foedoemoehoe

i just bought an 05 4 door civic si with 1.7l vtec and it went into limp mode and pulled a code p2646 witch is a vtec pressure switch low votage so after reading threads for hours i did a few things .
changes the pressure switch ,selonoid . the little screen filter . checked for shorts in the wiring from the ecu to the switch ad selonoid as well as changed and checked oil and added an oil additive claimed to clean out "the system" does anybody have anyyyyy idea what to try next really need help . did not want to take it to honda but looks like i might not have much choice

lazlong

Jump a wire from the solenoid to body ground then test for continuity from ECM/PCM connector B15 (green/yellow) to body ground. If there's continuity then you need a new ECM/PCM. If no continuity repair the wire between ECM/PCM B15 and the solenoid. Test the wire side of the connector. Connector B is the second one from the bottom when looking at it in the dash.

foedoemoehoe

finally got to test it looks like i need an ecu . can i use one out of an acura rsx ?

foedoemoehoe

Soo my car went into the garage today, a devoted honda /imports garage after changing the solenoid ,presure switch ,ecu.

the garage could not fix it but this is what we know
the ecu is good
the wiring is good
the solenoid is good
the pressure switch has over 60 psi so good
the oil is topped up

what we also found that the erg is valve is good but there is a code showing for it and when we took the egr off when the car was running it was not affected witch leaves me to think that the passeges are completly blocked off with dirt or it has the wrong intake gasket.
not too sure if that could somehow be connected.

so does annybody have anyyy ideas on what to try next this has turnt out to be quite a problem.
any suggestions might help


thanks guys in advance

ezone

So you no longer have the P2646, but you now have a P0401? Pull the intake and clean the EGR distribution chamber.

Simple.

foedoemoehoe

no still have both 2646 and 0401 im going to be taking off the intake and cleaning the chambers with in the next few days also to make sure i have the correct gasket on.

the main problem is the 2646 but i dont even know anymore with this car, the problems could be related ?

ezone

I should have said "the usual cause" of the P0401 is clogged ports, but if there is a wrong gasket somewhere that could cause it too. Anything that causes the flow to stop. If it had wrong gaskets causing the problem, that should have set the code on one of the very first drives after the wrong gasket went on.

Most people experience mysterious misfire codes while the EGR ports are in the process of clogging, but not always. Ports for cylinders 1 and 2 seem to be the last to clog up, and are the cylinders that misfire while the EGR tries to operate. This is one instance where Freeeze Frame data is valuable.
Not dirt. It is carbon. Plain black carbon.



No. Not related.

This should be a simple process if one has the right tools and thinking ability.
Someone needs to see what the system is actually doing LIVE while running and operating the VTEC. Then make decisions about what to do next. Gonna need some understanding about how it all works together, in order to figure out what part isn't right and why.

This is what the PCM had to see wrong in order to set the code:
When the VTEC solenoid valve was turned ON, the VTEC oil pressure switch remained ON.
I can't tell you WHY, because I can't test anything from where I sit. Could be electrical, could be mechanical, could be hydraulic. But it is fixable.

foedoemoehoe

ok so the mech that had my car tested the presure at the switch in the shop and had sufficient pressure acording to specs and he did have it out on the road with live feed and what he told me is that that the solenoid is funtioning properly and that presure switch is comming on and off according to the revs but it is comming delayed enough to set off the code. if that helps


really appreciate you helping me out

ezone

Can you explain more about "delayed"?


EDIT:
My chart says it should take 5 seconds of the wrong switch state to trigger the code. Does the switch action lag that much?

foedoemoehoe

well from what he was saying is that on the live feed while driving the car he could see that the the switch was on and then at the point that it is seposed to go out (3200 rpm i thought he said ) it would take a few seconds to go off soo im guessing it took longer than 5 seconds but it would eventually come on if it was held at the right rpm


I have never got anywork done with this garage but everybody has said that they are the best and they specialize in hondas but he had nothing else to try other than dropping the oil pan and checking the feed

I also had a though and maybe you could clear it up but there is alot of confusion with the canadian si thing and when ordering parts u have to make sure that the parts are for either a canadien si or an american ex if say the guy that owed the car beafore had a headgasket done and the wrong headgasket was put on with there be any of these symptoms?

ezone

I'm no expert on this, I didn't even realize there was any difference until I started hanging out on this site and learning from others about this.


An SI in the US market would have had a 2.0 K engine and was only available as a 3 door. I doubt the head gasket would even fit, but I suppose some idiots can go to great lengths to screw stuff up.

The way I understand it, an 05 SI in the Canadian market is the same as our EX here, and got the same 1.7 engine with VTEC as our EX here.




He should be able to see when the solenoid is turned on, and when the switch turns off.
I can rig it --with jumper wires and a test light-- to operate manually in the shop for testing purposes, on demand.
I would TEE the pressure switch with a manual oil pressure gauge too.

If there really is a significant delay, that probably tells me the oil flow is slowed, restricted, or leaking within the circuits between the oil pump and the switch. That includes all of the passages in the head and rockertrain. I'd have to think some more on this though.

