Slight miss?

Sounds like horse manure.

 

The CEL will only be triggered if misfire counts are beyond a certain threshold. Counts below the threshold will not log as an issue. But he's right....if misfires were the cause of the surge, I've logged plenty of time on a slight uphill incline where it's surging for a good 10+ seconds and it doesn't trigger a CEL, so I am very skeptical the surge is a misfire.

And you'll still have it with rev 1...it's the ECU tune, not the TCU.

 

Exactly.

 

They wouldn't even look at the data where it logged 7 misfires on cylinder one. The sassy service counter rep scoffed at me.

 

The surges I've experienced haven't been that bad..maybe 3 shorts surges or so at most. Low rpm for an extended period and then when I press the throttle a bit more it will hold, hold, hold that low rpm - surge - then throttle will respond. I will not be filling with ethanol free so that when I take it back in they can hopefully replicate the issue with their Techstream or whatever they use.

 

Keep in mind the way it's detecting a misfire is by looking at the speed of the crankshaft and those sensors aren't perfect...so count results aren't perfect either which is why there's a threshold in the amount of misfires counted before it will trigger a CEL.

 

Thank you for the 411. This is good information to have on hand. Would a tech be theoretically able to lower that threshold for the sake of diagnostics? Say, force the truck to throw a CEL after a certain # of misfires?

 

Not that I've ever seen...but my experience is limited to tuning using piggyback ECUs and reflash utilities that may not give the same level of diagnostic options.

 

Too late to lose hair over this now. It's time for a drink. Cheers y'all.

 

My fix has been to stomp on the gas in anger and yell....what a piece of S**T... at the top of my lungs. This engine/tranny combo is seriously the worst out of any vehicle I've ever owned.

In all seriousness, I'll try higher octane or boat gas and see if it helps.

Also, I'm hoping Rev1 will help a little. I'll request it during my upcoming 10k service.

 

I think the only fix would be an LS3 swap.

 

It is probably all in my head but I have tried running premium fuel three separate times (purely for this reason) and it did seem to help a bit. YMMV.

I really want to keep this truck long-term so I'm desperate to eliminate these little annoyances. Hopefully they'll develop an ECU flash for this. There is no way Highlander or Sienna buyers would tolerate this so Toyota must have some better programming available.

 

Toyota... hacked

 

i just took my truck in a week ago for this issue, made the lead service advisor ride with me to replicate while hooked up to tech stream. It didn't show any misfires. When trying to hold a constant speed, my truck shifts to 5th (AT) and holds 1100 rpms, whether 35 or 45 mph. This is when I feel the lugging, surging, misfire type sensation. I've had an open case with corporate for months, and have had both AT software revisions. I'm Going to get the regional rep out here and make him come on the next ride along.

 

Well..I'm really not sure now, 250 miles after filling back up with 91 E0, the learning for this fuel seems to have virtually eliminated the surging...I can't seem to reproduce it for the life of me now. I wasn't taking logs over the last 150 miles or so, but something's adjusted for the better on this fuel. Again...I'd strongly advise running E0 fuel if you can and see the difference it makes after a tank's worth of learning or so.

 

I run nothing but ethanol free 88 octane. And it still does it. Again mine went away for a few months for no reason besides warmer temperatures. Could it be the winter blend fuel?

 

I also run E0, but we can only get it at 91 Octane in my neck of the woods. I can tell you I've had this "fishbite" surge since day one, regardless of the season. Lower octane fuel makes it worse, which is why Scooby's data on timing being pulled makes sense to me.

Do you guys think the engine could be switching over to OTTO mode under increased throttle demand/load at the point that the timing is pulled? I mean, almost 12:1 compression ratio on 87 Octane??? I know that direct injection would help mitigate this... thoughts?

Frank

 

I think so Frank, but I have not confirmed yet. Agreed on the direct injection as far as detonation is concerned, but there are other "burn rate" related reasons for retaining the timing when switching to Otto.

 

The only E0 fuel here in Connecticut is race fuel. Not dropping $10+ a gallon for this