Engine Surging, Help Please!

Well, here's a new one for consideration. I had a plan for when I got home tonight of pulling coil packs and plugs and looking at condition even though the plugs are only 8k miles old. I noticed though, that there was old(ish) oil trails from the coil packs on 4 of the 8. Sure enough as I pulled those out they were dripping in oil. So I will continue with that problem and replace the valve cover gaskets and O-rings and clean or replace spark plugs as needed. Hopefully this will fix my problems. I will post some pictures of what I am seeing as I go so anyone can check for the same indicators.

8MINT8, I did call Toyota of Dallas and they advisor I talked to was awesome, but at the same time didn't know what an FFV Flash was. What he did say was that with a problem like this that seems pretty big and elusive, the shop manager would want to take it on himself for diagnosis. I am with you on the ECU being part of the issue , but the more I dig into this truck the more problems I find. Once I get the mechanical issues figured out I'll eliminate other issues before they happen with a D.A.P Tune.

 

@BTBAKER can prob help you out. He had same issues before toyota did the ffv update.

 

The flash worked great. My engine thought it was running 90 percent ethanol. I’ve had no issues since.

 

I have found several problems during this process and have been fixing them as I go. The biggest being that 6 of the 8 plug ports had oil in them. I have fixed that issue and im moving on.
It is significantly better feeling now, but there is still the occasional "bump" around 2500 RPMs under light load at highway speeds (when it is maintaining 75 up a slight grade type of load).

Being that the reflash of the ECU is not something that I can do myself, what did Toyota charge you to do it? I am going to check a couple more things out, mainly for peace of mind, but I think it is heading to a flash.

 

It was free but I was also under warranty.

 

I called the local dealer and it is about $300 to flash it. I can have them run the diag on it first for $150 to verify the problem can be corrected this way and if it can the price of the diag will roll into the repair. I am talking with Shrek at DAP Tuning now to see if their tune will correct the problem. I'd rather pay a little more and get a lot more. The fuel pump problems in this thread have me concerned I am going down the wrong path and that I am going to waste a solid amount of $ so I am probably going to shell the $150 out for a diag either way.

 

If you don't know what the problem is and can't take it to a reputable shop the next best thing you can do is start getting your regular maintenance up to date (filters, fluids, plugs, fuels system service).

Having said that, I don't think a dirty sensor or bad plugs would behave like this. It's too cyclical. RPM normal, rpm dips, rpm normal, repeat at a regular intervals while still acellerating. The truck speed doesn't noticably change because the torque converter is not locked up while you accelerate up the hill so it seems to be performing normally also.

This sounds more like it would be caused by inconsistant parasitic power loss from an engine accessory (alternator, powers steering pump, a/c compressor, etc). I would expect it to be an electrically controlled accessory (alternator or a/c compressor).

Did you have your air conditioner on while you were towing uphill and does it cool the truck well when it's hot outside?

If your a/c is low on refrigerant (134a) the low-pressure switch will cause the a/c compressor turn off shortly after turning on. Then when the refrigerant pressure normalizes across the expansion valve the low pressure switch will deactivate. That allows the compressor to turn back on and pump the refrigerant from the low-pressure side to the high-pressure side. Low side pressure gets too low and the low-pressure switch activates again to turn off the compressor.

I've seen a/c compressors cycle on and off at about that frequency when they are low on refrigerant. The 100 rpm drop is pretty consistant with a a/c compressor turning on too.

That's where I would start looking if my truck was doing this. Hook up the trailer and take it up a steep hill with the a/c on max. If it starts surging turn off the a/c and see if the surging stops. If so have a reputable shop check your a/c system pressures both with the a/c on and with it off.

I also thought initially it could be the Idle Air Control valve, but that wouldn't be a factor when the engine is under a load while towing.

Good luck.

 

Ihave new information so I figured I would update this thread with it. I took the truck to Toyota expecting to have to get it reflashed. They had it for a total of three days for the third day I took it and drove it until it was heat soaked and the "surging" was happening regularly. I drove to the dealer, tech jumped in and we went for a drive. He had hooked it to the computers and checked just about everything he could check and hadn't seen a problem at all. I got it to surge and he couldnt really tell, so I had him drive. He still couldnt really tell what it was or what the cause could be. We went back to the shop and I told him to humor me and put a fuel guage on it, and then I left. While he had the truck he put a pass through buage on it and sure as hell the fuel pressure was surging/dropping pressure around 30psi while driving. The FFVs should be around 45-50psi, but the truck wont throw codes until its down around 25psi and causes other low pressure failures.

So, my truck has a bunch of new parts so far and its about to get the last one for a while. I will change the pump myself and if you dont see me in this thread again, it worked.

 

I found the answer to this particular issue.
The fuel pump is a low speed/high speed pump
If you can bridge the low speed fuel pump resistor to where the pump is always in high speed mode and the hesitation stops.....there is the issue. it’s the pump
Changing mine next week even though the stealership said the pump was fine.....not sure how they would know without testing the fuel pressure under load since they tested it in the garage...

 

Had this exact same exact problem with my truck starting in January 2021 that slowly kept gettin worse. Between 2200 and 2700 rpm during acceleration it would pulse/miss/surge ... whatever you want to call it. Between this Tundra forums and a couple others I noticed it's a fairly common problem with the first couple year models that had flex fuel somewhere in the mid 100,000's mileage wise. I'm at 186k. Thanks to those who posted - it probably saved me a few trips to the Toyota dealership and lot of money going down the laundry list of all the "let's make sure it's not this" bs (maf, computer reset/re-flash, O2 sensors, spark plugs, spark plugs wires, ect ect ect) before they finally dropped the tank and changed out the fuel pump. First thing I did was buy an OEM fuel pump online and the local COOP station guys changed it out for $200. Problem solved. Hope this post keeps someone else from wasting the time and money too.

 

2010 Toyota tundra 245,000 miles. Start up, the truck surges. Engine revs and whines like a jet engine. The tachometer fluctuates as the surging happens. Step into the gas and nothing…. And then it engages. After it warms up it runs like a top. But this happens every time the truck starts up again. Someone suggested it happens until the catalytic converter warms up!?!?
I’m reading this thread and I seem to have the same issues. I changed the oil and then started coding. had to have both air injectors replaced, still coded. Cleaned MAF and throttle body per instructions.looked for vacuum leaks. Nothing. Anyone consider replacing the air shifter. Gonna give it to the mechanic for a couple days and let him feel it in person. Most frustrating thing ever!!!