[schneidm]

I just rebuilt my J35A7 engine. New heads, rockers, piston rings, oil pump, timing belt, etc. It started immediately. I have run it about a total of 30-45 minutes at this point.

Immediately, I had a high idle at 2000 RPM, a P3400 code, engine is stuck in limp mode and cannot accelerate past about 3300 RPM, and some random misfires that seem to change with each run of the engine. I am concerned with engine oil pressure first.

I never had an oil pressure idiot light on the dash, but I get this P3400 code which suggests there is no oil pressure at the rocker arm bank closest to the firewall.

Is there an oil pressure sending unit that serves only the dash idiot light? Why would that light stay off?

Meanwhile, the oil pressure switches on the rocker arm are detecting no or insufficient oil pressure. Actually to be more specific, the P3400 code itself reads Valve Pause System (VPS) Stuck Off Bank 1. But most discussions of this code point to a faulty oil pressure switch. I unplugged both oil pressure switches to see if I would get a second code and I did not. Instead, I got a flashing check engine light AND the P3400 code did not happen. Not sure why. I consistently got the P3400 code each time I ran it otherwise.

Also, I am having a very hard time finding a manual oil pressure gauge setup that will fit the Honda. My pressure tester (from Harbor Freight) is SAE/NPT and the VPS oil pressure switch on the Honda J35A7 is 10mm x 1.25. No one has an adaptor for this (male 10mm x 1.25, female 1/8 x 27 NPT). I am not sure why it so hard for me to locate a manual oil pressure gauge that is compatible with my Honda engine.

Bottomline is that I am scared to run the engine any longer without a manual oil pressure test so I can be certain if my oil pressure switch is bad or if there is indeed no oil pressure. I do have a back up rocker arm set up, but I am really hoping I am getting oil and not destroying the rockers.

EDIT 03/19/2023
As of today I have completed this project successfully and I wanted to let people know what to expect on this thread before reading the whole thing. Essentially this entire thread is just about me dealing with a P3400 and P3497 code. There is no magic here.... in the end I simply replaced two of the rear bank solenoids.... and truth is I probably only needed to replace one. I bought Dorman parts through Amazon, which is not recommended. But in this particular case, it worked fine. So feel free to read the whole thread if you wish, but recognize that in the end I just did what is typically required for these particular codes. Where this could be helpful to someone is if they are contemplating a full engine rebuild. I learned many lessons about how to do a more thoughtful and thorough re-build next time.

1. Pull codes from your broken engine before you clear the PCM and commence the project.
2. Make certain to clean and/or clear oil routes / ports in the block that deliver oil to the top of the engine and the VCM spooler banks.
3. If you replace heads, make sure to inspect closely the inside of the VCM spooler assemblies. Do not trust the entity that sold you the replacements heads/rockers to have ensured the VCM spoolers are clean and working.
4. This thread will teach you how to bench test the oil pressure switches, preventing you from buying new ones un-necessarilly.
5. Replace all critical parts that are hard to access and use Honda OEM up front, such as the oil pump and water pump.
6. If you buy remanufactured major components like I did (heads and rockers), check every single threaded bolt hole before assembly to make sure the threads are clean and working/not stripped. You don't want to discover a problem thread after assembly is largely complete and the engine parts are already in the car.

Enjoy this thread! And I owe a major thank-you to the folks who engaged me on this problem and stuck with me during the entire course of the problem solving.

 

[WiiMaster]

What warranted an engine rebuild? I suspect I know the answer but I'll wait.

P3400 is not necessarily related to the engine oil pressure. It refers to the oil pressure going to the VCM spool valve. That's the only rocker arm actuation system on this engine, there's no VTEC.

Your engine oil pressure is most likely fine. Probably a bad oil pressure switch or some other issue with the bank 1 VCM spool valve.

The oil pressure switch on these solenoids is not what controls the oil pressure light, there's a separate switch for that. That's why you didn't see the light.

 

[celicool]

Double check that plug connecting to the spool valve next to the firewall. Make sure it is plugged in all the way and click. Is the spool valve an original or Honda unit?
I would give it an oil change with correct viscosity oil and a Honda oil filter. Note how good or bad the oil looked. Then reset the code and try again.

