94 accord idle surge, better understanding?
 

Hello everyone, I recently installed an engine in my 94 accord, all is great except for the idle surge. I have tried everything in order to fix this. I've just been studying the way the system works, because as you all know, the more you understand the more you can fix, the farthest I have come, is that the iacv is in fact working, but something else is factoring in to the problem and throwing it off! I'm truly boggled by this, can anyone help me run through everything that factors into the actions of the idle air control valve?
Thanks!

Re: 94 accord idle surge, better understanding?
 

There are a few thigs that may cause the common Honda idle surge.

Air bubble in the coolant system (altered ECT sensor readings)
- Bleed cooling system

Vacuum leak
- Check all hoses and gaskets for leaks

Dirty IACV
- Clean IACV and throttle body ports
- https://honda-tech.com/zerothread/1844067

Dirty/maladjusted FITV
- clean FITV and adjust if required.
- https://honda-tech.com/zerothread?id=1003988


The IACV is controlled by the ECU. The IAT, ECT, MAP (engine load), ELD (electrical load) and vehicle speed all contribute to how the IACV reacts.

Re: 94 accord idle surge, better understanding?
 

Iacv is clean, and has been swapped out with four different ones, the fitvalve is good and adjusted properly, no air in the coolant system. I have bled it after every disconnection (numerous times) under heavy, or normal driving conditions (drive or reverse) it operates great and even idles spotlessly. Only when it is under minimal load is when it surges, up and down, and sometimes sits still a higher than normal rpm range.

While it is cold it does fine as well.

Re: 94 accord idle surge, better understanding?
 

So, I checked the thread you linked, everyone says it worked.

In the morning I am going to pull the whole throttle body, and ensure everything is clean and sealed properly. I will let you know how I turn out.

I've been fighting this battle since I installed this engine, and have swapped all the sensors from the old one, one at a time.

The issue has made me look like a fool lol
Could the ect sensor be faulty and causing this problem?
The change rises to NORMAL OPERATING TEMP then stays, could the resistance in the sensor somehow come to a halt in change?
I have never come across that situation but could it be possible?

Re: 94 accord idle surge, better understanding?
 

Usually if the ECT sensor is faulty you would have more of a rough idle, due to a rich fueling condition.

Re: 94 accord idle surge, better understanding?
 

You should check your base idle. If it's too high you will have the issues you have as the iacv will not be able to compensate.

Re: 94 accord idle surge, better understanding?
 

agreed Ghost, I tested my ect sensor, it's good. I just got back in.... as far as I can tell the idle situation is resolved. the base idle was a little off Holmes. I adjusted that as well as I could.
But the main cause I believe was the throttle cables being too tight... Not so much my main pedal cable, but the cc cable was very misadjusted; so when I would press the gas, the throttle would not come all the way back to it's original position...
Does this all make pretty good sense?

Thanks for all the help btw. I Really appreciate the feedback.

Re: 94 accord idle surge, better understanding?
 

That makes perfect sense.

I completely forgot to ask about whether or not you had set the base idle.

I just had this very same issue with my Mazda after the instal of a new throttle body. The CC cable was a wee bit short and caused a high idle.

Hopefully that tight cable was your issue and it's good to go!

Cheers :beer:

Re: 94 accord idle surge, better understanding?
 

I do believe this was the annoyance;) We will see!

Thanks for all your help!!!! I know where an awesome Miata is that I would love to have, but its just so high priced!

Re: 94 accord idle surge, better understanding?
 

You're welcome!

Yeah I tend to see them overpriced quite often. People seem to try to sell them as if it were comparable to a Z4 or Boxter. I don't get it! Does that Miata have an LS1 swap or something?...lol

Re: 94 accord idle surge, better understanding?
 

there are three LS1 swaps around here, there are all complete sleeper. even have quiet exhaust systems!!! It's crazy.

Re: 94 accord idle surge, better understanding?
 

Pretty sweet eh!

Re: 94 accord idle surge, better understanding?
 

Just another one of those of the chart mods