Hondata

Happy New Year all!

I've been racking my brain with this issue for far too long. Any direction or suggestions would be greatly appreciated.

Vehicle
04 2000
K24A swapped
K-pro V4
Rywire Harness
S2000 Modified Intake Manifold
Type S oil pump/50 Degree Cam
Modified OE header
AC
OE Cat
HKS Single

Problems:
Throttle percentages read perfect 0-100% when engine is off
Throttle percentage max out to maybe 9% or 13% when engine is operating. I can rev thorough all the RPMS.
AFR numbers spike to lean when off throttle.
Idle surges to 2k on its own when warm in driveway


The car has been swapped since late July with no issues. On a trip out of town while passing a vehicle on the interstate the car started to stumble and AFR started to go up and down. Pulled over found nothing, swapped the map sensor and checked connection plugs. The car went to limp mode so I limped it back home slowly late at night on the interstate. Pulled a few logs in my neighborhood and found the TPS % was pretty low only maxing 7%

**I'm assuming the low throttle percentage readings is causing for the AFR spike when off throttle- So most of my focus has been there.**

-I found the TPS connector had a slightly skinned wire I had to squint to see it. Put heat shrink on the tiny spot and no improvement.
-Changed the TPS (Calibrated the voltage .50-4.75 and on k-pro). *limp mode gone, but TPS reads perfect 0-100% when engine is off. When the
engine is on TPS percentage reads from 9-13% max. I can get to 3k rpm and it only reads 1-2%. (read from k-pro on laptop and app)
-Swapped MAP between the original OE and another used OE sensor - No change
-Checked grounds (harness to valve cover, engine to chassis, engine to sub) and all read good numbers
-Verified the throttle body physically opens and closes fully and reduced a tiny amount of slack in throttle cable(minimal amount of slack still
present.)- No change

Any suggestions or direction would be greatly appreciated!

I took the car out to get a data log to accompany the post. Some things have changed but Its still spiking AFR as soon as I let off the throttle. I live near a interstate on and off ramp so that allowed me to get on the throttle a bit. High RPM spots are on/off ramps followed by stopping at the light then getting back on the ramp.

What is the serial number that is on the K-Pro board inside the ECU?

The serial Number is 63587. I assume its the one on the sticker correct?

Have you tried your ECU on a known working vehicle?

Sorry, got busy with work this week. I do not have anyone local to test with. Will check around for someone.

Problem Resolved- In the odd chance someone has the perfect storm I experienced, I will update the post to help out.

Found that the header had a tiny weld crack. Got lucky watching a YT video of a turbo Miata troubleshoot issues and got the idea. As I let off the accelerator, it would suck in air throwing off the wideband. - I put my shop vacuum in reverse and pumped air in my exhaust then sprayed soapy water on the header...Bubble city.

Once the header was swapped out, the car was still acting throwing AFR all over the place and I checked my wideband wiring....surprise surprise the k motor vibration and poorly placed wired had some exposed wire. Fixed that and it got a little better. AFR still acting wonky and the honda idle surge was happening.

I took my focus off the throttle percentage reading and shifted to the manifold pressure. I noticed manifold pressure seemed to be all over the place...needless to say I did a ghetto smoke test (swisher sweets hooked up to a fluid pump) and I found a air leak in my intake manifold. I couldn't get it to seal so took it off. When inspecting the intake manifold, a large piece of the second intake runner literally cracked off. Had to be a victim of the vibration. I replaced the Intake manifold and made a brace for it. Big improvement there . The AFR would not bounce rich to lean as before but still was off a bit.

I sourced another MAP sensor for a Integra vs s2000 like I have in the past even though they are interchangeable (Rock Auto Denso for $50.) That made a huge difference and AFR was pretty good and somewhat drivable. Idle surge was still surging.

I took apart and thoroughly cleaned the s2000 IACV and put it together. I found out you can adjust/calibrate them and set the idle to 900. Money! We were in business. There was a little bit of hesitation (very slight) at startup so I changed the fuel pressure damper and regulator (thanks rock auto) and it made one of the biggest change. Start up was smooth and idle was so nice. Acceleration also got better.

I'm of the mind that all of the k24 vibration had a big effect on all of these items over a couple months of driving. In the interest of not repeating this same BS, I've been vibration proofing as much as I can in the engine bay and making sure wires are safe and dont rub. Hopefully this helps out someone.

-Walter