therest

So I recently swapped in my car (94 Accord EX) a F22B1 from another Accord that I knew had a surging idle. The surging idle, not surprisingly, is still there. That small detail helps me know that it wasn’t anything I did as far as connections. I used my original engine harness and I didn’t have a surging idle in my old engine. Anyways, I’ve cleaned my FITV and my IACV, and changed my MAP sensor too. The ones I used were from my old engine. Still the surging idle persist. It warms up at stable 2250 or so and then idles consistently from 1100 to 2100 rpms. I tried bleeding the coolant and I am going to try again today. My question is something I noticed today. While driving to work I noticed my temp gauge would go up and down, never past the normal operating temperature. Could this be related to my surging idle?

masospaghetti

It could be related, since the FITV uses engine coolant to moderate the valve opening.

Just "cleaning" the FITV is not usually sufficient. The o-rings inside become dry and ineffective with age. You really should replace them, its not hard.

I found that an assortment pack of A/C o-rings provide the best fit for the FITV. Box of them cost around $15 dollars on Amazon.

You can test to see if your o-rings are bad by tightening the plastic cylinder inside the FITV. This will disable the FITV so I wouldn't recommend you leave it like this, but if it stops surging you know that's what is to blame.

therest

Well, to start, I never cleaned the FITV. I thought all I had to do was turn to plunger all the way until it doesn't anymore. I will be cleaning the FITV today and go from there. Thanks masospaghetti.

masospaghetti

Your original post says Anyways, I’ve cleaned my FITV?

You can do that to test it, but again, that would disable the FITV completely so I wouldn't leave it like that. You may have trouble starting and idling when the engine is cold especially in colder weather.

therest

I meant to say the IACV, not the FITV. I've never read about it disabling the FITV, except for solving surging idle issues.


Also, I just remembered that the plug for the sensor that sends the temp. of the engine is loose. It's the one under the distributor that is like a small bleeder almost. That probably is why my temp gauge is acting that way.

As far as my idling, I will try to clean the FITV and bleed the coolant again.

MAD_MIKE

Did you verify the ECU thermo sensor is fine? Screwed into the head if it was off then it may cause some problems. Same with the thermostat, if it is failing or not opening/closing at the same temperature it may be affecting how the car idles. Although I would look for Vacuum leaks first.

IMO when changing out engines, you should reuse all the known good components. Strip the old engine of intake/exhaust manifolds and attach them to the 'new' engine. Same with sensors. That way you will have known good components on the engine.

therest

Thank you MAD MIKE. What I did today was clean the FITV. Still the same issue. Also, I covered the top hole inside the throttle body and the surging persisted but it was a lot more calm. So I guess I can rule out the IACV? One thing I still didn't do was bleed the radiator since I didn't have enough to top it off.

So what I did find out was an audible hissing noise, which is obviously a vacuum leak. I couldn't find it and wanted to spray WD-40 but the engine was too hot. I want to try and do it in the morning. I think the leak is from the intake manifold. Which I would hate for it to be that. But it is interesting that a failing thermostat can cause an idling issue. Except for the surging idle, the engine runs really well and want to keep driving it but I read it could be bad to drive it with an intake manifold leak. I'm not certain if it's the IMG but I feel like it is.

Also, I want to note that when the car is cold the engine idles at around 2500/2750 rpms. Then will idle like I stated before when warm or if I move the car before it is warm it will start the surging.

therest

So I went back outside to check with some PB Blaster since I couldn't resist waiting til the morning. I sprayed some of the PB Blaster on top of the intake manifold where the gasket is at and lo and behold, I found a huge leak. I'm going to double check tomorrow morning since I should have more light, but I'm confident that is where the leak is at. I mean, the hissing was pretty loud so I'm not surprised it's the IMG. Now I'm just wondering if the Autozone/Oreilly IMG are good enough. I know Hondata makes a nice one, but it's $40 though and I will have to wait for it to be shipped, which I really don't want to wait.

masospaghetti

DId you adjust the FITV, or just clean it?

Again, in my experience - these typically don't get "dirty" and cleaning them doesn't really help, they need new o-rings. But if you screw in that white plunger, it will prevent the FITV from EVER opening, effectively disabling it.

Also, know that there's a temperature sender and a temperature sensor, they are not the same thing. The sender is the single prong unit and the sensor has two pins. The sender only controls the temperature reading on the dashboard while the sensor is what feeds the ECM. In these Accords, both the sender and sensor are located underneath the distributor, side by side.

therest

I cleaned it and screwed the plunger. If that's the case, I will remove it again and unscrew it some. Eventually I'll just get a new one. However, as far as the surging idle, I realized it's a leak coming from the intake manifold gasket.

As far as the plug that has a loose fitting, it is for the sender. I was trying to describe it earlier as a bleeder look a like thing, but "single prong" is a lot better. Yes it's the underneath the distributor closer to the front of the engine. Thanks masospaghetti.