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Hi all, I'm having a million problems with my gen 4 swap. Basically the car runs terribly and even worse under load (drove down my street) so it's a gen 4 3s in a 91 n/a body. Im getting a code p1200 for fuel pump relay, the n/a never came with one. The car runs extremely rich and I cannot figure it out. With the fpr hooked up to the vsv on the back of the intake and then to the map sensor the car runs better but still bad and wants to idle around 2300 rpm. The code p1200 also is for an bad or open fuel injector circuit or for an ecu circuit malfunction. Really at a loss with this car anything helps.
 

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Prime get their harnesses done by Wiregap I think and he does good work. Everything in that harness is setup to make the engine work properly. The fuel pump resistor relay and resistor are not needed. Not sure why you are getting a code for that.

You should always have the FPR and MAP sensor hooked up. These are MAP sensor engines and without it the ECU cannot run it properly.
 

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Discussion Starter #5
Prime get their harnesses done by Wiregap I think and he does good work. Everything in that harness is setup to make the engine work properly. The fuel pump resistor relay and resistor are not needed. Not sure why you are getting a code for that.

You should always have the FPR and MAP sensor hooked up. These are MAP sensor engines and without it the ECU cannot run it properly.
They are both no hooked up and it still runs like junk, is there a way I could go through and test these senors?
 

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The FPR is just a vacuum switching valve that allows higher fuel pressure for hot starts. It's not used during normal engine running.

I think the MAP sensor has a 5V range so applying pressure to it will output different voltages for testing if you can do that. You'd apply 5V to pin 3 and an earth to pin 1 and measure the voltage output of pin 2.

What makes you think it's these sensors? Can you do a standard OBD1 style and let us know what codes it shows? P1200 doesn't show in my list of Caldina error codes.
 

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Discussion Starter #7
The FPR is just a vacuum switching valve that allows higher fuel pressure for hot starts. It's not used during normal engine running.

I think the MAP sensor has a 5V range so applying pressure to it will output different voltages for testing if you can do that. You'd apply 5V to pin 3 and an earth to pin 1 and measure the voltage output of pin 2.

What makes you think it's these sensors? Can you do a standard OBD1 style and let us know what codes it shows? P1200 doesn't show in my list of Caldina error codes.
I believe it is one of these sensors because the car runs very rich with black spark plugs, I just looked up "p1200 Toyota fault code" I'm getting a couple different things. One is for a the fuel pump relay. The other I just found is for the injector control circuit. It says the circuit is either open or has a week connection, I believe this is my problem. I know there are 2 ground on the back of the intake I'm not sure which one is for efi. I cleaned both grounds today with a wire brush so I'm guessing that the grounds are ok, how would I test the injectors? Would it be better to get them cleaned or just buy new ones?
 

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The injectors are very simple and if the spark plugs are black it due to too much fuel and not enough burning. Rough running will do that. Seems more like a spark issue than a fuel issue.
The injectors earth through the ECU, not directly to those points. So both earths need to be cleaned to be sure.

The FPR is not a sensor, it doesn't sense anything, it's just a valve controlled by the ECU.

Maybe you have a stuck injector? To test them apply 12v to one side and earth to the other. You should hear them tick open and closed.
 

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Kinda sounds similar to my recent issue. check coils and plugs. I had a bad boot and the current was arcing to the head before firing the plug. You may have more than one with this issue. I think the cause of the issue is moisture getting into the spark plug valley. With or without the rainguard installed on the hood it gets in there. I'm going to have to get/build something to cover it up. (the only one I found is carbon fiber and I'm not dropping 200 bucks on it) Right now I just cover the car when I'm not using it and don't drive in the rain. Garage is occupied with another project at the moment otherwise it be inside.

I pulled my harness apart and made sure everything was good before I realized it was just coils. I don't think you need to do that. In my case it was worth it as the harness was not done by anyone with real skill and did have a few things to fix/make better. =P
 

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Discussion Starter #10
The injectors are very simple and if the spark plugs are black it due to too much fuel and not enough burning. Rough running will do that. Seems more like a spark issue than a fuel issue.
The injectors earth through the ECU, not directly to those points. So both earths need to be cleaned to be sure.

The FPR is not a sensor, it doesn't sense anything, it's just a valve controlled by the ECU.

Maybe you have a stuck injector? To test them apply 12v to one side and earth to the other. You should hear them tick open and closed.
I checked the resistance in all of the injectors and got 14.1 in all of them, then I put 12v to each injector and they opened and closed just like they should. Checked the ecu pin out and each Injector has the right colored wire to the ecu. The code p1200 I'm getting states "ecu detects an incorrect voltage level on one or more injector driver circuits for more than 5 seconds." So I'm guessing I've got a bad connection in one of those power wires. Any other things it could be?
 

