PLEASE HELP! Surging Idle Issue
 

OK before i begin i have read MANY of the forums relating to this topic!
Motor is d16y7 on 98 civic 5speed.

I have so far tried..
-Bleeding Coolant 2x
-Cleaned IACV and Throttle Body
-Brand New IACV
-New OEM TB Gasket & IACV O-ring
-Checked TPS with Multimeter. All good.
-Vacuum leak test using carb cleaner. I've literally sprayed everywhere possible multiple times.
-Vacuum leak test by blowing smoke into brake booster line.

I have not tried..
-Replacing ECU and TB with junkyard parts.
-There's something else i've read about somewhere which i have forgotten.

**When i cover my hand over the TB it doesn't die out but i cannot find where the vacuum leak is coming from**

Also have CEL for P0500 Speed Sensor.

I really don't know at this point what should i try doing?! This is my daily and i really don't want to take it to a shop.

Thank You,

Alex.

Re: PLEASE HELP! Surging Idle Issue
 

Test the ECT sensor.

But your hand test indicates a massive air intake leak. Leaking TB and IM gaskets should be considered. And make sure the TB & IM nuts/bolts are torqued to spec in a crosswise pattern.

Re: PLEASE HELP! Surging Idle Issue
 

I'm gonna go ahead and try the ECT sensor thing but i'm almost positive that it's not the TB cause i just replaced the old gasket with an OEM one today after buying two i got from Oreilly's and the bolts were on there good but i'll go ahead and retorque them. As for IM, i've never messed with it every and when spraying carb cleaner the idle wouldn't change at all but i'll take a look. I'll update back soon.

Re: PLEASE HELP! Surging Idle Issue
 

Without question, the engine has a MASSIVE intake air leak. Focus there.

Re: PLEASE HELP! Surging Idle Issue
 

What other methods should I use to check for the vacuum leak? I wasn’t able to take a look at my car yesterday because I had to get some school work done. I don’t work today so I’m gonna start poking around again once I get home.

Re: PLEASE HELP! Surging Idle Issue
 

Update. I've double, triple, quadruple checked all the vacuum lines they are all in the correct spot. I sprayed water in between every gasket and every line for 5 min even spraying from underneath the car. Absolutely no change in idle no matter where i spray still surging. I think I'm just going to take it to Honda and see what they say.

Re: PLEASE HELP! Surging Idle Issue
 

There's a big leak. It needs to stall out when the intake is blocked. I don't remember if this version had the plastic fast idle valve on the thermostat housing. Those often get broken and cause a big leak.