HELP! Lagging Acceleration. Intermittent.

Does every Tacoma have VVT Pre Filter baskets? I couldn't see them when I pulled my VVT's.

 

They need a dislike button. What’s next?

 

Have you done a thorough visual inspection and wiggle test?

 

On what exactly? But maybe this is a joke. Lol. Any possibility it is an air intake clogged at the area under passenger wheel?

The filter looks great.

 

Can you pull the abs fuse on these trucks and get the abs system to shut down? My abs does some weird shit sometimes and cuts power. I wonder if yours could be messed up and not throwing a code.

 

Very serious - all the symptoms point to an electrical issue. You've replaced most of the components which could cause/effect this issue, therefore, the most likely remaining cause is the wiring harness and connectors. Get a good flashlight, and start in one area and follow each harness. Look for signs of abrasion and damage to the conductors, pop apart the connectors and look for corrosion. With the engine running, bend/wiggle every bit of harness every few inches, as well as every conductor going to every sensor.

If you find a damaged harness/connector/conductor, you've very likely found the issue. If the vehicle acts up during the wiggle test, you've localized the root cause.

A clogged air intake would be a constant problem, not an intermittent one.

 

Definitely dislike what I just read. I saw someone above mentioned ABS. You may want to check your brake switch. If it is engaging prematurely or delaying in disengagement, you may get some of those issues you are mentioning as well. Have someone check your brake lights as you take off and make sure they still aren't on. If that tests out good, then check it digitally. Logging it's PID data against RPM data.

 

Thanks again for the replies still coming thru!

I really dont think its brakes related as when Im going on highway it is def lacking power and Im not pressing the brakes at all. I will check these tho as I got nothing left. Thanks @12TRDTacoma

@tirediron I will also go look at every electrical connection point. Issue is that at idle its perfect, I will give it a go tho and see what happens.

 

That definitely makes it more challenging, and it may lead to naught, but this seems to be turning into a case of "When you've checked everything else, what is left, no matter how improbable, must be the problem!".

 

Reposting this one - I assume there are VVT prefilter baskets on this 2012. Can someone confirm so I can pull these as I didnt when replacing VVT.

 

the baskets are bolted into the head. One is located by the dipstick. It should be a 12mm bolt and the other one is behind where the alternator is.

 

One thing I can say is that when I dropped in new VVT this morning I disconnected battery. When put back together it immediately was like new and could burn the tires with a slight touch of acceleration. Aftera short 10 minute drive tho and stop at a light, I press the gas and back to issue.

Previously, I had disconnected battery and looked at every coil pack and again after battery disconnect for 20 minutes it was perfect but this time for a few weeks.

I have since tried to replicate the fix by disconnecting battery but doesn't work every time to fix the issue. This makes me think something computer related as well. Any thoughts?

 

It could be computer related, but generally a bad ECM is a little less random. This really feels like a wiring issue; a bad ground, partial short to ground that only occurs under certain circumstances.

 

Fuel pump relay? I swapped the relay to test something else and it was partially bad, causing the vehicle to drive erratically when accelerating

 

I swapped out my OCV last night they arrived early and so far so good but only out about 40 miles on her since then so we will see how this pans out fingers crossed

 

Well, now my eye is pointing at the air injection pump and secondary air valves. Funny enough, I had the truck in with Toyota in 2020 and supposedly they fixed the issue since it was a warranty extension or recall with the 2012's.

I left it with a 3rd well known mechanic this past weekend. He couldn't find anything asides from thinking that was culprit.

I plan to take it to the dreaded dealership tomorrow hoping they will confirm an issue and not be A holes. Considering it was a recall/warranty claim and been a year since the "fix" maybe they will be cool if indeed that part they know has issues and fails and "fixed" failed again a year later. Doubtful, but I have faith.

Any suggestions? Thanks everyone, this has been brutal to say the least.

 

How you looked at the throttle pedal? Since it's DBW, I wonder if it is on the fritz.

 

Fuel pump?? I've put this link in a couple other similar threads..might be worth taking a look at. This was my issue with acceleration hesitation. look at thread number 6
There's another thread somewhere here on tacomaworld with even more detail but i can't find it....but again was fuel pump issue.

 

Fuel pressure remained perfect between 41-42 at idle and accelerating. I think its the secondary air valves.

 

If the secondary air valves were open when they shouldn't be the 02 sensors would see a bunch of fresh air and that would be reflected in the trims. If the trims are normal while the problem is happening then the valves are likely fine.

The tech who mentioned the converters might be clogged may be on to something. You need an exhaust back pressure gauge, it threads into the 02 sensor hole. Anything over 1-2 lbs pressure is too much.