Ive been posting about this problem for a couple of months now here and there about my issue with the car's IACV. Here's some basic info on what the car is and the swap. It's an 89' si w/ an obdo b16a swap. Here's the good stuff.

The IACV on it right now shows good continuity and a resistance within spect at 13.5 ohms.

There is no continuity between each of the individual prongs inside the valve plug and the body of the car (good).

Now, the wiring harness side of the plug has a good confirmed ground but there is no voltage coming through the plug on the insulated side..I even ran a wire straight from terminal A11 on the ecu, still nothing.

I pulled my main relay and all the saulder points are in good condition, there was a bit of corrosion on them but I cleaned them off pretty well.

Could this be a main relay issue? I have a manual lying around and it says check for an open between the yellow/black wire coming from the main relay to fuse #14. Forgive me, but I dont know where to start with that.

Thanks guys....this is really bugging me.

One last thing, this is the only code i'm throwing other than a knock sensor code. Here's the weird thing, whenever i'm in nuetral and I put the pedal to the floor the revs will bounce between 1 and 2 thousand..could this be related to the codes?


help???

 

hahha..I know this one's kinda rough...anyone?

 

You said will bounce 1 to 2 thousands at neutral. Do you have the correct vacuum diagram. Any codes like 3 or 5. These are the MAP sensor. Either unplugged or wrong line running to it.

 

nope, everything's correct. The only codes are 14 and 23 I believe...and the knock code comes on a few minutes after the engine is running, but i'm definitely not getting the 12 volts to the IACV like I should. Any other advice? If I cant figure this im most likely going to throw this motor into another car that has a solid harness.

 

um...anyone?

 

Code 14 is IACV: check system and the unit. Code 23 I believe is Knock Sensor: check the sensor and circuit and if it is connected to the proper pin on ecu.

 

Ive been posting about this problem for a couple of months now here and there about my issue with the car's IACV. Here's some basic info on what the car is and the swap. It's an 89' si w/ an obdo b16a swap. Here's the good stuff.

The IACV on it right now shows good continuity and a resistance within spect at 13.5 ohms.

There is no continuity between each of the individual prongs inside the valve plug and the body of the car (good).

Now, the wiring harness side of the plug has a good confirmed ground but there is no voltage coming through the plug on the insulated side..I even ran a wire straight from terminal A11 on the ecu, still nothing.

I pulled my main relay and all the saulder points are in good condition, there was a bit of corrosion on them but I cleaned them off pretty well.

Could this be a main relay issue? I have a manual lying around and it says check for an open between the yellow/black wire coming from the main relay to fuse #14. Forgive me, but I dont know where to start with that.


Already checked that circuit, as for the knock sensor..it's just a bad sensor in the block that I havent pulled yet.

 

Not sure on exact ecu pin,but if it is indeed A11 and you dont have voltage,then try a different ECU. I believe,but will check later today,that its a direct line from ECU to IACV. Blk/yellow 12v constant. If you dont have that voltage the source of the failure is the ECU. Replace,retest,report back.

 

yeah, if you could check that then it would be great. Like I said a while back, ive already run my own wire from the ecu to the valve. It's of the same guage and the connections are pretty solid...I just dont get it. Good luck for me on the ecu thing...I'll see if I can find one.

 

you don't have the two sensors swapped do you? I know the plugs are similar, but don't remember well enough if they are the same. Anyway, also check the pins inside the plugs and and make sure the wire is seated correctly. I had code 14 for the longest time, and swapped a couple of IAC valves to no avail. finally I checked the plug, and one of the wires had gotten pulled out slightly, just enough to not make connection when plugged into the socket. pushed it back in, heard it snap back into place, and then it worked perfectly.

 

thanks for all the suggestions! But...nothing. Ive already checked the status of the plug and nothing, the plug is good...like I said, I measured circuit voltage coming straight from the ecu and nothing..

 

I forgot to check the ETM at work today and no ETM available on ISIS due to the age. Run a continuity test. Back probe A11 to blk/yellow wire on the IAC valve. You should have continuity. Make sure there isnt a break. Second,untill I check the ETM tomorrow ,throw the old SI ecu in and check voltage. If it has continuity then there should be voltage. If there is voltage w/ the SI ECU then you have found the problem

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike-y &raquo;</TD></TR><TR><TD CLASS="quote">I had code 14 for the longest time, and swapped a couple of IAC valves to no avail. finally I checked the plug, and one of the wires had gotten pulled out slightly, just enough to not make connection when plugged into the socket. pushed it back in, heard it snap back into place, and then it worked perfectly. </TD></TR></TABLE>

I had a similar problem this spring. the plug was in bad condition and caused intermittent IAC problems.. replaced the plug and problem solved.

