Moderator EDIT: Merging a bunch of posts and threads

 

Moderator EDIT: Merging a bunch of posts and threads

 

Moderator EDIT: Merging a bunch of posts and threads

 

hey I would love a reply. So I just swapped a 350z motor into my g35 coupe. It was an auto motor going into a manual car. Did the pilot bearing and everything. Swapped power steering pump and alternator bc different connections to harness. Used harness from original g35 motor and g35 ecu. But car is in limp mode. Essentially with a 350z throttle body the car will start but either have zero throttle response or it will act as if its limp mode won’t go above 3k rpm and climbs very slowly. I drove it once before the throttle body ended up stopping giving me response and the car started to get a little bit more responsive the more I drove it but it was on and off. Some points I’d have 5% throttle respond some times I would have 50%. Just throwing numbers off the top my head I didn’t have a throng to actually tell me. I have codes saying my app sensor is going bad and saying it’s sending a different voltage than the throttle body. With a g35 throttle body car will start then die right away as if the motor isn’t getting fuel but it like the throttle body just isn’t opening. Please let me know if I have to flash the ecu or what I’m at a stand still with this car too much money into it. Also don’t have the downstream o2 sensors(ones that go to cats) even installed or plugged in. Because with the swap we couldn’t get my old cats off the old headers so we used test pipes on new motor and the o2 sensors were seized in the cats so I just threw the car together without the 02 sensors. I’ve heard that could be causing this whole problem too. Just need a second opinion before throwing even more money into this car. Replaced throttle body and pedal with parts form junkyard from same year g35 as mine and still nothing please someone help.

 

Exactly which code is it throwing.

 

p2122 and p2138 both are for app sensor but I know 100% my gas pedal was fine before the swap and I went to the junkyard and got a new pedal and still nothing. Got a new throttle body from the junkyard too. The only thing that is different after the swap is I installed test pipes and I don’t have O2 sensors in them because the sensors were stuck in my cats and I couldn’t get them replaced in time. That’s my next purchase is o2 sensors

 

Did you have the ECM harness off of the ECM? If so then disconnect the battery, take the harness off and see if you bent a pin. I would double check the throttle body harness also, it's pretty easy to bend a pin over on both those harnesses if you don't insert them carefully.

Also, did you install the primary engine to chassis bonding jumper? It's the big ground wire that connects the right/passenger side of the timing chain cover to the chassis directly below the coolant reservoir.

 

not 100% sure if I even disconnected either the ecm harness or the ground wire down there. I took the engine out with the whole harness connected just pulled the ecu harness connection through the whole on the passenger side. I’ll have to check when it’s not raining. Got rain off the forecast for the next few days smh. This **** is taunting me

 

throttle body pins look fine

 

You definitely had the primary engine to chassis bonding jumper removed. Look directly under the coolant reservoir, there should be a heavy gauge wire landed on a 2-hole lug on the chassis. The other end of that wire gets connected to the timing chain cover, if you don't have that hooked up there is no electrical ground path for the engine controls and it will DEFINITELY malfunction.

The ECM connection is that harness you pulled through the firewall under the glove box, disconnect the battery, take that harness apart F102 and make sure none of the pins are bent. It's basically a breakout harness that connects to the F108 ECM harness.

You reused the same engine harness right? They aren't all the same from year to year and even though they will all plug into that breakout harness F102 they might have sensors on different pins. The 2003-2004.5 harnesses are different than the 2004.5-2007 harnesses. And the rev-up harnesses are different from both of those.

 

If you didn't keep the existing engine control F102 harness then take the existing one and compare it to the one you installed under the glove box. Just verify that it has wires in all the same pins and that they're all the same COLOR wires on each pin.

 

yes I reused the harness from my old engine and I swapped out the power steering pump and alternator and also a sensor under the alternator and cam shaft sensors with the ones from my original engine that had rod knock. I genuinely have zero recollection of that ground wire you are talking about under the coolant reservoir so I’ll look at that after. I do have a question though. Are the downstream 02 sensors that go into the cats are those wires apart of this same harness that goes into the ecm? Because in the fsm it says that if there’s an open circuit between the ecm and the gas pedal sensor it will send off the codes I’m getting.

 

Those downstream O2 sensors are all part of the same harness yes. The harness tapes together around the alternator area and also has the upstream O2 sensors on it.

The APP gas pedal splices into the ECM harness between F102 and F108. If you didn't take apart F108 which connects directly to the ECM then you haven't changed any of that wiring. The APP connects to a smaller 10 pin harness F1 which is right next to F102. I don't know why it would have been unplugged because you can access F102 without moving it but you should check it anyways.

There's 3 harnesses of that size right next to one another E10, E11, and E12. It's possible they were unplugged to make more room to feed everything out of the grommet on the firewall.

 

I will have to check all these connections but I do know that I didn’t touch the app sensor or the harness to the app sensor u til after the swap was done idk where we unplugged the harness from on that side but we never were in the driver seat moving any wiring under the dash only under the glove box. Maybe if the wires do down under the trans tunnel and have a connection point down there that’s where we would’ve disconnected it. It’s been over a month since me and my buddy did this swap so and I honestly don’t have the best memory. But if the down stream o2 sensors are part of that harness and circuit than the fact that the downstream o2 sensors aren’t installed they could very much possibly be tricking the ecu into throwing this code. Because I also heard that 2003-2004.5 g35s don’t have a cel light for down stream o2 sensors and since I’m not getting a light for my o2 sensors maybe the computer is just fighting to act normally but that won’t let it. Also the fsm said if there is an open circuit between e10 and f1 it will throw the code. Is the down stream o2 sensor in between those two connections? I feel like it would be judged by the fact that if there is a connection between those two the 02 are in a perfect spot to be that connection in between. I’m gonna go over a lot of things tomorrow when it’s finally not raining. O2 sensors coming on Tuesday so I’ll try that out too.

 

E10 is under the glove box, not near the O2 sensor harness.