Ok so I've been fighting with this issue for several weeks now. only codes I'm throwing on my car is P0113 (IAT circuit Voltage high) and P0630(mismatch Vin). I'm trying to figure out how to get rid of P0113, I've swapped the maf out for a used one that I was told was good before I bought it. Tested the voltage at the plug which is 2.0-2.5v depending of which maf I have plugged in. I pulled up the Maf scaling table in the ecu and it matches the stock evo ix table. But when I monitor the IAT with my obdII reader it says its at -40*c and Evo scan is reading -76* and its about 80* in my garage so that's obviously not right. The engine is mostly stock with an aem intake and dryflow filter. Maf is clean and I've done a boost leak test and eliminated most of the boost leaks. And the car seems to run just fine according to the wideband and doesn't try to stall itself out except for when taking off in first it stumbles a little. There was a harness for a gm IAT sensor but no sensor and I have since removed the harness and like I said the IAT scaling maps are the same between stock and mine so I don't think its that. Any help would be much appreciated, thank you.

 

Bump

 

while it is probably extremely rare and far less complex then this I have seen a similar problem and I cracked open the maf circuit board and seen a lot of burnt contacts .....I wouldn't recommend opening it if your unsure but the fact that you got it elsewhere makes it always a suspition

 

Yeah I would condemn it as a bad maf but both mafs r throwing that code but car runs well like they're working we'll jus thinks its a dif temp than it is. But I'll crack one open n c how it looks if I mess it up I've at least got a 2nd one

 

Well I cracked open one of the mafs, doesn't appear as if anything is wrong. No obvious burnt spots jus a spots of amber colored goop but I'm thinking that's from the manufacturing process. N I took a log of the car for a ten minute drive home from work I'm guessing its something in the wiring cuz the maf reading for temp and wut not didn't change one but but the map readings did. Guess I've got a fun little project for the weekend, I hate chasing wiring issues haha

 

Ok I am completely stumped, I've got the same voltage at the connector as I do at the correct pin on the ecu, I have continuity on the ground at the connector with less than half an ohm of resistance. The resistance climbs and decreases with heat and the circuit isn't seeing over 5v but is still throwing the code for IAT circuit high voltage which is described as the ecu seeing over 5v for more than 3 sec. And the code pops up immediately after I clear it with the key only in the on position. With it like that the circuit only has 1.9-2v. Any other ideas on what to check, considering attempting to reground the ground wire but I don't want to do it if it won't affect anything because I'm scared I may royally screw something up.

 

Ok I've narrowed the problem down to the wiring/ecu. So I'm just gonna run my own wires and I need someone to tell me how the ground is run I kno ultimately goes to the ecu but according to the wiring diagram it looks like it shares ground with the cam pos sensor on the way to the ecu. Any input would b appreciated

 

I think I may have figured out the problem. I was double checking my work before I ran my own wires, and low and behold sure enuff I made a mistake. I was testing the wrong wire to the ecu. Still unsure y it was carrying the same current and ohm testing with the iat wire. But I went to check the correct pin on the ecu and what do you kno there's no wire and no pin. So I'm going to try to find some ecu pins locally and if not order some from spoolinup. But I'm going to re run the wire from the correct pin to the iat and see if that fixes the problem.

 

Ok for anyone who looks through this thread for an answer, I fixed the problem. Turns out the previous owner had an early version of speed density on the vehicle so the IAT signal wire was run to the Fuel Temp port on the ecu. Picked up sum ecu pins from Spoolinup and tapped into that wire and plugged it back into the IAT signal wire port on the ecu so that it runs both signals so I don't throw another code for the fuel temp circuit malfunctioning, so far no problems. I will update if I run into any problems from this set up but if I don't update it worked.

 

Hey. I have the same issue, can you tell me which wire from the IAT sensor was tapped into which pin from the ecu?

 

On mine it was the Blue/red (blue with red stripe) wire that was pin 6 (left to right as plugged in) on my MAF. This ran into the ecu and was placed in pin 96's slot (fuel Temp Sensor). It is supposed to be in pin 62's slot. You can find a pin out of the ecu on google just search "evo 9 ecu pinout". An easy way to verify that the plug is misplaced is to disconnect the battery, once that's done disconnect the plugs on the ecu. Then you tape 2 wires, one to each end of a "AA" battery (any battery can be used but wouldn't suggest using one over 5v might fry something important). Disconnect the maf connector and plug the positive wire into the blue/red wire's slot and ground the negative to the frame. Then you just probe all the pins with a multimeter and the one that shows 1.6v is your winner.