00CIVIC_R

I have a 2000 Civic EX 1.6L Auto.
The car will start and Idle for however long I leave it.
It will drive when cold.
When the car gets to a regular running temp and I push on the throttle once I release it the car goes to idle below 500RpM or it stalls. It does this in gear as well as in N or P.

I have replaced the distributor cap and cleaned the IACV.
My next move is a TPS and adjusting the throttle.

Any help?

Before this started I would lose power going up hills and burn oil. I get no smoke from the exhaust and the car is not throwing any codes. I have no oil leaks and I also do not have a A/C compressor belt. Was wondering if this could cause any problems other than a hot interior.

ezone

Clogged cat?

And...just how well does it drive when cold? Is it obvious there is still some running problem while cold?

Don't touch the throttle.

Unbolt the IAC valve from the back of the intake manifold. I can do this without disconnecting the hoses. See if there is a screen in one of the ports. Brush or pick the carbon buildup out of the screen. Reinstall, see if that helps the low idle issue.

Get a scantool that can display live engine data. Let's take a look at what info the computer is seeing before you go tampering with stuff that you have no business touching and throwing more random parts at it..

00CIVIC_R

The car does still show signs of running poorly when cold it does not run great at that temp I am unsure if the cat is clogged and was thinking of cutting it off and putting a straight pipe on it as it is not illegal in my state.


I have cleaned the IAC numerous times and still get the same problem as the low throttle.

Would a clogged Cat possibly cause a low idle after warm the Idle is high when cold and gets lower as the car warms usually from just over 2K to 1500K rpm until the throttle is pushed then it goes below 1k rpm or stalls only when warmed up does not do this until its at a regular running temp.

ezone

Clogged cat limits flow, so you first lose a bit of power at redline and wide open throttle, then as it gets a little more clogged it loses more off the top end, then your top speed gets limited slower and slower...... etc.
(I had one clog up on a road trip once. I was limited as to my top speed and it kept getting slower and slower as it clogged more and more. Top speed was down to 45 MPH by the time it limped home.)


A clogged cat shouldn't care if the engine is warm or cold, a serious restriction is going to limit how much exhaust can go through no matter what the temperature is.

Like going out jogging while trying to breathe through a coffee stir-straw. You are going to very very slow.

If you can go out and stomp the gas pedal to the floor and the engine pulls good all the way to redline and shift, the cat is not significantly clogged.

And it won't normally have any effect on your idle unless it was so clogged up that the engine wouldn't run any faster than idle.


Yeah, I can't really sit here and point at one thing to tell you to replace.

It sounds more like something I'd be going over basics and seeing what the computer is thinking as far as live engine data. You can have wrong stuff happening and not get any codes. The ECM isn't all that smart (GIGO).

Once you figure out why it doesn't run right, that may solve the idle issue too.



I might be looking for too much or too little fuel (if the computer isn't controlling the right amount of fuel)......Create a vacuum leak, or spray in some carb cleaner to add a little more fuel, see how it reacts to each situation.
Um, try it with the EGR valve disconnected or blocked? I wonder if it's getting stuck open.

LexIS77

Couple things you can do...if you are suspecting a clogged cat, you can create an exhaust leak before the cat by unscrewing the upstream(before cat) oxygen sensor. With that removed try snapping the throttle to 2.5-3k and see if you notice a big difference in engine pickup. If it now revs fairly freely, clogged cat is your cause.

On to other things...idle control valves usually behave worst when the engine is cold. They tend to bind on the inside where the plunger needs to pull open to give the engine extra air. You should be able to put your finger over the port in the throttle body with the engine idling and see if it is pulling a strong force of air. If you feel nothing there, put in a new idle control valve.

Throttle Position Sensor(TPS)-If you have a DMM(Digital Multimeter) Check your voltage on the TPS Output wire. It should have 3 wires I believe-ground, TPS Input(From the PCM) and TPS Output(What it is telling the computer the throttle position is at). A scantool should also give you that information. Even basic scanners usually have TPS Voltage. They are 5 volt reference sensors, so idle should be somewhere near .5V with no throttle, and usually go up to around 4-4.5V at wide open throttle. You can test it with just the key on, engine off. See if there are any points at which the voltage drops to 0V or doesn't ramp up smoothly as you move it towards WOT.

I'm going to assume your oil consumption is just an underlying condition. Your oil control rings on your pistons are probably collapsed, and can't do much about that without an engine teardown. However, some things you may have to check---Engine vacuum at idle should read around 17-21" hg. Lower than that suspect a vacuum leak-carburetor cleaner spray can help you locate a vacuum leak, and would smooth out a rough idle. Higher than that suspect valve train issue(advanced engine timing).

Thats pretty much the order I would go in if you don't have much in the area of tools.