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Injector Solenoid Resistor Pack needed

 
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ZrodOffline
Joined: 03 Aug 2004
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PostPosted: Tue Aug 03, 2004 3:37 pm    Post subject: Injector Solenoid Resistor Pack needed Reply with quote

Looking for the injector resistor pack for the 7mgte swap into my '91 swb, extra-cab. I also need the plug from the harness if possible.

Additionally, an accordion hose for the AFM to the turbo would be nice, but not necessary.

Thanks for your time.

Rod
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SuperRunnerOffline
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PostPosted: Tue Aug 03, 2004 4:19 pm    Post subject: Reply with quote

I don't think I have any resister packs yet, but they usually are pretty easy to find at wrecking yards.

I personally don't use the accordian hose, but just make my own out of 3" pipe.
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ZrodOffline
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PostPosted: Wed Aug 04, 2004 7:29 am    Post subject: If a pack becomes handy, Reply with quote

just PM and I'll contact you.

I've not had the chance to shop the local yards yet, but they're pretty proud of their stuff. If I strike out, I'm thinking of trying three 3.3 ohm, 50 Watt resistors from Digikey. They're only $5 each.

Thanks for the reply.

Rod
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MikeOffline
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PostPosted: Wed Aug 04, 2004 12:09 pm    Post subject: Reply with quote

Where did you come up with those values for resistance and power?
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ZrodOffline
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PostPosted: Thu Aug 05, 2004 11:30 am    Post subject: Reply with quote

Well, the values were initially a SWAG based on the Haynes service manual Solenoid Resistor value of 3 Ohms and an extrapolation of the 25 Watt power per injector recommendation from the Megasquirt site.

Since you asked, I figured I'd better double check. The Supra System runs two ~2.5 Ohm injectors, parralleled, in series with the Solenoid resistor. The resistance for the parralleled injectors is ~1.25 Ohms, 1/Rt=(1/R1)+(1/R2). Add this with the solenoid resistor, 3.3 Ohms, and total circuit resistance is 4.55 Ohms, Rt=R1+R2. Current through the circuit is based on I*R=E, where I is current-amps, R is resistance-Ohms, and E is voltage. I=E/R, I=14V/4.55Ohms=3.07amps. Power required, Watts, is V*A or 14V*3.07A=43.07Watts.

Hmm, looks like they'll work fine.
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SuperRunnerOffline
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PostPosted: Thu Aug 05, 2004 11:39 am    Post subject: Reply with quote

Sounds good to me.

I have a dummy load for my ham. 10 watt 50 ohm. Big resitors
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MikeOffline
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PostPosted: Sun Aug 08, 2004 11:56 pm    Post subject: Reply with quote

I took a look at the toyota wiring manual for the 7mgte, and thought I would let you know that the information in the Haynes manual appears to be an average. The toyota manual lists injector resistance to be between 1.8 and 3.4 ohms, and the injector resistors to be 2 ohms rather than three. The manual I have is for the 89 model, which is the same as 90,91,92, but I am not certain that 87-88 are the same on this.

So for the power calculation, the worst case scenario would be when a branch consisting of two injectors and one of the resistors was operating with the injectors providing 1.8 ohms each, for a net .9 ohm. Add that to the 2 ohms, and you have 2.9 ohms resistance in that branch to drop the input voltage, which you say is 14 volts. Power can also be found from voltage squared divided by resistance, giving 196/2.9 or 68 Watts. Granted, this would only happen if both the injectors in a given bracnh were at the lowest resistance possible, but it would be safer to go with some 75 watt resistors at least. Also, if the input voltage is higher than 14 volts you will really want to increase the power rating of the resistors since power is a function of voltage squared.

If it would be helpful I could take a picture of the info in the toyota manual and send it to you.
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Paul ElbisserOffline
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PostPosted: Thu Aug 12, 2004 1:35 am    Post subject: you can use the 4cyl resistor Reply with quote

Acualy you can use 2 truck resistor packs. Each injector shares a resistor, so the 4cyl will have 2 in the pack, and the 6 will have 3. you can get away with taking 2 packs from the 4cyl and rewireing them to run in the 6cyl motor. And you will have a spare onboard.
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ZrodOffline
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PostPosted: Mon Sep 13, 2004 3:59 pm    Post subject: Found one Reply with quote

I broke down and went to the salvage yard. I called a local yard and they said, "Come on down. We have a couple of cars that might have what you are looking for." I asked how much, and he said $10-$15. Great! I used a vacation day to visit the yard. I checked in at the front desk. They sent me around back with some car numbers. One of the yard helpers gives me a ride to the first pick. Talk about picked clean, but it had the reistor without the plug. I grabbed it and went to the others. Second one was and '82. Wrong part. The third pick, Bingo! It had the resistor, plug and more. Grabbed the good one with plug, and dropped the plugless one. I got to the front desk and the manager says, "That looks like a $25 part. I bet it costs over a hundred from the dealer." I said no its not. I can build it brand new for $15. He said I'll meet ya half way at $20. I figured by the time the shipping was added to the digikey parts that was close enough. I told him if he's going to charge that much, he needs to give his helper $5 for running me to the cars, and tossed him a $20.

Working on A/C and power stering lines now. Getting closer.

Rod
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camicaztoyOffline
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PostPosted: Thu Apr 28, 2005 11:42 pm    Post subject: Reply with quote

do you need this to run the engine? would not having this cause a lack of spark?
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SuperRunnerOffline
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PostPosted: Fri Apr 29, 2005 9:23 am    Post subject: Reply with quote

You need it for you injectors to work.
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