Hello,
I just had an engine swap on my 96 accord due to a timing belt broke on my old engine with 170K on it resulting in bent valves, I put a 2002 V-Tech 2.3L Engine with only 19K miles on it. Car runs fine at high RPMS, but when stopped it hesitates to take off, like it misfires and when left at a constat idle around 2000 RPMS it misfires and makes the check engine light come on giving an ODB code of P1381. CYP sensor has been replaced inside the distributor, coil, cables seem good, spark plugs look good, even ran the car with the alt. disconnected as I was told the alternator can send weak electricity to the coil causing misfire and non of this have solved the problem....Im frustrated now!!
Can anyone help please!!!

 

Most of what I'm seeing on the internet is either distributor or defective / damaged wiring as a possible cause.
Considering this is a swap of a newer engine into an older chassis, I would suspect the later. Try rechecking your connections.

P

 

Thank you P. I will look around for loose or damaged cables.....see if that does the trick.

 

If you dont mind spending a few bucks, you can prove out the real problem during your misfire scenario. An oscilloscope will be needed to see what the CYP sensor is doing or whatever the actual name of it is but I say that is your problem once you have verified good connections as instructed. Do a wiggle test of the wire harness in several locations during your misfire, if it does not clear up then your connections and wires are probably ok.

 

Hey P. I just finished checking all cables around the engine and did not find any damaged cables or plugs. I noticed something weird though, I cleared the ODB code and idled the car just above 2000 RPM's, when the car misfires, and the check engine light comes on, it will not misfire again, if I turn the car off and turn it back on and idle it back to 2000 RPM it will misfire again for a few seconds and then it will not do it again.....I test drove the car after it misfired and it ran fine, it doesnt stall or anything.......

Duane thanks for your reply, but right now I really dont have the few bucks to spend on an oscilloscope, but thanks for your input

 

After searching for damaged cabling, replacing the coil, spark plug wires, changing and Testing all distributor sensors, my friend pulled the distributor out for the last time and spun the distributor shaft to make sure it was freely turning.....there was the problem, the distributor shaft will turn a few times then it will hit on something or it feels like its hitting something...iand I guess when it does that the CYP sensor is sending a misfire signal to the ECU. P_adams you were right...the distributor was bad. I just put a brand new TEC distributor and the problem is gone....Thank you all for your help; hope this can help other people solve the P1381 issue. I guess all my frustration trying to figure out the cause of this misfire issue, will save others a few headaches.

TampaBoy