 

Also, I have an online b16a service manual and in the step where there's no voltage in A11 to the valve it tells me to "Repair open in BLK/YEL - YEL/BLK wire between the EACV and main relay.

Suggestions?

 

That would be the point when you check continuity between ECU and IAC valve. If you dont have voltage at the ECU it really doesnt matter. Replace w/ stock ECU and retest.

 

Tomorrow i'm gonna try and substitute in a new ecu to check for power, also, I think I stumbled onto somethin tonight, this "fuse 14" that I was supposed to check for a break in the wiring between it and the valve does have a relation to the IACV. The thing is, the under dash cover for the fuse box has been removed on my car and I dont know where the fuse 14 is, some helping photos or diagrams would be nice because I just cant find any. Here's the thread, it is an EWD of the fuse 14 circuit. See what I mean? Can anyone help me locate the black/Yel wire between fuse 14 and the IACV? https://honda-tech.com/zerothread?id=2095208

 

There it is. The diagram helps. Dont worry about swapping ECU's. Its a direct 12v power from fuse box to the EACV. I dont know what I was thinking. Your signal wire would be from the ECU which is actuallyC451 pin 5(17 pin connector on ECU). The BLK/Yellow is going to run from the fuse box directly to the jumper in the engine compartment


This took me about an hour to dig up and host so I hope it helps


12V from fuse 14 directly to EACV through a jumper in the engine compartment





Plug C211 #1 pin(dont know exact location,couldnt find it



Plug C407...directly off the fuse box pin 18


Good luck


Modified by IMALLSLO at 6:50 PM 9/26/2007

 

Wow man, thanks alot. I managed to steal my multimeter and test light from my tech class today at school, i'mma get right on it.

 

ok...so far ive got source voltage at the fuse 14 which is good, having some trouble getting used to reading these ewd's though..cant seem to find the right blk/yel wire coming off the right jumper connector..there's like...20 of them behind the fuse panel.


one last thing...if i'm running the power wire from the fuse to the iac valve..what do I need to do with the A11 pin on the ecu?

 

The IAC has two pins. One blk/yellow and one blu/yellow. You can run a direct 12v to blk/yellow from any blk/yellow. All it needs is key 12v key on voltage. A11 needs a direct line to the blu/blk wire on the IAC. Dont need anything for A17
Heres a pinout location

