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Discussion Starter #1
My 2007 Sienna with 140k miles has been throwing codes for several months and so far all my repairs have failed. I will start by saying the car has been well maintained with a full tuneup at 120k including ND FK20HR11 and new ND coils for all cylinders. The van started dying intermittently at idle usually after being started which resulted in a P0300 (Generic misfire) code. At this point the MAF was replaced and the problems disappeared. Later in October P0300 appeared again followed by P0174. At this point I checked vacuum hoses and for leaks in the intake system. Cleaned the throttle body which had been cleaned before. Code P0302 (Cyl 2 misfire) and P0300 appeared. I took the van to a mechanic and he recommended all 4 Air Fuel sensors be replaced. All 4 sensors were replaced with ND sensors. The problems persisted with additional P0302 codes generated. while checking the system I found a loose ground on bank 2 and thought I solved the problem but soon the misfire P0302 reappeared. I figured the problem could be in the fuel system so I checked the fuel rail and noted cyl 2 injector not firing as good as the others. Replaced 3 injectors on bank 2 with rebuild ND injectors. Now I have code P0174 multiple times and My Innova 3100F reader indicates intermittent 0 voltage on the Bank 2 Air Fuel sensor and suggests it be replaced. The sensor was previously replaced with ND 234-9049. The van dies intermittently at idle and then exhibits lack of power. Shortly after this occurs it starts normal and runs great with lots of power. Could this Bank 2 AF sensor have failed or was I sold a bad sensor? Any help resolving these issues would be greatly appreciated. P.S. Replaced the Bank 2 AF sensor with a new ND sensor but this did not solve the issue P0174 reappeared. I am at a loss as to what the problem is.
 

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A few ideas / thoughts / questions:

What are your fuel trim numbers (long term and short term) for banks 1 and 2 at idle, engine warmed up and just driven? I'm assuming there is a dramatic difference between the bank 1 and 2 trim numbers at this point, but if there's not, that opens up some other possibilities.

Have you done a vacuum test and bank 2 compression test to verify basic mechanical condition and absence of vacuum leaks at the manifold?

Have you verified end-to-end wiring continuity and electrical power supply to the O2 sensors and bank 2 injectors?

Regarding the cyl 2 injector, how did you determine that it was not firing as well as the others? Did you flow test it right off the rail, or do you have a flow bench, or... ?

Assuming everything above checks out, I would want to get a 4-channel shop oscilloscope on this engine to see exactly what those bank 2 injectors are being commanded to do and exactly what's being reported by the upstream O2 on bank 2.

- G
 

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Discussion Starter #3
Sorry about the delay. The fuel trim is way off. Here are the numbers.
P0174
Short term trim bank 1 =-0.78%
Long erm trim bank 1 = 22.66%
Short term trim bank 2 = 7.03%
long term trim bank 2 =33.59%
RPM 2050
Speed 20 Mph
Air flow rate 3.73 LB/min
O2 sensor output v(B1-S2) =0.00
Short term fuel trim (B1-S2)=99.22%
O2 sensor output v (B2-S2) =0.04%
Short term fuel trim (B2-S2)=99.22%
Time since engine start 231 sec
Engine coolant temp 176F

My OBD2 tool only provides a snapshot when the code is read no real time numbers.

Checked for vacuum and it is present but I was not able to check during the bad idle event.
Compression Bank 2 (No oil with Fuel injectors disconnected) Cyl 2=130 psig, Cyl 4= 125 psig, Cyl 6= 130 psig
Not sure how to check 2 sensor v supply.
Cyl 2 injector spray pattern appeared less but this is unscientific. In the end I changed out the injectors (ND reconditioned) too see if it would help.
Plenty of fuel pressure but I have no good way of measuring it. I have a traditional vacuum fuel pressure gage for a hose. Any advice would be helpful.
At this time I am getting only repeat code P0174. The other codes have disappeared.

Hope someone can help I am out of good ideas.
 

