BrokenLimits

Well I have tried a bunch of things and I am out of options:

I have a 2000 Civic Si B16 with a Skunk2 Intake Manifold. I am running OBD1. On the 2000 SI the Intake temp sensor is in the intake tube (AEM) so I had a hole in the mani.

The Idle was surging so I bought the sensor JUST to fill the hole. I personally tightened all of the bolts on the manifold and the only other thing I could think of is throttle body gasket.

I am going to try that next but I was hoping you all could give me other suggestions. If the ObD1 ECU is in the cvar it surges from 1k-1.5k.

It DOESNT DO THIS ALL THE TIME. Sometimes the idle will be fine.

If I put the OBD2 ECU in It goes from 1k-2k Rpms (much higher).

I throw NO CODES even with the OBD2 ECU.

So any ideas?

DaZman69

could be a few things....
-vacuum leak-spray all ur vacuum lines and even ur intake manifold with some carb cleaner (not brake clean) and see if it stops. If you have a vacuum leak, the vapor will get sucked into it and temporarily plug the whole causing it to stop. Hondas are very sensitive to vacuum leaks.
-throttle position sensor-try taking of the plug, spraying both ends with brake clean very good to get crap out of them, let it dry and plug them back in. If that does nothing check the voltage with a multimeter on the two prongs. Should be .5 volts at idle, and 5 volts and WOT i believe.
-the secret ******* valve that fucked me for 10 months and honda techs didn't even know..... I think its called the IACV, looks like a miniature thermostat. If your looking at your throttle boddy from the front of the car, its all the way to the left in front of the throttle plate, there are two coolant lines going to it I believe. If u take that off theres this plastic thing inside that unscrews itself and causes idle surging. My car idled like that forever and when i got it fixed I **** a brick. It was the most annoying thing in the world

c1civic

sounds to me like a vacuum leak..they can be a pain to find..how bad is it surging?

99blusi

I'm experiencing the exact same thing with my 99 si...only difference is I have the AEBS manifold. It worked perfectly fine before...but I did the mani, ecu and a bunch of other stuff all at the same time so I have absolutely no idea where it's coming from. What you described is IDENTICAL to my situation. If you find the problem, please let me know...it's killing me not knowing...

justinh595

this is a very common annoying problem some hondas have. i just installed my skunk2 manifold on my gsr motor and have an idle surge. before i used to just block the iacv all together to get it to stop but i think i might actually try to find it this time. If i find it i'll let everyone know what it is.

JDM R

i got the same problem, 97 hatch w/ itr swap and obd1 conversion chipped p28, i bled the coolant and it still surges. 1000-1500 rpms

BrokenLimits

yeah, I am going to give all the stuff above a shot. I dont think its a vacuum leak because I didnt mess with many lines and the ones I did mess with I put back..

99blusi

Anybody have any luck finding the problem. I tried the carb cleaner yesterday and there was no luck. Few weeks I'll be buying a wideband...maybe it's a tuning issue.

fishnfst

Does anyone know if the 99-00si uses a 2 wire or a 3wire iacv? I had this problem with my 98 dx hatch going to obdI. My hatch uses a 3 wire iacv and the obdI ecu would only recognize a 2 wire iacv. All I had to do was change to a 2 wire iacv and repin the ecu. Look up Katman on these forums he gave me all of the info.

To the original poster I don't know if this will help you but I think someone asked about a 97 hatch with the same problem. you will have to do this fix to make yours run right. here is the link to my original post that has the pics in it for the fix

https://honda-tech.com/zerothread?id=852762

BrokenLimits

after reading into that, I dont think thats my problem. I am using a VTEC ECU and an Si wiring harness (I have an Si)

99blusi

IT's a 2 wire for the 99-00 Si...so back to square one.

