Another No CEL no VTEC

[CivicIsFast]

Yes ive read all the other no cel no vtec posts.

08 Si, turbo car.

Like the title says, no cel no vtec. I take logs of pulls trying to get into vtec, VTS comes on and it switches to vtec tables but hits a limiter of some kind. I checked the wires to the solenoid, theyre fine, put a brand new solenoid in even though the old one would still click. Ive checked my oil, and my mechanical gauge shows good pressure. The only lights on the dash are abs and handbrake, but vtec would work before tuning (while it was still NA) with these lights on. Ive tried completely retuning on a different tune file and have the same issue, Ive had problems going into limp modes because of a corrupt tune file before so it was the first thing I tried. Ive taken the valve cover off and looked over rockers and all that, nothing is loose or missing, lost motion springs look fine. Short of pulling the head apart Ive done everything I can to make it work, I think.

Looking at the logs, as soon as it goes into vtec, both wideband and stock sensor show super rich. I pulled fuel out slowly until it was almost the same as the low cam map, and still comes up rich. The sensors work fine doing full rpm pulls in low cam. I have cam angle zerod and ignition dropping 2 deg on the switch. Pressure switch is disabled, vtec set to engage at 4k and 1bar. Boost cut at 15psi, Im only getting to 8 at the highest.

Is there some setting in hondata that im missing? Have I forgot to check something? What the hell is going on? Ive been working to fix this for months now and no matter what I check everything seems to work fine, but it just hits a wall as soon as vtec engages.

Heres the most recent tune file and logs.

Thanks.

high cam tuning 1.fpcal

(27.02 KiB) Downloaded 77 times

vtec engage 4.fpdl

(8.74 KiB) Downloaded 77 times

vtec engage 3.fpdl

(7.72 KiB) Downloaded 66 times

[EFICU]

I don't think this is necessarily the issue, but have you adjusted the vtec window pressures? Looking at your calibration, you have them set 25% higher than a Hondata turbo file for 8th gens. Granted you appear to be reaching this threshold, but for the sake of testing you should lower that value to inspect. On an NA car, if that window pressure is set too high it will hit a limiter as you mention. When the value is correct, the limiter issue is removed. What it does is basically kick the car out of open loop operation and back to closed loop quickly, effectively feeling like a limiter.

Also, since you're testing, are you wanting vtec to come on at 4000 or 4200? You should set both the upper limit and lower limits to the same RPM you want vtec to kick in. Then in the final calibration you determine the high and low thresholds.

I can make the changes I mention and send you the next file if you want to try these out. Let me know whether you want vtec at 4000 or 4200, but choose one or the other for this test.

If you have already messed with the vtec window pressures, then I will keep looking. If you haven't adjusted them, it might be a place to start.

[CivicIsFast]

I don't think this is necessarily the issue, but have you adjusted the vtec window pressures? Looking at your calibration, you have them set 25% higher than a Hondata turbo file for 8th gens. Granted you appear to be reaching this threshold, but for the sake of testing you should lower that value to inspect. On an NA car, if that window pressure is set too high it will hit a limiter as you mention. When the value is correct, the limiter issue is removed. What it does is basically kick the car out of open loop operation and back to closed loop quickly, effectively feeling like a limiter.

Also, since you're testing, are you wanting vtec to come on at 4000 or 4200? You should set both the upper limit and lower limits to the same RPM you want vtec to kick in. Then in the final calibration you determine the high and low thresholds.

I can make the changes I mention and send you the next file if you want to try these out. Let me know whether you want vtec at 4000 or 4200, but choose one or the other for this test.

If you have already messed with the vtec window pressures, then I will keep looking. If you haven't adjusted them, it might be a place to start.

The issue was happening at 0.8 as well, but I changed the vtec rpm windows to 4500 and 4500, also tried pressure window at 0.5, 0.3, and 0.0. All with the same issue.

It might be too much to say that it feels like throttle position directly affects the "jerkiness" when it switches to vtec. So, more throttle makes for a more aggressive wall it hits. This can be seen in the following 0.3 log, the relatively low throttle input has a less dramatic fluctuation in rpm, compared to the following 0.0 and 0.5 logs.

If you have any other ideas please let me know, Im at a loss with this and pretty much ready to try whatever to make it work.

Here are the new logs and updated tune file.

Thanks.

vtec 4500 0.5.fpdl

(9.97 KiB) Downloaded 73 times

vtec 4500 0.3.fpdl

(9.98 KiB) Downloaded 77 times

vtec 4500 0.0.fpdl

(9.79 KiB) Downloaded 72 times

high cam tuning 1 new.fpcal

(27.03 KiB) Downloaded 68 times

[EFICU]

In your 0.3 datalog, you're not letting off the throttle pedal at 4363rpm on the pull, the ECU is doing that? Both the pedal and t plate go shut is why I ask.

Are you using the stock map sensor?

What are you using for boost control, wastegate spring?

[CivicIsFast]

In the 0.3 datalog, TPedal is about 80% from 16-18 seconds, then goes to 87% at 4523 rpm. Thats where it hit the wall and pushed me forward in the seat. Right after that is when I let off. Looks like TPlate stays open until then as well.

Ive got the skunk2 4 bar map sensor in it, and set it to Hondata 4 bar in Calibration > Sensors.

It only has a line from the turbo to the wastegate, no controller in it yet. On the gate it gets to about 8psi on a full pull on the low cam.

Tomorrow I'm switching it to thicker 5w50 oil to see if some extra oil pressure would help.

Thanks.

[EFICU]

Gotcha. And if you were to move vtec to say 5000 rpm it would rev out to 5000 then stumble you think?

Have you tested the same problem with the stock map sensor?

Sorry for thinking out loud (typing). Trying to think of anything it could be

[CivicIsFast]

Yes I’ve tried all the way to 7000 and the same problem comes up.

When I first turbo’d the car I had the stock map sensor in it for a few weeks and no difference.

Also, any ideas are helpful. I’m thinking this has got to be something obvious that I’m just missing.

Thanks.

[Spunkster]

You should try the ECU on a known working vehicle and see if the VTEC operates as it should.

[CivicIsFast]

That's what I was thinking this morning. I tried the thicker oil with no change. Problem is I don't know anyone with another Si whos willing to let me mess with it. It is pretty high mileage, maybe physical damage in the ecu.

Too bad I've already given up. I'm going vtec killer and that'll be the end of it. I don't care much for drivability or fuel economy anyway.

Thanks.

[Spunkster]

Sorry, for some reason I thought this was a K-Pro, so swapping ECUs is not really an option.