 

[schneidm]

Double check that plug connecting to the spool valve next to the firewall. Make sure it is plugged in all the way and click. Is the spool valve an original or Honda unit?
I would give it an oil change with correct viscosity oil and a Honda oil filter. Note how good or bad the oil looked. Then reset the code and try again.

Thank-you very much for engaging me on this topic. I don't know the plug you are describing. What is the "spool valve"? I will look that up. It is likely the original Honda spool valve, as I have owned this car since new.

To clarify, this is a 100% rebuilt engine on its first run. The oil and filter are brand new and the crankcase is clean as a whistle. I have reset the codes several times and they always come back. I spoke to an ASE mechanic and he said the P3400 is the single most common code on the engine. He feels I likely have good oil pressure elsewhere. We developed a plan of attack which I will describe in my reply to WiiMaster's comment.

I also have random cylinder misfire codes, my idle is too high, and I have a VSA problem indication on the dash. I think I will clear the VSA problem once I am ready to take the vehicle for a drive. I already repaired the VSA system in the recent past, which included a new rack and pinion and some calibration to the system. I think its just upset because the battery has been out of the car for 18-months. But I will address all these other problems after the P3400 code and I am satisfied I have oil circulating properly. I will appreciate you sticking with me until I get all of the issues resolved on my new engine.

 

[celicool]

Spool valve/VVT valve/or sometimes vtec valve are all meant the same thing here. It usually is the one causing P3400 code.

BTW, the P3400 code will usually trigger the VSA to come on and puts your van in limp mode. Hence, you cant go over certain RPM or speed. Fix the P3400 and your VSA code will go away.

the spool valve is on the driver side, in the rear of the Engine across from the firewall. Its gasket has a filter element/strainer. That strainer could have sediment and whatever which could affect the oil pressure and set the p3400 code. Some posters here just replace the gasket with a cheap amazon unit , and it worked fine. Some triggered the code and had to replace the entire spool valve with an OE unit. Basically, its a crap shoot. Sometimes you get lucky with just a cheap replacement gasket from Cardone. Sometimes you have to put in an expensive $450 OE spool valve. Honda does sell the gasket only for like $32.

Did you adjust or check your valves before assembling? That could certainly cause your misfiring. Yes, it happened here before. You sound like you know what you’re doing though.

the spool valve has couple solenoids on it with a quick disconnect plug. Be sure that plug is fully seated and click. If not, you could get both the P3400 and VSA codes.

 

[schneidm]

What warranted an engine rebuild? I suspect I know the answer but I'll wait.

P3400 is not necessarily related to the engine oil pressure. It refers to the oil pressure going to the VCM spool valve. That's the only rocker arm actuation system on this engine, there's no VTEC.

Your engine oil pressure is most likely fine. Probably a bad oil pressure switch or some other issue with the bank 1 VCM spool valve.

The oil pressure switch on these solenoids is not what controls the oil pressure light, there's a separate switch for that. That's why you didn't see the light.

Thank-you very much for discussing this with me. I was expecting a delayed response or no response at all. I am very appreciative.

Why the rebuild? I have owned this car since new. Raised my family in it. We love the car. I replaced the timing belt at 125,000 miles. Then stupid me forgot about it until 245,000 miles and it failed. BUT.... the broken belt was a symptom and not the cause. My forensic study revealed the following order of catastrophic events. Rear cam shaft bearing disintegration caused drag that increased over time. (after head removal, I literally could not turn the cam by hand). But there was never an unusual sound that we noticed. Eventually, this drag caused 4 rows of "teeth" on the timing belt to shear and the interference engine design caused literally all 6 cylinders to get bent valves. (and we were driving slowly at the time). The sudden stoppage of the engine caused the harmonic balancer woodruff key to shear. So technically, I could not have avoided this catastrophe. However, during my rebuild, I discovered lots of signs of my declining care for this engine over time. It was worn out and I had become lazy on my oil changes. It was filthy and low on oil. Between 2008 and now, I became very busy at work and a far less attentive grease monkey.

Now back to the problem at hand. And again... thank-you for conversing.

