Fuel injection resistor

[firefighterwhite89]

All plugs on my fuel injection resistor read 9.3 Ohms across the board. IIRC resistance should be 5-7 Ohms. What would cause this to be slightly higher in resistance? Could it be dirty terminals? Or maybe a short?

[lostforawhile]

thats not much to worry about, even a small amount of resistance at the leads could cause that, you are mainly looking for one that is a lot different then the others. Since they are all the same, I wouldn't worry about it

[gp02a0083]

All plugs on my fuel injection resistor read 9.3 Ohms across the board. IIRC resistance should be 5-7 Ohms. What would cause this to be slightly higher in resistance? Could it be dirty terminals? Or maybe a short?

If you encountered dirty terminals or bad connections with the multi meter probe tips your resistance measurements can swing a bit, having all measurements reading the same can rule out bad connection. A short would typically read as an open or low resistance below 1 ohm. Most likely the cause of the increase in the resistance is due to age, material fatigue, thermal degradation which would be normal for a 20+ year old part and also reading similar resistances. regardless I would suggest to replace the box


thats not much to worry about, even a small amount of resistance at the leads could cause that, you are mainly looking for one that is a lot different then the others. Since they are all the same, I wouldn't worry about it

First of all if they all match @ 9.3 ohm, all that indicates is that the resistance increase is not isolated to one particular portion of this resistor array. However this still, exceeds the 5-7 ohm factory spec by 24%-46%, outside the tolerance rating for the resistors. Second, the increase in resistance would have an effect on the drive current required to open the injector properly when using the same pulse width signal, to little current and the injector has opening / on-time ends up with lag or doesn't work at all. Third, resistors can end up having a dynamic resistance characteristic when overstressed and /or damaged in an operating circuit, I see things like this readily on my Lab bench with 600V circuits. If the resistor is unable to hold its resistance value within its spec this can cause a problem and can damage the injector and possibly the ecu's drivers. Interconnects of any type are always suspect to contact issues, however a good contact should always be below 1 ohm.

[firefighterwhite89]

Is the resistor box something I can simply pursuede open and replace 4 resistors, our too much of a hassle to even fool with? Bear in mind I live in the country where 90% of the vehicles driven around here is the American made hunks of junk hence the oldest model Hondas I can find are `97+...and ordering the part new without going to a dealership is pretty much impossible. So if I have to dremel the box open, replace some electronic parts and jb weld the protective case back together, that's what will happen. I'm definitely not as lucky as the western coast guys. Seems most southerners are all 'Made in America!' Type douches when it comes to vehicles.

[firefighterwhite89]

I think this may be the reason behind my injection issues. Cold or not, it still idles somewhat rougher than it should.

[cygnus x-1]

Before yo do anything else, touch the probes together on your meter and see what it reads. Subtract that number from what you read on the resistor box. Some meters are not very accurate at measuring low resistances. I had one years ago that added an extra 2-3 ohms.

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[firefighterwhite89]

If I subtract 4.3Ohm from 9.3Ohm I get right at five ohms. Is this how you're supposed to test it? Should I go to radio shack and test a few resistors for accuracy? It is a cheap multimeter. Came from harbor freight for $7

[firefighterwhite89]

I get what you mean. When touching the probes together I get between 40.5&18.9ohms resistance depending on where on the probes I cross them...wtf?

[firefighterwhite89]

My multimeter is on 200 ohms setting. Should I have it on another?

[lostforawhile]

My multimeter is on 200 ohms setting. Should I have it on another?

I think you are fine, those type of power resistors can be off an ohm or two anyway, and still be within tolerance, the fact that they are all consistent is more telling

[cygnus x-1]

Sometimes the outsides of the probes get dirty and don't make a good connection. It helps sometimes to rub them together a few times and then hold. You should be using the lowest setting there is, probably 200 ohm.

I'm with lost on this one. If they all measure the same they're probably ok.

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[firefighterwhite89]

Excellent. Thank you gentlemen.