Need Some Assistance - 06 Injector/Idle Issue

Good Afternoon Tacoma World,

I'm currently experiencing an issue with my 06 Prerunner v6. I've had rough idle for a few weeks, especially at stop lights and the like. But under acceleration, it feels fine. I've been trying to make heads and tails of it, but I'm officially stuck. I have a P0201 trouble code which is an Injector 1 Malfunction. I thought it may have been the injector with some trash or what not, so I picked up a new injector and put it in. I tested the old one and it tested the same as the new one at 11.8 ohms. Cool. I put it in and reset the ecu and took it for a drive to see if the code would come back. It does, along with the rough idle. I disconnected the injector harness from the injector and it really ran and idled like it was on 5 cylinders, like really bad. I plugged it back in and it went back to the rough idle. ECU is firing the injector.

Well today, I caught a break with weather, I figured I'd test the wire harness from ecu to injector. I disconnected the wire from each end to test for a short to ground with no issues, even wiggling the harness on the engine side, everything tested good. I'm getting appropriate voltage on the one side and appropriate continuity. And this is what I don't get, for every test related to cylinder 1, I did on cylinder 3. Everything mirrored each other. The wires ohm'd the same. Both with no fluctuations when wiggled.

So with the injectors good. The wiring is good. The ecu is firing. I'm at a loss. I'm going take it for a drive to get it to cycle and see if the code comes back because the idle is rough still once it warmed up. Has anyone seen anything like this? Or maybe have an outsider's suggestion? Something I'm not thinking of? Any help is appreciated. Many Thanks!

 

Are you loosing coolant?

Could be a blown head gasket.

 

No. I don't think I'm losing coolant. And I haven't seen any white smoke coming out the exhaust and coolant reservoir has a good amount in it every time I look at it and the radiator is full. I've been adamant about checking coolant levels in the Louisiana heat and my fiance's truck just had it's radiator changed 2 months ago. I'll do a compression check to see if its low after work tomorrow. I would think that something like that would cause a misfire code and not an injector code. Power seems decent if I give it to her, just at idle it's wanting dip and get a little rough. Like the a/c compressor kicked on but it's already on.

 

Sorry I was thinking P0301 which is a misfire on cylinder # 1.

You may need professional assistance locating the source of the P0201...

 

*** Update ***

Hey Tacoma World,

I wanted to update everyone to my situation. Since I've last messaged/posted, I've done a compression test on all the cylinders, all 6 are good. I've swapped coil packs, no change. I've changed out the PCV, which was the original one from 2006, to a new one. No change. Between crap weather and traveling for work, that's all I've been able to do. So I took it to a local dealer and decided to let them check it out and just let the chips fall where the may. Whether it was a bad ecu or harness or what ever it may be that is causing the idle issue. I drop it off this past Friday to let them have a go at it.

Well I get a call yesterday, and they said that there is no injector issue, to come pick it up. The only thing they found was the 2 codes about my exhaust leaks, which I know about and need to get more gaskets. But that would not cause my idle to drop like it does and get rough, whether the clutch is in or it's in neutral. The only way I can describe it is that my usually engine idles from 750-850 rpms, roundabout. Right under the 1k mark on the tach. Well when I'm sitting at a stoplight, it drops to say 550 - 650 rpms. Just enough to get rougher and for me to notice. And a whole lot closer to the 500 rpm mark.

I'm glad that it wasn't a bad ecu or messed up harness, but it still doesn't help me any. Now, the dealer did ask me if I had an ecu tune on it, because of my mods, as they suggested that because I have modified it to where it is now and not having a tune on it, that's what is causing my idle issue as well as the o2 codes. Is there any validity to what they're saying, about needing a tune? I have a pair of DT Long tubes, a DT pipe bomb mid pipe, and a MBRP exhaust with a Magnaflow muffler added in to help with rasp. Also a K&N intake and URD o2 simulator. That's it. I'm second guessing myself and what I know at this point because in my past experience, an intake and exhaust system on a stock engine never made the idle lower or rougher, only deeper and smoother. Is the 1GR different in that regard? Or am I overthinking it, like I always do? Given my truck's age, I'd imagine that some of the vacuum lines are starting to crack and look bad. I know the PCV hose (driver side manifold to bank 2 valve cover) had a small crack that was about to leak or was leaking. I changed it out when I changed the PCV valve itself. I've also cleaned the throttle body and cleaned the MAF sensor as well. No change.

