Surging idle problem, just want some advice for tomorrow morning...

[Jon]

Ok, I just finished up a huge amount of stuff on my Accord including.

Changed timing belt and all other associated belts.
Replaced crank and balance shaft seals.
Replaced the water pump.
Replaced the valve guide seals.
Upgraded to a Bisi Level 2 cam.
Upgraded to Bisi Pro Valve springs.
Upgraded to a A6/H23 intake manifold (A6 runners, H23 throttle body and plenum, and two gutted IAB plates).
Replaced all seals, gaskets, and everything as I went through.


So I get everything put back together today, start the car up, and sure enough it runs and sounds really healthy! HOWEVER after running for about five minutes it starts surging (LOL, like this has never happened to anyone... ). So I reroute the coolant lines so it bypasses the FITV on the bottom of the throttle body, hoping this would eliminate my problem (so now the coolant line runs from the bottom of the intake manifold straight to the thermostat housing). Start it back up and it still surges up and down.

So tomorrow my plan is to remove the throttle body, take the FITV off and install a block off plate, reroute the coolant lines to bypass the IAC valve and leave the IAC plugged in so it hopefully wont throw a CEL.

My question is, am I overlooking anything that would cause it to surge? Possible vacuum leak? I would think if I had a leak it would show up as soon as I start the car, not several minutes of it idling.
It really gives you a crappy feeling when you get everything installed and it does this...

Any help or info would be appreciated.

[quickangel93]

probably vacuum leak or air in the cooling system

[Jon]

probably vacuum leak or air in the cooling system

Oops, yeah need to check the cooling system for air, that is one thing I forgot to bleed.

Thanks!

[Fake Thug]

Ok, I just finished up a huge amount of stuff on my Accord including.

Changed timing belt and all other associated belts.
Replaced crank and balance shaft seals.
Replaced the water pump.
Replaced the valve guide seals.
Upgraded to a Bisi Level 2 cam.
Upgraded to Bisi Pro Valve springs.
Upgraded to a A6/H23 intake manifold (A6 runners, H23 throttle body and plenum, and two gutted IAB plates).
Replaced all seals, gaskets, and everything as I went through.


So I get everything put back together today, start the car up, and sure enough it runs and sounds really healthy! HOWEVER after running for about five minutes it starts surging (LOL, like this has never happened to anyone... ). So I reroute the coolant lines so it bypasses the FITV on the bottom of the throttle body, hoping this would eliminate my problem (so now the coolant line runs from the bottom of the intake manifold straight to the thermostat housing). Start it back up and it still surges up and down.

So tomorrow my plan is to remove the throttle body, take the FITV off and install a block off plate, reroute the coolant lines to bypass the IAC valve and leave the IAC plugged in so it hopefully wont throw a CEL.

My question is, am I overlooking anything that would cause it to surge? Possible vacuum leak? I would think if I had a leak it would show up as soon as I start the car, not several minutes of it idling.
It really gives you a crappy feeling when you get everything installed and it does this...

Any help or info would be appreciated.

with the work that you have done only two things comes to my mind. The intake mani gasket might be unevenly torqued, the coolant was not bled properly. If you still have the Iac valve in the picture then it can cause that problem with idle.

[Jon]

The intake mani gasket might be unevenly torqued

Wouldn't that cause a problem from the get go, rather then several minutes of high idling?

I'm definitely going to bleed the coolant system.

I can't believe that completely slipped my mind... I think I was more worried about everything being bolted back together, vacuum lines being routed properly, and all of that stuff.

[Fake Thug]

Wouldn't that cause a problem from the get go, rather then several minutes of high idling?

I'm definitely going to bleed the coolant system.

I can't believe that completely slipped my mind... I think I was more worried about everything being bolted back together, vacuum lines being routed properly, and all of that stuff.

You are right, however I've had my img leak the next after installing it before.

[Jon]

You are right, however I've had my img leak the next after installing it before.

True, I did have something similar happen to me a long time ago.

I'll triple check all of my vacuum lines and all of that and make sure I don't have a leak.

[cb9wagon]

did that do it?

[Jon]

did that do it?

I'll be going out in about two hours (it's below 20° right now). I'll let everyone know what fixes it, if anything does.

[Jon]

Ok, I went out and pulled the plenum, throttle body, and IAB plates off.
Made block off plates for the FITV, IACV, and air boost. They're kinda thin, so I'll be making thicker ones later down the road (getting it running is a priority). I used high temp RTV sealant on everything, so I'm letting that cure overnight.
I made sure my EGR valve was sealed and not leaking.
Re-torqued the intake manifold nuts.
And added some more coolant.

One thing I noticed when I was doing all of this that may or may not be the problem is that the five bolts that hold the plenum and IAB plates to the runners were a bit loose.

So tomorrow I'll put everything back together and see if it still surges. I will also see if I can't purge some of the air out of the coolant.
If none of this works and it still surges, then I'll look for a vacuum leak.

[Jon]

Ok, I went out and put everything back together, hooked everything up and after a couple of minutes it starts to surge. So I'm like WTF!?
I play with everything for a couple of minutes and it just keeps surging. At this point I am getting kinda frustrated and am about to shut it off but before I do, for some reason or another I decide to grab ahold of the throttle plate (where the throttle cable connects to the throttle body) and push on it just to make sure it's closed and the surging quits...
... so I let go of it and it still doesn't surge... so I just barely tap the plate with my finger and it starts surging! So I grab the plate again and push on it again just to make sure it's all the way closed and it quits...

So it has something to do with the throttle body not being adjusted correctly or the TPS sensor is off voltage wise (stock was throttle body was at .42 and I have this one set at .45). Any suggestion as to what on the throttle body might need adjusting? I'm thinking the throttle plate's "stop" isn't allowing it to close all the way or something.

[preludeman92]

My prelude had the surging issues you're talking about. It seems my throttle body wasn't closing all the way either. Make sure the cable is slack before you go try to adjust the throttle stop. I didn't have the cable adjust right and my car would either idle high or surge... I adjusted it and now it does neither.

[Jon]

My prelude had the surging issues you're talking about. It seems my throttle body wasn't closing all the way either. Make sure the cable is slack before you go try to adjust the throttle stop. I didn't have the cable adjust right and my car would either idle high or surge... I adjusted it and now it does neither.

Yeah I removed the throttle body from everything and adjusted it off the car. Once I did that and set the throttle stop, problem solved.

Got the idle adjusted and it's idling at 890, I can drop it down to 800-825 and it idles pretty well but it's a bit too shaky for my liking (balance shaft belt removed).

So I'm going to break all of this in over the winter and hopefully come spring/summer I can get a new ECU and tune it properly.


Thanks for all the help guys and gals, it's much appreciated!