Holy DTC code hell!!! 2008 Limited

A

alia176

Senior Member
Holy DTC code hell!!! 2008 Limited V8

Folks,

My girlfriend is having a hell of a time with her recently acquired 2008 Limited V8. Last Sunday the vehicle started to act up on her so I took over the wheel and tried to understand what was happening. Lucky for me, she bought a scanner few weeks back so it was nice to monkey with the DTC codes.

Let me do my best trying to explain the symptoms. Please forgive the long dissertation but web Dx is easier when you have as much facts as possible.

-CEL was OFF but the engine had a hesitation on accel. I was able to induce the same thing by simply power braking in place. Again, no CEL at this time.

- plugged in OBD scanner while driving and two codes are persistent: P0171, P0174. Even after clearing, they return.
- engine hesitates and stumbles like it's starving for fuel. Engine coughs, sputters, and accelerates poorly while stumbling.
- as the condition deteriorates, the engine fails to idle well and just dies.
- finally, the engine won't start or it won't stay running. At this time, codes are P171, 174, 300, 301, 302, 304, 306 & 308
- C1201 - I don't know what this code is! Something to do with the ECU?

Things done on the side of the road:

- checked fuel filler cap for tightness
- unplugged POS batt term, reconnected. - improvement for a short while, just enough to pull off the road into a side road.
- checked the air intake tube for tightness, appears to be ok
- upon starting up the engine, CEL comes on along with VCS and TRAC off lights are now on.

GF took it to the dealership last month but they weren't able to recreate the issues. Can you say FRUSTRATING for my GF?

Things the dealership did:
- checked fuel pressure - ok
- fuel trim ok while driving
- wrote "can't condemn the fuel pump at this time, fuel pump maybe going out under very hot conditions and vehicle may need fuel pump"

My thinking:

- all of the 171,174 and 300 codes are the "effect" not the cause. When the ECU is trying to run the engine and it simply can't run at the proper air/fuel ratio, you're going to have wonky O2 numbers and cylinder misfires.
- when BOTH O2 sensor codes are appearing, I highly suspect that they're actually going bad with ONLY 77k miles on them.
- some common denominators from this site are: MAF sensor, fuel pump starvation, coolant temp sensors and I don't know what else!
- I'm ruling out spark plugs, fuel injectors and 02 sensors at this time.
- MAF sensor cleaned with spray cleaner
- I'm ruling out the fuel pump sock being dirty because this issue is not happening consistently, all of the time.
- also ruling out bad gas. If the entire tank was full of bad gas, the engine shouldn't run well at all.

So, we leave the vehicle in front of a VW dealership and I call a friend for a ride home. This was a sunday with the family and it was hot as hell outside. Thankfully a local buddy with a '04 SR5 came and took us home. My mother, nine year old daughter, me and my GF were happy to be at the house in ice cold A/C!!

Monday morning

I take her to the vehicle and it started RIGHT UP like nothing ever happened! Normal hwy acceleration and decent power. BUT, there is a slight hesitation on accel as reported by her. So this makes me think there *could* be these possibilities:

- temp related. Super hot ambient temp is making the fuel pump get hot or some connectors making intermittent connections?

- Maybe the EFI relay? I can easily swap it out and see what happens.

- I'm leaning towards coolant temp sensor. From my past experience, the ECU relies on this sensor heavily and can really mess with the normal operation of the engine.

Thanks for your help. My GF is at her wits end on this one. Again, this is for a 2008 Limited V8 with 77,xxx miles.
 
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Girlfriend here.

The first occurance of this issue was on June 2nd. I limped the vehicle to Toyota, as I was only 2 blocks away. CEL came on along with VCS and TRAC off lights. Toyota's Service department was closed for the evening. They were not able to recreate the issue the following morning. They kept the vehicle for about 4 days trying to recreate the issue.

I picked it up drove it and could still feel slight hesitations and surging. But still drivable and no CEL.

The next major occurance was June 20th. again, CEL comes on along with VCS and TRAC off lights. Car is undrivable. I had the vehicle towed to Toyota the next day and again, they were unable to recreate the issue. They were even unable to pull any codes. They kept the vehicle for about a week and said, there was nothing they could do becuase the vehicle was operating without issue.

