Bad Torque Converter?

[djpope09]

I have an 04 V6 4x4 with 224k miles. I've been nursing it along with poor mpg for a while now because we mostly drive it around town. High gas prices have me chasing down the potential cause now and I would like to drive it farther without wasting money when the gas mileage should be better.

The main issue it has occurs at highway speeds while cruising when any sort of hill comes up. If the road is flat or downhill this doesn't happen. I'll be cruising at say 60mph and <2000rpm, start going uphill and I get a bouncy misfire feeling until the torque converter lockup clutch releases and the engine speed goes up to ~2300rpm. Usually this takes enough time that I've slowed down quite a bit so the transmission has to downshift from 4th to 3rd.

If cruise control is on, the truck tries to speed up to get back to the set speed, but it usually overshoots the set speed before upshifting and settling back down. If it's a long hill this happens multiple times in a row. I can baby it uphill without cruise control and it's not so bad, but it's killing my gas mileage. I'm getting about the same mpg in city driving as I am highway driving.

The other issue happens when the truck is stopped in Drive. When I release the brake pedal, the truck doesn't creep forward at all. It doesn't roll back when stopped facing uphill though. I have to use the gas pedal to get it moving.

I don't have any fault codes so I don't think it's a bad solenoid. I thought maybe it was a real misfire even though I don't have any misfire codes. I went ahead and replaced the fuel injectors which improved the gas mileage, but the misfire feeling is still there at highway speeds on hills. It's not as bad as it was, but it's still there.

What do you guys think? Is it the torque converter lockup clutch, do I need to replace the torque converter? Is it an ignition coil causing a misfire that the OBD system isn't picking up?

**Edit to add that I have done at least 5 drain and fills of the transmission fluid with the last one being maybe 10k miles ago. I also tried ShudderFixx with no change.

 

[waypoint]

What trans fluid did you use for your refills?

This doesn't read like the usual shudder complaint associated w/ bad fluid causing TCC lockup problems.

Can you scan it and report some data:

• 
  LTFT % for both banks during hot idle, cruising, and accelerating uphill
  Misfire counts by cylinder (may be misfiring but not enough to light a code)

Edit: also, what injectors did you install? New factory injectors from a Toyota dealer, third party "rebuilt" injectors, other? I had horrible experience on my prior Tacoma using "rebuilt" injectors which turned out to be chinese knockoffs. Minor cosmetic differences between them any my factory injectors, and when I finally removed them and had them flowbenched they were all over the place with one dribbling constantly.

 

[djpope09]

Thanks for the feedback waypoint.

To answer your questions:

I used Toyota T-IV fluid, it's the recommended fluid for the 4 speed A340F transmission.

I've checked LTFT during multiple driving conditions and it's around 0-4% on bank 1 and 7-9% on bank 2. I'll pull this information again during the conditions you listed and report back. That will probably have to wait until Friday or Saturday.

I swapped the A/F ratio sensors to the opposite sides back in November just to see if one was measuring higher than the other. The LTFT didn't change, but the sensor that had been on bank 2 and was now on bank 1 went bad not too long after that and started reading 30% LTFT so I replaced it with a Denso sensor from Amazon.

This might make you facepalm, but I bought the injectors from CS Performance Injectors on eBay. They're remans, but are supposedly flow tested and matched as a set. They mention the Chinese knockoff issue in their listings and claim to only use genuine OEM injectors. I've only had them installed for maybe 2 weeks, but fuel economy is ~2mpg better in both city and highway driving. I did a 500+ mile road trip last weekend without any issues. I checked the LTFT after installing the injectors and it was the same for both banks, but I haven't checked it since then. Cosmetically, the injectors are the same as the OEM and they didn't require a core, so I kept the OEM injectors to potentially be rebuilt or flow tested.

I'm using the TorquePro app to scan for codes and check for LTFT. As far as I can tell it can't scan for misfires. Any recommendations for a scanner that can? Would Autozone have one that I could rent?

