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TPS reading ~20% and no VTEC sounds normal to me, you haven't met the MAP requirement yet. Also, your WOT graph shows TPS only at 80%?
 

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Discussion Starter · #22 ·
don‘t know for the Ktuner, but on KPro or Doctronic ECUs for the older K20a2, you need a minimum speed for VTEC to engage. VTP also needs to be active for the switch to be triggered. No VSS speed signal, no VTEC. This is until you disable the use of the VSS sensor.
On my K20a2 build, VTP is active from as litte as 3000 rpm. You can log it and it being shown on a graph.
Interesting about the VTP needing to be active. On every run, the moment VTS engages, VTP drops off (disables) and when VTS disengages, VTP reactivates (enables). You are saying they both need to be simultaneously active? If so, that's not the case at all from the datalogs. The plot thickens for sure. VSS looks good, though. The datalogs show that it is registering speed signals. What should the minimum speed be set to for VTEC engagement? My understanding is that having the Engage and Disengage Speed set to 0 meant that it doesn't require it to engage VTEC. So, I have it at 0, as you can see from my first post on the 4th image.

Regarding VTP, that's active even at idle (look at my RPM relative to VTP being enabled at idle):

Rectangle Slope Line Parallel Font


Should the VTP be active only at 3k RPM's or higher and stay on when VTEC is engaged?
 

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Discussion Starter · #23 ·
TPS reading ~20% and no VTEC sounds normal to me, you haven't met the MAP requirement yet. Also, your WOT graph shows TPS only at 80%?
This is true even when TPS is maxed at 80%, though. If you look at the other datalogs I've pasted, VTEC doesn't engage at all regardless if it's WOT or partial throttle. I thought WOT was maxed out at 80% anyway?
 

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at least for drive by cable throttle cars, TPS % needs to go to 100%.
for the K20a2, VTP needs to be on (triggered by sufficient oil pressure) for the cam switch to happen. If VTP drops the moment VTEC engages, it will disengage again instantly as indicated by the VTS status. VTP is positive at higher rpm at all times as this just indicates sufficient oil pressure for the VTEC mechanism to work.
In KPro you can disable the VTP switch and it will ignore the VTP signal and engage VTEC at any oil pressure.
 

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Discussion Starter · #25 · (Edited)
at least for drive by cable throttle cars, TPS % needs to go to 100%.
for the K20a2, VTP needs to be on (triggered by sufficient oil pressure) for the cam switch to happen. If VTP drops the moment VTEC engages, it will disengage again instantly as indicated by the VTS status. VTP is positive at higher rpm at all times as this just indicates sufficient oil pressure for the VTEC mechanism to work.
In KPro you can disable the VTP switch and it will ignore the VTP signal and engage VTEC at any oil pressure.
Thanks for the input. If what you are saying is true, I am not sure how to move forward here. VTP is active even at idle but switches to off the moment VTS is engaged. From your info and pairing that up from what I see in my datalogs, this indicates that the moment VTS engages, I lose appropriate pressure, which is why VTP disengages and I hear no VTEC when VTS engages. I'm also on cable throttle. I'm wondering if there is some calibration that needs to be done for that. My TPS itself is at the right calibration voltage on the throttle body itself. I used a multimeter for this and got it dialed in. Not sure if KTuner requires some additional calibration.

Any suggestions on what I can try next?
 

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Discussion Starter · #26 · (Edited)
For what it's worth, I'm also not getting any CEL at all not just for VTEC but for anything. Everything checks out fine. I would expect to throw a CEL at some point if this were an issue. I've checked the Error Codes on KTuner as well as my OBD2 device and both are cleared of any issues. The only CEL I got was when I disconnected the downpipe from the exhaust manifold, which in turn complained about not seeing the O2 sensors.
 

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Discussion Starter · #27 ·
Can I just bypass the pressure switch at this point to see if I can pin-point this? If this is possible, how can I do this? I just recently learned from a previous post on this thread that the JDM engine, which is what I have, doesn't use the pressure switch at all. I'd like to see if this is something I can bypass somehow. If without needing the pressure switch I can get it to engage, I can just get an oil pressure gauge at that point to ensure I always have proper oil pressure at all times
 

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Tuner also says he's not seeing evidence of VTEC engagement
From what you have shown in the logs it looks like air is missing, which could be an indication of a not engaging VTEC pin and not proper priming VTEC spooling valve.

What makes me confuse is why TPS is limited to 80 % opening. Did you calibrate it like this: WOT = 80 % TB opening?

you need a minimum speed for VTEC to engage
Here it is set to 0 mph. From what I've seen in the #1 post all requirements are met for an engaging VTEC: temperature limit, engine speed limit and MAP limit. But I assume this are not all to be checked for this manner: VSS, VTS, VTP, oil pressure, and so on.

