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2012 Tacoma V6 auto engine brake

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Old 06-16-2012, 11:39 PM   #1
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2012 Tacoma V6 auto engine brake

I didn't notice anyone mentioning a new feature in 2012 Tacoma V6 automatic transmission: engine brake (some type). I'm not talking about automatic downshifting and that's it, that is not engine brake, is just a way to mess the transmission. I'm talking about a device which creates a back-pressure in the engine or something like that.

If you look inside engine compartment towards passenger side fender there is a new "thing" installed, which is connected with a small rubber pipe somewhere in the engine. The strongest feel of engine brake was around 40-45mph (65 kmh) going downhill and if I would press the brakes continuous for like 4-5 seconds transmission downshifts and I felt a strong braking force, much stronger than just a simple downshift, and the truck was holding around 50mph, without me touching the brakes. Also, a slight touch of engine brake was almost always available when approaching stops.

All good for 6 month then ... don't know what happened, going down same hills doesn't even want to downshift, and if somehow does it feels more like a simple downshift, just the transmission keeps me back.

Anyway, does anyone knows how this "thing" works, or is just my truck weird? (or me... )
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Old 06-16-2012, 11:55 PM   #2
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I think that " Thing on the passenger side " is the evap system check pump. It has nothing to do with the imaginary " engine brake thing " that doesn't exist.

:P
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Old 06-16-2012, 11:56 PM   #3
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That thing on the passenger side is emission crap Toyota put and the downhill asist is tranny doing engine braking
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Old 06-16-2012, 11:57 PM   #4
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Quote:
Originally Posted by Jimmyh View Post
I think that " Thing on the passenger side " is the evap system check pump. It has nothing to do with the imaginary " engine brake thing " that doesn't exist.

:P
Beat me to it
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Old 06-17-2012, 12:21 AM   #5
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Originally Posted by Wildlandtaco View Post
Beat me to it
Sometimes I'm pretty quick for an old fart........
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Old 06-17-2012, 03:52 AM   #6
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When you touch the brake the lockup converter disconnects that might be what you are feeling.
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Old 06-17-2012, 05:34 AM   #7
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That "thing" on the side of the engine is what makes my engine sound like a dentist's drill on startup and has people running away from my truck...It's particularly badass sounding driving through the parking garage with that high pitched noise going off...

One day turn your truck on in the morning and immediately turn it off and you can hear the pump pushing air into the exhaust...
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Old 06-17-2012, 06:19 AM   #8
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That is the #1 reason I didn't want a 2012. When that air injection fails on a Tundra it's only about a $4000 repair - and it'll stay in limp mode until you do it.
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Old 06-17-2012, 06:21 AM   #9
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Quote:
Originally Posted by cintocrunch View Post
That "thing" on the side of the engine is what makes my engine sound like a dentist's drill on startup and has people running away from my truck...
Yes, I heard that "dentist drill" from the first day. First of all, can you tell me the name of the "thing"? Second, do you know how is working, what is for?

Thanks!
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Old 06-17-2012, 06:22 AM   #10
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Quote:
Originally Posted by iroh View Post
That is the #1 reason I didn't want a 2012. When that air injection fails on a Tundra it's only about a $4000 repair - and it'll stay in limp mode until you do it.
Its only on the sport model not off road at least I don't have it.
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Old 06-17-2012, 06:26 AM   #11
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Originally Posted by andrew8404 View Post
Its only on the sport model not off road at least I don't have it.
hmmm mine does
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Old 06-17-2012, 06:29 AM   #12
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I have a Texas made TRD offroad and I have it...
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Old 06-17-2012, 06:32 AM   #13
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I have a Texas made TRD offroad and I have it...
Mine says Baja CA but made in Mexico
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Old 06-17-2012, 06:38 AM   #14
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Quote:
Originally Posted by daopi View Post
Yes, I heard that "dentist drill" from the first day. First of all, can you tell me the name of the "thing"? Second, do you know how is working, what is for?

Thanks!
Air injection pump. It pushes fresh air down the exhaust at engine startup to light the cats faster and reduce startup emissions. That's the only time it's active.

Why I don't like it...

The failures on the Tundras was caused by a) the inlet tubes pulling from the fenderwell which b) the pumps on engine start would blow all the water that somehow kept getting into the system to the control valves on the back side of each cylinder head, resulting in c) those two valves rusting open allowing exhaust to blow backwards to the pumps and destroying them.

