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EDIT: The problem was solved, so this is more or less just a general thread about my poor car.

Hi folks. I'm having issues with sporadic loss of fuel delivery while driving, usually after at least 15 minutes of driving (sometimes much later), occurring for maybe 30-40 seconds at a time. Not stalling, not losing electrics, nothing other than being unable to give the engine gas despite consistent pedal pressure. It cuts in and out of getting gas (maybe one spurt every 5-10 seconds) like this for 30-40 seconds then is perfectly fine like nothing happened. I haven't floored it in this scenario so I don't know if that would do anything. There's no forewarning of this occurring, it just deteriorates to this condition within 3 seconds out of nowhere, lasts another 30-40, then normal. First thought was that the fuel filter was getting occasionally clogged, but after replacing it, the issue persists. Next attempt will be the fuel pump.

I've looked into the issue online and while I can't find any solved cases despite tons of threads, I do have a list of possible culprits:

-IACV
-Cat
-MAP sensor (no MAF on 6th gen Accords)
-Intake/vacuum leak (unlikely since it would be a consistent issue rather than isolated and sporadic)
-FPR
-O2 sensor (unlikely, but not impossible)

Repairs currently attempted:

-Fuel filter
-TPS
-Valve cover gaskets/seals
-Spark plugs/wires
-Fuel pump

Any further suggestions?

P.S.
Idle is consistent.

This post has been edited by kyonpalm on Dec 27 2016, 10:00 PM

O2 sensor is how the ECU detects A:F ratio.

FPR self-explanatory.

Cat, IACV, TPS, Intake/Vacuum unlikely as it should be consistent, but you could check the TPS voltage easily enough. The correct values should be in the service manual.

Is the MAP a heated-element type? Anything that is temperature or flow-related is more likely than electronics.

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I could try that. Posting this for future reference:

Image size reduced, original size: 1113 x 37. Click here to view the image in its original dimension.

Dunno anything about MAPs, but this is the most information I could find in the service manual:

I've given a theory to Zach since from what he's told me, the issue is temp related.

Apparently, his issue occurs ONLY after a longer period (15 minutes ish) of driving.

My guess was Cats. No, cats are not constant, they need to warm up. Its part of the reason why warm cats can produce such different smog readings warm vs cold.

so what did my crazy mind think of?

Clogged cats. basically, they're restricting his flow. Could happen from the cat warming, or they could just be clogged and restrictive at any temperature.

How does this factor into his randomly bogging when his car has been warmed up? Pre-ignition.
There's an excess amount of warm exhaust gases that's causing pre-ignition, the knock sensor is picking up on it, and retarding the engine.
the only issue of course is its not throwing a knock code.

Can confirm that zach is filling up with 87.


just a crazy and worst case theory.

This post has been edited by Sensation! on Feb 3 2016, 07:30 PM

Yeah, that's possible. Could also explain the fuel trim issue since the O2 sensor would be getting way false readings.

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So after it happens for 30-40 seconds, it goes away afterwards?

Good question! And if so, when does it come back (if ever)?

Yes, as I mentioned in the OP, the condition resolves itself almost immediately (within a second) and is perfectly back to normal as if nothing ever happened.

By the way, if I haven't mentioned already, the engine's idle is rock solid.

I haven't driven the car more than an hour or so at a time since this started happening, so I wouldn't know if this could occur more than once in the same drive, but it hasn't so far. Remember, though, this has occurred anywhere between 15 and 50 minutes of driving. I suppose it could come back in the same drive theoretically, but it hasn't in the 6-odd drives it's occurred in.

Also worth noting that there have been a couple drives since this started where it hasn't happened. For instance, the very first time it happened was 15 minutes into an hour-long drive up north. On the drive back (also an hour long, of course), the issue did not occur. IIRC, I made the drive again the next day, and that time too it only occurred on the northbound trip, also about 15 minutes in. The last time I made that drive, however, it occurred both northbound and southbound - northbound about 50 minutes in, and southbound about 30-40 minutes in. Could be the issue getting worse, or just dumb luck the first two round-trips.

Outside of this highway drive, it's only happened once in the city - but I've been limiting my driving out of safety and have only driven it around town once before confirming the issue, so that doesn't really count.

Does it happen out of the blue in perfectly normal, straight, even driving? Does it seem to happen more when climbing a hill? Does it seem to happen related to wet/humid weather? Does it seem to happen after driving through a bumpy section of road?

Basically, that's way more random than I thought it was, so anything that can pin down a rhyme or reason to such randomness would help round down the possibilities.

Yep, completely straight, consistent speed leading up to it, totally normal.

>Florida
>hills
lel. Seriously, no, there are no inclines for that to even happen on.

