Code 51

mk3_chris

mk3_chris

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Ok I finished putting the car back together after my 7mgte swap and its not starting. I've set the cps to tdc, I'm getting gas(know because I had some leaking out of the fuel line b/c of a missing washer), I just replaced the spark plugs(and checked the gap). The tsrm says 51 is

Diagnosis
No "IDL" signal, "NSW" signal or "A/C" signal to ECU, during diagnosis check.
Trouble Area
A/C switch circuit
A/C switch
A/C amplifier
Throttle position sensor circuit
Throttle position sensor
ECU

I don't have my ac hooked up yet though so I'm not sure if I'm getting the code because of the ac or the tps.

It got to dark on me to finish but tomorrow I'm going to make sure the spark plug wires are correct(which I'm pretty sure they are) and going to make sure the plugs are sparking. How would I be able to test the tps without another to put in?
 
mk3_chris

mk3_chris

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the ac was off to begin with, my condenser was some how smashed on both bottom corners so it leaked out all the freon. So I haven't used it since I got the car
 
mk3_chris

mk3_chris

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Ah ok will do. Do you have any other ideas why the car won't stay running at idle(even while I give it gas)?
 
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Victor Charlie

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Aug 18, 2009
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mk3_chris;1443113 said:
the ac was off to begin with, my condenser was some how smashed on both bottom corners so it leaked out all the freon. So I haven't used it since I got the car
Click to expand...

If you have a regular spark, the CPS is probably working. Test it with a spare plug, and EFI fuse pulled out in case gas is sitting in the cylinder from starting attempts, which may explode if you have the plug out and test spark.

You can test gap and impedance off the CPS with a DVM. If you just have to see it work, you can see a voltage generated as you spin the shaft, if you rig something to do that. If you have a steady spark when you crank, but no ignition at all, it's probably not the CPS.

Some people, including me, had trouble starting the car because the timing was too far off. I think the cylinder flooded when this happened so even setting it correctly didn't get it to start right away, but I don't really know. I waited until the next day, cranked with the EFI fuse pulled, then put it back and it started and it has started every time since then. By then I had the timing figured out, and I had tried to seat all the wiring connectors, so i don't know if pulling the EFI fuse made any difference or even make sense. The best way to install the CPS is with the cover unscrewed so you can see that the spindle is pointing roughly up and just slightly to the right of the coil when the engine is at TDC. Seeing is believing.

The TPS can be tested at the ECU per the EFI section of the TSRM. If that checks out, it's probably not keeping it from starting.

IF you jumper the fuel pump at the diagnostic block you can hear it come on and you can feel the gas flow easily by pinching the fuel return line. This is probably sufficient to prove you have fuel, but if you are stumped and want to be thorough, you can test the injectors one by one for rate of flow per TSRM instructions.

i have a weird AC problem that I haven't finished investigating, but it looks like I get voltage at the AC input to the ECU if and only if the AC switch is OFF, which is backwards. This throws a code 51, but it's so weird I don't trust my own results until i check it all over again. Apparently a code 51 my also throw the timing off, though I confess I don't know why or how.

If none of this works, I'm stumped.
 
mk3_chris

mk3_chris

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Victor Charlie - I actually found/read some of your thread. I can actually hear the fuel pump(walbro 255) which btw has gotten really stupidly loud compared to how it was with the n/a engine my only guess to why is because the injectors are larger. I set my cps again today because it was slightly off but I swear its seriously dead on perfect now.

Failure14 - I was actually going to ask about your egr block off earlier, I just finished that with my car and was wondering how bad it effected your cold start?

Thank you both for the input :bowdown:

I'll update tomorrow
 
mk3_chris

mk3_chris

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Ok upon futher investigation of the tps i found 2 wires going no where. Do you happen to know where these two go?
 

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mk3_chris

mk3_chris

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Maybe a better pic will help. I've checked all of my plugs around that area and none of them are missing wires.
 

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Victor Charlie

Supramania Contributor
Aug 18, 2009
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mk3_chris;1443671 said:
Maybe a better pic will help. I've checked all of my plugs around that area and none of them are missing wires.
Click to expand...

This is the wiring diagram for the TPS.

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=48

It doesn't look like those wires are related. Could you clarify the wire color and stripe color for each, and where they are coming from?

It looks like possibly wiring to the Fuel Pressure Up Vacuum Switching Valve.
 
Failure14

Failure14

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mk3_chris;1443400 said:
Victor Charlie - I actually found/read some of your thread. I can actually hear the fuel pump(walbro 255) which btw has gotten really stupidly loud compared to how it was with the n/a engine my only guess to why is because the injectors are larger. I set my cps again today because it was slightly off but I swear its seriously dead on perfect now.

Failure14 - I was actually going to ask about your egr block off earlier, I just finished that with my car and was wondering how bad it effected your cold start?

Thank you both for the input :bowdown:

I'll update tomorrow
Click to expand...


Im not sure if my egr block off is the reason its so hard to start
but maybe it is, i cant really give you a 100% answer.

Only reason im blocking it off is because i didnt have the full
egr so im only blocking it off untill i get the full thing.

Because i know it taking 3-4 cranks untill it starts is definetly
not good on my starter.
 
mk3_chris

mk3_chris

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sorry for leavin you guy hanging i couldn't find my volt meter. I'm going to check the tps here shortly.
 
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Victor Charlie

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Aug 18, 2009
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Just out of curiosity, what relays or switches did you add or swap when you did you engine swap, and which are still from the original body? Any parts attached to the engine that were taken from the NA engine? Thanks.
 
mk3_chris

mk3_chris

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The only relay that was changed was the fuel pressure resistor(that I know of). I didn't change that it was changed by the supra shop that spliced my harnesses together.
 
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Victor Charlie

Supramania Contributor
Aug 18, 2009
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mk3_chris;1447724 said:
The only relay that was changed was the fuel pressure resistor(that I know of). I didn't change that it was changed by the supra shop that spliced my harnesses together.
Click to expand...

Thanks, I want to double check the TEWD to see if there are any other electrical parts that might be affected by an engine swap, since I also have a na-T swap.
 
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