If I drive around with my OBD scanner plugged in I will consistently pull P171, 174, 300, 301, 302, 304, 306 & 308.
I am not certain what causes the CEL to come on along with VCS and TRAC off lights. when this happens the vehicle is undrivable.

MOST of the time I feel intermitent loss of power / hesitation for a few micro-seconds and sometimes lurching accelleration. it basiclly feels like it's running out of fuel. but then it will be fine and I wont have any issues for days.

Any thoughts?
 
Check over the engine electrical harness real good for signs of rodents eating at it or previous damage. Check all the vehicle grounds. Try wiggling the harness around while it's running as well.
 
C1201 "Engine Control System Malfunction"
This code pretty much just states the MIL is on. It's an effect, not a cause.

P0171 "System Too Lean (Bank 1)"
P0174 "System Too Lean (Bank 2)"
These two together mean the entire engine is (or at least thinks it is) running lean. A too-lean or too-rich condition can cause misfires. Speaking of...

P0300 "Random Misfire"
P030X "Cylinder X Misfire"
Since the air-fuel ratio isn't correct, you're not getting reliable ignition in the cylinders. The various P030X codes also correlate that the entire engine is being affected, not just a single cylinder.

I think your instincts are correct; I'd start by looking at the MAF and temp sensors or the fuel pump as the likely root cause. In order of increasing difficulty:

-Trace the wiring harness to the sensors & pump with engine on, pull and wiggle any connectors to try to replicate symptoms
-Measure MAF output voltage (sorry, I don't know the proper procedure or what values to look for)
-Measure temp sensor resistances (again, I don't know what values are correct) at various temperatures (maybe pull the intake air temp sensor and put in in your freezer / room temp / oven? Coolant temp in ice / room temp / boiling water?)
-Measure fuel rail pressure while engine is running poorly

Hopefully it's an easy, obvious problem with a simple fix: "Oh, a tab broke off the temp sensor connector and it's just barely hanging on!" If not, hopefully it doesn't take too long to find and replace.
Good luck!
 
mrpurplepenguin said:
C1201 "Engine Control System Malfunction"
This code pretty much just states the MIL is on. It's an effect, not a cause.

P0171 "System Too Lean (Bank 1)"
P0174 "System Too Lean (Bank 2)"
These two together mean the entire engine is (or at least thinks it is) running lean. A too-lean or too-rich condition can cause misfires. Speaking of...

P0300 "Random Misfire"
P030X "Cylinder X Misfire"
Since the air-fuel ratio isn't correct, you're not getting reliable ignition in the cylinders. The various P030X codes also correlate that the entire engine is being affected, not just a single cylinder.

I think your instincts are correct; I'd start by looking at the MAF and temp sensors or the fuel pump as the likely root cause. In order of increasing difficulty:

-Trace the wiring harness to the sensors & pump with engine on, pull and wiggle any connectors to try to replicate symptoms
-Measure MAF output voltage (sorry, I don't know the proper procedure or what values to look for)
-Measure temp sensor resistances (again, I don't know what values are correct) at various temperatures (maybe pull the intake air temp sensor and put in in your freezer / room temp / oven? Coolant temp in ice / room temp / boiling water?)
-Measure fuel rail pressure while engine is running poorly

Hopefully it's an easy, obvious problem with a simple fix: "Oh, a tab broke off the temp sensor connector and it's just barely hanging on!" If not, hopefully it doesn't take too long to find and replace.
Good luck!
Click to expand...

thanks for the insight, I think we're on the same page. I love this kind of stuff so it's fun for me but then again, it's not my vehicle :becky: (poking fun at Run4Nuts above). Thankfully, there are two V8 Runners side by side on the driveway so I have a "control" vehicle to look at for reference.

As you said it, it's probably an easy solution but will take lots of thinking and head scratching to come up with the solution. It is definitely heat related so that's a huge clue for us. Now, where did I put my Oscope..... :-)
 
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Hmm, I think [MENTION=112757]mrpurplepenguin[/MENTION] is pretty spot on with the approach to go with. It sounds like the vehicle is for whatever reason not getting/supplying enough fuel. That's the direction I'd start with for now in my opinion...

Out of curiosity though, has this issue only been happening on very hot days after driving the vehicle for an extended period of time, and after letting it cool it seems to work perfectly fine again? Another question; did the dealership just check fuel pressure, or did they inspect the rest of the fuel system as well?
 