First, can you please tell me precisely where the oil pressure light on the instrument cluster gets its data from? Where can I perform a manual test of oil pressure? All I am aware of are the VCM oil pressure switch ports.

I appreciate you stating that I most likely have good oil pressure. I had thought it likely that the engine oil would follow multiple paths to the top of the engine and that the oil used to operate the VCM system was NOT the primary path for oil to lubricate the valves, cam, and rockers. In fact, it would not make any sense for oil used to activate the VCM to also be used for lubrication because that would imply an open loop and no pressure build up.... and pressure is what is required to actually slide the rockers back and forth, right?

I spoke to an ASE mechanic yesterday and he said the P3400 code is the most common code on this engine and is usually a faulty oil pressure switch on the VCM bank. He too felt my oil situation in the engine was likely fine. Although I will acknowledge now that I have added 5 quarts of oil, while it calls for 5.3 quarts after an engine rebuild. I'll add a third of a quart today, but the dip stick reads FULL.

So here is the plan of attack developed with the mechanic: (1) remove spark plugs (because I am replacing them anyway later today)
(2) while plugs are out, rotate engine by hand and make sure it still feels smooth with no undue resistance. This to answer my fear that I have been running the engine w/o adequate oil to the top. In other words, to satisfy my hopefully misplaced paranoia. (3) Perform a manual oil pressure test on the next start of the engine. (4) if it passes the oil pressure test, replace the oil pressure switch associated with the P3400 code. (5) start engine and check for codes again.

If I kill the P3400 code, I will then engage this discussion regarding my idle situation and random misfires (if they don't rectify themselves.)

BTW way, it was my intention to muzzle the VCM system as a precaution and to ensure my newly cleaned pistons and new rings remain so. But I obviously need it working correctly first. I never had any particular problems with VCM, although towards the end of the engines life, there was some smoke exiting the tail pipe on warm-up. Probably the old valve stem seals though. So I personally never experienced big problems with VCM through 245,000 miles.

 

[schneidm]

Spool valve/VVT valve/or sometimes vtec valve are all meant the same thing here. It usually is the one causing P3400 code.

BTW, the P3400 code will usually trigger the VSA to come on and puts your van in limp mode. Hence, you cant go over certain RPM or speed. Fix the P3400 and your VSA code will go away.

the spool valve is on the driver side, in the rear of the Engine across from the firewall. Its gasket has a filter element/strainer. That strainer could have sediment and whatever which could affect the oil pressure and set the p3400 code. Some posters here just replace the gasket with a cheap amazon unit , and it worked fine. Some triggered the code and had to replace the entire spool valve with an OE unit. Basically, its a crap shoot. Sometimes you get lucky with just a cheap replacement gasket from Cardone. Sometimes you have to put in an expensive $450 OE spool valve. Honda does sell the gasket only for like $32.

Did you adjust or check your valves before assembling? That could certainly cause your misfiring. Yes, it happened here before. You sound like you know what you’re doing though.

the spool valve has couple solenoids on it with a quick disconnect plug. Be sure that plug is fully seated and click. If not, you could get both the P3400 and VSA codes.

Thank-you for the reply.

So I understand now what part you are discussing. I will go through that aspect today. Although I was focused on the pressure switch. You are illuminating the fact that any aspect of this system could cause the code.

Can you explain to me why there are similar components on the front bank? I thought VCM only managed cylinders 1-2-3. Would the system shut down 4-5-6 as well? Maybe this is to maintain engine balance during operation by shutting down one cylinder on both sides of the engine?

Glad that VSA will resolve on its own after I get passed the P3400.

I gapped the valves myself on Friday and started the engine Saturday morning for the first time. Yes, I generally know what I am doing. But I am not an experienced mechanic. Just a garage "fun" mechanic. I set my lifter gaps very tight. It calls for 0.20 to 0.24 mm on the intake and I went for snug at 0.20. It calls for 0.28 to 0.32 mm on exhaust, and I went for snug at 0.28. Perhaps I made it all too tight? This is representative of my lack of experience and I went by my old school days when I did this on an 80's vehicle and it worked well and made the engine very quiet. But maybe tighter is not better on these late model Honda engines?