OBD 0 Pinout '88 HF/Si '90-1 DX (Std.) '90-1 HF/Si '89-92 EF8/9 SiR
A1 No.1 INJ Aux INJ w/A3 No.1 INJ No.1 INJ
A2 GRD w/A4 to Main Relay GRD w/A4 to Main Relay GRD w/A4 to Main Relay GRD w/A4 to Main Relay
A3 No.2 INJ Aux INJ w/A1 No.2 INJ No.2 INJ
A4 GRD w/A2 to Main Relay GRD w/A2 to Main Relay GRD w/A2 to Main Relay GRD w/A2 to Main Relay
A5 No.3 INJ Main INJ w/A7 No.3 INJ No.3 INJ
A6 Purge Cut-Off Solenoid Valve Purge Cut-Off Solenoid Valve Purge Cut-Off Solenoid Valve (HF Only) Purge Cut-Off Solenoid Valve
A7 No.4 INJ Main INJ w/A5 No.4 INJ No.4 INJ
A8 Lock-up Control Solenoid Valve Lock-up Control Solenoid Valve Lock-up Control Solenoid Valve Spool (VTEC) Solenoid Valve
A9 - - - -
A10 - EGR Valve (CA A/T Only) EGR Valve (HF Only) Pressure Regulator Cut-Off Solenoid Valve
A11 EACV w/A17 EACV w/A17 EACV w/A17 EACV
A12 Main Relay w/A14 Main Relay w/A14 Main Relay w/A14 Main Relay w/A14
A13 Main Relay w/A15 Main Relay w/A15 Main Relay w/A15 Main Relay w/A15
A14 Main Relay w/A12 Main Relay w/A12 Main Relay w/A12 Main Relay w/A12
A15 Main Relay w/A13 Main Relay w/A13 Main Relay w/A13 Main Relay w/A13
A16 GRD w/A18 GRD w/A18 GRD w/A18 GRD w/A18
A17 EACV w/A11 - - -
A18 GRD w/A16 GRD w/A16 GRD w/A16 GRD w/A16
B1 Hazard Fuse w/Brake Switch Hazard Fuse w/Brake Switch - Hazard Fuse w/Brake Switch
B2 Tandem Valve Control Solenoid Valve Tandem Valve Control Solenoid Valve - -
B3 A/C Clutch Relay A/C Clutch Relay Fast Idle Valve A/C Clutch Relay
B4 Radiator Fan Relay Radiator Fan Relay Radiator Fan Relay -
B5 Alternator Alternator Alternator Oil Pressure Switch
B6 Check Engine Light Check Engine Light Check Engine Light Check Engine Light(10A)
B7 Shift Position Sensor (A/T Only) Shift Position Sensor (A/T Only) A/C Switch w/B8 -
B8 A/C Switch A/C Switch A/C Switch w/B7 A/C Switch
B9 - - - Brake Switch
B10 - - Crank Angle Sensor Crank Angle Sensor
B11 Shift Position Sensor (AT Only) Shift Position Sensor (AT Only) Clutch Switch (HF Only) Rear Defogger Switch
B12 - - Crank Angle Sensor Crank Angle Sensor
B13 No.2 Fuse (10A) No.2 Fuse (10A) No.2 Fuse (10A) No.2 Fuse (10A)
B14 Alternator Alternator Alternator Alternator
B15 Igniter Unit w/B17 Igniter Unit w/B17 Igniter Unit w/B17 Igniter Unit w/B17
B16 Speed Sensor Speed Sensor Speed Sensor Speed Sensor (Electrical)
B17 Igniter Unit w/B15 Igniter Unit w/B15 Igniter Unit w/B15 Igniter Unit w/B15
B18 - - - -
B19 ELD ELD ELD Knock Sensor
B20 Ign. Timing Adj. Connector Ign. Timing Adj. Connector Ign. Timing Adj. Connector Ign. Timing Adj. Connector
C1 Crank Angle Sensor Crank Angle Sensor Cylinder Position Sensor Cylinder Position Sensor
C2 Crank Angle Sensor Crank Angle Sensor Cylinder Position Sensor Cylinder Position Sensor
C3 TDC Sensor TDC Sensor TDC Sensor TDC Sensor
C4 TDC Sensor TDC Sensor TDC Sensor TDC Sensor
C5 TA Sensor TA Sensor TA Sensor TA Sensor
C6 TW Sensor TW Sensor TW Sensor TW Sensor
C7 Throttle Angle Sensor Throttle Angle Sensor Throttle Angle Sensor Throttle Angle Sensor
C8 - EGR Valve Lift Sensor (CA A/T Only) - O2 Sensor B
C9 PA Sensor PA Sensor PA Sensor P/S oil switch
C10 Brake Switch Brake Switch Brake and Reverse Light Switch (HF Only) Brake Switch
C11 MAP Sensor MAP Sensor MAP Sensor MAP Sensor
C12 PA Sensor PA Sensor Throttle Angle Sensor Throttle Angle Sensor
C13 PA Sensor PA Sensor Throttle Angle Sensor Throttle Angle Sensor
C14 MAP Sensor MAP Sensor MAP Sensor MAP Sensor
C15 MAP Sensor MAP Sensor MAP Sensor MAP Sensor
C16 O2 Sensor A O2 Sensor A O2 Sensor A O2 Sensor A



Good luck from here

 

Hell yeah, everything is fixed now. Pin 18 was pulled slightly out of the underdash fuse box. My idle issues are fixed and I can now go full throttle. The only thing now to fix is my knock sensor. Are there any ways to replace it w/o pulling the intake manifold?

 

Glad you found it!
A long extension from behind the intake manifold. May be a little difficult but its easier then pulling the mani.

 

Hey, I really appreciate the help, this problem's been bugging me for about 6 months now..I just never had the knowledge to diagnose it until I started taking my Auto Electrical. I'm taking full time classes to be a Technician like you..only 2 more years of classes to go...

 

Sweet. Study up. We are no longer mechanics but electricians. If you know your electrical you'll go far in this business. Any monkey can do a service,a real tech can diagnose an electrical problem with his eyes closed. Think about it,most Hondas are running 5+ computers these days. The last thing you need to worry about is a mechanical issue.

 

To be honest with you, continuity is not really a good test. All you're seeing is if there is a complete path. You don't know how good of a complete path there is. It could be one measly wire hanging on, or there could be a ton of unwanted resistance somewhere.

Available voltage or voltage drop would be a much better test.