 

[MikeinNH67]

I've used Torque Pro to watch misfires on a Ford so it should do a Toyota too. It's a bit odd to find though, it's one of those sections that takes forever to load as there's so many PIDs in there but then you can search for it after loaded if I remember correctly. I think there's videos on YT, try this one.

https://www.youtube.com/watch?v=RZ_DLBQN548

 

[djpope09]

I've used Torque Pro to watch misfires on a Ford so it should do a Toyota too. It's a bit odd to find though, it's one of those sections that takes forever to load as there's so many PIDs in there but then you can search for it after loaded if I remember correctly. I think there's videos on YT, try this one.

https://www.youtube.com/watch?v=RZ_DLBQN548

Thanks for the link Mike. I looked into this a while ago, but most people are only interested in temp values, not misfire. I added the gen 2 Prius PID for misfire to my app, but thought it wasn't working.

I'll try it the way this guy does in his video and let you know if it works. It's only for an overall misfire count, but that should be enough to tell me if it really is misfiring.

 

[waypoint]

Just based on a quick search, CS Perf seems to be a reputable company. If the injectors really came from them, they're not likely the issue. Also not likely your trans fluid is an issue.

I use ScanTool MX with my iPhone, and it can report individual cylinder misfires.

But...based on your road trip report it sounds like it may be fixed? LTFT imbalance is noteworthy but not a red flag, grab fresh LTFT data under the various driving conditions.

How certain are you that the Denso air:fuel sensor from Amazon is authentic? I've had issues there with counterfeit parts sold through Amazon, but by external vendors. What actual vendor fulfilled your order, and how reputable are they?

 

[djpope09]

Just based on a quick search, CS Perf seems to be a reputable company. If the injectors really came from them, they're not likely the issue. Also not likely your trans fluid is an issue.

I use ScanTool MX with my iPhone, and it can report individual cylinder misfires.

But...based on your road trip report it sounds like it may be fixed? LTFT imbalance is noteworthy but not a red flag, grab fresh LTFT data under the various driving conditions.

How certain are you that the Denso air:fuel sensor from Amazon is authentic? I've had issues there with counterfeit parts sold through Amazon, but by external vendors. What actual vendor fulfilled your order, and how reputable are they?

This is the Denso sensor I ordered:
Amazon.com: Denso 234-9047 Air Fuel Ratio Sensor : Automotive

I don't think that's the issue since the sensor I replaced was showing LTFT of 30%. After I installed this sensor on that bank is back down to 0-4%. And the performance and mileage didn't change afterwards. Edit to add that I did just notice the listing says the sensor is from China so it's a knockoff for sure, but it does seem to work fine.

I have Android and it looks like that app isn't available for me. I'll try to find a misfire with Torque Pro and if that doesn't work I'll look for another scantool that can find individual misfires. And I'll get that LTFT data as well.

Thanks guys.

 

[diverscale]

does the truck rolls freely in neutral? like, you can push it by hand?

 

[djpope09]

does the truck rolls freely in neutral? like, you can push it by hand?

I haven't tried that. Are you thinking the brake calipers are stuck? I replaced the front calipers a few years ago with Napa parts and I replaced the rear rotors and pads maybe 18 months ago. The calipers weren't seized so I left them on.

I was thinking recently that I should pick up an infrared thermometer to see if any of the brakes are hot after driving, but I haven't done it yet.

 

[djpope09]

I checked out my LTFT over the weekend.

Hot idle: LTFT1 = 3.91%, LTFT2 = 7.81%
Cruising: LTFT1 = 4.69%, LTFT2 = 6.25%
Accelerating uphill: LTFT1 = 4.69%, LTFT2 = 4.69%

The LTFTs seem to be similar during acceleration and usually close during cruising. During coasting they tend to be more than 5% different. I never saw LTFT2 above 8% though so I'm not overly worried about it.

The engine still bogs down when trying to drive up hill until it can release the TCC and by then it needs to go from 4th to 3rd before it has enough power to accelerate up the hill.

I tried out the prius PIDs in Torque Pro using the method from Mike's link. I was able to get the Misfire monitor to read -1.0 which it didn't do before, but the Vehicle Test Results section didn't show anything about misfire. I'll need to find another way to look for misfires.