Mjcsupra;1651032 said:
Hey, im at a loss with whats going on here and i have a couple of questions that i hoped to get answered. io have a 7mgte, metal head gasket, arp bolts. i had thought that i had a vacume leak from my egr valve on the head. i have since removed the entire egr and replaced all my intake manifold gaskets. i now have an issue where the car runs rough (sounds like a subaru if you know what they sound like). and i have 2 codes one is a 24(IAT) and the other is a 52 (knock sensor) i dont have any idea if there is a problem that will cause both. i checked the wireing on both knock sensors and they look good. let me know if you have any ideas. thanks
For future reference, check the TSRM for what the error codes mean, it will make finding the actual problem a breeze:
http://www.cygnusx1.net/Supra/TechTips/engine_error_codes.aspx
We will start with the code 24.
TSRM said:
24 Intake air Temp Sensor Signal
Diagnosis
* Open or short circuit in intake air temp sensor signal (THA).
Trouble Area
* Intake air temp sensor circuit
* Intake air temp sensor
* ECU
The intake air temperature sensor is in the AFM. Check the connection at the AFM, test it per the TSRM:
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=96
Make sure it tests within spec. If so, trace your wiring and make sure it's in good shape. I can almost guarantee it's not the ECU causing the problem. 7M ECUs rarely fail.
Then there's your code 52:
TSRM said:
52 Knock Sensor Signal
Diagnosis
* Open or short circuit in knock sensor signal.
Trouble Area
* Knock sensor circuit
* Knock sensor
* ECU
Most of the time the problem with this is old wiring, however first check to make sure that both knock sensors are plugged in. They're located below the intake manifold, on under runners 2-3, and one back near the starter. They could be green or gray, with green or gray circular connectors. If they're plugged in, verify that the wiring is intact and conducting properly. Grab your DVOM and set it to continuity check. Place one lead on the center pin of the connector, and the other on a good ground. If you get a tone for either wire, do the knock sensor rewire:
http://www.supramania.com/forums/content.php?135-Knock-Sensor-Rewire-Write-up-(code-52)
Most code 52s are caused by bum wiring. It's not a bad idea to rewire regardless of the condition, but certainly not needed if your wires in good shape.
If your wiring checks out, you have a bad knock sensor. You can test them with an oscilloscope. I recommend checking/replacing the front knock sensor first, as it's easy to get to. The rear one is sortof blocked by the starter (depending on year of car) and thus more difficult to get to. No matter what you do, if you replace the sensor(s), test them beforehand to verify that they operate properly.