It's never happened during or just after rain, no. Haven't driven it in those conditions since it's been happening, either.

Nope. Even the least smooth parts of the highway I drive on aren't that bad to begin with.

This sounds suspiciously familiar to when I had to have a Jetta fixed after a head gasket issue. I experienced weird power loss at random times. This inconveniently decided to kick in at some really bad times, such as merging onto highways. This went on for a week before I could have it scheduled for repairs. I rode my bicycle to school, weather permitting, as I didn't want to murder the engine that I just paid out the ass to fix.

Turns out the TPS was all kinds of fucked up. I replaced the O2 and MAF at the same time just to push the reset button on all of that shit in one go. The car never acted like that ever again.

It sounds kinda like the issue my Honda is having. I'll agree with Sensation! On this one and venture a guess to the root of the issue being the cat.

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TPS easier and cheaper to diagnose/replace. Start there.

I like the TPS for this as well. What would be ideal is if you could get a computer log of a sweep of the TPS. If it's hitting maximum or minimum voltage per spec is irrelevant when the issue happens at cruise; between those two values.

I had to help a buddy diagnose a bad one on his Evo, ended up needing to do a graphed sweep of the sensor via a computer scan tool, which turned up some really inconsistent readings that jumped all over in the 20-30% range. With the visual it was plainly obvious that the sensor was shot.

This is why I refuse to own an automatic. With a stick, you can tell if it's stumbling under load or not.

Has it been particularly hot? Do you think your fuel is boiling?

Boiling fuel would be scary as shit, what the fuck he lives in Florida not Needles wtf.

Fuel boils all the time. Admittedly not very frequently in the winter, or with 3 bars of fuel pressure, but my cars all have fuel coolers from the factory. I'd check fuel pressure anyway, it's an easy check. T in a gauge, have it dangle behind the hood by the wipers and Robert's your dad's brother.

No way it's boiling. Weather has been fairly cool (for Florida), ranging from 60s-70s, lowest point sometimes 50s at night.

and Robert's your dad's brother.

Actually Robert's his dads son.






It's an inside thing, just had to say it...
Carry on

This post has been edited by Sensation! on Feb 12 2016, 12:23 PM

What!? People don't call it *punch line drum-fill* anymore~!? ...god I feel old...

*looks at all the real world car tech-talk*

da fuuuuuuuuuuuuuuuuuuuuu~??? O__O??

I'm out of dis supersupreme topic pizza nuggaz! ffsshhoooooo~

Xiao don't be that guy. Don't be that guy who buys a sports car and doesn't know how to do shit on the sports car. Come on man.

I have a sports car. I shit on it all the time.

d'aww N1, Imma just kidding~ I love being techy about everything including the kitchen sink. Cars aren't that different from computers; and if when praying I get that blue bunny ice cream Subbie and/or NSX someday, I'll be trying my darnest to put an LS1 in it, so I'll need to know my OBD-2's from my Subie Rally Pearl Blues~ dun worry about little xiao brother~ I have tiger blood!

I dunno man, I want one from Japan so I can shit on the right side~

Update:

After replacing the fuel filter back when I mentioned in the OP, the issue occurred on the drive down, so initially I thought it wasn't the fix. But for several trips around town since then, it didn't occur - even after another 120-mile (roundtrip) drive up north, nothing! So, filter or otherwise, I thought all was well. But yesterday I fired it up, and not even two minutes after driving, the thing attacked with a vengeance.

Fortunately this time I was on streets instead of the highway, so I had ample opportunity to test the nature of the issue better. One thing I noticed is that the cutoff seemed not to occur when I went past 50% throttle. This could have been coincidence, but I'm not 100% (more on that later). In addition to occurring much earlier than normal, the issue persisted far longer - it must have been eight or nine minutes from start to end. Four or five minutes in, I pulled into a CVS, put it in neutral and popped the hood.

I observed the throttle cable while slowly revving just for the heck of it. Cable worked fine throughout the testing that followed. I can say for sure that when I rev anywhere up to I guess around 2.5k it holds for maybe half a second then loses power for a few seconds, then comes in strong to rev past where I had it originally (imagine holding the pedal at 20%, getting 20% for half a second, 0% for three seconds, then like 50% out of nowhere, all while holding at 20% throttle). It seems that when I hold the pedal anywhere past 50% it doesn't lose power at all, but I didn't hold it for longer than a second or two since I didn't want to rev too high just for safety's sake. Still, that's a good second longer than -50% where it loses power quite quickly.

So I've gone ahead and finally ordered a new TPS and set of O2 sensors, which will arrive Wednesday. Hopefully will be able to swap them all the same day, if not Thursday. Will report my progress then. If this info tells any of you guys something new, feel free to let me know.

Good luck with the TPS. Here's hoping!