@Teedohs What I am wondering about is why does the VTEC engaging line has no lower pressure limit after the upper engine speed limit is met. Once you are on WOT and go through the gears, every shift you need to lift the pedal and disengage VTEC for a short time (using a normal shift procedure), just causing wear on the pins an the mechanism. Is this setup done intentionally?

Please add always MAP, TPS, engine speed, INJ and Lambda in first prior, these are the vital parameters. In a second order duty cycle of injectors, VSS, VTS and IGN as well as CAM and CAMCMD (commanded and actual VTC). Without MAP you know less about the engine, as you can't see if breathing capacity follows the TB.
 

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Discussion Starter · #30 · (Edited)
From what you have shown in the logs it looks like air is missing, which could be an indication of a not engaging VTEC pin and not proper priming VTEC spooling valve.

What makes me confuse is why TPS is limited to 80 % opening. Did you calibrate it like this: WOT = 80 % TB opening?

Here it is set to 0 mph. From what I've seen in the #1 post all requirements are met for an engaging VTEC: temperature limit, engine speed limit and MAP limit. But I assume this are not all to be checked for this manner: VSS, VTS, VTP, oil pressure, and so on.

@Teedohs What I am wondering about is why does the VTEC engaging line has no lower pressure limit after the upper engine speed limit is met. Once you are on WOT and go through the gears, every shift you need to lift the pedal and disengage VTEC for a short time (using a normal shift procedure), just causing wear on the pins an the mechanism. Is this setup done intentionally?

Please add always MAP, TPS, engine speed, INJ and Lambda in first prior, these are the vital parameters. In a second order duty cycle of injectors, VSS, VTS and IGN as well as CAM and CAMCMD (commanded and actual VTC). Without MAP you know less about the engine, as you can't see if breathing capacity follows the TB.
Here are the readings after testing:
  • TPS Closed = 0.45v - 0.48v
  • TPS WOT = 4.43v
  • VTEC Pressure Switch = 12v on ACC 2
  • VTEC Pressure Switch = good continuity at switch
  • VTEC Solenoid = good continuity
  • VTEC Solenoid = 3.2v on ACC 2
I have not done any calibration of the TPS on the KTuner and WOT reads at 80% max and 0% closed.

What I am wondering about is why does the VTEC engaging line has no lower pressure limit after the upper engine speed limit is met.
Where do you see this or where can I set this? I'm not sure where this is set and what a good starting limit is


Once you are on WOT and go through the gears, every shift you need to lift the pedal and disengage VTEC for a short time (using a normal shift procedure), just causing wear on the pins an the mechanism. Is this setup done intentionally?
Whatever the current setting is, that was done by the tuner. Unfortunately, I'm completely blind to a lot of the tables because my tuner has them locked and I can't read most of the tables only some feature settings.

I'll see what else I can add from what I'm able to access.
 

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That last log shows a distinctive step in AFR half way through each wot pull. The ktuner is certainly fueling for the high lobe map.
 

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Discussion Starter · #32 · (Edited)
Did another run with some logs. This looks better but I still can't hear VTEC at all. I'm going to have to run the open headers again to test but I see more fuel being request this time and both VTS and VTP lights are on simultaneously when VTEC engages at 4800 RPMs. When VTEC is not engaged, only VTP is on, which is what I expect.

The one thing I did was bypass the VTEC pressure switch completely and now I consistently get both VTS and VTP to stay on at 4800 RPMs and above (4800 RPMs is my VTEC engagement point). I'm still not sure about the 80% throttle but I'm checking in the KTuner forums for that.

Rectangle Slope Font Parallel Pattern


Here is another look:

Rectangle Slope Line Font Parallel
 

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Discussion Starter · #33 ·
FYI - 80% WOT is the accurate reading from factory. Confirmed by both my tuner and KTuner themselves.
 

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Discussion Starter · #34 ·
Hooked up a gauge today for oil pressure. I'm getting around 30~ PSI at idle and ramps up while driving. At around 4800 RPMs, I have 80~+ PSI so not an oil pressure issue.

At this point, I'm going to have to pressure test the VTEC assembly, which is a bit more involved and I need to pick up some additional tools for that. This will take me a couple of day's.
 

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On the ktuner it's normal behavior for the VTP light to go off when the VTS/vtec gets activated. I also think that your
vtec is engaging. You running the stock intake,cams ect ?

Tune WOT finish set the higher cam angle to 0 degrees and see if the AFR's has changed also check your cam angles that its then using.You could also try and set vtec lower at 4000 to see if theres a change in the AFR graph before the initial 4800 engagement.