People who experienced this were shocked to find that the 5.7L engine has two of these puppies and each one is nearly $1400 from the dealer. The GM version of these things only costs in the neighborhood of $150, hence the shock. Once you add in those two valves that rusted, and labor, it's almost always more than $4000. Its frickin cheaper to blow the transmission.

Not only that but to prevent fire from exhaust going up those hoses the computer would limit throttle to a very low level and set the redline at about 1800 rpm as long as those valves were stuck open. Might as well be rolling around in a 5.7L moped.

There was one trick fix someone found. When the intake air temp is lower than something like 37 degrees F the injection system won't start because it would cool the cats more than the fresh air would help. He whacked the control valves on the heads until they'd close, and then soldered up a control board that would interrupt the signal from the IAT sensor and send a false reading of 20F whenever the starter was cranking plus a few seconds. The air pumps would never start, the PCM would never open those valves on the heads, and nothing needed to be unplugged (which ironically if they were would result in limp mode just like the failed valves). Reset the battery to make the PCM forget, it wouldn't go into limp mode on next start and think all was well.
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Old 06-17-2012, 06:39 AM   #15
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So the DAC has a jake brake? Wish it sounded like one...Although that would be a funny sound to hear a Tacoma making...

Matt
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Old 06-17-2012, 07:00 AM   #16
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Quote:
Originally Posted by MGMTacoFF View Post
So the DAC has a jake brake? Wish it sounded like one...Although that would be a funny sound to hear a Tacoma making...
Looks like it's only "joke" brake...
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Old 06-17-2012, 07:11 AM   #17
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Mine says Baja CA but made in Mexico
Mine is made in Baja too weird.
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Old 06-17-2012, 07:14 AM   #18
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So my truck is now 7 months old. Few weeks ago I started to hear the "dentist drill" sound while I was driving around 40-50mph going downhill or flat with not much acceleration. The sound was not continuous, was on and off. The noise was there for like a week, and gone. After that two things changed: going downhill doesn't want to downshift, and second, going uphill or harder accelerations make a strong smell of exhaust or something, to come in the cabin. And I'm saying strong, I almost need to crack the window.
Anyone had same experience?
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Old 06-17-2012, 07:26 AM   #19
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Quote:
Originally Posted by iroh View Post
Air injection pump. It pushes fresh air down the exhaust at engine startup to light the cats faster and reduce startup emissions. That's the only time it's active.

Why I don't like it...

The failures on the Tundras was caused by a) the inlet tubes pulling from the fenderwell which b) the pumps on engine start would blow all the water that somehow kept getting into the system to the control valves on the back side of each cylinder head, resulting in c) those two valves rusting open allowing exhaust to blow backwards to the pumps and destroying them.

People who experienced this were shocked to find that the 5.7L engine has two of these puppies and each one is nearly $1400 from the dealer. The GM version of these things only costs in the neighborhood of $150, hence the shock. Once you add in those two valves that rusted, and labor, it's almost always more than $4000. Its frickin cheaper to blow the transmission.

Not only that but to prevent fire from exhaust going up those hoses the computer would limit throttle to a very low level and set the redline at about 1800 rpm as long as those valves were stuck open. Might as well be rolling around in a 5.7L moped.

There was one trick fix someone found. When the intake air temp is lower than something like 37 degrees F the injection system won't start because it would cool the cats more than the fresh air would help. He whacked the control valves on the heads until they'd close, and then soldered up a control board that would interrupt the signal from the IAT sensor and send a false reading of 20F whenever the starter was cranking plus a few seconds. The air pumps would never start, the PCM would never open those valves on the heads, and nothing needed to be unplugged (which ironically if they were would result in limp mode just like the failed valves). Reset the battery to make the PCM forget, it wouldn't go into limp mode on next start and think all was well.
This is very good information. Most people aren't aware that the 2TR-FE has had these pumps since 2005 (i.e. all 2nd Gen 4 cylinder Tacomas). I had no idea that they were causing such issues, or that the pumps were so expensive.

Did the guy who bypassed the system do a write-up or anything?
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Old 06-17-2012, 08:33 AM   #20
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He did, but it's been a couple years since I've read into it so I don't remember what website it was on.

If the 2TR pumps haven't been giving issues that's a good sign. Many postulated that the Tundra issue was from poor placement of the pump inlet tubes.
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