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K24A2 running rough during acceleration at low RPM

Posted: Mon Jul 22, 2019 4:45 am
by Ecky
Could someone take a look at my kal and suggest what might be causing my symptoms? K24A2 mostly stock (K20A2 oil pump, custom intake and exhaust, wideband + KPro). I'm seeing the engine run a little rough, almost hesitate, in the ~1500-2000rpm range, especially before it's fully warmed up. I suspected it was gear compensation pulling timing that was causing it so I turned that off, but it didn't seem to help. Anyone willing to look at a kal + log and give some suggestions?

Re: K24A2 running rough during acceleration at low RPM

Posted: Mon Jul 22, 2019 10:42 am
by Spunkster
No calibration or datalog was uploaded.

Re: K24A2 running rough during acceleration at low RPM

Posted: Tue Jul 23, 2019 4:38 am
by Ecky
Attached. This morning I noticed it most at ~1300-1600rpm, engine definitely smooths out above 2000, and it doesn't always do it.

I also notice my fuel trims gradually decrease as the engine warms up - what's the correct way to compensate for this? Is that water temperature compensation under Fuel Compensation?

Re: K24A2 running rough during acceleration at low RPM

Posted: Tue Jul 23, 2019 9:30 am
by Spunkster
Have you calibrated your TPS at idle?

Re: K24A2 running rough during acceleration at low RPM

Posted: Tue Jul 23, 2019 10:42 am
by Ecky
Spunkster wrote:
Tue Jul 23, 2019 9:30 am
Have you calibrated your TPS at idle?
If you mean, set TPS minimum with my foot off the pedal and maximum while the pedal is to the floor, then yes. Is there a different procedure?

Re: K24A2 running rough during acceleration at low RPM

Posted: Tue Jul 23, 2019 10:45 am
by Spunkster
Yes that's what I meant. Has this been tuned on the dyno?

Re: K24A2 running rough during acceleration at low RPM

Posted: Tue Jul 23, 2019 11:03 am
by Ecky
Spunkster wrote:
Tue Jul 23, 2019 10:45 am
Yes that's what I meant. Has this been tuned on the dyno?
Nope. I've been (learning as I go along) street tuning it. Fuel maps I have within 2% on all cam angles when the engine is fully warmed up, but they're off a few percent before it gets up to temperature, tend to be a hair lean at low loads but spot on at high load. Cam angles I picked out by interpolating highest fuel used along the higher vacuum columns, and followed the FAQ/Help of setting 30 degrees at cruising loads / RPM - my last tank (~225 miles from Boston to Burlington VT) I eeked out 65.3mpg, so I'm not terribly unhappy with the results. Ignition timing I was using the 04-05 TSX 310 base map until a few days ago when I got a dyno tuned map from a friend who also has a nearly stock K24A2, so I've been using his slightly more conservative than base map ignition timing values until I find it in my budget to pay for a load dyno tune of my own.

Pertinent engine facts:
KProv4
JDM K24A(2) 04-05
K24A2 06-08 cams
03-05 Accord TB (cable)
RBB + short ram intake
04-05 K24A2 header, ceramic coated
2.5" custom exhaust from cat back
RSX wideband O2 sensor
K20A2 oil pump
50 degree VTC mechanically limited to 40 degrees

Re: K24A2 running rough during acceleration at low RPM

Posted: Tue Jul 23, 2019 4:30 pm
by Spunkster
With that kind of gas mileage I would suspect it might be running very lean.

Re: K24A2 running rough during acceleration at low RPM

Posted: Wed Jul 24, 2019 8:09 am
by Ecky
Spunkster wrote:
Tue Jul 23, 2019 4:30 pm
With that kind of gas mileage I would suspect it might be running very lean.
My wideband is reading that it's still achieving 14.7:1. This is in a Honda Insight, car weighs under 2000lbs full tank of gas and with the K motor, has skinny LRR tires in the rear and low drag coefficient, plus a silly tall 3.4 final drive and 0.647 6th gear. I bet I can do even better if I lean it out at low RPM low load, but I'm not ready to start playing with ignition timing like that yet.

Think the hesitation might have to do with my cam advance? It feels like ignition timing is severely retarded (based on my limited experience), but I guess it could just be poor combustion due to a lot of EGR happening from valve opening. Seems much more noticeable before the engine is warmed up enough - maybe poor atomization of fuel in a cold engine?

Re: K24A2 running rough during acceleration at low RPM

Posted: Wed Jul 24, 2019 9:11 am
by Spunkster
Have you done a leak down and compression test when the engine is cold?

Re: K24A2 running rough during acceleration at low RPM

Posted: Wed Jul 24, 2019 9:16 am
by Ecky
Spunkster wrote:
Wed Jul 24, 2019 9:11 am
Have you done a leak down and compression test when the engine is cold?
I haven't. Bought it from HMO and I understand they test compression before they send it out (basically the only testing they do), and to this point I've just trusted that. It runs well from idle to around 1250rpm, above 2000rpm, and everywhere once warm (at least as far as I can tell). I can buy a compression tester if you think this is likely a mechanical issue.

Re: K24A2 running rough during acceleration at low RPM

Posted: Wed Jul 24, 2019 11:10 am
by Spunkster
It's possible it could be a slight valve leak until it gets warm and seals better.

Re: K24A2 running rough during acceleration at low RPM

Posted: Sun Aug 18, 2019 12:11 pm
by Ecky
Noticed some weird behavior in the logs today. Attached my log and kal.

Image

Looks like an issue where all of the sensors went haywire for a second or two, a few times during the drive. Cam, TPS, O2, others. I can't find any other examples of this in the logs. Bad ground maybe?

Re: K24A2 running rough during acceleration at low RPM

Posted: Mon Aug 19, 2019 5:22 am
by Ecky
Resolved the hesitation. I advanced timing in that region a little, disabled tip-in retard and turned off cold engine timing retard. I think timing was just getting retarded in this zone so far that it wasn't making any power at all.

Looks like the above issue is somehow tied to air conditioning.