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Discussion Starter #1
Greetings all...I have a 2006 Tacoma 4dr, 4.0. When accelerating around 2000 rpm it feels like I am letting off the gas in a perfect 1 or 2 second rhythm until it gets around 2500 then it's fine. No trouble codes and the dealer can't find anything wrong. If it runs out of closed loop the issue is gone and it runs fine. Any help from anyone who may know what this could be would be great. My only option is to start replacing stuff like the throttle body or fly by wire accelerator pedal.

Thanks everyone,
Chuck
 

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I would say it sounds like the throttle position sensor in your throttle body assembly or the throttle body motor (same assembly either way). The dealer should have been able to monitor the throttle position sensor voltage and see it jump or not. I would try to look at a graph of the live data stream for that sensor to see if it fluctuates while you drive it through that rpm range.
I suspect it is that because you say "If it runs out of closed loop the issue is gone and it runs fine". When in fail-safe mode the throttle actuator motor is cut off and the throttle return to 6 deg. and then relies on fuel injection and ignition timing based on the pedal angle to operate if driven slowly. They can be bad and not trip any codes, you could also wait till it worsens to see if it does throw a code but who knows if or how long that could take.
 

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Discussion Starter #3
Thanks for your reply. I was hoping the dealer would figure out that is what it was but when they drive it they say they can't get it to fluctuate. I am so used to it I can make it do it every time and when i drive it the dealer tec will say..yea, I feel that too but offers no suggestion as to what it might be.

I will ask if they can graph the live data when I drive it to see if it is the TPS. It fluctuates about 100 rpm back and forth until I reach about 2500 or goose it and make it stop. If they can't see it in the data I will order a throttle body, they aren't too expensive aftermarket.

Again, thanks for your help. I will post a follow up...
 

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Well...I replaced the throttle body but no change in the condition. It still has the same rhythmic 100 rpm or so fluctuation between 2100 and 2500 rpm. Really strange??

My next attempt would be either the accelerator pedal (electric) or the ECM. The dealer still says it's not a drive-ability issue but I can't see why as it's very noticeable. If I go up a long hill and can keep the rpm in that range it will do it for a mile.

If I accelerate hard it will not do it at all. If I disconnect a sensor such as the air/fuel sensor and it goes into open loop it will not do it either.

Unless anybody ha a better suggestion I will buy an accelerator pedal or used ECM and try that next.
 

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Discussion Starter #5
So I thought I would update this post...

Still no answer to my stall/miss/hesitation issue between 2K and 2500 rpm.

Since last I have replaced throttle body, accelerator pedal and also the ECM with no difference in issue.

Still no CEL and no pending codes.

Next plan is to one by one replace coil pack and matching spark plug until I have tried all 6.

Any suggestions welcome...lol

Good news, I did find how to replace ecm and program old key without dealer help and free!!
 

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Discussion Starter #6 (Edited)
OK, A follow-up post after a year of troubleshooting my miss/surge at 2000~2500 RPM with no CEL ever...

So my local dealer never could figure out my surge/hesitation between 2000 and 2500 RPM. In my own mind I ruled out the fuel pump because it ran fine in open loop and also ran fine at all other rpm's even under a load. After replacing the TB, A/F sensors, removing cat's for test, spark plugs, ECM and accelerator pedal I decided I would take it to a dealer an hour away for a second opinion. Took the truck to Pearson Toyota in Newport News. Now I don't like dealerships so keep that in mind..

There I was greeted by a very nice service adviser who teamed me up with a Tech. The tech heard out my long story and then we went for a ride where he asked me to drive and duplicate the issue. Same as the other dealerships.. Then he took my truck along with another tech and they went for a ride to read all the sensors. 30 minutes later they sat down with me and showed me the pages of data that all pointed to the fuel pump. Surprisingly it was fine until 2000rpm then dropped off pressure and that's when the surge started. At 2500 it was fine again... After a year and many trips to the dealer it took this tech less than 10 minutes to correctly diagnose my problem. $120 diagnostic fee which I was more than willing to pay and off I went.

The repair...Bought a Denso replacement pump from Amazon for $98, came with filter and was exact match to OEM. Took me right at 45 minutes to drop the tank (very easy), replace the pump in the existing module and reinstall the tank.

Truck runs perfect......
 

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Great troubleshooting.
My Tacoma does the exact same thing at 180k miles.
Would you still have the part number from Amazon or a link?

Much appreciated.
 

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Hey Nutsy, crazy that you live in the Hampton roads area and you’re having the exact same issue I’m having. I’ve actually taken my truck to Pearson a couple of times for the same hesitation during acceleration issue. They’ll just tell me it’s a hiccup that’s specific to my truck. My response is, it hasn’t always done this, I didn’t notice it until after about a year of driving and around 150k miles. Things I’ve tried: replacing spark plugs, fuel injector cleaner, MAF sensor, PCV valve, check and replace bad fuses, disconnect battery and reset computer and nothing has fixed my issue. I wanted to drop the fuel tank and replace the pump and filter last. My question is, to replace that fuel pump and filter how hard was that? How long did it take? Thanks so much for your help!
 

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OK, A follow-up post after a year of troubleshooting my miss/surge at 2000~2500 RPM with no CEL ever...

So my local dealer never could figure out my surge/hesitation between 2000 and 2500 RPM. In my own mind I ruled out the fuel pump because it ran fine in open loop and also ran fine at all other rpm's even under a load. After replacing the TB, A/F sensors, removing cat's for test, spark plugs, ECM and accelerator pedal I decided I would take it to a dealer an hour away for a second opinion. Took the truck to Pearson Toyota in Newport News. Now I don't like dealerships so keep that in mind..

There I was greeted by a very nice service adviser who teamed me up with a Tech. The tech heard out my long story and then we went for a ride where he asked me to drive and duplicate the issue. Same as the other dealerships.. Then he took my truck along with another tech and they went for a ride to read all the sensors. 30 minutes later they sat down with me and showed me the pages of data that all pointed to the fuel pump. Surprisingly it was fine until 2000rpm then dropped off pressure and that's when the surge started. At 2500 it was fine again... After a year and many trips to the dealer it took this tech less than 10 minutes to correctly diagnose my problem. $120 diagnostic fee which I was more than willing to pay and off I went.

The repair...Bought a Denso replacement pump from Amazon for $98, came with filter and was exact match to OEM. Took me right at 45 minutes to drop the tank (very easy), replace the pump in the existing module and reinstall the tank.

Truck runs perfect......
Finally a possible answer to the issue I am having with my 2007 FJ Cruiser. The problem is exactly as you have described. I first noticed it before warranty was up and of course the Toyota Techs couldn't fix it. I have 118,000 miles on it now, its been doing it since about 32,000. I am going to change my pump and see if it fixes it. thanks you!
 
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