Ash,

You're in a good spot to start ruling out a few of the components real easily. First and foremost, look under the intake into the valley and see if anything is living in there. It's a common place for mice to nest in. I would also look on IH8Mud in the hundy section for similar symptoms. You might find some good threads there.

I would take your MAF and swap it over to her truck and see if it cures the problem. Fuel pump could be acting up when hot, but if it tested ok, I don't know if I'd swap it out just yet.

The coolant temp sensors can be easily swapped over for a test drive without too much coolant loss. So, you either have fixed the problem now, or you have eliminated a lot of the whatifs and easy items and can really dig in to the fuel system, injectors, etc. You can also test the TPS (or swap it over). Also what can be an intermittent problem is a coil pack on its way out. Take one of yours and swap it out into her truck one cylinder at a time, and see if the hesitation disappears. Also, make sure the plugs are all tight into the head.

Start there... report back. Its fun giving the engine guru tips on fixing his truck..
 
Thanks for the good suggestions everyone. I'll let Jessica answer some of the questions on how her vehicle is acting.

As far as compatibility of parts between our two rides, the MAF is NOT compatible, which is a huge bummer. She has the VVTI and I don't :cry2: But I'm secure with my manhood and don't let that bother me...too much:dancin:I'm sure the coolant temp sensor is compatible so that's what we'll start out first. I also have a drawer full of O2 sensors for Toyota that I'll swap out too. Admittedly, I'm having difficulties believing that the O2 sensors are going bad since they didn't throw actual sensor malfunctioning (heater circuit fault) codes. Not to mention the engine has 77k miles on it.

I like the rodent idea and I'll have her look into it. But, if the little critter did chew through a harness then the engine should be experiencing issues on a constant basis, not when it's heated up? Just thinking out loud. On a side note, the pack rats LOVE my 80 series Landcruiser. I find one in the mouse trap just about twice weekly!

According to the dealership work order, the fuel system was pressurized and left that way overnight and the system checked out fine but I'll let Jessica elaborate on that further.

Thanks again for the ideas, please keep them coming.
 
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The more I think about it, the more I am not as suspect of the coolant temp sensor (although your logic makes sense) but more towards the intermittent coil pack. Heat kills electronic components and where you are, you do in fact get some heat from time to time. Try to swap in a good coil pack for each cylinder. Start towards the back of the V to save some time since it seems to be slightly hotter towards the firewall.
 
chitown40 said:
The more I think about it, the more I am not as suspect of the coolant temp sensor (although your logic makes sense) but more towards the intermittent coil pack. Heat kills electronic components and where you are, you do in fact get some heat from time to time. Try to swap in a good coil pack for each cylinder. Start towards the back of the V to save some time since it seems to be slightly hotter towards the firewall.
Click to expand...

If I had one single bad coil pack, I'd expect a consistent P30x misfire code for that one cylinder, no? The V8 should still be able to run smoothly on seven cylinder with a slight hesitation I'd think. Remember, this engine only has 77K miles on it.

Right now, when this engine acts up, it goes from a slight hesitation on accel to a full blown meltdown. At that point, the engine can barely hold the idle, stepping on the gas results in sputtering, backfiring and FORGET about putting her in Drive to actually moving the vehicle.

Is my thinking logical or am I missing something important?
 
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Out of curiosity though, has this issue only been happening on very hot days after driving the vehicle for an extended period of time, and after letting it cool it seems to work perfectly fine again? Another question; did the dealership just check fuel pressure, or did they inspect the rest of the fuel system as well?
Click to expand...

Yes honey, your manhood is secure ��

Blackworksinc,
I drove my 4Runner several times yesterday. I kept the Obd plugged in all day. It did not detect one code; nor did it exhibit any signs of hesitating, surging, chugging... It drove like the little princess I know her to be. It was balmy 97 degrees yesterday. Today it will be in the mid-80s.

The dealership did pressure test the fuel line overnight and detected zero drop in pressure. They initially were going to replace the fuel pump, but the Toyota engineers said, nope. The vehicle was too young to have that kind of issue. So they did many tests on the fuel pump and the pump cleared all the tests. I'm not sure of specific tests, but the service guy told me there were pressure and electrical tests done on the pump itself... So their diagnosis was, " I got a bad tank of gas".... And they put some cleaner in my line and told me to get high octane fuel for a few fill ups...

