Help with IAC Valve and ECU

Lead Pill

New Member
My buddy helped me change out my wiring harness today cause the one that was in it has splices everywhere and looked really bad. Anyway Vtec wasn't kicking in so he swapped my ECU from a P2E to a P2P. Vtec still not kicking in said something bout a Knock sensor or nox senser idk what that is or means, but that it was busted on mine or just wasn't there. Next after we put in the P2P ECU and the IAC is connected it bogs at 1500 RPM. When i disconnect the IAC it drops to around 1K but when i rev slowly it stops at 1500 and bogs until i give it enough gas then it revs normally again.. Anyone know what might be going on with this?

Oh here's a pic of the sensor/valve i'm talking about. It's kinda hard to see but there's not much lighting back there.



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Lead Pill

New Member
Oh sorry it's a 2K Civic D16Y8, Intake, Header only. I remember there was code 65,14 and 41, then later a 23 i think came up, but that was after we switched to the P2P ECU.
 

RonJ

Banned
What codes return after you reset the ECU? Is dash fuse 15 blown?
 


Lead Pill

New Member
RonJ said:
What codes return after you reset the ECU? Is dash fuse 15 blown?
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Umm... that's a good question. I didn't clear out the ECU codes and check again is there a way to clear them without a code reader? I'll have to check fuse 15 we didn't check any fuses.
 

RonJ

Banned
Reset the ECU by removing the 7.5A hood Back Up fuse for 3 or more minutes.

Fuse 15 has a 7.5A rating.
 

Lead Pill

New Member
Cool thanks.. I'll have to check that out in the morning.

Oh one more question, the ECU that i had in my car says P2E-A 2000 Si-R P28-A. Is it possible for a P2E to be a P28? I mean on the side of the unit it says P2E and with a little research i'm assuming it's just a DX ECU but just thought i would ask.
 

Lead Pill

New Member
Right on, that's what i figured just cause that's what i found when i googled it.. Lol. Thanks for checking it out though.
 

Lead Pill

New Member
Alright so went through and checked out all the fuses and actually a lot of them were either wrong Amperage or didn't even need to by plugged in i think i pulled like 7 or 8 extra out. Anyway none of the fuses were blown and after resetting both ECU's i got CEL Code 14 from the P2E and CEL Codes 41 and 65 for the P2P. Also found out that that i don't have a Fan Relay so i need to pick one up for bout $42. I checked that Fuse 15 and i think i remember it said something about the Alternator and something else so if that's the right fuse it was fine. Anyway i'm gonna check those codes out but there was one other thing. The RPM's rock between 1K and 1500 sometimes. It's not always, so i unplug the IAC and it settles down but then when i rev it stops and bounces when i hit 1500 RPM until i give it more gas then it revs up real quick, any thoughts about what might be causing that?
 

RonJ

Banned
You obviously want to use the P2P ECU. Using this ECU, you only have two codes, both for the two O2 sensor heater element (primary and secondary). With the key in ON(II) and the O2 sensors unplugged, check whether the Blk/Yel wire (primary) and Blk/Wht wire (secondary) in the connectors has battery voltage to body ground.

Is there an idle problem using the P2P ECU?
 

Lead Pill

New Member
RonJ said:
Is there an idle problem using the P2P ECU?
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Yes. but it seems like it's only after i rev past that point. When i start the car it's fine but then say after driving i it bounces between 1-1,500 RPM's. I unplug the IAC it then drops to around 1K but when i rev to 1500 it has trouble passing that point. If i give it enough gas it'll go past but not till then.

I'll have to check out the sensors tomorrow. Hopefully i can get to it early in the day.
 

Lead Pill

New Member
Checked the o2 sensor today and i have 2 in the front that aren't connected and have nothing to connect them to on the harness. The sensor on the front of the headers has just the plug hanging and i can't find a plug anywhere around it. Then the sensor at the end of the headers was cut and the wires coming off of it were twisted with another male ended plug that doesn't fit the plug that's near by cause it is also male. I'm starting to regret buying this thing.
 

RonJ

Banned
Is your Civic actually a DX (non-EX) trim? Those are likely plugs for a D16Y7 engine, which was probably the original engine. The stock D16Y8 O2 sensors are located more downstream in the exhaust system, so you'd have to extend the wires to them.
 

Lead Pill

New Member
Yea, the actual trim of the car is a DX a D16Y8 was swapped into it. I have i believe 5 plugs total that are not connected right now. There's the 2 from the o2 sensors then there a big blue one and a big gray one. Then one that comes off of the harness that hangs out around the manifold.
 

Lead Pill

New Member
I'm thinking the A/c was either removed or just wasn't installed when the swap was done as far as the transmission i have no idea. When i bought the car the wire harness that was in it was cut and spliced in just random spots. I just recently replaced the wire harness to an EX now i have extra plugs.
 
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