Hybrid/Tech B16 / B18 / ZC / D16 / H22 / Mini-Me Ask your Honda Engine Questions here.

Major idle problem with 1989 JDM B20A swap

Old 01-30-2010, 08:53 PM
0.0 BAR
Thread Starter
Join Date: Jul 2007
Posts: 17
Default Major idle problem with 1989 JDM B20A swap

Hey I don't talk on here much, but I read must of the threads. Anyway I am having a major idle problem with my car that I can not seem to fix. I'll give you a break down of whats happening and what I have done to the car, and what I have already done to try and fix the problem.

Break down:

So, I have a 1989 Honda Prelude SI 4WS, I have swapped into it a JDM B20A. It has:
- JDM B20A motor
- USDM Transmission
- USDM Intake Manifold (ITM)
- USDM Exhaust manifold (EM) [with all o2 sensors, which connect to the (EM)]
- USDM Speedometer cable since I am running the USDM transmission


I have started the car successfully and it drives fine, however when it comes to idling in the driveway or at a red light it is horrible!!!

- Sometimes, not all the time, when started the idle will jump strait to about 3000 RPM or 4000 RPM and just hold, until the motor is shut off.
- Other times, majority of the times, the car's idle will bog. Generally it will go from 1200 RPM to 3000 or 4000 RPM over and over, until the car will shut down.
-The next thing is the ECU flashing code 9, which is the NO. 1 Cylinder Position Sensor. It used to flash Code 14 which is the Electronic Air / Idle control. But I believed I fixed that when Intake Air Control Valve (IACV)

What I have done to try and resolve my problem:

- Changed the Idle Air Control Valve - I cleaned it with sea foam on a Q-tip, and changed it twice, (But I'm pretty sure that's what fixed the Code 14, but did not fix my Idle problem.
- I fixed the Fast Idle Thermo Valve (FITV) by pushing moving the wax screw all the way down so it wouldn't give the car a fast idle.
- Changed the throttle body sensor, the TPS (Throttle position sensor)
- Swapped the distributor 3 times, I have tried: 1 used USDM, 1 used JDM, and 1 new USDM
- Changed the PCV Valve
- After all of that the car's idle is still the same.

Please HELP!


**** SIDE NOTE*****
- What is the piece that connects to the exhaust cam right next to the distributor, specifically closer to the front bumper. It is smaller then the disributor, and can fit in your hand. It is held in by 2 or 3 bolts, , it plugs in similar to how the distibutor would.
StreetTuner is offline  
Old 01-31-2010, 12:50 AM
0.0 BAR
Join Date: Jan 2010
Location: Cottage Grove, WI
Posts: 2

it could probably be the ecu or O2? cause it did idle like that when I used a different ecu on my civic
tswjfwm is offline  
Old 02-02-2010, 12:19 PM
0.0 BAR
Thread Starter
Join Date: Jul 2007
Posts: 17

I am fairly confident the ECU is fine. Since it has been giving me proper error codes and has stopped giving me certain error codes once, the problem has been fixed and the ECU has been reset.

I believe the O2's are fine, but I will check them regardless.
StreetTuner is offline  
Old 02-10-2010, 08:44 PM
0.0 BAR
Join Date: Feb 2010
Posts: 16

Try checking your ground wires, I know it sounds funny but a bad ground can do extremely weird things check your main engine and ecu grounds and clean the battery terminals. also check for any vacum leaks, spray carb cleaner or starting fluid around your intake and if the idle changes when you spray then you have found a leak.
jacman747 is offline  
Old 02-11-2010, 06:14 PM
0.0 BAR
Join Date: May 2007
Posts: 30

did you try posting this on H-T...
duomaxwell814 is offline  
Old 02-14-2010, 01:12 PM
0.0 BAR
Thread Starter
Join Date: Jul 2007
Posts: 17

Yes, and sadly, I have received no comments what so ever, and it has been up there for 2 weeks or so. Not one comment

I have also tried here and preludezone.
StreetTuner is offline  
Related Topics
Thread Starter
Last Post
04-15-2011 02:47 AM
Turbo Parts For Sale
07-04-2008 12:54 PM
Forced Induction
10-29-2004 08:50 PM
Turbo Parts For Sale
01-26-2004 02:47 AM
06-10-2003 05:20 PM

Thread Tools
Search this Thread
Quick Reply: Major idle problem with 1989 JDM B20A swap

Contact Us - Sitemap - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.