blurat

Hi, got the civic together this weekend. Runs good, no drive issues, but check engine light.
Codes are 131, 325, and 505. I looked these up and one has to do with low voltage to the ox sensor, one is knock sensor, one is idle air.
My question is : could these be related as to water in the exhaust system from when the head gasket was bad or from any other quirk in the system?
The light came on in less than a block but I told my son to clear the codes at work and maybe the 30 mile drive will evap any water in the system. We will check the codes when he gets back this eve if the light comes on again.

ezone

Post your vehicle info for each new thread please. I hate searching everyones posting history.



My general rule when these pop up immediately after a large job: Make SURE you got everything plugged back in!

Clear codes and see what returns. Address each code as they return.


P0131 O2 B1S1 Low voltage. Coolant contamination can poison an O2 sensor, just like some silicones can ruin an O2 sensor.

P0325 Knock sensor circuit, make sure it got plugged in and nobody pulled the wire out of the connector when the head got yanked off.

P0505, Control unit could not control the idle speed for some reason. RPM was either higher or lower than desired.

blurat

2000 ex, replaced the ox sensor last night. error code 0505 after the 30 mile trip to Livermore. The car will not hold a steady rpm, it surges at freeway speed. Runs fine under acceleration, or seems to.
I could not get the idle below 1200. I pinched off the pcv hose to the intake and it made no differance. I can hear a hissing noise somewhere under the intake.
This is not something new, we could not get the idle below 1200 for 8 mos now. Keep in mind I am going by what my son is texting me, I have not personaly driven this car to experience these problems because I simply dont fit into small cars like that.
I think after taking the head off maybe the purge valve is causing the hissing noise. All the intake bolts are tight, new gasket, vacuum hoses good no cracks.
Thats all the info I have.
Thanks

ezone

There's your P0505 code.
Head swap? Was done when?
Do all of the ports in the intake manifold actually match up with the ports in the head, or is there some area left open/uncovered?

ezone

Have junior get a length of tubing (vacuum hose, garden hose, fuel line, I.V.drip, whatever), maybe 3 feet long or so.......

stick one end in his ear, and probe around with the other end to locate/pinpoint the actual source of the vacuum leak noise.

blurat

OK, the intake manifold is leaking. I can drop a 15k feeler gauge in between the manifold and head and see the gasket move. Both surfaces were clean when I assembled the top end. All bolts are tight. Is it common for the manifold to warp? I guess my only alternative is to disassemble and go back to the machine shop.
The head was warped 10k due to overheating. Maybe it got a lot hotter than I am thinking it did.

ezone

Not really, but I suppose it's possible. IOW, I would not be looking there first.....but

If you pull it off, measure its surface for flatness just like measuring a cylinder head for flatness.

Doubt it. You're probably overlooking something easy.


All bolts are STILL tight?

Did the bolts bottom out before they tightened the manifold?


Oh yeah, the vacuum leaks may explain the O2 sensor code too.

blurat

All bolts were tight when I removed them. I can tell by the intake gasket that the ports are sealed. The loose gasket part involves a small chamber above the ports where the fuel injection assist hose is. There are 4 small holes drilled to the injector port. We had to replace the valve which is mounted on the thermostat housing and was only used in 1999 and 2000 ex models.
The valve has no computer connections on it, just heat operated and probably useless if they only used it for 2 years.
Im thinking of a small spot of JB weld to plug the holes and vacuum leak is gone.
Your thoughts?
And thanks so far for the input.

ezone

So the head and manifold are not a matching set, right?

Could this be for EGR distribution? Kinda sounds like it could have been, for one version of the engine or another.


I can't tell what exactly you are dealing with from here, but I guess you need to do whatever it takes to cork the holes so they are not vacuum leaks.

blurat

The head and manifold match. The little chamber above the ports is only used on 1999 and 2000 vtec ex models. Don't know what it is for other than to give me a headache.
Im plugging the holes and will post results after I get it running again. Ill post a pic if I can figure that one out.

blurat

Ok, I opened my flapper last post a little soon. When I was taking pictures of how everything fit I noticed the top rail on the head where the intake gasket is supposed to seal wasn't even machined. Under further investigation I find that the head is from an earlier year. The vacuum galley on the head is longer than the manifold and a 98 intake gasket fits perfectly.
This head has been on the engine since August last year at least.
I'm glad I'm not a doctor or everyone would be dead.
Thanks for the replies. Always helpful.

ezone

Without going back to look at previous posts, isn't this about the time the idle problems started?

blurat

Absolutely. "junior" smoked the motor by running it out of oil. My part was to do the bottom end and a helpful friend put the rest together. He bought a rebuilt head but evidently it wasn't from a 2000. It has had a check engine light ever since. IAC valve, FIA, sensors, etc.
The buddy finally disappeared one day so I inherited the problem.
Last night for the first time the car actually idled below 1200 rpm.
Tonight I will raise the idle to 800 and get back to my Subaru VW project.
Thanks for all the suggestions,