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Yeah, those fuel trim numbers, both banks, are showing fairly strong corrections for lean conditions. Bank 2 is just much worse than Bank 1. With those numbers that far off with the engine under load, I do not think this is a vacuum leak issue - a vacuum leak bad enough to throw the trim off that much under load would create high idle issues. But I do suspect your problem may be system-wide rather than with one bank or injector.

Sadly, there's no fuel pressure test port on these engines. You have to use a special service tool that has an inline tee. Consider having a mechanic who has that tool do a fuel pressure test for you, to verify fuel pump and fuel pressure regulator operation. There is also a fuel pressure pulsation damper on the inlet corner of the fuel rail (looks like a tiny regulator) which can cause a lot of havoc if it fails, including weird misfires and so forth (this is actually what I think is most likely the culprit here). Finally, inadequate fuel pump delivery could also be caused by failure of the high / low fuel pump current setup: these vans have an inline fuel pump resistor that reduces current draw by the pump under low engine load conditions. There's a relay that controls that high/low power mode (this is in addition to the relay that turns on the pump). The fuel pump resistor is near where the wiper motor wiring harness enters the wiper tray.

You might also consider the small possibility of a defective replacement MAF sensor, since that sensor initially appeared to fix things for you. You could get a used MAF from a salvage yard cheap, clean it, and test using that. I'd think it quite unlikely that the MAF is carbon-fouled this soon after replacement, but that should be checked too. A carbon-fouled MAF will cause a lean running condition (the carbon on the MAF sensor will reduce its ability to sense air flow, thus reducing the computed fuel delivery). You can buy a cleaner specifically for these delicate MAF sensors to decarbon them.

- G
 

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As far as testing the O2 sensors, do you have the sensor #1 numbers for B1 and B2? (S1's are the upstream sensors, and the main ones used for air/fuel feedback; S2's are the downstream ones used for monitoring catalyst performance). I'd suggest getting a copy of the factory service manual, perhaps through alldatadiy, for further information on testing those circuits and testing the heater voltage and such.

- G
 

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Discussion Starter #6
Thanks Greenlight for some great information.
From your first reply I do not think it is the MAF sensor since I tried another sensor from another sienna and I still had an idle issue. The fuel pressure pulsation sensor (Toyota 23270 -xxxx not sure which one) seems like a real possibility but I think I will let a shop check the fuel pressure first before throwing more parts at it. The Fuel pump resistor is another possibility but I am not sure how to check it maybe you can help. The Air fuel sensors and O2 sensors installed are as follows

Upstream Bank 1 Denso 234-9012
Upstream Bank 2 Denso 234-9049
Downstream Bank 1 Denso 234-4516 (Not replaced yet I can not get it loose)
Downstream Bank 2 Denso 234-4149

Please let me know your thoughts
 

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Discussion Starter #7
Checked the fuel pump resistor and it shows 0.30 Ohm at about 50 F so that is probable within spec. Not sure which relay is associated with the resistor for the Hi/Lo function?
 

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Sorry, I worded that poorly regarding the O2 sensors. I'm curious what the upstream O2's are reading on your scan tool, since they're the ones that "matter" for this purpose.

My FSM shows your resistance measurement is spot on. The relays involved are C/OPN relay (main fuel pump relay, or "circuit opening" relay) and Fuel Pump Relay (high/low speed) according to the wiring diagram.

Of course wiring harness issues and grounding issues are always possibilities.

- G
 

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Discussion Starter #9
Thanks for the relay info. I will test the fuel relays and try to check the harness.
All the data from the Innova report has been posted. Except
Ignition timing advance 36 deg
Intake Air temp 96.80 F
Abs throttle position 23.14%
The tester does not provide additional info.
 

