(The car is a 92 integra with b16a) I've been having an idle issue for the past month. It just bounces up and down and wont stay steady. Last night I replaced the iacv, pcv, all my vacuum lines, took the chip off my ecu and ran it on the stock chip, tested my tps, and nothing fixed it. I also checked my oil and there was nothing on my dipstick. Now i've never had an issue with my motor burning oil, and i've never seen my dipstick have nothing on it. I added a qt and it brought the level up to normal. Now today I was driving and my step dad was driving behind me and he said he saw white smoke coming from my exhaust when I accelerated hard. I know that is normally caused by coolant in the combustion chamber but, I haven't been losing any coolant at all. My thought is either it is my head gasket, my valve seals, or my piston rings. The car runs perfectly when driving. It's just the idle that is acting up. I'm gonna do a compression test tonight to check if my rings are shot. My question is, Can a blown head gasket, bad valve seals, or bad rings be what has been causing my idle issues for the past month? The engine has roughly 110xxx miles on it, stock internals, never had boost on it.

 

Bad valve seals or bad rings MIGHT cause the idle issues...but sometimes a varrying idle like that can be cause by a bad mass air-flow sensor or un-metered air getting in. If the ECU doesnt know how much air the engine is getting, it doesnt know how rich or lean to make the air/fuel mixture (obviously). The smoke sounds like it's from a bad head gasket... If you had low oil, the smoke might have been caused by burning oil. Your step dad might have seen the light-blue smoke and thought it was white (I could be wrong of course). That's really all I can tell you, hopefully it helped in some way

 

vacuum test the head, warm engine, hook up vacuum gauge to any port. brake booster, pcv, just something that sees manifold vacuum, report back

sounds like you have valves that are not sealing. the vacuum test will confirm it

the needle should not bounce and you should have at least 18"hg

my last ITR has 22" even with a fried bottom end. vacuum tests are kind of like compression tests for the head

if you have a leakdown gauge that would also be worth doing since you could easily have a blown HG

vacuum gauge is $10 at harbor freight

 

valves that aren't sealing won't cause oil consumption though.

a vacuum test wouldn't be a bad idea though, since there may be a vac leak somewhere causing your idle problem.
you can try spraying starter fluid at all vac seal locations. see if idle acts erratic when sprayed in a specific location.
or try removing the intake boot and covering the throttle plate. see if the engine dies or not

have you tried adjusting your idle as per procedure?

i'd run that compression test as well. see where you're at
have you tried checking your codes yet?

 

valves that aren't sealing will show up on a vacuum test in a jiffy. the reason they aren't sealing in a lot of high mile motors is worn rings, guides and valve seals, carbon coat the exhaust valves and they leak.

vac leak can cause an idle issue obviously but the smoke, would absolutely do a leak down or compression test to see if the HG is blown

 

Yea idk what color he saw, but he said it wasnt much.
I've got a vacuum gauge, just havent done that yet, but I will when I get a chance. And i'll do the leakdown as well.
I forgot to mention that I took a can pf propane and poured the gas over all my vacuum lines and only found one leak. It was the hose that connected the brake booster check valve. I replaced that and the problem is still there. That was the only vacuum leak I found. I took the intake pipe off and covered the hole inside the throttle body that leads to the iacv with my finger, when I did that the surging stopped and the idle just sat really low. When I let off that hole the surging started again. I also covered the entire throttle body with my hand and that stalled the car. Yes I have adjusted the idle the right way. When I put the new iacv I warmed it up, unplugged it, and then adjusted the screw on the throttle body, then plugged the iacv back in. Idk what else this issue could be. I can't get my car to pass inspection unless the idle is steady.

Ok so just did the compression test. I did a dry test and a wet test where I added a teaspoon of oil into the cylinder.
(FYI I used the cylinder closest to the distributor as #4)
Dry Test :
Cyl # 1 - 215
Cyl # 2 - 215
Cyl # 3 - 190
Cyl # 4 - 235

Wet Test :
Cyl # 1 - 240
Cyl # 2 - 250
Cyl # 3 - 235
Cyl # 4 - 270

Cylinder # 3 was my lowest and has always been my lowest. I did this test when I first got the car 2 years ago and # 3 was a bit low then too. I don't think I have to worry about anything.
Not sure what to do about the idle, but i will do the vacuum test and leakdown when i get the chance. Thanks guys

Here is the video I shot right before I did the compression test. Not really any smoke until the very end
http://youtu.be/5UW7zpaEw2w

 

ok. the smoke didn't look all that bad. although it's probably worse under load. cylinder 3's worn rings are likely the culprit.

on your idle issue, for whatever reason, the ecu is attempting to adjust idle through the iacv. could be due to poor engine vacuum, as mentioned, among other things.
run the vac test. if that checks out ok, test the iacv and circuit.

have you checked for codes? because the ecu relies on inputs from the map sensor, among other inputs, to keep idle stable.
check the codes.
also, check ignition timing

 

with the above on the advice, this one is going to require some testing. normally a worn bottom end won't effect idle that much but a worn top end will.

real curious to see vac numbers. also watch to see if the needle bounces or is steady

by the way, read

http://www.linnbenton.edu/auto/perform/vacuum.html

it's a great guide to compression and vacuum

 

Alright thanks guys. I'm gonna do the vac test tomorrow. I know i've got at least two of those gauges in my garage somewhere. I was also reading this other guys thread, I don't remember his username but you guys were helping him with his idle issues as well. He had mentioned that his engine idled fine when cold and wouldnt start to surge until it came up to temp. That's is exactly what mine does. It acts fine until it warms up and i either turn the ac on and back off, or touch the gas. He said he took his o2 out and the surging stopped. I'm gonna try that tomorrow as well, i'm gonna wait till it's surging and then unplug my o2 and see if it makes a difference.

