Hi Guys,

My girlfriend's car is acting up. If you give it any more gas above just barely feathering the peddle it won't go. It kind of bucks or misses. The car will barely make it up even the gradualist of inclines and unless you barely give it gas just won't go.

My first thoughts were to give it a tune-up and the basics just to rule them out, spark plugs, air filter, fuel filter, oil change and then go from there.

Instead she went and had it scanned at auto-zone or some place and a code came back for the vtec oil pressure switch. Code: P2647. She bought one, the whole entire solenoid that bolts to the block of the car with three bolts, not just the sensor that you take out with a 22mm socket.

I put it in the car last night. I drove it for a half an hour and the car ran great. Revved up fine, had no issues. It sat overnight and now its back to normal, chugging and bucking and just won't rev up.

Now I'd like to change the plugs, fuel filter, air filter and then go from there but I checked and the fuel filter is $75 bucks. I about crapped.


I hate to just throw parts on the car that aren't necessary.

I've got a 98 civic that I put a jdm b18c in and then put a jrsc on the motor. All sorts of other crap too. So I don't mind working on these cars.


I just was hoping maybe someone out there has had this same exact issue and could tell me what they did to solve it.

Of course she wants the car fixed right this minute. I've always had a second vehicle and could take my sweet time working on my honda but this isn't the case. haha women.


To make a long story short:

2003 Accord 2.4l chugs/bucks/misses under any type of load.

Codes: P2647: Vtec Oil Pressure Switch

Changed Oil, Vtec Oil pressure switch recently. Still misses.

Has been missing for a month or so and seems to be getting worse.

 

Is the code still there/come back? Did you check the oil level.

If the plugs are old/due then I would replace those and the air filter - these are "tune up" items and should be kept up to date.

PS - the fuel filter is part of the fuel pump.......

 

I replaced the vtec oil pressure sensor/solenoid and the code went off and then came back on and is still doing it.

I've found out a little bit more information since I first made the post. Maybe I already wrote some of this but here it goes. I guess she let her car go 14,000 miles on conventional oil without an oil change. I know she never let it get very low on oil because I would check it and fill it up as needed but I never knew she let it go that long without and oil change.

I think she may have done some damage to the motor or atleast has some major sludge buildup. I could take the oil cap off and scrape my fingernail against the valvetrain and comeout with black almost dry crusty ****. Old burned up oil residue.

What I am thinking is: The sludge build up is not allowing the vtec rocker arm switch(could be wrong on exact name) to work properly and that is throwing it into limp mode.

She just got an oil change 100 miles ago and thought the oil change place told her they put 10w30 in the car and since she wasn't sure I changed it out to the recommended 5w20 and I replaced one of the quarts of oil with a quart of marvel mystery oil. After driving the car only 30 miles I try to scrape some **** off the valve train and it had already broken it down into a much runnier substance so I think its doing its job of breaking up the sludge.

I plan on changing the oil in like 500 miles but am not sure if I should do it sooner or later than that. Any recommendations here guys?

When I do change the oil I am going to do the same thing again and replace a quart of oil with the marvel.

I'm hoping as time goes by the sludge will dissapate and allow the rocker arm switch to start working properly again. Problem is I just don't know enough about the motor or this so called rocker arm or how any of the vtec stuff works.

I want to change the plugs but she is low on cash and already feels like she is getting screwed because she bought that $95 Vtec pressure solenoid and that didn't fix the problem. And then 35 for the oil, marvel and filter.

I'm assuming that any mechanic she took it to would have seen the code for the vtec sensor I replaced and would have replaced it as well.

I really think her not changing her oil in such a long time has something to do with the problem she is having.

I wish I knew more.

The car will drive fine for 10 miles and then all the sudden will go into limp mode. I can put the car in neutral, turn car off and then back on and put back into drive though and car won't be in limp mode anymore and the last couple times I did this never went back into limp mode as long as I drove it.

Makes me wonder if this is more sensor related that sludge related??

I've probably already lost a few of you with all this typing so I'll end it now. Or maybe I won't.

So I was thinking of changing the fuel filter. I can't just change the filter without having to change the fuel pump? I have to change both together?


Thanks,
Aaron

 

2 things:

Is there a check engine light? Find out what the code is, and what it means.

Secondly, the code may point to something else, but it very well could be a clogged VTEC screen, or simply a clogged oil filter, preventing the proper oil pressure to reach the sending unit, which puts the car in limp mode.

If you are mechanically inclined, hook up an oil pressure guage and read what is coming off the oil pump at the sending unit. Oil pressure is the #1 reason the car goes into limp mode, no matter what computer code is being thrown. Been there done that.

 

This story kind of reminds me of a situation I ran into twenty years ago.My ex had an Accord(1985) that she had bought new.Her husband had changed the oil and the oil light was now on.The car was still running and not making any noises but as she was driving it to my shop the engine died about five miles down the road.I sent a wrecker,got the car in the shop,determined that the engine was seized and removed the oil pan.The oil pick up had a glob of sludge blocking it completely!I loosened the bearing caps and broke the engine loose.I removed each bearing cap one at a time,inspected each,coated with lubriplate,reinstalled and torqued checking to make sure the engine was still free as I went.I cleaned the sludge(almost jelly like) from the oil pan,valve train and valve cover,put it all back together,added fresh oil & filter,spun it over with ignition disabled until I had oil pressure.With the ignition hooked up ,I started the engine,it ran Ike it should and she drove the car for several years(with regular oil changes).

 

I realize I wrote quite a bit but you must not have read either my original post or reply because in both of those I talk about check engine lights and the corresponding codes.

It's no problem. I realize you don't have to even read the post at all if you don't want too.

Check engine light has came on and off as I've changed oil/filter and changed vtec sensor but as of this moment it is on and car still is in limp mode.


Engine is sludged up. I put a quart of marvel in it. I'd like to know how long to leave in before changing oil again. I hate to leave that sludged up marvel oil in the car for a full 3000 miles. I was going to change it in like 500 miles or maybe less and then do the same thing again, add a quart of marvel to it.

I'd like to check oil pressure. I guess I'll have to do some research as to what guage and parts I need to do this and where to hook it up.

Thanks for tip.

Aaron

 

Just wanted to let you know that after hours and hours and hours of research I've come to the conclusion that sludge inside the motor is the culprit for limp mode. Specifically, sludge is lowering oil pressure enough to the vtec sensor to throw car into limp mode.

I will be pulling the head and cleaning either tomorrow night or the next. I'll let you know what I find.

Thanks for the help,
Aaron

 

There is a little screen on the front of the head, I would removed that and clean it and see what you have....I don't have my manuals with me or I'd post a pic of it.