Weird stutter after vtec engages then below vtec engagement

Civic/Integra/etc with a K swap
TheOhKcivic
Posts: 13
Joined: Sat May 27, 2017 2:04 am

Re: Weird stutter after vtec engages then below vtec engagem

Post by TheOhKcivic »

My question is how would testing that ecu in another fully functional vehicle cause it to do the exact same thing on both cars even after I swapped ecus back.

Literally drove the test car around to make sure there were no issues put in other ecu and instant problems switch ecus back and problem persists.

You said to start with tps and map but how do suggest I start with them
KTuner
Site Admin
Posts: 3744
Joined: Mon Jul 22, 2013 8:13 pm

Re: Weird stutter after vtec engages then below vtec engagem

Post by KTuner »

You admitted you're using the wrong O2 sensor, perhaps that's your issue. Your fuel trims are all over the place. You need proper tuning with a properly completed setup that has the right parts.

If a sensor was damaged it would give false readings at all times or not function at all.

A K20Z1 ECU and K20Z3 ECU can't be used on the same harness, so unfortunately I can't understand or help you with that issue. A K20Z3 is drive by wire. RSX is drive by cable. If you're talking about some other RSX or aftermarket ECU then that's not the Z3 ECU. If you're swapping from 02-04 and 05-06 ECUs the O2 sensor needs to change with it.

TPS went to 0 and MAP went to 158 at a point your tuner suggested was a stutter. Only you know whether or not you let off the throttle at that point. If you didn't then the TPS and MAP signals were lost. Check your sensors and wiring.

Beyond those suggestions this is not something we can help you diagnose.
zellers88
Posts: 4
Joined: Tue Apr 09, 2019 1:51 pm

Re: Weird stutter after vtec engages then below vtec engagem

Post by zellers88 »

Bringing back an old thread but I think I'm having a similar issue. Hit VTEC and let off, then even when just idling it stutters and the knock count starts increasing. Any ideas?

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KTuner
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Joined: Mon Jul 22, 2013 8:13 pm

Re: Weird stutter after vtec engages then below vtec engagem

Post by KTuner »

Your AFR says 15.9. I'd start there.
zellers88
Posts: 4
Joined: Tue Apr 09, 2019 1:51 pm

Re: Weird stutter after vtec engages then below vtec engagem

Post by zellers88 »

The portion where it is stumbling and the knock count increases is right around 14.7 AFR
KTuner
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Joined: Mon Jul 22, 2013 8:13 pm

Re: Weird stutter after vtec engages then below vtec engagem

Post by KTuner »

So adjust that area in the maps. You have access to them and map trace to guide the way.
zellers88
Posts: 4
Joined: Tue Apr 09, 2019 1:51 pm

Re: Weird stutter after vtec engages then below vtec engagem

Post by zellers88 »

I don't think you're understanding. It's not just one place on the map. No issues until going into VTEC, then after coming back down it knocks pretty much anywhere for at least a few seconds. This particular time was at idle and 14.7 AFR which normally has no issue. I don't think tuning fuel will help.
KTuner
Site Admin
Posts: 3744
Joined: Mon Jul 22, 2013 8:13 pm

Re: Weird stutter after vtec engages then below vtec engagem

Post by KTuner »

Knock count is not always indicative of knock. If you're at an idle level you're not going to see real knock with 14.7 afr because there's hardly any air in the cylinder and you're not under load.

You said there's a stutter. If that's from timing or fuel you can work on tuning fuel and timing to adjust that out. If it's something mechanical there's a chance no amount of tuning will help.
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