 

it probably will. but that really doesn't tell you a whole lot. all that does is stop the ecu from interfacing. that is, communicating with it's inputs. so if it runs steady, it means it's a problem with one or more of the inputs or the ecu's interpretation of the inputs

 

It kind of looks blue in the video, at the end. That would explain your oil consumption. Have you cleaned your IACV recently?

 

Hooked a vacuum gauge up to the manifold. I used the hose that goe to the pcv valve. It read 20hg and when i turn the ac on it went down to 17

 

was the needle steady or did it bounce, shake at all?

if there was any vibration, shake or wobble you're seeing the down cylinder

20" is okay and 17" with the ac on is expected, as rpm rises vacuum drops

 

The needle was shaking back and forth really rapidly but it didnt shake enough to move off the 20 mark. I just contributed that to the gauge being old and cheap.

Forgot to mention that when the idle started surging the vacuum fluctuated between 20 and 22hg

 

shaking needle is usually due to one cylinder leaking. as your engine goes through it's intake, compression, power, exhaust strokes, the intake stroke causes vacuum. when one cylinder isn't pulling as much as the other 3. guess what, needle shakes. if you could slow this all down you would be seeing the needle drop on the low cylinder.

anyway you stack this you have a cylinder with bad rings, bad valves or...and this would be odd...a leaking head gasket.

my first guess is rings. but you can test this by taking an air compressor, hooking it up to a compression tube and screwing it in the spark plug holes with the header off and TB open. check each cylinder with the valves closed and see where you're leaking air. oh, and pull the dipstick, if it's rings that's where air will come out

 

have you checked for codes yet?

 

So what your saying is my rings are bad? Runs great though...besides the idle
Yes. Um, not sure if I mentioned that my ecu is chipped. I'll try to explain something real quick. It's a p28 with a p30 basemap that has been tweaked a bit. My friend burns the chips for me so it's not my doing. He had to turn all the stuff on the chip off such as eld, o2, and things like that. I don't remember them all, but he did it cause it kept throwing a solid cel when i put the key in. Turning it all off was the only way to get it to stop. Now I have the ability to take the chip out and run it on the stock ecu chip. I tried doing that and that's when I'm getting 2 codes. I get a code 20 for the ELD, which i've always had cause my car doesnt have it. So that one is fine. The only code is 41, which is heated o2 or something like that. Now the o2 is fairly new, so i dont think it's bad but it might be. On the aftermarket chip I don't have any codes though. Now the idle issue happens on both the stock chip and the one i have tuned. I'm waiting on him to reset the chip to the stock p30 basemap with everything turned on, but he's been busy so I havent gotten it done yet.
On a side note. I recently picked up a wideband and i'm going to put that in as soon as I get another bung welded on and my regular o2 turned back on.

 

hmm. ye it's hard to say now, since you've got an aftermarket chip.
you'll have to test the o2. with engine at operating temp, back probe the o2 signal wire. should get a voltage reading switching from .1 to 1volt, roughly. if that checks out, you'll need to check continuity of the o2 wires to the ecu

 

sounds that way. if you had a leakdown tester it would confirm it. how much oil is this car burning?

 

I've got one somewhere in my garage. It's a disaster in there so not easy to find things. I'm not sure how much oil it's burning. The other night when I checked it and it didnt have anything on the dipstick was the first time i'd ever seen it low. I know for sure it's not leaking any. My engine and engine bay are spotless so i'd know if anything was leaking or had dripped. I was talking to this with some people on another site and they asked me if I had ever replaced my plugs and wires. I just replced my plugs last month and when I did the comp test they looked fine. Now the wires...those are ngk but i've never replaced them. They were on the car when I bought it. The car runs fine so I dont think theyre bad, but I also don't know if that alone could be causing my idle issue

 

whole thing sounds like a down cylinder. if the oil was that low and you're not leaking it's obviously burning. idle, compression.

now it's just tracing down if it's on the bottom end or top. either way if you do new pistons and rings, a valve job isn't that much more and they motor will have a long ways to go again

 

well, considering the results of the wet test, i'd say it's rings in cyl 3.
but we don't know for sure he's burning the oil. who did the last oil change? maybe it wasn't topped up? i think you need to monitor it now that you know what level it's at for sure
when you adjusted idle, you reset the ecu afterwards?
you need to find out what's going on with the o2 sensor as well

 

would explain the bouncy vacuum reading and the compression

and true we aren't certain he's burning oil but if this is the case above....he is

 

The last time I change the oil was in october when I put my motor back in. I have hardly checked on it since then cause I knew nothing was leaking anymore. I'm not driving my car right now cause the inspection is out, so I can't really tell if i'm burning any. I'm gonna try a different ecu tomorrow and if that doesnt work i'm gonna ty to change the wires, if that doesnt work i'm gonna try a different map sensor. I've been told it might be the map..i don't know.

This is my motor. Just showing as an fyi. I've always taken really good care of it so it's really frustrating to be having these issues just randomly all of a sudden.

 

for sure. just didn't want him to go to that extreme until he's absolutely certain.
compression numbers don't lie. even if he's not burning oil, the block will need to come apart at some point. but really, it's just delaying the inevitable.
it's still quite possible that all his problems stem from that cylinder