZ

 

you can take a meter and measure the resistance on a fuel injector. my stock type r injectors measured 14 ohms, my rc engineering measured 3.9 ohms...so I used 10 ohw 10 watt sand block resistors. its not the same for every injector setup but basically you want to check the resistance on the stock setup and install resistors to maintain the stock resistance.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syner-G-Racing &raquo;</TD></TR><TR><TD CLASS="quote">you can take a meter and measure the resistance on a fuel injector. my stock type r injectors measured 14 ohms, my rc engineering measured 3.9 ohms...so I used 10 ohw 10 watt sand block resistors. its not the same for every injector setup but basically you want to check the resistance on the stock setup and install resistors to maintain the stock resistance. </TD></TR></TABLE>

beat me to it darn it

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95stangkillah &raquo;</TD></TR><TR><TD CLASS="quote">I used to use those stupid Radioshack 10 ohm resistors. They kept coming loose or breaking (connectors) off even after we soldered the thing on.

it was hard to start and puttered a bit at idle. Switched to a honda oem resistor box and...... the difference was night and day.

it idles perfect now, but it's still hard to start from time to time. Sometimes it starts on the first crank, and sometimes it takes a few more.

Honda oem resistor box </TD></TR></TABLE>

I'm using the oem box, and my car will start right up every time. I always let the fuel pump prime too thou. .

 

I use 10watt 10ohm inline resistors from radio shack with my DSM's....97% of the time it starts immediately, maybe 2 cranks max. 3% of the time it will start hard. This only seems to happen when its real cold out though. Ive had this setup for about 2 years now.

I let the pump prime as well, always.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PHiZ &raquo;</TD></TR><TR><TD CLASS="quote">

MS ?
-PHiZ</TD></TR></TABLE>
megasquirt