g35silversurfer

Hello,

I have recently got a 2001 civic ex coupe.

Since owning it the last few weeks, the CEL has been on, at idle it revs up and down, sometimes calming down to normal idle rpm. Also can only drive up to 4,000rpms I'm guessing because of the CEL being on = limp mode...

for a few days the CEL was off and it idled fine.

I noticed the IACV was loose.

When the CEL came back on I went and had it ran, came up for IACV and Vtec system malfunction.

Today I finally got around to working on the car.

The IACV was just loose. I tightened it up. oil was a little low, thought maybe that was the vtec code popping up.

thought I had it all figured out lol... nope.

Cleared the codes.

took it for a drive, as soon as I revved up high between shifts twice in a row the CEL came on, now won't let me go past 4,000rpm and back with the annoying revving up and down at idle.

went straight to Autozone. code this time only for P1259.

It revs up and down at idle, won't go past 4k rpm...

I've been researching and researching.. found a thread that has this post:
Fixed.

I cleared the code to see when it would come back. Generally if it comes on at idle or under 4000rpms it electrical .... as in the Vtec pressure sensor is bad, it has a bad connection, or a damaged wire ; at or over 4000rpms its usually oil pressure related.... as in low oil level, clogged screen, or the Vtec solenoid has gone bad, etc.

Well after clearing the code two or three times it would throw the CEL with the key in the on position with the engine off ... so I concluded it must be electrical and suspected the Vtec pressure sensor...

I removed the sensor and priced a replacement through AZ and it was $80 and special order ... so I cleaned (and accidentally dropped ) the sensor to replace it just so the car would be driveable until I could get another sensor.

But when I replaced the sensor and reconnected the battery cable the code did not come back I drove it and it now accelerates above 4000rpms which it wouldn't with the CEL

Hope this helps someone else with a P1259 code.

I have a multimeter and have searched for a easy DIY for checking/testing your vtec solenoid and vtec pressure switch, but I'm having a hard time figuring it out.

From what that guy^ said, if the CEL comes on above 4k rpm then it's the vtec solenoid.

I took my vtec solenoid off tonight. someone has put freaken goop along with the oem gasket to seal it.

I peeked in at the screen, it looked fine. I guess i can take it completely out and look at it tomorrow. I didn't want to tonight with the permatex crap on it.

So... has anyone else experienced this? one thing I really don't understand is, if the vtec solenoid is bad, sure, be bad, don't let my vtec work, give me a CEL and put me in 4k rpms only limp mode, but what the hell is up with the revving up and down at idle?

is it most likely the vtec solenoid and I should just get another one, slap it on and be fixed?

I'm guessing the bozo before me took it off to check the screen and then used permatex for some idiotic reason when he put it back.

but the problem still persists because it's the solenoid itself that is bad.

If you have a d17 vtec solenoid that works and want to sell it, sell it to me please lol. I have paypal.

g35silversurfer

I just went for a drive again. with the computer reset.

I noticed even with no CEL the engine revs up and down still...

drove it around staying under 4,000k rpm. The first time I got on it and got about 4k rpm the CEL came on.

So,, I'm now assuming just get another vtec solenoid and slap it on there.

as for the revving up and down? is that still my IACV acting up?

I already tried taking it completely off the throttle body, but the dam phillips head screws holding it to the tb are so tight one came loose and the other two started to strip. Why couldn't they be 10mm like on older hondas?!

So since I can't just take the IACV off and swap it with another one, I'm now thinking about buying a complete D17 throttle body w/ all sensors....

Any advice?

g35silversurfer

just bought a complete 2004 ex 5spd throttle body w/ all sensors,

and a 2004 ex vtec solenoid.

going to swap them in this week and will post results. hopefully good results lol.

It Wasn't Me

Are you doing any troubleshooting, or are you just throwing parts at it until it's fixed?


Search + "p1259" = https://honda-tech.com/forums/honda-civic-2001-2005-78/2002-civic-ex-v-tec-problem-please-help-asap-2758006/

Search + "vtec" = https://honda-tech.com/forums/honda-civic-2001-2005-78/aftermarket-vtec-oil-switch-replacement-civic-2001-ex-2885882/


Amazing.






The fluctuation idle: Have you tried resetting the ECU and doing the Idle Relearn? Checked for intake leaks?

g35silversurfer

well I started troubleshooting but needed some illustrations to figure it out for sure.

thanks those links made is so easy. Just tested it all on my EH3 in the garage.

Will test the EM2 when it gets home in an hour.

I never could figure out honda-tech search. I type vtec solenoid. it brings up every thread w/ the word vtec in it.. just meaningless crap and not what I was trying to find.

The CEL brought up a code for the IACV a couple weeks ago. It didn't show that code yesterday, but I'm pretty sure it's the IACV that's causing the idle up and down. dam phillips screws are stripping, have to swap the entire throttle body.

Unless there's a voltmeter check for the IACV? I could do that first too.

