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Discussion Starter · #1 ·
I just replaced the engine in a 2002 Accord with a Vtech 4cyl. It runs fine at idle. When it's cold it fluctuates RPMS when you hold it steady around 2000 rpms. It will fluctuate between 1000 and 2000.

It threw code P0505 first so I took off the IACV and replaced it. Same thing. When engine gets warm it will hardly run at all without playing the the accelerator. then it will throw a P1399, P0505 and P0325.

I know the knock sensor is the P0325. I broke it putting the engine in. My understanding is that will not make it run bad and it will just throw the code.

I thought the P0505 would go away after changing the IACV but it came back. Could there be a vacuum leak somewhere? If so any idea what vacuums it pulls from?

What about the P1399? There are no individual cylinder misfires and the CEL does not flash. Plugs and wires have been changed.

HELP! Thanks
 

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Discussion Starter · #3 ·
I did not use a new gasket. It has the rubber o-ring type gasket and it seemed to be fine. there is only one vacuum line attached to it and it has no cracks. I did spray starting fluid around all the hoses and the intake plenum and no change in idle was detected.

The wiring connector is connected correctly and the plug is tight. I can unplug the connector and the vehicle will barely run. So there is a noticeable difference in when it is connected and when it is not.

I may just change the darn thing and see.
 

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Discussion Starter · #5 ·
That is correct. It idles fine but only starts the fluctuating when you raise the rpms. Then it throws the P0505 code. The P1399 went away and has not came back as of yet.

The original motor in the car was an A4(ulev). I have replaced it with an A1. The new motor did not have a throttle body on it so I am using the one from the A4. I have tried both IACV from both motors and get the same result. The intake and plenum are the ones that came on the A1.
 

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Discussion Starter · #7 ·
It has the A4 O2 Sensors. Should I use the A1? I used the A4 sensor because I used the A4 exhaust manifold on it instead of the one from the A1.

I have not taken it for a test drive yet. Sort of scared it won't make it back!
 

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Discussion Starter · #9 ·
The A4 O2 sensor is the one I am using. I have tried the ECM reset by disconnecting the battery cable from a few minutes to overnight to no avail.

Things got weirder today. While it was running and the RPM's were fluctuating my father unplugged the MAP sensor. The fluctuating stopped. It wouldn't idle well and when the engine was revved up then backed off suddenly it would die. Plugged the MAP sensor back in and it acted like it didn't exist. Bought a new one and the same thing happened.

I decided maybe it needed a good drive to see if the ECM would re-learn itself. It ran ok out of the drive until i got into the road and it would not hardly run and it took two hours for me to get it back to the house from a half mile away. That's how bad it ran. The only code it shows is a P1106. Something about fuel/air mixture. The 1399 and 0505 have not returned. But it runs worse that it ever has. I am so frustrated.
 

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Discussion Starter · #10 ·
After changing pretty much every sensor on this motor and lots of cussing and head scratching I found the problem.

The connectors between the TPS and MAP were switched. I didn't know there were two connectors on this thing that would interchange. Now I do! Runs like a champ now.
 
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