This thought popped into my head, had to search a little for it:
Might be like this? https://www.civicforums.com/forums/3...ing-p1259.html

Wouldn't it be great if it was this easy?

foedoemoehoe

yea here in canada our si is you ex and the 2.0 ,3 door (EP3) is known as an SiR. but im just wondering if maybe a non-vtec headgasket could have been put on in the mits of the confusion at the parts store... my guess would be that i would get 0 pressure at the switch but then again this is not turning out to be a normal case anyways



well i think im gonna have to just take the valve cover off and take a look if it is something that painfuly simple im gonna be a little mad i drove it like this for 6 months and never checked under the valve cover ..... unnfortunatly we have got some 95 kmh winds and freezing rain going on today on the lovely east coast of canada soo i dont think im gonna be at it tonight but im going to find a garage to stick it in and take a look tomorow

ill check for that bolt and any othe weird signs, maybe take some pics to refrence.

Thank You again
I really cant get over all the help that every body gives on this site seems like every were you go nobody wants to talk unless its makin money

ezone

1.7 head gaskets shows the same part number for both VTEC and non.

I was trying to think of stuff that would keep the system from building pressure instantaneously. A leak in the hydraulic circuit such as that could certainly cause it to be slow, right?


If that isn't it, then there are ways of applying air pressure to the circuit to look for leakage.
Other causes might be akin to some sort of debris built up in a passage.

foedoemoehoe

okk that answers that question
that would make sense. if it is leaking someweres along the cuircuit it would take that extra time to pressurize it within the 5 second gap we were talking about ..
I will take a look at top end under the valve cover tomorow and see what I see , and if nothing comes from that I will have to drop the pan and check there . might have to talk about applying air pressure after to check for leaks but i guess ill see what the valve cover has to offer

In the case that I will need to apply pressure to test for leaks though that would be done from the bottom with the oil pan off correct ? or is there a test I can do on the head ?

Matt_75

I vote for sludge build up and/or leak in hydraulic circuit from an improperly maintained engine prior to the current owner buying it. Just my thoughts on the matter.

ezone

What would you expect to find there?

I wouldn't do that without a lot of reason.
I'm lazy, I hate unnecessary work.
If there isn't sludge immediately visible in the head areas once you get the valve cover off, there probably isn't sludge down below either.

But if there is, then look out. You may be in for a heap lot of work.

If you get a service manual, there should be descriptions of VTEC ROCKER ARM TEST that are done with air pressure on the VTEC system. There are adapters made to plumb regulated air pressure into the VTEC system.

ezone

You said the head has been off of it, right?

I cringe at the thought of some of the disasters I have seen when unqualified people "work on cars".

Matt_75

Hey! Watch it! I resemble that remark.

foedoemoehoe

I have no proof ....but there is an engine heat tab put on the front of the head witch usually means work was done on it could be wrong though ?

and im reallyy hoping it will be on the top and wont come to taking the oil pan off cause its not sounding like a fun time

ezone

Which part?

I was thinking of a used 2.0 SI civic that came from the next state over, brought in by a used car dealer that just bought it.

Someone had JUST replaced the timing chain in it and it jumped time again during the trip....
I straightened that out....test drove and RATTLE RATTLE CEL comes on with VTEC codes now...... Found the VTEC screen clogged up with RTV from an idiot using waaaay too much sealer on the timing cover and globbing it into the oil pressure passages in the cover and pump.


Unholy mess. Someone needed to be shot.

ezone

The factory does not install those.

Some apply/install them to protect themselves/their reputation/their work.

Is the center melted out of the heat tab or something? If not, no worries.


Again: Not without a damn good reason. You have no reason right now.

foedoemoehoe

it is all intact but it just points to the fact that there must have been some work done to it with the previous owner , hopefully also a sign that the same mech that took the time and care enough to put it on also took same care in doing the work

exacly ,see what turnes up tomorow

foedoemoehoe

soo this morning after the storm all night it was nice and calm and was up to 0 deg c so I whent out to tackle the valve cover .. soo when I got it off this is what I found that bolt just sitting ontop of the hole exacly how it is in the picture I was absolutly astonished at what I seen and cant beilive that all this time (7 months ) and all the parts that Honda and other garages tried on it. it came down to a simple bolt (that Im guessing vibrated free?) was the cause of all the problem and I also cant beilive that it just sat on top of that post for that long and did not fall down into the valve erea .. torqued it down and took it for a drive and all is good now


super big thank you to ezone I would have never found that without your help

ezone

This is not mentioned in any service manual or TSB that I have seen.

I sure wouldn't have ever thought of it without someone else discovering it before me.
(See? Even someone like me can learn here!)

Thank whomever made that thread I linked for you.


The service books don't really even cover much about the oil paths and flow at all. (But that air pressure test would have let you find it.)




This was not a factory problem.

The bolt did not just "vibrate free" on its own.

99.99% positive a human being did this.
Probably whomever did the head gasket job, or maybe someone at the machine shop disassembled the head for some work there, it's possible.

Congratulations, you have been "moroned" (the guy I work next to always says that when it's obvious an idiot was in there.)




You can send me your credit card info too. I have a power bill due in a couple days.