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Discussion Starter #11
Kinda sounds similar to my recent issue. check coils and plugs. I had a bad boot and the current was arcing to the head before firing the plug. You may have more than one with this issue. I think the cause of the issue is moisture getting into the spark plug valley. With or without the rainguard installed on the hood it gets in there. I'm going to have to get/build something to cover it up. (the only one I found is carbon fiber and I'm not dropping 200 bucks on it) Right now I just cover the car when I'm not using it and don't drive in the rain. Garage is occupied with another project at the moment otherwise it be inside.

I pulled my harness apart and made sure everything was good before I realized it was just coils. I don't think you need to do that. In my case it was worth it as the harness was not done by anyone with real skill and did have a few things to fix/make better. =P
That sounds like a very real possibility and I will look into it, but if it's a bad coil shouldn't I be getting a code for a bad coil or at least a misfire in cylinder "whatever"?
 

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That sounds like a very real possibility and I will look into it, but if it's a bad coil shouldn't I be getting a code for a bad coil or at least a misfire in cylinder "whatever"?
It took a while having intermittent performance issues before I saw the code for misfiring.
I'm with GDII on the 1200 code. It's not in any of the caldina literature I have and cannot be certain what it means.
if it is as you describe then you should have a 1201, 1202, etc. where the last digit of the code is for the cylinder where the error is occurring.
 

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It took a while having intermittent performance issues before I saw the code for misfiring.
I'm with GDII on the 1200 code. It's not in any of the caldina literature I have and cannot be certain what it means.
if it is as you describe then you should have a 1201, 1202, etc. where the last digit of the code is for the cylinder where the error is occurring.
I'm using the torque app with a bluetooth obd2 I'm not sure if that's making a difference. But here is the screenshot of the faul codes all the others besides p1200 are for the transmission
70108



The car has never ran correctly I've only ever driven it down the street
 

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I'd try the old OBD1 code flasher method instead of the OBDII. The MR2 code method still works with a Prime harness which is useful as trying to get the bluetooth dongles to work on these ECUs can be impossible for some people. I'm just curious to see what codes it drops.
 

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I'd try the old OBD1 code flasher method instead of the OBDII. The MR2 code method still works with a Prime harness which is useful as trying to get the bluetooth dongles to work on these ECUs can be impossible for some people. I'm just curious to see what codes it drops.
I'll give it a shot later tonight when I'm home
 

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I'd try the old OBD1 code flasher method instead of the OBDII. The MR2 code method still works with a Prime harness which is useful as trying to get the bluetooth dongles to work on these ECUs can be impossible for some people. I'm just curious to see what codes it drops.
So I could not check the obd1 port because I decided to replace my injector o rings and seals while I was in there, however I was reading another thread and saw something about an iat sensor. I realized that this controls the fueling for the car and decided to test the resistance. I got no resistance at all 0. So just want to make sure I'm measuring this correctly, you put the 2 leads of the multimeter onto the 2 prongs from the sensor and switch the multimeter over to resistance. Am I missing something here??
 

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at about 70 degrees the sensor should read 2000-3000 ohms resistance according to toyota.
with the key turned but the car not running there should be 1-3volts on the red and blue wire coming from the sensor to the ecu.
i've ran mine with and without the IAT and seen little difference. the temp sensor that matters most to the ecu is the THAM sensor in the intake manifold.

in my car this sensor is the same as the engine bay sensor, if yours is the same you can swap for test purposes.
 

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at about 70 degrees the sensor should read 2000-3000 ohms resistance according to toyota.
with the key turned but the car not running there should be 1-3volts on the red and blue wire coming from the sensor to the ecu.
i've ran mine with and without the IAT and seen little difference. the temp sensor that matters most to the ecu is the THAM sensor in the intake manifold.

in my car this sensor is the same as the engine bay sensor, if yours is the same you can swap for test purposes.
Are you sure it's the same? The GEN4 uses a different type for the engine bay sensor on the engine lid and the intake manifold. The only ones that match the engine lid is the one in the airbox of which most swaps seem to not use.
 

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Bit confusing after I looked at what I said but what I meant was the AIT sensor is the same as the engine bay sensor(again at least on my car/swap). The intake manifold sensor is different and it is the one that the ecu cares about. so yeah... what you said. :p

Didn't know that most people ignored the AIT. I have tried running with and without (not entirely on purpose) and have found that there is little (if any) difference anyways. I have it hooked up because its there and I don't think its hurting me any.
 
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