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Discussion Starter #10
Today I also got another P0174 and P0171 Lean Bank 1 A/F code. This actually may confirm that the issue is in the fuel system because both banks are sending codes. Some more Innova results below.
[TD]DTC for which Freeze Frame was Stored[/TD]
[TD]P0174[/TD]​
[TD]Fuel System 1 Status[/TD]
[TD]Closed Loop[/TD]​
[TD]Fuel System 2 Status[/TD]
[TD]Closed Loop[/TD]​
[TD]Calculated LOAD Value[/TD]
[TD]37.25 %[/TD]​
[TD]Engine Coolant Temp[/TD]
[TD]188.60 °F[/TD]​
[TD]Short Term Fuel Trim - Bank 1[/TD]
[TD]3.13 %[/TD]​
[TD]Long Term Fuel Trim - Bank 1[/TD]
[TD]22.66 %[/TD]​
[TD]Short Term Fuel Trim - Bank 2[/TD]
[TD]3.91 %[/TD]​
[TD]Long Term Fuel Trim - Bank 2[/TD]
[TD]31.25 %[/TD]​
[TD]Engine RPM[/TD]
[TD]687.50 rpm[/TD]​
[TD]Vehicle Speed Sensor[/TD]
[TD]1.86 mph[/TD]​
[TD]Ignition Timing Advance #1 Cylinder[/TD]
[TD]14.00 °[/TD]​
[TD]Intake Air Temperature[/TD]
[TD]149.00 °F[/TD]​
[TD]Air Flow Rate Mass Air Flow Sensor[/TD]
[TD]0.67 lb/min[/TD]​
[TD]Absolute Throttle Position[/TD]
[TD]15.69 %[/TD]​
[TD]Oxygen Sensor Output Voltage (B1-S2)[/TD]
[TD]0.68 V[/TD]​
[TD]Short Term Fuel Trim (B1-S2)[/TD]
[TD]99.22 %[/TD]​
[TD]Oxygen Sensor Output Voltage (B2-S2)[/TD]
[TD]0.10 V[/TD]​
[TD]Short Term Fuel Trim (B2-S2)[/TD]
[TD]99.22 %[/TD]​
[TD]Time Since Engine Start[/TD]
[TD]858 sec[/TD]​
I went ahead and ordered the Fuel rail damper. It will take some time to get here as the part was not locally available.
 

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Discussion Starter #12
I tried to get the pressure test done but the first shop does not have time to work on it and the other shop does not have the correct tool. I went and ordered a fuel pressure tester with the special SEA fittings. It will be here on Saturday. Hard to get things done these days.
 

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I just went through something similar with my 2004 Sienna van. Here is the link I posted.


My symptoms were a constant misfire code on the rear bank as well as fuel/air mixture faults.

We finally replaced the fuel pulsation damper on the fuel system. On the 2004 Sienna it is screwed directly into the drivers side of the rear bank fuel rail.

Its job is to dampen the fuel delivery pulses induced by having 6 injectors snap open and slam closed thus allowing the cylinders to receive a smooth flow of fuel without pulsations. When this fails injectors can receive an uneven and constantly varying amount of fuel throwing off fuel trims and causing misfires in cylinders. The part cost $70 and is not that hard to install. Use new gaskets for it or you will end up with a fuel leak after you install it.

Here is what I did before replacing the fuel pulsation damper assy to fix my 2004 Sienna van

Symptoms were misfires and fuel/air mixture faults on bank 1

1. Switch coil packs to see if problem followed pack = problems did not move problems remain
2. Replace all three Bank 1 injectors= no good problems remain
3. Check , clean and temporarily replace MAF sensor=no good problem remains
4. Check fuel pressure= fuel pressure ok
5. Drain some fuel and check quality of fuel= fuel quality ok
6. Remove #1 bank cat and see if it was clogged = Cat is fine no problems
7. Replace Bank #1 before and after cat sensors = no change
8. Check timing to see if #1 cam had jumped time= Timing is okay
9. Replace Fuel Pulsation Damper = engine immediately runs great and all codes (misfires and fuel /air mixture fault) go away

Steps 1 thru 3 where done by myself
Steps 4 thru 8 were done by an independent certified repair shop. At this point I needed someone who was familiar with reading diagnostics, fuel trims etc.
Step 9 was done by myself and the shop after paying $45 to access a Toyota Technical Support line for diagnostic support. They repair shop suggested we contact them as none of the repair procedures were working and we were at a dead end on what to do next.
 

