HELP! Lagging Acceleration. Intermittent.

That's a good point, OP check your VVT-i pre-filter baskets too!

The right head one is stupid easy to remove and inspect, the left head... Not so much.

But whatever condition the right one is in should closely approximate the left.

 

Thanks a ton. Had a friend of a friend who is a full time mechanic ride with me with a high end computer from his shop. Nothing stuck out and fuel trims both looked good. The only thing is he thought the catalytic converter was running hot and may be clogged. Above 1300 degrees F.

I asked him about vvt and didn’t that would be it but I’ll pull mine and check anyways. He also didn’t think fuel pump with the fuel trim looking good but we plan to hook a gauge up to both pump and catalytic converters to check.

thanks a bunch everyone as any suggestions gives me a place to look!

 

It won't be the cats. Those go up to 1500* in some instances.

Upon visual inspection you won't notice anything wrong with the VVTi's. When you replace and retest though, you'll see the immediate change in drivability, if you have eliminated all the other variables.

 

Ok. You are suggesting grabbing 2 new ones, pulling and replacing. Cleaning filters/baskets and give her a go?

thanks a ton, hope is renewed.

 

I am having a similar issue with my MT '15. My clutch release point is the same, but I have no power when I get on the gas until it is over 3k RPM. It seems that for most regular driving I am bout 1k RPM over what I would say was "normal" before this started. Issue has been present before and after an oil change and new air filter. I cleaned the MAF and the throttle body and would say there was a marginal improvement. At this point I am having to avoid the highway since I cannot get up much above 40 mph before the end of the onramp.

-=mte=-

 

I wouldn't even bother with the screens. It's a parts electronic issue and I know that based upon your intermittent symptoms.

Plus if you have been great on maintaining your oil changes between 5-6K mile intervals, there is no reason for the screens to be an issue. If you or the previous owner was not good about it or there is a question mark in between ownership (unless you are the first owner) I personally wouldn't touch them.

If everything rules out okay and your fuel pressure is good, give it a shot. You are at the average failure mileage for those junks and the worst slap in the face about it is that the PCM does not pick up the failure. It certainly did not for myself and has not for many other members.

 

One more thing. Since you have access to a scanner, hook back up and inspect mode 6 data for the cats on both banks. If either are bad, they will indicate a value below the MIN specified value. If they do, then in my opinion do you have sufficient reasonable doubt to go in and take pre and post pressure gauge readings. Otherwise, it's a waste of time.

 

@12TRDTacoma Awesome, thanks for this info. Just took a drive and had him monitor the VVT - they were not in sync. One would go one then off while other one stayed on and vice versa. Not sure if thats the issue.

First, Im checking fuel pressure - I looked around but couldn't get a clear understanding of what the fuel pressures should read - anyone have this info handy for a 12 Tacoma 4.0 6L 2WD Auto?

 

41 - 42 psi is what it needs to read, but based on your issue. You need to make sure it stays steady when the issue is occuring.

The lack of sync makes me raise my eyebrow. It only further makes me think they are indeed the issue, but I never checked my issue with the scanner so I couldn't tell you, OCV's are finnicky to diagnose and I've never had success using digital PID info when determining if they are bad or not.

 

Feel free to ask any Q's if you're going to do that job.

My guess is that the actuators are weak - they operate on an electric solenoid. New, thicker oil makes the problem worse. After some time when the oil thins a bit they start working (mostly) properly again.

 

@12TRDTacoma I puled them and they moved great when hooked up to voltage. Do you still think I should go ahead and just replace? OEM from toyota is $140 each but Ive seen some Duralast for $80 a piece. Thanks again.

No luck with fuel pressure as the gauge I rented didnt have the proper fitting to secure to fuel line.

 

Before you replace them you need to ensure fuel pressure is okay. If not, replace them. Testing them is just as reliable a test as testing EVAP solenoids. It doesn't mean shit. Hahaha.

You have pulled your TB to clean the blade and opening and such right?

 

10-4 - TB is good to go. All clean. I pulled the VVT today just to see what Im working with - very easy. Will report back on fuel pressure before spending the couple hundo on VVT replacements. Hoping it is just VVT! Thanks!

 

Make sure you tee into the fuel supply line and do not dead head the pump. The pressure regulation is at the other end of the fuel rail where the excess is dumped back to the tank. If dead headed you will get a false high pressure.

 

@Jimmyh Thank you - does anyone have any suggestions for a kit that will fit the fuel line? The nipple on the T is to big to get to secure into the fuel line that has the snap on clap. I didnt want to force it in there but no way it was going to fit. I went and looked at 3 other kits from Napa and Autozone and all had same exact T joint. I must be missing something.

 

The below T is on every pressure test kit I looked to rent. It will not fit the fuel line that has the adapter. Also, maybe Im just an idiot and there is another way to get them to securely sit together. Thanks again!

 

Im having the exact same issue as you are on my 12 tacoma offroad v6 auto, I have been chasing this issue for quite some time now cannot duplicate it at first i kept saying it is something with my brakes dragging but still cannot say they arnt. However no signs of pads wearing weird, tires spin normal off the ground, everything up front is pretty much new all within the last 5-7k miles " new wheel bearings, LCA's new steering rack, all poly bushings on rack and sway bar, new cv shafts JBA UCA's Toytek alumi coils ECGS 4.56 gears completely assembled by them i installed, all pro 3" leafs with firestone air bags on daystar cradles..

Enough of that I have been monitoring via techstream with nothing popping up as abnormal fuel trims all close to zero, fuel pressure numbers Im not sure about i have the urd tap and monitor it all the time in the mornings first thing its at 40-41psi, start driving it sits around 38psi if i stomp on it jumps up to 40psi however when this unknown happens randomly the fuel pressure doesnt change one bit.

I just got in today new Oil control valves i am going to throw in this weekend i have previously checked and cleaned the screens which were clean

Have a new MAF, all new ignition coils and plugs put in last weekend, all new vaccuum hoses, no MIL's it seems that if I reset the ECM via techstream and relear the YAW sensor the truck will run fine for a day or so and then go back to having isssues, However i have done it before and it made it way worse,

Im hoping this OCV will do the trick cuz im out of ideas/ things to try....

And im sure I missed other things i have tried to fix this issue and if anyone else has some insight on my numbers and things i tried please let me know so i can try them....

 

BRUTAL DUDE! I am getting the OEM VVT this morning and dropping in right away. The one thing I did notice on the computer was the VVT were not in sync. I.e. one would go on then off and other would stay on or vice versa etc...

Ill report back by this afternoon to see if this gremlin is gone. According to this forum as well as a trusted nearby import auto shop, everyone points at VVT. I even spoke with a dealer tech and he said flat out "Not your fuel pump or pressure, you would get a stall out or no start at one point over past several months"

Who knows, but again I really appreciate everyone jumping in here and helping out. Long live da tacossss!

 

All right, installed new OEM VVT - first 5 minutes it was like a new truck. Moments later back to complete shiiiiiiz. Serious lag in acceleration, delay from pedal to it going, at high speeds wont maintain RPM's and need more power to stay at speed. Sluggish is the best way to describe it.

According to Toyota tech, he said the fuel pump would just fail not run weak. Also said I would have had a stall or other issues since its been going on for 4 months.

Lord help me.

 

I knew it wouldn't be VVT.