LegoZ81

How many miles you have on the Si if the O2 is old (high miles) it might not be responding quick enough and it enginge could be going lean rich lean rich and so on causing the surging due to the slow responce of the O2. I can MAKE my 92 hatch do this with my Innovate wideband by customizing the narrowband output to a reverse linear output the ecu will keep leaning out the engine due to the ecu thinking it is richer than it is, eventually this causes the idle to start surging.

Try these if the step does not resolve the issue go on to the next:
1. Clean the intake manifold/throttle body with throttle body cleaner and long brush if possible (MAKE SURE that the brush will not loose any bristles in the intake track!)
2. Try the trick with adjusting the IACV
3. Try take off the IAVC and clean it well and clean the air paths that lead to it
4. Try replacing the primary O2
5.If none of these resolve the issue try replacing the IACV but it is not cheap

BrokenLimits

well the manifold and TB are brand new so I know its not that. I will try to yank the IACV as soon as I get the car back next week.

99blusi

My intake is brand new also, and I made the throttle body look shiny new inside before I bolted it up. The o2 is only about 8K old. I'll have to see about adjusting the IACV...see if anything comes up in a search.

greenf1

I just fixed a vacuum leak 2 weeks ago on my civic. It was the part on top of the thermostat housing that connects two hoses. I think it's called the idle control valve.

99blusi

Still got nothing here.

trooper0641

I had your problem...my **** use to surge from 1,000-1,500rpm sometimes...and you know what the problem was? THE FUCKEN THROTTLE cable was a bit to tight. YOU SHOULD check it and loosen it up a bit because thats what **** me up. I thought it was the faiv or that iacv **** but it turns out to be the throttle cable. SERIOUSLY

let me know if its your throttle cable. because it that was my problem...i was stupid and haved it overlooked.

99blusi

that was one of the first things I checked, figured that the new mani might have placed the cable a little off. So, that's not the problem in my case. Today, I just decided to say F it and I blocked off the air passage for the IACV and turned the idle screw up. Everything is cool now, I'm just going to roll with it blocked off until I can pinpoint the exact problem with the IACV...because that is definately the problem. I've tried everything and I am sick of the surging, brings waaaayyyy too much attention from the local law enforcement. I'd rather not have them inspect my car for some dumb *** reason and find that there's no cat.

Jamez

I had the same trouble after taking my head off. All I did was re-adjust my idle speed following these steps (taken from 92 Civic factory service manual) :

NOTE : (Canada) Pull the parking brake lever up. Start the engine, then check that headlights are off.

1. Start the engine and warm it up to normal operating temperature (the cooling fan comes on).

2. Connect a tachometer (I was able to do it with the factory tach).

3. Disconnect the 2P connector from the EACV

4. Start the engine with the accelerator pedal slightly depressed. Stabilize the rpm
at 1000, then slowly release the pedal until the engine idles.

5. Check idling in no load conditions : headlights, blower fan, rear defogger, cooling fan, and air conditionner are not operating.
Idle speed should be 420 +/- 50rpm
Adjust the idle screw, if necessary, by turning the idle adjusting screw.

6. Turn the ignition switch OFF.

7. Reconnect the 2P connector on the EACV, then remove BACK UP fuse in the under-hood fuse/relay box for 10 seconds to reset the ECU.

(The rest is for testing purposes, your idle should be set now)

8. Restart and idle the engine with no-load conditions for one minute then check the idle speed.
Idle speed should be :
Manual : 670 +/- 50 rpm
Automatic : 700 +/- 50 rpm

9. Idle the engine for one minute with headlights (Hi) ON and check the idle speed.
Idle speed should be : 750 +/- 50 rpm

10. Turn the headlights and rear defogger off. Idle engine for one minute with heater fan switch at Hi and air conditionner on, then check idle speed.
Idle speed should be : 810 +/- 50 rpm

Hope this helps, worked for me.

99blusi

Tried to reset it, worked great until I revved up a little bit then back to surging again. I'm going to check the TPS next...I'm running out of things to check here.