CODE 71...help anyone?

[noremacsupra]

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I blew my HG and I just got a used stock 7mgte engine, however i had to use my egr system because of the sensor on the egr...so i installed my old egr to the engine that i have now...now i have a code 71? help anyone?

 

[MK3Brent]

All your vacuum lines hooked up?
That's weird... I've never gotten that code.

No EGR on my car either.

 

[suprarx7nut]

I have a code 71 also. It came on shortly after my BHG fix.

I need to triple check my vacuum routing.

 

[jdub]

Code 71 is only on CA cars...if the sensor is not hooked up (or if there's a circuit problem), it will throw a code on those cars. The other reason is EGT gas temps are below a certain level...the real reason the code 71 is programmed on a CA car

 

[suprarx7nut]

How does the ECU know to expect a certain temp? My code 71 comes on normally after highway driving for at least 10 miles, sometimes more than 50. What triggers the temp sensor to look for a certain temp?

 

[jdub]

It's the ECU...the sensor simply provides input to the CA ECU (labeled THG). The code can also indicate a problem with the EGR VSV or it's circuit....again, only on CA cars.

I tried to find the temp threshold that triggers the ECU, but no luck.

 

[MK3Brent]

Code 71 is only on CA cars...if the sensor is not hooked up (or if there's a circuit problem), it will throw a code on those cars. The other reason is EGT gas temps are below a certain level...the real reason the code 71 is programmed on a CA car

Ahh... knowledge...


The more you know..**STAARRR**

 

[noremacsupra]

cool...so meaning if i have a faulty vsv that could trigger the ecu to throw a code 71?

 

[noremacsupra]

same thing exactly happened to me..a friend of mine told me to clean it due to all the carbon build up..but i dont know..i havent done it yet..

I have a code 71 also. It came on shortly after my BHG fix.

I need to triple check my vacuum routing.

 

[jdub]

cool...so meaning if i have a faulty vsv that could trigger the ecu to throw a code 71?

That's one of the potential problem areas listed in the TSRM

 

[noremacsupra]

I traced and tracked all the lines...all of them are connected...i used the diagram on the manual...

 

[noremacsupra]

alright thanks..i have a question...there are two vsv's that i see..how would i know which goes were?the 2 wires that connect to the vsv's are the same and fits both vsv?

That's one of the potential problem areas listed in the TSRM

 

[jdub]

The two VSV's are the same...the forward one on the manifold is the high temp fuel pressure up VSV. It is vented to the atmosphere when 12 volt power is applied (from the ECU) to it:
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?S=FI&P=116

The EGR VSV is mounted on the rear of the manifold. It operates and can be tested the same way:
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?S=EC&P=18

My '89 wiring diagram shows a red/black stripe wire going to the fuel pressure up VSV and a red/blue stripe wire going to the EGR VSV.

 

[isnms]

Maybe your EGR temp sensor is not fully connected.
Maybe you have a leak in the EGR Cooler gasket or EGR mounting flange.