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Discussion Starter #14
Johnxyz
It sounds like we went pretty much through the same procedures looking at coils, MAF, A/F sensors, O2 sensors and injectors for the problem. I ordered a fuel pressure gauge with the proper connectors to check the fuel pressure. Most of the independent shops really do not want to deal with it at this time of year. At this point it is either the fuel pump, fuel pressure regulator (both in tank ) or the Fuel pressure damper. One thing that surprised me is how the car drives perfectly 90% of the time and then when it is warm and sitting for 15 minutes refuses to idle. Once it cools and especially now that the weather is cold the van behaves perfectly. Did your van behave similarly?
 

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vinder1, let us know what you find out...

One quick fuel pump test is to listen to it. Listen down by the tank & learn what the pump motor sounds like when the van is running well, and then listen again when the van is running poorly.

I actually have an extra fuel pressure damper. I noticed from your compression PSI, it looks like you may be at high altitude. If you happen to be nearby here in Colorado, you could borrow my extra damper & see if it helps you.

To remove the damper, you first release the fuel pressure, then remove the clip, and then gently pry the damper out. It's a different design than the one on the 3MZ-FE. There is an o-ring to replace.

(I have an extra because I had to replace my 2GR-FE engine this summer. The replacement came with an entire fuel rail still attached, which I used with its low mileage.)

- G
 

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My car would run smoothly sometimes at idle and at other times not so much. My symptoms where the ever present check engine light and misfire-air/fuel codes. My van would run rough at higher speeds and had no power at high end. Flooring the gas pedal the van would have trouble making it up to 55 mph.

If someone had told me before this the Fuel Pulsation Damper Assembly could cause this I would have told them they were crazy. I learned a lot troubleshooting this problem not the least was how to eat humble pie and realize I was lost and needed help.
 

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Discussion Starter #17
Thanks for the offer for the Damper but I am well South East of you in Texas and I was able to order the part. Unfortunately It was not in stock but it will be here in a few days. With the holidays I do not need the van so much so I can wait. Meanwhile I will try to check the fuel pressure this weekend.

John you mentioned eating humble pie well I am used to fixing my own cars and they almost never go to the shop. My coworkers been having some fun on my account especially with my wife getting stranded multiple times and calling the office.
 

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If someone had told me before this the Fuel Pulsation Damper Assembly could cause this I would have told them they were crazy.
I'm totally with you there! I wasn't even aware of the pulsation damper until I saw your story a week ago, and so it was your information (and other stuff I gathered online studying about it) that led me to mention it on this post here on siennachat.... Here is the best writeup I found about its operation (and failure modes): https://www.motor.com/magazinepdfs/012004_08.pdf -- and I would never have imagined the severity of the symptoms from a part like that unless I had read that article and seen your post.

Looking at the extra 2GR-FE damper I have on hand (for our '08), it does not have the adjustment screw that the 3MZ-FE damper has. There's just a little rubber tail coming through the housing where the 3MZ-FE damper has a screw. I'm hoping that may make it less likely to develop a serious leak. But if the diaphragm is perforated, fuel could gradually leak into the rest of the housing, filling it up and eliminating the damping capability of the part.

One thing that surprised me is how the car drives perfectly 90% of the time and then when it is warm and sitting for 15 minutes refuses to idle. Once it cools and especially now that the weather is cold the van behaves perfectly.
That does sound like a fuel pump issue....

- G
 

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Discussion Starter #19
Anybody know where on the 2007 Sienna to take the fuel pressure measurement? It looks like the special connector is at the fuel tank but I am not sure.
 

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I don't think these vehicles have a fuel pressure test connector at all. The instructions I have are to disconnect a quick-disconnect point (there is one at the rail), and to use the special service tool (consisting of a tee and related pieces) to hook up the pressure gauge. The tee and fittings connect to the quick-disconnects.

- G
 
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