I have determined that it's not a fuel issue. At least not a bad fuel problem. The issue truly is intermittent and frustrating.....
 
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My first two thoughts are intermittent fuel pump/pump relay problem, or a vacuum leak. I find it hard to believe that a faulty coolant temp sensor would cause these problems, because at most it would cause a persistent open loop issue that would still allow the truck to start and run.

On the vacuum theory, you could have a plastic connector with a crack that is expanding under higher heat conditions. Just some guesses to go on.
 
alia176 said:
If I had one single bad coil pack, I'd expect a consistent P30x misfire code for that one cylinder, no? The V8 should still be able to run smoothly on seven cylinder with a slight hesitation I'd think. Remember, this engine only has 77K miles on it.

Right now, when this engine acts up, it goes from a slight hesitation on accel to a full blown meltdown. At that point, the engine can barely hold the idle, stepping on the gas results in sputtering, backfiring and FORGET about putting her in Drive to actually moving the vehicle.

Is my thinking logical or am I missing something important?
Click to expand...

Ok, I suppose that could all be true. Maybe start thinking TPS. I don't believe there is an IAC on that throttle body, but its been a while since I've look at the 4.7 up close.
 
chitown40 said:
Ok, I suppose that could all be true. Maybe start thinking TPS. I don't believe there is an IAC on that throttle body, but its been a while since I've look at the 4.7 up close.
Click to expand...

All our Electronically Controlled Throttles lack an IAC, the ECM modulates the throttle blade by itself to adjust for idle.

The reason I asked about the hot soaking question is because we have seen in the past when one or more injectors fail electrically at high temperatures; but start working fine at low temperatures. I've seen this mainly on older Camry, Corolla, and the 5VZ-FE in Tacomas and 4Runners, but I suppose it is possible it could be a factor here? Though I feel it's probably unrelated.
 
The symptoms don't sound like any one component of 8 like a coilpack, injector etc.

It either sounds like something major in the control system (no O2 sensor) like a MAF, or more likely, the fuel pump or fuel pump relay is going. You'll get some fuel as you bleed down pressure when the pump dies, so it's not like hitting a wall. It'll sputter and you'll feel like you're losing more and more power over about 10-30 secs. Then it's toast and the best you can hope for is a really rough idle before it completely stalls.

So honestly, I'd say it's related to the fuel pump in some manner.

It might be worth it to get a cheap fuel pressure gauge (mechanical), and take a look at it when it acts up again with the key on. It should build pressure. So if it doesn't, at least then you know it's related to the fuel pump in some manner. If you've got good fuel pressure and it won't run at all, you can at least strike that off the list.
 
RPS13 said:
The symptoms don't sound like any one component of 8 like a coilpack, injector etc.

It either sounds like something major in the control system (no O2 sensor) like a MAF, or more likely, the fuel pump or fuel pump relay is going. You'll get some fuel as you bleed down pressure when the pump dies, so it's not like hitting a wall. It'll sputter and you'll feel like you're losing more and more power over about 10-30 secs. Then it's toast and the best you can hope for is a really rough idle before it completely stalls.

So honestly, I'd say it's related to the fuel pump in some manner.

It might be worth it to get a cheap fuel pressure gauge (mechanical), and take a look at it when it acts up again with the key on. It should build pressure. So if it doesn't, at least then you know it's related to the fuel pump in some manner. If you've got good fuel pressure and it won't run at all, you can at least strike that off the list.
Click to expand...

I'm leaning towards a fuel supply issue as well, a control issue is also possible.
 
It is one of two things. Either fuel contamination, in which case, just top it off and drive it and it should clear up or carbon build up on the throttle plate... in which case clean the MAF sensor and throughly clean the throttle plate. What are your short term fuel trims at in closed loop?
 
BRossman said:
It is one of two things. Either fuel contamination, in which case, just top it off and drive it and it should clear up or carbon build up on the throttle plate... in which case clean the MAF sensor and throughly clean the throttle plate. What are your short term fuel trims at in closed loop?
Click to expand...

I don't see how any of those things can cause the symptoms he's seeing.

It's not like it just runs a little rough, or has an occasional misfire. The whole thing goes kaput... then is fine some time later.
 
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