I have a 1993 civic with a B18C1 and have been dd it 150m per day for the last couple months just fine. All of the sudden the other day it started to idle surge badly when I pulled into my driveway. It would surge from 1000-1500rpms somewhat rapidly only at idle.

I read a few discussions and thought to replace the IACV and MAP sensor to be safe. After replacing both of them and refilling coolant it started to idle from 1000-2000rpms and the same rate and at any temperature. It also seems that it is burning a lot of fuel or oil now, you can smell it in the cab and if you put your hand in front of the tailpipe it'll throw some black/brown liquid.

I would also like to point out that there is no oxygen sensor anywhere that I can see, maybe that is part of my issue.

Has anyone had the same issue or knows enough about this to help? I can give more information whatever is needed to fix this.
thanks

 

Fast Idle Thermo Valve (FITV) issues are very common with '92-95 Civic and '94-95 Integra engines. If your throttle body has a device bolted to the bottom with 3 10mm headed bolts, then proceed with the following: With the intake tube removed and the engine idling, cover the hole in the inlet of the throttle body at the 8 O-Clock position. If the engine immediately idles down to normal, you will need to repair the FITV.

 

My throttle body does not use a FITV, it only has one hole near the 10 O'clock position for the iacv. I probably should've said that.

 

You will need to check the health of the engine.

First look for anything that could cause a vacume leak, check your vacume hoses etc.

Check your timing both ignition with a timing light and mechanical timing, you need to remove the vc and set the engine to TDC and check your timing marks

Do a compression and leak down test, its possible you have worn out rings or even a blown head gasket. Check the oil and coolant to see if its mixing.

 

This motor is pretty new and I'd say fairly well built, I bought it from someone who seems to know what they were doing and it makes pretty decent power for what it is.
I did a compression test last night and everything checked out, all ranging from 200-210psi. I checked the condition of the plugs and they looked good. The oil does and has always looked good with no fuel or coolant mixed in. It runs so good everywhere else except for at idle so I don't think it's out of time but if I have to I can verify timing.
As for the vacuum leaks I started by having the engine running and spraying carb cleaner around any gasket or hose coming out of the intake and everything was sealed. Then I wondered if my PCV valve or brake booster were malfunctioning, because those are the only two hoses coming out of the intake. I plugged the PCV valve port in the intake and the surging stopped but the idle was still high (2000rpm), but it would go down to 1300 when it was warmed up. I put a brand new PCV valve in and it started surging again.

Do you think I could run the PCV hose into a port on my intake before the throttle body for now until I figure it out? I tried doing it and it stopped the surging but I don't know if it'll cause any harm.
Thankyou

 

post pics of your engine and the intake and PCV setup/ vacume hoses.