So I've been trying to smog this beast for about a month now. It had a CEL for missfires which I fixed recently with a tune up. Right after that cleared I got code P0135-025 and had a mechanic look at the car. Car idles high on start (1400rpm) then jumps when warm (900-2000rpm). I have a crack in the exhaust manifold/ cat. Mechanic said "R&R 02 sensor B1S1/ Clean heater circuit idle air count sensor & passages both water & air". Just need a little clarification on what I should do exactly. Thanks!

 

Replace the manifold. It's dumping air over the sensor and telling the ecu the mix is lean, for which it tries to compensate and you end up dumping fuel. This is an almost universal failure for these.

 

Take this^ advice seriously.

Also, P0135 indicates a problem in the heater circuit of primary O2 sensor. This is a separate issue from the cracked manifold. Start by checking whether fuse 15 is blown.

I have no idea what -025 means here.

 

Thanks for the feedback. The mechanic told me the code with the -025... i have no idea what that means either.

 

Fuse 15 is good. I'm going to pick-a-part monday to get the manifold. I'll update after that. Thanks!

 

They probably won't sell you the part since it has the catalyst attached.

 

Can the OP switch it to e-bay headers and cat-back exhaust for under $250 ?

 

Perhaps, or he can fix it correctly for about that too:

http://www.ebay.com/itm/Catalytic-Converter-fits1996-2000-Honda-Civic-1-6L-/141565281515?fits=Year%3A2000%7CMake%3AHonda%7CModel%3ACivic%7CSubmodel%3AEX
Add two new O2 sensors and done.

 

Measure resistance across the two heater terminals of the primary O2 sensor. It should read 10-40 Ohms. If not, replace it.

If resistance is good, check whether the connector gets battery voltage from fuse 15.

For the idle issue, clean the IACV.

 

Hey guys, I'm pretty sure this fits but I want to make sure before I buy it. http://www.amazon.com/s/ref=nb_sb_ss...73%2Caps%2C310

 

^That's the one.

Agreed. I recommended just replacing them though as I can probably count on one hand the number of times those sensors have come out of a cracked mani with the threads intact. If they are working and manage to come out undamaged, by all means return the replacement ones. Sucks to be unprepared though.

 

 

A typical lx/hx/dx manifold has a life span of 180k miles. My amazon replacement unit has aged much more gracefully and still looks new even after 100k miles where as the stock unit would show stress and discoloration if I remember correctly

 

I got the Dorman exhaust manifold recently. I don't have any instructions and their live support is down until tomorrow. Can't seem to find an E-copy anywhere for this product. It comes with a few parts, the manifold, the cat, a gasket for the manifold/engine and a weird circular gasket/ ring that doesn't fit on any parts. Also is there supposed to be a gasket between the cat and exhaust? If anyone here has done this job before, or knows of a video for this exact part, let me know please.

 

This one?





Dorman Products - 674-439

O-ring gasket should go between the cat and the A-pipe.

Three studs and nuts should go to the same.

Four bolts and washers should hold the cat to the manifold with the gasket sandwiched.

Not sure what that bung adapter (or whatever it is) is for, or the five smaller bolts. Looks like it is a plug if you don't have a secondary HO2S.

 

I got all that except the gasket for the cat/ manifold.

 

What can be used as a replacement for the gasket? Will Auto-zone carry one?

 

Doubt it, but maybe. Dorman or whoever you bought the kit from needs to send you one.

 

Got the kit attached. CEL still on so I'm going to replace O2 sensor next.

 

Replaced O2. CEL is off thank god... but the idle issue still persists. It does this when the engine is warm only. When I fire it up it idles at about 1400 and then slowly goes up to 1.9k (warm at this point), then it drops to about 900 then slowly climbs back up to about 2k and continues this. Some say to change the PCV valve. I already cleaned the IACV. Any ideas?

 

Bump

 

Try to find a vacuum leak using carb cleaner or brake cleaner. Spray around the intake manifold to find any leaks.

What check engine lights are you throwing

 

No CEL right now. If I had a vacuum leak would the CEL be on?

 

Clean the IACV and bleed the cooling system.

 

Just bleed the system. Still idles high, then jumps when warm. No CEL still. Any other ideas? Should I do a full flush? If I do flush it, is it okay to run water through it?