Rep Power: 0

Alright guys, I need your help.

I've already made a post about this but it's died down so here's an updated post. In January of this year, I took my car in to get a head gasket replaced by Honda after several months of overheating. This may have damaged some internals, such as piston rings and such, but I haven't experienced a loss of oil so I hope there isn't damage.

Here are the things I've done so far:
*Changed oil from 10W-40 back to 5W-20 with Honda oil filter.
*Replaced VTEC solenoid
*Replaced the VTEC oil pressure switch
*Used multimeter to check connection from ECU to both connections to the VTEC solenoid
*Turned electricals on to run power to solenoid, checked connections.

The car goes into limp mode after about 15 minutes of driving, especially if holding RPM at 3,000 for a minute or so (like going uphill).

I'm starting to think the engine needs to be taken apart but hopefully not. Do you guys know any other connections that may have been missed?

Thanks.

 
Rep Power: 209

Here's a description of the P2646 code: https://www.yourmechanic.com/article/p2646-obd-ii-trouble-code-a-rocker-arm-actuator-system-performance-stuck-off-bank-1-by-jay-safford

and this: https://www.autocodes.com/p2646_honda.html

symptoms of the P2646 code:

• The engine valve train will not move as designed causing a low power condition.
• The Check Engine Light will be illuminated.
• The valve train may be excessively noisy if one or more rockers are stuck in the incorrect position.

Did a new gasket (with screen) come with the replaced vtec solenoid? If not..pull the vtec solenoid and replace or clean gasket/screen. Did you perform an ECU reset? Is oil at correct level?

Remove the valve cover and look for sludge. With the valve cover off it's a good time to do a valves adjustment (unless performed within past 20k miles). When was the PCV valve last checked or replaced?
Check the oil pressure .. will need an oil pressure gauge or mechanic.

 
Rep Power: 0

So when I bought the solenoid, it came with a screen. I checked it recently and it was clean so it can't be that. The oil level is also at the correct level. I also took off the PCV valve and did a deep clean, but it was clean when I took it off. Where under the valve cover should I look for sludge? And how do I adjust the valves? Should I let a shop do it? Thanks so much for the response.

 
Rep Power: 517

Has the head ever been off?

 
Rep Power: 209

You shook it and heard the ball rattling inside?
Reset the ECU ? (disconnect battery + drain residual charge)

If there's heavy sludge you would notice it immediately caked on the cam shaft and rocker arm assembly. Removing the oil pan might reveal sludge too but, it's not an easy job to remove it. If you've been driving it daily and changing oil per service manual then there shouldn't be sludge buildup but, in this case you should at least check under valve cover to rule it out.

Do you have any service records of when valves adjustment was last performed? If you have moderate mechanical skills a valve adjustment is pretty straight-forward. Just takes patience, a couple wrenches and a good set of feeler gauges. Search and download a free copy of a 6th gen service manual (FSM) and all the info will be in there. 6th gen ('96-00') is the same adjustment proceedure as 7th gen. Probably some youtubes on it as well but the FSM trumps videos.

 
Rep Power: 517

If valve adjustment needs to be done then get it done, but be aware it won't cure a P2646 or any other VTEC related code.

Can OP post the freeze frame data for the fault code?