Also, I now can't trust my diagnostic program/tool anymore. I have an OBDII to serial to USB adapter that goes into my laptop and I have 3 programs that I use to check the CEL light. And 2 of 3 of those programs told me that the ecu had a P0201 code and P3701 code, which I don't know what that other one is. And the other program gave me the two codes for the exhaust, P0158 and P0137, which I know about and need to fix when the weather isn't crappy. I guess I will need to upgrade to something else, especially with my laptop's battery is just about dead. Any suggestions on a decent and trustworthy scan tool is appreciated as well.

I need to keep this thing running as long as possible, I can't really afford a note at the moment. So any ideas or suggestions to check out or what not, is welcome and appreciated. Thank you!

 

Well,
that post is a perfect storm...don't really know where to go here...but I'd start with the exhaust...seems some significant changes there.

And get your electronics up too speed as well.
Jeff

 

*** Update 12/3/2019 ***

Alright. Between work and weather and every weekend filled with some kind of event, birthday, or holiday, I believe that I have results. Sort of. I managed to drive myself crazy chasing exhaust leaks. At first, I thought it was the manifold gaskets then the collector gaskets then the header mid-ports. But with a shop vac creating positive pressure within the exhaust via tail pipe and some good ole soapy water, I confirmed it was the collector flanges. I still don't understand how they can leak so much with fresh gaskets. Alignment was good before and after install. But with the help of copper rtv, hose clamps, and some header wrap. It's ugly as sin but its not leaking after 1 week. Long term, I'll have to see about a different option. I also picked up one of those fancy Bluetooth OBDII scanners and it's miles better than lugging a laptop, serial adapter, and inverter every time I needed to look at a code.

Well it still showed P0158 and P0137 (lean), which is one bank is lean and the other is rich and both cause idle issues. It kind of explains the rough idle, 1 bank's afr is different than the other and they are fighting each other. To see if it was the rear sensors that was the source of my issue, I swapped bank 1 sensor 2 with bank 2 sensor 2. Same results, P0158 and P0137. I cleared the codes and left the rear sensors swapped, but unplugged the o2 simulator and it took a day to come on, several drive cycles, but they popped up still. No P0420 for no cats. On a hunch I swapped the front sensors, bank 1 to bank 2, and I got one code that popped up Sunday. P0138 as a soft/pending code. And this morning, its a hard code. But that's it the only code. And that's with the o2 simulator still disconnected. And that result makes absolutely no sense to me. I believe the next step is throwing a large sum of money buying 4 really expensive sensors and hope it fixes the issue. What says the community? Should I look at other sources of issues?

 

*** Update 12/9/2019 ***

Scratch everything I said. Well mostly. P0138 is gone but the P0158 and P0137 is back. No P0420. Exhaust is leaking again and I can not figure it out. I've tried the URD gaskets, factory style gaskets from Orielly's, even ordered some Remflex gaskets that I read good things about. Torqued it down to their specs. Still leaking. Hose clamps, header wrap, and copper rtv. Collector flange still leaking. Idle still funky. Engine and ECU still pissed off. I'm out of ideas. Tired of spending time on this as brakes and suspension need TLC. Welding the flanges isn't really an option. And I can't really afford a new truck note. If anyone has any ideas or suggestions, I'm all ears.

 

All else being equal, you have a warped manifold it appears. Remove it and have a machine shop resurface it.

 

*** Update 12/26/2019 ***

I hope everyone had a Merry Christmas. I wanted to give another update since the last in diagnosing my issue. No, it has not be resolved. I ordered some more URD donut gaskets. I also readjusted the exhaust hangers one the DT midpipe. I finally got the exhaust to seal. I pressured it up with a larger shop vac and sprayed soapy water everywhere. Header to engine, collector to mid pipe, mid pipe to rear exhaust. Zero bubbles. I then looked over the intake side of things. Took the filter off and put my boost leak cap on and pressured up the intake to about 2-4 psi. I then sprayed everything with more soapy water. Found a three small leaks, one where the PCV hose from the passenger side connects to the intake tube right before the throttle body and the other where the intake tube meets the throttle body, it wasn't seated correctly and leaked, and the last one was where the MAF sensor sits on the intake tube. Not sure why, but it bubbled when I pressure tested it. Fixed all of those and retested everything. All good, no leaks. Cleared the codes and stopped there. Didn't take it out for Christmas but I took it to work today and she drove great. Well leaving work this afternoon, the damn CEL came back on and its P0158 "Bank 2 Sensor 2 Voltage High" and P0137 "Bank 1 Sensor 2 Voltage Low." And it's still idling crappy. I don't think the dealer will mess with it being entirely aftermarket and there isn't an auto shop or exhaust shop around here that I trust to not gouge or rip me off. Does anyone have any ideas or new suggestions on what would cause those codes? I've read up on them and exhaust leaks fit but I've fixed those. Same with vacuum leaks. I don't have any fuel leaks or broken wires anywhere. Thank you in advance!