I did spray water everywhere around the intake manifold searching for leaks, didn't find anything.

g35silversurfer

downloaded the manual...

got it downloaded, opened it up , can't find anything on "testing" vtec solenoid.

The manual sucks. I don't understand, it isn't like the pdf I have for my eg.

g35silversurfer

update

tested the vtec pressure switch, it has continuity. tested from 1 female to ground got 12+ voltage w/ key in II position.

tested vtec solenoid male pin to ground in ohms. got 17-17.5 so it's good.

So what does that mean? does that mean there's no possible way that there's a "break" in the wiring from the ECU to the vtec ?

And would mean it's most likely the metal screen is jammed up too much and I need to replace the screen?

If that's the next step, then I'll go by honda today to get another one, and swap it out tonight.

let me know.

g35silversurfer

went by honda and got the gasket/screen.

the guy said if both solenoid and pressure switch tested good, that it's most likely the screen/gasket.

so installing tomorrow morning. will post results

g35silversurfer

posting this because it keeps my thread going with knowledge if someone else has same problem

Originally Posted by eg6.merrill
how could it be a electrical issue when it all tested good? the guy at the Honda place said if they both tested good it's most likely the gasket/filter...


Loose connection, intermittently wonky ECU, etc.
Have you checked your oil pressure?

g35silversurfer

No, I haven't checked my oil pressure... I hope that's not the problem

After I install the new screen/filter today, if it doesn't fix it, then I'll see when my buddy w/ a shop/tools can get me in there...

g35silversurfer

just did a oil change, installed the new vtec filter, and did idle re-learn.

taking it for a drive here shortly.

will post results...

g35silversurfer

well after starting it up with the ecu being out for 15mins it started up nice and idled nicely. I let it run for 15mins, during which it idled great, shut it off, turned back on for the relearn.

took it for a drive. It revved up and down as soon as I hit the gas to go in reverse. I stayed under 4,000rpm the whole time. after about 5 mins the CEL came on.

so now what? ECU ? some mysterious break in the wiring?



going to get the code read at autozone tomorrow... hoping it's for IACV this time and not vtec since I never even went up to 4k.

or does that make sense? does vtec on these 01-05 Civic EX D17s kick in past 4,000rpms?

wannabboosted

same thing happend to me ended up being idle air control valve. 130 bucks for new. 10 mins to put in.

g35silversurfer

wait a sec. did it make a P1259 CEL come on instead of a IACV ??? Please elaborate, I really want to fix this.

g35silversurfer

dammit. you have 10 posts and logged off... prob never get my answer lol.

g35silversurfer

well I can't get this dam IACV off this throttle body so I found a complete one from a 2004 ex with only 36,000 miles on it. $85 shipped. hopefully gets here by the end of this week.

will post when it's installed.

Lovin_the_EM2

Oh god man let me know what happens. My 01 ex is doing the exact same thing as yours is. The codes I'm getting: p0141 OS heater bank 1 sensor, p1259 vtec system malfunction, p0113 intake air temp sensor 1.

g35silversurfer

is yours revving up and down?

well if my fix ends up being IACV yet it will only show a code for something other than that, then maybe that's your problem too.

these newer civics are more tricky than a easy obd1 I'm finding.... :/

exb18c1

In order for the VTEC solenoid to be engaged the VTEC oil pressure sensor should see 55 PSI (I think), if not forget about engaging.The IAC valve thing shouldn't affect the VTEC.IACV takes over engine speed control on idle only.It has no effect on the higher RPM (like such as engaging point of VTEC).You might have two different troubles.

g35silversurfer

got the new throttle body on, fixed it! idles perfect, no CEL :D

Theroy

Thanks for keeping this thread alive, my friends civic was having the same problem... and for the life of me I couldn't figure it out... I assumed it was the TB... but now I know to install a new IACV... thanks mate!

j.bro

Where did you pick up the throttle body?

g35silversurfer

http://car-part.com/

junk yard in Michigan. from a 2004 ex 5spd coupe that had only 36k miles. $85 shipped

It Wasn't Me

Ah ha! Cool beans, man! Glad you got it figured out. I'll have to keep this in mind next time someone is at wit's end dealing with a P1259 code.

Thanks for the update, btw.

g35silversurfer

update it didn't fix the p1259 issue. taken me a while to get back on here and post.

It's been my wifes daily driver and I didn't notice the CEL come back on.

So... I tested the vtec solenoid wire from the engine bay to the b15 connector on the b(24 pin) connector for continuity and it was good.

I tested continuity from the vtec pressure wire to the ecu connector and it was good.

I did a few other things too. ( I think they really just are the same as what I did but in a different way)

leave the connector un-hooked to the vtec solenoid and check for continuity between b15 and ground, if no continuity do this:

took a jumper wire from the vtec solenoid harness connector and touched it to ground.
then from b15 to ground check for continuity and it checked good.

So now I'm aiming at the ECU... I'm hoping it's just a bad ECU.

I didn't have the special tools to do the pressure checks in the factory manual.

I did the touch a jumper from 12v to the solenoid pin and listen for a click as well.