Hi All,
I've only one other thread in this forum and I received a good deal of help from it, so I am posting again.

I have a 97 civic ex coupe with the 1.6 sohc vtec (i think d16 series? I can get the exact motor model if it winds up being relevant). When I start it up when its cold.... below freezing, for the first 2-3 minutes, the engine misfires and runs roughly, the tach jumps around and it very clearly is not firing on all cylinders.

Attempting to drive the vehicle before this stops, results in the car bucking wildly like I'm a noobie that has never driven a 5-speed manual before.

I replaced the distributor/rotor,spark plugs and engine-bay area fuel filter this summer, so I would be hesitant to drop another $45 for a new dist/rotor set if I'm not sure this is the problem. I swapped out the plug wires with an old set that I know works, to no effect.

Any ideas?

Thanks in advance,

Stimrob

 

I know my car (94 civic ex) has a FITV (fast idle thermo valve) located right under the throttle body. This controls idle somewhat, and is prone to get clogged up. Even if it is not, if there is air inside of it, it will make the car idle roughly.

Here is something easy to try that fixed the same exact issue for me:
When car is !COLD! take off radiator cap.
Start the car up, then slowly add coolant into the radiator. As you are filling it up, your car should start to idle more normally.

Let me know how this works.

Also try to search for the fitv on the forums i know there is a how to on cleaning that out somewhere... I am not exactly sure your model has it however.

 

first post in this thread seems to indicated that I don't have a FITV valve (seems like they stopped existing on 96+ models).

I will still try filling the radiator while its cold, though I'm not sure what that will do.

Any other ideas?

 

So you looked at your throttle body and you do not see what they pictured there?

 

I did not physically check the connection. I am going by what the OP of the thread I linked to in the first post said:

1) Now you got to locate where the FITV is. If your car is 1996 and newer you don’t have one. But for the older Gen 3 models like me, we do.


I will surely check though if theres a possibility that I indeed do have one, but he seems convinced otherwise....

 

The engine idle speed is monitored and controlled by the Engine Control Module/Powertrain Control Module (ECM/PCM) which uses the Idle Air Control (IAC) Valve to regulate the idle speed. The valve controls the amount of air that is allowed to bypass the intake throttle plate, which enables the engine idle speed to remain constant even though the engine loads change during idle. This is especially true when electrical consumers such as the air conditioner are used.

The minimum idle air speed is set at the factory with a stop screw. This setting allows a certain amount of air to bypass the throttle valves regardless of IAC valve positioning. A combination of this airflow and IAC positioning allows the ECM/PCM to control engine idle speed. During normal engine idle operation, the IAC valve is controlled by the ECM/PCM and properly positioned. No adjustment should be required during routine maintenance. Tampering with the minimum idle speed adjustment may result in premature failure of the IAC valve or improperly controlled engine idle operation.
========================
Alloy Wheels, Chrome Wheels & Performance Tyres
chicago limo bus

 

That was my 1st thought too. IACV. I would try to remove it and clean it. My 93 Civic Si had 214,000 miles and idle rough too when I got her home from Michigan (to PA). The 1st thing everyone recommended was remove it and clean it with some carb cleaner. Also check the rubber seals and the screen. It was clogged pretty badly for me. I actually cleaned and rinsed that thing about 4-5 times. Made sure it was dry and then reinstalled and she idled perfectly for about 2 years until I needed to replace the FITV last year. LOL.

 

i had a similar problem, threw new spark plug wires on it... good as new

ive been told hondas can be picky with their plug wires.. might want to test another pair.

 

I've seen this problem a few times. Have you tried replacing the o2 sensors? If one of them was clogged, then it would have similar issues. But remember that you can't really clean o2 sensors.. they usually have to be replaced.

 

I have the same prob with my 99, im sure its the injectors leaking and the car misfires till its warm.