 

*** Update 12/30/2019 ***

Hey Tacoma World,

I had found the testing procedure for the P0158 code within the FSM so I spent all day yesterday checking out the wiring going from the o2 sensors to the ECU. And after checking all the wiring, I did not find any shorts or open circuits. Everything was within factory specs. So the wiring is good, all 4 brand new sensors are good, and the ecu is good. And that FSM test procedure points directly at an exhaust or fuel leak. I don't know how or what would be the best way to test the exhaust as I've tested it multiple times already using a shop vac to blow into the tail pipe and spray the entire exhaust to look for bubbles. And I've fixed all the leaks that I've seen so it doesn't make any sense. So I'm open to new testing procedures.

What does make sense, is that something is going on with the fuel system. Now, I may be spit balling, but would it be possible for a fuel injector to get clogged to where it would dump fuel but not throw an injector code? I ask and say that because I was reading about the fuel pressure regulator and how it is set up on our trucks and I came across a thread that said that injectors 2, 4, and 6 on bank 2 have a tendency to get dirtier and clogged more than the ones on bank 1, attributed to how the fuel hits bank 2 and then wraps around to bank 1 and then deadheads at the FPR, all without a fuel filter, aside from the in-tank strainer sock, so I've read. While that scenario fits my issues almost identically with very poor mpg and crap idle, one of my reservations is the AFR sensor on bank 2. I would imagine that the sensor would pick up on excess fuel and the ecu would pick up on the variance and send out a CEL. But I'm still learning how these trucks/engines think. And before I start swapping in injectors, I wanted to see what everyone thought. When I get off, I'll see if I can log voltages to see what they are doing.

 

Time to do fuel pressure check.

 

Yeah, I'm going pick up one of those fuel pressure gauges tomorrow. But on the way home, I took a screenshot of the sensor outputs, as read by the ECU and my phone. This was idling at a red light. Bank one at the top looked alright. But bank two, both sensor 1 and 2, reading high consistently, both pointing towards exhaust leak or lack of fuel to some degree. Or that's how I am reading the FSM.

 

I am having almost the exact same problems right now. I pulled 20% fuel from LTFT and still showed rich bank 2. I thought I had leaky injectors so I purchased new ones. After installation and another tune, for the injectors, I started running lean bank 1 rich bank 2. I’ve also changed the ecu, up and downstream 02 sensors, and MAF sensor. Still haven’t figured out what’s going on and it is back in the shop. I’ll update this tread whenever I get any info.

 

Maybe your tps? Cant think of anything else since it seems like you have checked everything.

 

Mechanic is going to look into fuel pressure and vacuum leaks tomorrow. My truck still ran rich with all 02 sensors unplugged.

 

*** Update *** 5.14.2020
Good Afternoon Tacoma World,

I hope everyone is doing good and staying safe with this viral pandemic that we are dealing with. I wanted to give an update on my current issue with my truck and maybe someone knows something somewhere. I broke down and brought the truck to a local dealer and asked if they can figure out something beyond everything I've tried. For kicks, I put on the factory exhaust manifolds before I brought it to them and I still got the same fuel trim issues. They changed out the rear o2 sensors (sensors I had just changed) and gave it back to me and said it was fixed. Not even 2 days later, the same codes came on and it was running way worse. I brought it back to them and it sat there for well over almost 2 months and nothing was done to it. I called about it one day and they wanted to through a couple grand worth of parts to MAYBE try and fix the issues. I decided that it wasn't worth it to just throw parts at it and hope its fixed. So I threw the long tube headers back on I'm still encountering a rough idle, after the engine warms up and not near as bad as what it was, and I'm getting codes for Bank 2 Sensor 2 High voltage and Bank 1 Sensor 2 low voltage. Fuel pressure looks good. Fuel trims are pretty close but not identical, one side is still higher in voltage than the other side. I figure if it blows, I'll swap something else in. Can't really afford a new truck, mainly because manufacturers are EXTREMELY proud of their trucks and it shows in the price as well as dealers thinking everyone is a sap and not wanting to make a deal. So, if anyone knows or has any ideas what I can check out to correct the fuel trims and/or the rough idle, feel free to share.

Also, if anyone knows of any engine swaps that would be doable on a budget, should my engine fail, I'm all ears as well. I'd like to keep the stock drive shaft and not mess with a custom made drive shaft. And I'd also like to keep the truck manual either with my factory 6 speed or a different manual transmission. Not sure if a v8 would an option, like the tundra 4.7 2uzfe. Not looking to do a full build but I'd imagine that there may be some kind of combination that would be an option. Just kicking around ideas.