Idle issues after Skunk2 Intake Manifold swap

ASSISTANCE Hybrids & Advanced Aftermarket Engine Performance
1

Okay, so here goes…

I finished installing my Skunk2 Intake Manifold today and I’m currently experiencing some high idle and surging idle issues. When I first start the car, it wants to idle around the 2500-2800rpm range. Then, after it warms up, it will surge from 1000-2100rpm (give or take, some times higher, but that rpm range seems to be more the more constant range).

I used some Brake cleaner around every possible spot for any kind of intake manifold leaks and got nothing. (for those that don’t know, brake cleaner/carb cleaner sprayed into possible manifold leaks will cause the idle to change dramatically for a few moments, thus potentially pinpointing leaks)

I sprayed every inch around the top, sides, and bottom of the intake manifold, so there aren’t leaks at the manifold/head mating surface. That much I’m sure. Couldn’t find anything around the throttle body, either, but I didn’t do too much spraying in that area, honestly.

I’ve been told that it could be air in the coolant lines, but I went through the burp procedure 3 times today, and after the 1st “burping”, I received ZERO bubbles. Neither small, nor large. So, from what I can tell, there is no air in the coolant system.

The FITV wasn’t messed with, as it was still attached to the throttle body and was untouched during the swap over. The IACV was also not messed with in any way, but I’ll be taking it off tomorrow to inspect it for dirt or potential seal issues.

I believe, after driving, that my throttle cable might be a BIT too tight, so I’m going to release a small amount of tension (maybe 2-3 threads, or so, on the adjuster) But, that definitely wouldn’t cause the idle to surge.

Also, when driving, if I’m driving at low speeds (below the 2500rpm range) the car drives almost normal, but if I go WOT just to see how it responds, it seems to bog for a split second before taking off as normal.

As far as information goes, that is all I can come up with, but I am looking for any insight and suggestions as possible as to potential causes of this idle surge.

2

it does sound like a vacuum leak somewhere. Maybe check the breather box area and pcv? Worse can be a bent intake valve. Goodluck.

Or maybe the MAP and/or resetting ECu.

3

I have reset the ECU, and that didn’t fix it, unfortunately.

4

what engine are you running on this?..stock b18? give it some time for the ecu to learn the intake manifold. I had the same problem on my rsx when i put on the rbc IM and it idled fine after about a day, but would always idle funny like that if i were to have disconnected the battery

5

Found the issue, and fixing it in the morning. It is on a JDM B18C.

6

well let us know what it was.

7

What was the issue?

8

sorry. The intake manifold had been bored out at the throttle body opening, and it was causing a serious leak in the upper air passage to the IACV. I had that whole welded shut on the throttle body (would have been a lot easier than doing major repair to the intake manifold).

Fixed it this morning, and the idle is silky smooth again. The ONLY negative I’ve noticed is that while driving around, as I come to a stop after coming off the throttle, the RPMs will drop a little lower than normal for a second. They’ll drop to around 550-600rpm for about 1-2 seconds. Then, it climbs back up to the 800-900rpm range where it’s supposed to be.

Would adjusting the idle screw remedy this? Because, otherwise, the car runs perfectly.

9

Actually your supposed to idle at 1k to even it out. that happens when you have a bigger intake plenum than stock. You don’t have to but your going to have to deal with very low idle and possible shut offs.
it would be a good idea to get a fuel pressure regulator and fuel pressure guage and make your your fuel psi is spot on 43.5psi. Do not exceed more than 10psi over stock or you’ll damage your injectors.

10

Hmmm, I’m having this same problem right not, I just did the b18c1 swap and my car is idling at 2300-2500 rpm. So you’re saying it’s a leak problem?