Flashing CEL, loss of power at highway speeds with difficulty restarting

09 Sport A/T at about 176k miles

About once a month, but sometimes every 2 months, my Fit has a seemingly random episode (throws a fit!) where it idles very rough and stalls or loses power on the highway, sometimes accompanied with misfire (flashing CEL). Sometimes happens 10 minutes into the drive, sometimes 2 hours or more. The most common occurance is that you pull up to a stoplight, the idle stumbles once or twice, then it dies. Car can usually restart, although some throttle and extra long cranking is sometimes needed, but it will only stay running if throttle is maintained whenever stopped (transmission is drive or neutral, while also maintaining brake pressure). Sometimes this behavior continues for the rest of the drive until the car sits for awhile. Sometimes, by the time we limp it home (10 minutes later), it will idle and drive fine (full highway and acceleration power) like nothing ever happened. Sometimes, by the time we limp it to our destination, it will die in the parking lot.

We now try to carry a datalogger to try to captch an "episode", but it's almost like it knows when we have the ability to capture OBD-II data, and always chooses those times to fix itself. One time while it started to lightly surge on the highway, I knew it was getting ready to throw a fit, so I floored the accelerator as a test, and as soon as the transmission kicked down, we lost all power, the CEL flashed, and the car seemed to go into limp mode with almost zero power.

Data afterwards frequently shows random misfires and misfires on multiple cylinders (P0300, 0301, 0302, 0303, 0304). Freeze frame data almost never looks suspect, but we did get a 99% EGR error on the latest iteration (but no EGR code). Most recent episode was 2000 miles and about a month between. At one point long term fuel trim was showing double digit positive, but now both LTFT and STFT are between 0 and 10%.

Seems related to idle control, but in researching those parts, most seem like always or never work, not randomly quit for 10 minutes. We've searched around here quite a bit but I haven't come across anything Intermittent like this.

Recent maintenance/fixes
August: Starter and Alternator (Alternator was seized, but symptoms led us to believe it was a starter issue)
October: EGR valve (car died completely and wouldn't try to restart that day, started next day briefly and gave a code)
December: Spark plugs and coil packs (coil packs were original, one spark plug was a little loose and the pack had some discoloration)
I believe the issue started sometime between the starter and EGR valve being replaced. Prior to the starter, this thing ran like a champ and extremely rarely had any issues.

 

What's the maintenance record like? Specifically your spark plugs?

 

Replaced plugs and coils in December. Coils were original prior to that.

Husband and I were discussing the post over email and I missed copying over part of it - all of the recent, probably unrelated, maintenance actions are now in the post.

 

I figured. It sounds like you guys have really been going through it.

 

Did you get OE coils? Seems that aftermarket ones are garbage from what I read on this forum.

 

After reading a lot on here, we got Hitachi from Rock Auto - they are supposedly the OEM but we did not get them directly from Honda.

Edit: And this did start before we did those, that was one of our troubleshooting steps.

 

Good, Hitachi seems the way to go.

 

In case anyone stumbles on this, it was the EGR valve. Yes, we replaced it early on but apparently it was defective. Took it off to inspect when the car got worse and worse and the valve was stuck open. Replaced it and the car has been running smoothly for months.

Interestingly, when we first put a block off plate in, almost immediately got a check engine light for flow mismatch (or something like that)..that but never got one for too much flow when the valve wouldn't close!

 

I was thinking EGR before I got down to where you mentioned an EGR error but no code. I'd be willing to bet the EGR is sporadically getting stuck open.. Try blocking it off and see if the problem ever happens again, if it doesn't you know the EGR was faulty, replace it, leave it blocked off whatever at that point, depends on if you have the means to tell the ECU to ignore the code so you don't have a constant CEL on or not imo. I personally usually block EGR's on most vehicles if I can easily keep the CEL from coming on due to it.


ETA: NEVER MIND! I see this is what I do to myself for not actually reading the thread before responding...