 

[schneidm]

Just to add to the discussion. I found the main oil pressure sender. It is a three wire sensor mounted just above the oil filter housing on the right side of the engine. So now I know for certain that actual oil pressure is measured independently from the oil pressure at the VCM bank. And I have no low oil pressure light on the dash. So I should be getting adequate lubrication through out the engine.

What is interesting is that the sensor is a single three wire sensor, whereas the Factory Service Manual shows two sensors side by side. I presume the single 3-wire sensor measures actual pressure rather than just a yes/no condition. Probably serves as a combo oil pressure measurement in PSI as well as a switch.

EDIT - further research finds this sensor referred to as a VVT oil pressure sensor. (Variable Valve Timing) and appears to contribute to the VCM system.

 

[celicool]

Thank-you for the reply.

So I understand now what part you are discussing. I will go through that aspect today. Although I was focused on the pressure switch. You are illuminating the fact that any aspect of this system could cause the code.

Can you explain to me why there are similar components on the front bank? I thought VCM only managed cylinders 1-2-3. Would the system shut down 4-5-6 as well? Maybe this is to maintain engine balance during operation by shutting down one cylinder on both sides of the engine?

Glad that VSA will resolve on its own after I get passed the P3400.

I gapped the valves myself on Friday and started the engine Saturday morning for the first time. Yes, I generally know what I am doing. But I am not an experienced mechanic. Just a garage "fun" mechanic. I set my lifter gaps very tight. It calls for 0.20 to 0.24 mm on the intake and I went for snug at 0.20. It calls for 0.28 to 0.32 mm on exhaust, and I went for snug at 0.28. Perhaps I made it all too tight? This is representative of my lack of experience and I went by my old school days when I did this on an 80's vehicle and it worked well and made the engine very quiet. But maybe tighter is not better on these late model Honda engines?

I think 08-10 VCM equipped vehicles have VCM2, which affect cylinder 1-4. Hence, you also have front spool valve.

 

[schneidm]

I think 08-10 VCM equipped vehicles have VCM2, which affect cylinder 1-4. Hence, you also have front spool valve.

I just read my valve clearance instructions and realized I did NOT follow them correctly. I must have gained my instructions from the web somewhere and forgot to look at my own FSM. I rotated in sequential order to each TDC and adjusted the clearance. But the instruction in the FSM give a specific cylinder order to follow and the torque specification on the nut changes based upon the cylinder. I did not do this. And I also failed to rotate the engine one additional time to check my settings. Unfortunately, I think I must re-do the clearance adjustment to resolve my cylinder misfires. It will be interesting to check the clearances now after running the engine.

 

[WiiMaster]

There are 3 different versions of VCM. Your engine has VCM-2, which can either disable all 3 rear cylinder (1-3) or one rear cylinder (3) and one front cylinder (4). Hence, there are VCM components on both banks. 08-10 Odysseys with VCM have VCM-2.

But P3400 is a rear bank code anyway so you can ignore the front bank. It may be worth checking the front bank VCM spool valve though as this valve commonly leaks after a while and the leak makes its way straight into the alternator, frying it.

IIRC the main oil pressure sensor is in the oil pan area, can't remember exactly.

 

[WiiMaster]

Also, don't feel too bad about the camshaft troubles. This generation of J series engine, especially the ones with VCM, is known for having somewhat sensitive cams that are prone to premature wear.

 

[schneidm]

Also, don't feel too bad about the camshaft troubles. This generation of J series engine, especially the ones with VCM, is known for having somewhat sensitive cams that are prone to premature wear.

Yes. It actually happened to me twice. In 2016, I replaced the front CAM and 1 or two rockers due to pitting on the cam that transferred to the rocker rollers. It was making a bizzare ticking sound that was on like 3-4 second interval. The sound wasnt every single engine rotation. Took me a while to figure that one out.

 

[jdm06ody]

I just rebuilt my J35A7 engine. New heads, rockers, piston rings, oil pump, timing belt, etc. It started immediately. I have run it about a total of 30-45 minutes at this point.

