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Discussion Starter · #1 ·
I have been sifting the forum, trying to see if other Honda IACVs will fit onto the PK3 head / intake manifolds. I have read that some folks got IACVs that had the wrong bolts hole locations. While searching eBay, it seemed like a lot of the 1992-96 Prelude IACVs had the same mounting pattern as the ones on the Si motors, with slight differences on the actuator plug location and the coolant inlet / outlet geometry.

May anyone here confirm? I think my IACV is going out; when cold and the engine under load, the acceleration shakes around, and then I'll hear a "pop" sound coming from the IACV along with a CEL, and smooth acceleration. I shut off the car and restart it, and the engine continues normal operation. Only happens after cold start.

thanks in advance.
 

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Have you checked to see what the trouble code is? Code #14 is for the IACV. Seems to me that I was able to use the IACV from a 90-93 Accord on a 91 Prelude SI. The 2.0SI uses the same valve as the 88-89 Accord LXi, though.
 

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Discussion Starter · #3 ·
Procedure-wise, would I be able to check for the CEL while the engine is running? I believe the process is jumping a connector on the passenger area, and then looking for the long and short blinks on the CEL light, on the dash, correct? Would the blinking work while my engine's running?, since the CEL turns off each time shut off the car.
 

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Discussion Starter · #4 ·
I should also point out that the car's speed seems to cap at around 20-25mph, and I'm searching around the interweb and seeing that it could be the mass airflow sensor. Interesting...
 

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Discussion Starter · #6 ·
Yes, I've been seeing a lot of those on the Bay. I guess these weren't previously available, as many people on the forums were saying the mounting holes were not lining up.

I'm starting to wondering if my MAP sensor might be the culprit instead, but $37 for a new IACV can't be beat. Good looking out.
 

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Yeah buddy, mine went and the parts store here said 6 months and 300$ for a new one. So I cracked off a shot in the dark and this one worked for me.
Have about 30,000kms on it and it seems fine. responds normally to control through Hondata too.
 

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Also, I dont know much about all the problems with your car, but if your speed is limited by poor operating conditions and you think its, IACV / MAF related also do a good inspection of your
O2 sensor/s. Ive had them shit the bed before and nearly make the car undriveable.
 

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Procedure-wise, would I be able to check for the CEL while the engine is running? I believe the process is jumping a connector on the passenger area, and then looking for the long and short blinks on the CEL light, on the dash, correct? Would the blinking work while my engine's running?, since the CEL turns off each time shut off the car.
Unless the backup power fuse for the radio/ECU is burned out or missing, the code will be stored in the control unit, regardless of whether the light is on.
 

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Discussion Starter · #10 ·
Update to this thread:

Finally got around to figuring out that cold start low idle. Adjusting the Fast Idle Valve (that wax piece) allows the cold idle to eventually reach ~1500 RPM, but upon startup, the engine seems to bog at 1000 for 10-20 seconds. Also, as mentioned, I'd get that no-power symptom around 20-25mph, like the engine was choking. Suddenly I'd hear a "pop" near the IACV, and along with the CEL illuminating, the engine would resume normal function.

I decided to buy a replacement IACV for a 4th gen Prelude. Everything fits, but the fuel injector wiring harness plastic covers will have to be removed in order for the IACV valve to plug in.

The engine fires up with immediate 1500 RPM cold idle, sweet. No more bogging / choking, and engine sounds much stronger / smoother. HOWEVER, I will still get a CEL during a warm engine startup. No symptoms or anything either. Wasn't sure if CELs get stored in OBDI cars.
 

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Discussion Starter · #12 ·
The code is stored, but is the CEL supposed to come back on immediately upon startup? I know with OBD2 cars the CEL will stay lit whenever the car is on. For my car, the CEL will not come up after subsequent startup. It's like the OBD1 system "resets" once your shut off the engine; therefore I was never able to do the "count the CEL blinks" because when I turned off the engine, and then turned it back on to "ACC," the CEL was essentially off.

Again, the car runs fine, good cold idle, no bogging, no surge. Glad Massachusetts don't care about CELs on cars older than 15 years old!
 

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The code is stored, but is the CEL supposed to come back on immediately upon startup? I know with OBD2 cars the CEL will stay lit whenever the car is on. For my car, the CEL will not come up after subsequent startup. It's like the OBD1 system "resets" once your shut off the engine; therefore I was never able to do the "count the CEL blinks" because when I turned off the engine, and then turned it back on to "ACC," the CEL was essentially off.

Again, the car runs fine, good cold idle, no bogging, no surge. Glad Massachusetts don't care about CELs on cars older than 15 years old!
That behavior completely depends upon the code that is stored, on all versions of the software, OBD0, OBD1, and OBD2. You need to look on the ECU to see what the code is if it is an '88-89, while the '90-91 should have the jumper connector in the passenger footwell.
 

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Discussion Starter · #14 ·
So I've tried looking for that jumper connector in the passenger footwell. I took off some panels by the door opening, and didn't see any said connector. Would you have a picture of what this connector would look like?
 
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