With vtec set so high on stock cams which iam assuming it is you might not be able to hear it engage. With the stock oem cams i usually engage vtec at about 3600 to 4000 rpm depending on the setup.

Water Rectangle Slope Line Font

Water Rectangle Slope Font Parallel


I also think it's kinda impossible to get the fueling right on the car using etuning if the car was not going into vtec.

The tuner will be adjusting the high cam fuel tables from the logs you sent surely he would have picked up if something is wrong. Maybe i am wrong but from what you posted that is my take on it.
 

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Discussion Starter · #36 ·
On the ktuner it's normal behavior for the VTP light to go off when the VTS/vtec gets activated. I also think that your
vtec is engaging. You running the stock intake,cams ect ?

Tune WOT finish set the higher cam angle to 0 degrees and see if the AFR's has changed also check your cam angles that its then using.You could also try and set vtec lower at 4000 to see if theres a change in the AFR graph before the initial 4800 engagement.

With vtec set so high on stock cams which iam assuming it is you might not be able to hear it engage. With the stock oem cams i usually engage vtec at about 3600 to 4000 rpm depending on the setup.

View attachment 105527
View attachment 105528

I also think it's kinda impossible to get the fueling right on the car using etuning if the car was not going into vtec.

The tuner will be adjusting the high cam fuel tables from the logs you sent surely he would have picked up if something is wrong. Maybe i am wrong but from what you posted that is my take on it.
Thanks for the info. I'll share this with my tuner. I hadn't thought about lowering VTEC either. This is indeed stock cams, intake, etc. Everything is stock inside and out including the exhaust and manifold.

My concern is that my tuner also thinks it's not engaging based on the logs I've sent. I also would have expected to hear engagement at open headers but then again the fact that at open headers, I get no O2 reading, it may be causing VTEC not to engage at all so not sure if that was a good test.

When I say you can't hear VTEC at all, I mean just that. Not a dent in sound pitch. I've had stock TSX's in the past that from factory, you can hear engagement so not sure what to think here. Wondering if my catalytic is that clogged or something?

Nevertheless, I'll try the tips you provided because I'm out of ideas at this point for sure. I also didn't know that in KTuner it was normal for the VTP light to go off when VTS engages. I guess I can add that pressure switch back on to the VTEC solenoid assembly.
 

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Discussion Starter · #37 · (Edited)
Whewww...this mystery is solved! Here is what I tried:
  • Tested continuity on VTEC pressure switch (both sensor connector and wiring)
  • Tested continuity on VTEC solenoid (both solenoid connector and wiring)
  • Checked oil level
  • Checked oil pressure
  • Checked VSS
  • Checked TPS calibration
  • Tested primary and secondary rockers at 42 PSI (per service manual) for each TDC cylinder
  • Bypassed VTEC pressure sensor
Those tests above all checked out good. Here is what didn't work and/or added to the confusion:
  • Testing with open headers
    • This was a bad test for several reasons. It's before both primary and secondary O2 sensors, which throws a MIL and possibly prevents VTEC from engaging since there are no AFR values being reported to the ECU. I could never get VTEC to engage here but I suspect it was due to the MIL I created when both O2 sensors were bypassed when I disconnected the downpipe from the exhaust manifold
  • VTP and VTS indicators in KTuner
    • The fact that the VTP indicator was shutting off when VTS was turning on made it seem like the pressure switch was either sending a bad signal to the ECU or that the pressure switch was bad. I learned that this is how KTuner works for those indicators (thanks @20v_lover for pointing this out and I was also able to confirm after your suggestion)
  • 80% TPS at WOT
    • This was confusing because some were saying this should be 100% at WOT. I thought the reading was normal at 80% for this ECU and was able to confirm with KTuner that 80% is the factory reading and this is normal.
  • Changed VTEC to 4k RPM engagement with corrective lower/upper limits
    • This didn't make a difference. I still couldn't hear anything
Solution

Since the exhaust and catalytic were rusted shut, I took a leap of faith and just cut the exhaust bolts RIGHT AFTER the catalytic and ran it open this way. Took it for a test drive and I could finally hear a very, very faint/subtle but repeatable sound at VTEC engagement point. Now I know it definitely works. The issue here is that the catalytic seems clogged.

Next steps
  • Replace catalytic completely with just a straight runner (now)
  • Replace 2" stock exhaust (later in the future)
Thank you all for the assistance on this one
 

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This is one of the best trouble shoot problem solve threads posted in a long while. Thank you for creating this thread, I am sure it will help others in the future.
 

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Discussion Starter · #39 ·
This is one of the best trouble shoot problem solve threads posted in a long while. Thank you for creating this thread, I am sure it will help others in the future.
Thank you kindly!
 
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