Immediately, I had a high idle at 2000 RPM, a P3400 code, engine is stuck in limp mode and cannot accelerate past about 3300 RPM, and some random misfires that seem to change with each run of the engine. I am concerned with engine oil pressure first.

I never had an oil pressure idiot light on the dash, but I get this P3400 code which suggests there is no oil pressure at the rocker arm bank closest to the firewall.

Is there an oil pressure sending unit that serves only the dash idiot light? Why would that light stay off?

Meanwhile, the oil pressure switches on the rocker arm are detecting no or insufficient oil pressure. Actually to be more specific, the P3400 code itself reads Valve Pause System (VPS) Stuck Off Bank 1. But most discussions of this code point to a faulty oil pressure switch. I unplugged both oil pressure switches to see if I would get a second code and I did not. Instead, I got a flashing check engine light AND the P3400 code did not happen. Not sure why. I consistently got the P3400 code each time I ran it otherwise.

Also, I am having a very hard time finding a manual oil pressure gauge setup that will fit the Honda. My pressure tester (from Harbor Freight) is SAE/NPT and the VPS oil pressure switch on the Honda J35A7 is 10mm x 1.25. No one has an adaptor for this (male 10mm x 1.25, female 1/8 x 27 NPT). I am not sure why it so hard for me to locate a manual oil pressure gauge that is compatible with my Honda engine.

Bottomline is that I am scared to run the engine any longer without a manual oil pressure test so I can be certain if my oil pressure switch is bad or if there is indeed no oil pressure. I do have a back up rocker arm set up, but I am really hoping I am getting oil and not destroying the rockers.

heres the info I get from tsb. check the oil level low oil pressure can set this, clear the DTC and turn the ignition on without starting if the DTC came right back, the likely problem in the rocker arm oil pressure switch circuit, if they dont come back start the engine idle for 1 min. if the DTC came back the rocker arm oil control valve is leaking or stuck. replace the rocker arm control valve for DTC p3400

 

[schneidm]

heres the info I get from tsb. check the oil level low oil pressure can set this, clear the DTC and turn the ignition on without starting if the DTC came right back, the likely problem in the rocker arm oil pressure switch circuit, if they dont come back start the engine idle for 1 min. if the DTC came back the rocker arm oil control valve is leaking or stuck. replace the rocker arm control valve for DTC p3400

I just bench tested both of my oil pressure switches and they both work. They are normally off and have no continuity until I apply pressure (using air) and they both get close to zero resistance or a continuity of 1 when I apply pressure. I am focusing on the control valves. Two on the rear bank. I had to transfer them from my old rocker arm and its quite possible I messed something up during the transfer.

 

[schneidm]

Update. I removed plugs and rotated engine by hand and it feels fine after 30-45 minutes of operation. So I am proceeding on the assumption I have had adequate oil pressure all along and have not damaged anything due to lack of oil pressure.

I also bench tested both oil pressure switches and they seem fine. I am now inspecting the rear two rocker arm control valves.

 

[schneidm]

heres the info I get from tsb. check the oil level low oil pressure can set this, clear the DTC and turn the ignition on without starting if the DTC came right back, the likely problem in the rocker arm oil pressure switch circuit, if they dont come back start the engine idle for 1 min. if the DTC came back the rocker arm oil control valve is leaking or stuck. replace the rocker arm control valve for DTC p3400

You know there are two valves on the rear bank. I'll have to test them to decide which one or both to replace.

 

[WiiMaster]

You know there are two valves on the rear bank. I'll have to test them to decide which one or both to replace.

Each bank should only have one, though they are usually split into halves.

 

[WiiMaster]

Easy way to eliminate the pressure switches even after testing is to simply swap the front and rear bank ones. If the issue moves to the front bank (P3497), then you found the problem. They're identical switches so you can swap them.

 

[jdm06ody]

Update. I removed plugs and rotated engine by hand and it feels fine after 30-45 minutes of operation. So I am proceeding on the assumption I have had adequate oil pressure all along and have not damaged anything due to lack of oil pressure.

I also bench tested both oil pressure switches and they seem fine. I am now inspecting the rear two rocker arm control valves.

rear rocker arm 1P connector for DTC P3400. and front rocker arm oil pressure switch 1P connector for DTC 3497
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