'04 Civic w/ swapped in K20a2, stalling issue on stop

Bainz

New Member
Good Evening Ladies and Gents,

My old man and I swapped a K20a2 into my old '04 Civic about a year back. It was running great for a while but was getting very little drive time, but now it's getting a lot of attention and is a problem child. Over the past week, the engine has started to stall once the engine is warm and I press the clutch in.

To be more specific. When I start the car, it idles anywhere from 400 RPMs to 1800 RPMs depending on the day, and possibly if I revved the engine before shutting it off the night before (I really have no idea if this affects the car's idle). It will drive fine until I slow the car down with the transmission engaged, say a red light is coming up. I can feel the engine adjust the idle, almost like it's shifting which is weird in a manual. From this point forward, I can be going 80, or 15, if I press the clutch in while the RPMs are over 1500 the RPMs drop to 0 and it stalls (unless I push the accelerator). If I am extremely careful, I can coast while pushing the clutch in and walk the engine down with the accelerator. In this case it will idle, while borderline stalling. I say borderline stalling, because when I press the gas to bring the RPMs back up to start driving, the engine shakes like it's stalling but then cleans up and runs fine until I have to stop again.

While this is a fun game, and keeps me SUPER engaged while driving, I would prefer to stop losing my power steering and I worry about my car. Local Honda dealership was useless, I already tried having them help out.

A few details that may or may not have anything to do with this issue are listed below with pictures.

Throttle Cable: My throttle cable has a ton of play in it, pic 1. It is also the stock cable that came with the '04 civic. I'm not sure if the long cable is an issue but I have no idea TBH, pic 2. The cable is adjusted as tight as possible. Does it matter that the cable is coming into the Throttle Body at a steep angle? Pic Below.

There is enough slack that I can stretch it to the metal at my fingertip before anything moves.


The cable starts under the clip on the firewall to the right, Wraps around to the left of the engine and then back around into the throttle body at the bottom of the pic. It's long.

Throttle Body: Today I noticed a sheered off piece where the mounting bracket for the throttle cable connects. It doesn't look like it is impacting the vacuum. Once again, I really have no idea if this would compound the issue. Pic below.

That piece is no longer attached in any way shape or form to the throttle body.

Random Sensor: I have no idea what the hell this sensor goes to, or where it was to start. I think it may have been for the exhaust on the old civic engine. The Honda dealership told me to cut a hole in my air intake pipe and mount it there to keep it out of the way and secure. Pic Below.

It's currently suspended with zip ties until I figure out what it is.


The sensor cable starts here. It seems to branch off from a cable going to the throttle body.


Honda's tech said to drill a hole in my air intake and mount the sensor where the light spot is (middle of the light). Pretty sure they are full of crap.

Sorry for all the questions and the lack of knowledge, I probably called something by the wrong name. Thanks in advance for the help! Also, if anyone knows a good performance shop in Charlotte, NC. I'd be all ears.
 

Bainz

New Member
I have not done the ECM idle procedure since the swap, that will be tomorrow's project. I did have a performance shop in FL do it after the swap was completed. Should I do it again?

I have to take it back in tomorrow to Honda tomorrow to check for codes. They didn't give me any and the tech had already left for the day. -.-

How would I clean the IACV? and I ran into a forum that recommended to bleed the coolant system for potential air pockets. Is that also a good thing to do?
 


XpL0d3r

I had a Civic once.
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:welcome: to ClubCivic!

That hanging sensor does in fact go inside the intake -- it's the Intake Air Temp sensor (IAT). The tech is right, you may have to get a bung and weld it in. Whatever intake you have on there now must not have a spot for it. Honestly it may be a better idea to get a different intake. A

I don't think the throttle cable has anything to do with your issues. If the cable had too much slack, the throttle plate would stay closed until the pedal travels further, and you may not actually open the plate all the way when it's floored, but shouldn't cause the car to shut down when idling.

The car runs fine when cold, but has issues when at operating temp? This suggests that it may be a sensor related issue, as the car will only use sensor feedback once the car is at operating temp.

I would start by cleaning the IACV and make sure that the TPS is within spec. Other things to look at may be the "Intake Air Bypass Thermal Control Valve" as well as the Primary 02 sensor.

IABCTV (wtf!) testing:



@Bainz, I just uploaded the RSX service manual for you:
Link to manual.
 

Bainz

New Member
Thanks for the manual and the help so far. Here's a diagnostics update after I installed the sensor.

Engine temp is fine, never above half on the gauge.

No vacuum leaks, plenty of coolant in the reserve and rad.

Had a local shop try and override the computer to electronically adjust up the throttle when the engine is warm. Wouldnt budge. Looka like it may be the IACV seizing. Explains the cold engine being fine, FITV is letting in extra air at start, then it gets warm and the IACV is closed. Provided my car has a FITV... to the manual!

Taking off the TB/IACV this weeked to clean everything with carb cleaner and a toothbrush. Have to wait for spare gaskets, just in case. I'll update once I reassemble.

Thanks again for the help so far!
 


XpL0d3r

I had a Civic once.
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The K20 doesn't have a FITV.

You may be correct about the IACV though. That valve should close when the car is at operating temp.

You should be fine to reuse the IACV gasket -- it's rubber.

The TB gasket you should be able to get at your local parts store. I picked up a good quality one a few weeks ago for $7.
 
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Bainz

New Member
Sorry for the delay, I work 6 days a week. :/ Update time!

Cleaned the IACV and reassembled. No joy. :(

No vacuum leaks.

Replaced the TB with a Hybrid Racing 70mm TB. ($450 vs $900 OEM...)

TPS is an Acuity Hall Effect, 1878-A.

We are reassembled and back running. However, I still have to run the ECU back through the learn mode. Currently the engine runs, But if I open the throttle it climbs as expected and then cuts back down to idle.

Potentially air stuck in the coolant system?

Cannot maintain 3k rpms to put the ecu into learn mode. :(

Engine dives back down at or above 2k then will bouce between idle and where the gas is held. Idles at about 500 - 600 rpms still., thought 800 is norm. If I apply the gas and hold, it will climb there and drop back to idle then climb back up to where im holding. I think this is called hunting? Maybe there is air in the coolant system after all.

If I spike the engine to 4k and then let it drop to idle it doesnt stall anymore!!! But I'm not holding my breath until the boucing issue is solved.

:D

Thanks again for your help!
 
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Bainz

New Member
Stupid Question. When you hold the gas at 3k rpms when the ecu is learning. Does it run the rpms all over the dam place?

I held it at 3k and it bounced between 3k and idle for a few, then spiked to 6k and held for 10-15s. Dropped back to 3k bouncing, spiked to 6k and back to 3k bouncing. I noticed the temp was at half and fans were on so its idling now. Shut it off after 5 min if idleing.

Still bouncing abouve 2k rpms.

What the hell is my engine doing? Lol
 


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