Feels like DI isn't kicking in but no CEL
 

Uhh oh...what did I do? So this morning on my way to work I was stopped at the top of a hill, but when I went to take off forgot I was still in third...chug...chug...die, slight moment of embarrassment. When I went to fire the engine back up I noticed it took several cranks...like so many more than normal that I'm bringing it up. But it eventually turned over and off I went.

I got about half a mile or so down the road and went to turn onto another street and accelerated in first, and instantly noticed that it felt like half my power was missing. For example instead of feeling the slight pull at around 3500 or so there was nothing until around 5500 and even that felt off. Got to work, parked it, thought...eah maybe it's just in my head.

This evening after work, jumped back in and nope...wasn't in my head. No power up until 5500/6000 and it just doesn't feel "right". No CEL though...which I find strange. Almost feels like it's starved for air, like something's choking it out. I pulled the air box off of it just to check and nothing at the filter level or down in the inlet pipe is obstructing airflow (for as far back as I could fit my hand (the piece that runs into the front bumper cover)).

Started thinking maybe the DI system isn't engaging...but you'd think there'd be a CEL in that case. Has anyone else experienced anything like this? Have any ideas?

Not sure if it's worth mentioning or not, but I have a stage 1 OFT flash on the ecu (that was done like 4 or 5 months ago with no issues).

Bonus question: If I wind up taking this to the dealer should I flash back to the factory tune? I mean it's a 2013 that has no warranty left on anything. If I don't need to, I'd rather not flash it back.

Did you fill it with the wrong fuel? My car runs like absolute shit on regular 87 octane. Very sluggish.

Try just doing a battery disconnect reset and see if that helps.
If you do take it back to the dealer it should be on a factory tune or else their equipment won’t be able to access it.

Negative. Nothing but 93 since I've owned it. But your comment does remind me of an issue I had on a DSM once. Fuel filter was trash and so much dirt had gotten into the injectors that they were barely able to fire. Actually feels kind of similar to what that did if I'm remembering correctly.

I've got this OFT. I'm wondering if I did a datalog if that would show anything. Like if the narrowband would report accurately enough that I could tell if it's running rich or leaning out?

Sadly, I just tried this (left disconnected for a good 2 minutes) and it seemed to have no effect. Appreciate the idea though.

The next thing I was going to suggest was datalog and upload to datazap.

RPM, Maf Voltage, Engine Load, Command AFR, AFR, FLKC, IAM


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You may have to drive it for 50 miles or so for any change to be felt. It doesn’t take ahold right away.

Will do the log this evening and post findings (unless the condition progresses into throwing a CEL during today's commute).

Log it in a steady state, IE cruising. If there is anything wrong with the MAF or O2 it should pop out and we can see it there.

Got it. Other than the mentioned channels: (RPM, Maf Voltage, Engine Load, Command AFR, AFR, FLKC, IAM) should I include any others?

Maybe injection mode. Really, we are just trying to see what the MAF and O2 are doing.

I don't see iam in here is that an acronym for something else? Ignition advance multiplier?

It might just say advance multiplier. I can't remember.

Got it. I'll have these graphs up in the next couple hours.

Log successfully uploaded to datazap: https://datazap.me/u/ziltoid/001?log=0&data=1

Started from a dead stop on an on ramp, accelerated then cruised for about a mile or so, hit stoplight...waited...then did another pull and cruised for maybe 1/4mi

I've had a couple no-starts where my engine wouldn't start on first crank when my engine was hot. I don't think it's much to worry about it besides something being out of range the moment you tried to start it again.

Injection sound is what makes up 90% of engine bay noise. You should just listen to the engine in different settings and states. I test mine every morning, doing different revs taking note of the injector and exhaust-sound feedback. I drive off down the road a couple minutes, pull over and park somewhere where I can hear the engine, listen for injector changeover.

You can also get a long screwdriver or long metal probe and listen to the injectors. I use a flexible claw grabber like pic: https://i.imgur.com/bHePgGc.png Very easy to listen to the injector pulses. You can also listen in on the valvetrain clicking away (it is very quiet and smooth).

At a quick first glance everything looks pretty normal. I will take a closer look later.

Greatly appreciated!

Haven't been able to get romraider to load a v4 tune on my laptop. Still looking at.

Honestly, it looks okay. Could be something with the AVCS. The MAF and O2 look like they are reading fine.

@steve99

Thanks for checking it out! I'm unaware of how the AVCS works on these engines, but I'll do some googling. I see where that would make sense though as what I'm experiencing could probably more accurately have been described as "VTEC ain't kickn in yo". For example, normally when accelerating from a stop you mash it, and it's like...yeah ok I'm moving, then there's a point around 3500/4000ish where you think, hey alright this isn't too bad...I don't get that "this isn't too bad" feeling anymore, just flat until around 5500 and even up that high it doesn't pull like it did at 4000 before whatever happened happened...It's strange.

If it were some bad gas, that probably would have been visible in the logs as quite a bit of knock I'm guessing?

