I had a skunk2 intake mani on my b18c1 swapped civic and decided to take it up and swap on the stock one on. I had already bought a hondata gasket so i just reused it.

My problem is that I'm getting an extremely high startup around 2.3k rpms, then it comes down to 1.8k-2k for the idle. I'll drive a block and stop and the idle will come down to 1.5k. Once the car is fully hot, then the idle is smooth as butter at 700rpm but before that it's very high. Also, I'm getting horrible gas mileage. I went from getting about 280 miles a tank to 220. I think it's mostly due to how this car drives when cold


The only thing i can note here is that I hooked everything up right but since the shop that did my swap did some weird wiring, my PCV chamber didn't have a checkvalve to keep the car from sucking in oil. I burned a lot of oil before i figured out what was wrong.

 

bump, less for an answer about the high idle but more for the horrible mpg i'm getting.

 

have you torqued everything down to specs?
sounds like a vacuum leak

 

Yeah, normally I used to idle with this car around 1.5k to start and I'd get around 28 instead of 23 mpg. Would a vaccum leak cause a severe loss of mileage? What about having the stock intake and a cheap-o filter vs an AEM intake? Would that cause a loss in mpg too?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FuNkDrSpOt &raquo;</TD></TR><TR><TD CLASS="quote">I had already bought a hondata gasket so i just reused it.</TD></TR></TABLE>

reusing the gasket
Could be sucking air in between the manifold and head. Also what about air leakage around the throttle body? Bad throttle body gasket could cause the same thing.

One other place to check on the throttle body is with the intake removed there are 1 or 2 ports inside the throttle body, but outside the butterfly. Try plugging these with a piece of rubber or something while idling to test for an effect on idle speed. (I had a high idle problem that was fixed when I plugged one of these ports, a new throttle body gasket prolly would have fixed it, but I didn't feel like spending money on a piece of s*** car).

I wouldn't worry about gas mileage unless you still have a problem AFTER the idle gets fixed. If you are pulling in extra air not seen by the sensors who knows what your ECU is doing to try and balance out the readings coming from your O2 sesor.

 

cheap o air filter wont effect your idle and u better not to reuse the intake manifold gasket. didnt your skunk2 manifold come with a new one ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crazyguy &raquo;</TD></TR><TR><TD CLASS="quote">cheap o air filter wont effect your idle and u better not to reuse the intake manifold gasket. didnt your skunk2 manifold come with a new one ?</TD></TR></TABLE>

No they dont come with new ones. The hondata gasket is a solid peice of plastic. It doesn't need replacement. It's advertised as such.

You probably have a vacuum leak somewhere, OP. Do this:

Turn on the car, let it warm up.
Spray some carb cleaner or brake cleaner LIGHTLY around the intake manifold area. Listen for a hike in engine speed. If the engine revs as you spray an area...you just found a vacuum leak.

Are all your fuel fittings in good order? The fuel pressure regulator plugged in to vacuum? The return line not kinked? Did you eliminate your butterflies properly? This is a stupid question...but are you sure all the vacuum ports on the manifold are accounted for?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B serious &raquo;</TD></TR><TR><TD CLASS="quote">

No they dont come with new ones. The hondata gasket is a solid peice of plastic. It doesn't need replacement. It's advertised as such.

You probably have a vacuum leak somewhere, OP. Do this:

Turn on the car, let it warm up.
Spray some carb cleaner or brake cleaner LIGHTLY around the intake manifold area. Listen for a hike in engine speed. If the engine revs as you spray an area...you just found a vacuum leak.

Are all your fuel fittings in good order? The fuel pressure regulator plugged in to vacuum? The return line not kinked? Did you eliminate your butterflies properly? This is a stupid question...but are you sure all the vacuum ports on the manifold are accounted for?</TD></TR></TABLE>

I'm pretty sure that all the ports are accounted for because I'm not getting any surging idles.

I'm fairly certain that I do have a vacuum leak because my thinking is that it must be small since it doesn't cause a surge and be covered when the metal expands when the mani gets hot.

 

yea it does sound like a vacuum leak another way to test its out is to cover the throttle body with your hand and if it contiunues to run that means its sucking form air form somewhere

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mtsepulveda85 &raquo;</TD></TR><TR><TD CLASS="quote">yea it does sound like a vacuum leak another way to test its out is to cover the throttle body with your hand and if it contiunues to run that means its sucking form air form somewhere</TD></TR></TABLE>

good idea. I will test out both ideas tomorrow, as the car only runs like this when it's not warm.

Another weird thing is that I'm noticing that the car cools off much more rapidly when i turn it off from before when i had the other mani on.

I was also thinking my IACV was broken possibly.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FuNkDrSpOt &raquo;</TD></TR><TR><TD CLASS="quote">

good idea. I will test out both ideas tomorrow, as the car only runs like this when it's not warm.

Another weird thing is that I'm noticing that the car cools off much more rapidly when i turn it off from before when i had the other mani on.

I was also thinking my IACV was broken possibly. </TD></TR></TABLE>

Maybe your coolant lines are not run properly. You might be getting bad gas mileage because you just got a new manifold and you are beating on the car more than usual to check out the manifold.

The other theory is that maybe the throttle cable is not adjusted well enough, so maybe the plate is partially open at all times.

Also, are there any check engine lights on? If so, for what?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B serious &raquo;</TD></TR><TR><TD CLASS="quote">

Maybe your coolant lines are not run properly. You might be getting bad gas mileage because you just got a new manifold and you are beating on the car more than usual to check out the manifold.

The other theory is that maybe the throttle cable is not adjusted well enough, so maybe the plate is partially open at all times.

Also, are there any check engine lights on? If so, for what?</TD></TR></TABLE>

No check engine lights

I'm not beating on it. It's the stock mani i switched back to.

The throttle cable seems to be adjusted just fine because my idle problem is only when cold.

There's only 4 coolant lines to the IM. 1 from the block to the IACV, 1 from the IACV to the TB, and one from the TB to the block.....ok so i can't count, there's 3.

 

Does your IM have a FITV?

 

nope. '97 motor.

 

Is your tps sensor plugged in tight?

 

sure looks like it.

Oh, let me remind you guys that I had an issue with my PCV chamber. Long story short, i didn't have one of the plugs into the chamber that had a check valve and I kept surging AND getting lots of oil in my IM.

I only drove it a 10th of a mile but by the time i found out what it was, I probably burned almost 2 Qt. of oil. I took off the intake and opened up the TB and there was a small pool of oil coming out. So i got it all out, wiped off 2 of the sensors, cleaned out the IACV and ran almost a full bottle of seafoam. That helped but not as much as i thought it would.