Push comes to shove, I'll reflash the factory tune and take it to the dealer to see if they can find anything...although I'm like 1 of 3 of these cars in my area so the chances of them knowing what the car's suppose to run like compared to what it's running like now are slim at best.

Yes, but your IAM is going up during the log so it rules that out.

Wait a minute. I just remembered something. Way back when I first got this thing I took it to the dealer I got it from (was a hyundai dealer someone traded this in after putting 6k miles on it for some reason) for an oil change once (cause free oil changes for a year) and they put conventional 5w-30 in it! I made it a couple miles down the road and realized something wasn't right...It was running kind of similar to how it is now, like it felt way down on power. I turned around, took straight back and said...tf? This thing should be running a full synthetic 0w-20. They changed it out, and back to normal.

So with this realization, plus if the avcs system uses oil pressure for engagement (like those solenoids on the bseries engines...just guessing)...now I'm wondering if, hell maybe I just need an oil change? Last change was about 14 months ago...BUT...BUT...hear me out....It's only been driven about 4k miles sense then. Think this full synthetic oil could have broken down to the point that it's ****n off the avcs system? Or am I connecting dots that aren't there >_<.

That would be my reckoning (about the dots) - ;)

Log data with oft


post logs to www.datazap.me


check di computer eathed with all three bolts


car starts on port


then switches to di and port

I'm running 5W30 synthetic right now, it's not affecting the AVCS.

log uploaded to: https://datazap.me/u/ziltoid/001?log=0&data=1

if thats a petrol oft tune its running lean at full throttle high 12 should be high 11


fuel trims look ok at idle so bit unusual but check fot inrake and exhaust leaks clean maf sensor and check di comluter bolts all three in and tight

Stage 1 oft tune for 91, and I run 93 through it. Will do the aforementioned and report back. Thanks! :)

@steve99 @NoHaveMSG

Think I've got it figured out. I fired it up this morning before heading to the parts house. Popped the hood and was examining the di computer. All bolts were tightly fastened. I decided to give the plugs around it a nice jiggle, and Lo and behold as soon as I jiggled the connector in the attached image there was an auditory difference in how it was running, instantly sounded much smoother.

After this I went and grabbed maf cleaner and some carb cleaner for checking vacuum leaks, and while doing so I noticed the issue was much improved. Still a little flat, but definitely better. When I got back I did a datalog of it in this state.

I let it cool down for several hours, then went back out to check for vacuum leaks, all good on that front. I then unplugged the previously mentioned connector, checking the pins, all good, plugged it back in firmly. It's at this point that I disconnected the battery to reset ecu. After re-connecting I let idle for a few minutes, then went on a test run up and down the street. Bingo. She's back! I then did another datalog of this state

Now as you've probably guessed, I don't know what I'm looking at in these graphs. Like I know what the values represent, but I don't know what they should be in relation to each other. It was mentioned that at WOT my afr should be in the high 11s? I see the afr still in the 12s, but the command afr eventually gets into the high 11s. I'm guessing command afr is the value the ecu is attempting to reach, and afr is the actual value?

With all that being said, does the last log I posted seem good or does it indicate that I may still have something going on (even though the issue which lead me to create this thread seems to be resolved)? Still haven't cleaned the maf, but I didn't want to do that quite yet (introducing more variables into the equation and what not).

Ok its looking a little better but still lean top end


Commanded afr is afr the ecu is asking for and AFR is the actual measured afr


If your intake is stock and sensprs working ok then afr and commanded afr should be pretty close like withing 4% or so


Id remove and clean the plugs and sockets on the di computer


Id probably loosen and retighten the three di computer mount bolts as well jist in case there is bit of corrosion and its not earthing\grounding well

Going to make this my project for the weekend. I'll remove the di computer entirely, check the contact points between the mounting bracket and computer (maybe wire brush them), clean all plugs, and go ahead and clean that maf. Will report back once all is completed. Greatly appreciate the assistance!

@steve99

Reseated the DI computer bolts, checked all plugs, cleaned maf sensor, reset ecu (by pulling negative from battery). Took it out for a spin and these are the results (got two really good third gear pulls on this log): https://datazap.me/u/ziltoid/004-res...f?log=0&data=1

Driving down low feels solid, mid range from like 4500-5500 seems kinda soggy, and then after 5500ish seems to pick back up a bit. You had mentioned that commanded afr and reported afr should generally be within 4% of each other, so I wrote a script to calculate out that percentage for the log (just to give me some value to look at to be like, yeah that's lean or yeah that looks good) and low and behold from about 4500-5500 she still appears to be running on the lean side.

You think being lean in this range could simply be from needing some adjustments to the default stage 1 oft tune? I had mentioned (I believe) before that my intake was stock...that's basically true, but it might be worth mentioning that I have a perrin intake tube running from the factory air box to the tb, and a k&n filter. Maf is still in factory location and everything. Think that could have something to do with it?

MAF scaling?