ISO HELP, 96 Accord, 200,000 miles. 4- cyl SOHC F22B2 Automatic trans. Ran perfect until lower heater hose let go and my son continued to drive it down the highway. It blew the head gasket so here's what I did. ALL NEW PARTS- head gaskets / bolts, timing belt, idler/ tensioner, water pump, spark plugs, plug wires,EGR valve, IAC valve, injectors, All coolant sensors, thermostat, distributor shaft oil seal, gaskets for the spark plug sleeves, EGR canister, EGR solenoids and cleaned all the EGR passages. Also cleaned the TB.

So... my problem is AFTER the thermostat opens the engine runs ruff. Doesn't matter if I'm sitting still or going down the highway. Again this ONLY happens after it warms up and the RPM is under. So basically ANYTIME my foot is off the gas peddle ( butterfly is completely closed) it misses and acts like it's only running on two or three cylinders. And when I drive it and come to a stop light, the RPM's will drop down to about 400 right before it dies. I've done everything I know to do from this forum and I'm out of answers.

I've also pulled the fuse to reset the CPU several times..still no luck. And it's NOT throwing any codes. I've read on this site that if you have idle problems you need to start with your BASE IDLE.. but I can't even get it to idle at all unless I crank out the throttle cable to let more air in the TB... And I know that's not the right way to do it.

From what I've read I could have a bad CPU and I'm not past the point of replacing it but right now my wife is battling cancer so I don't have the money to just throw at a new (or salvage one) unless I'm completely sure that's the cause. Any advice would be much appreciated. Thank you guys.

 

You don't mention bleeding any air out of the cooling system. Back at the thermostat housing is a bleed valve (looks like a brake bleed valve). Honda's idle-control system gets all confused if there's air in the cooling system. (since you know about the base idle, you probably saw my warnings about that)

Considering it probably overheated when he continued to drive, did you have the block & head checked for flatness before bolting them back together?

 

 

The engine runs rich when you first start the car. When the car gets to a operating temperature, the engine goes into closed loop mode. This is when the engine computer takes control over the control of fuel.

Running problems at idle means the intake is under the greatest vacuum. You may have a vacuum leak you created when you put everything back together.

Do you have a scanner that can read some live data? I would look at the fuel trims when the engine is running rough at idle.

Check that you didn't switch connectors to the map sensor with the throttle position sensor. The 3 wire colors to the map sensor are yellow/white, green/white, and white/yellow. The throttle position sensor wire colors are green/blue, red/black, and green/blue.

Another connector you can swap is the resistor bank that is near the firewall on the driver's side of the engine. The injector resistor bank has metal cooling fins on it to help you find it. The connector to the resistor should have 4 wires that are the same color (red, or red/black). The 5th wire will be red/black, or red, but opposite the other 4 wires. The identical connector nearby will have much different wire colors going to it.

Also check that you connected ground (G101) to the upper part of the intake manifold on the drivers side. That is an important ground for the engine computer.

 

 

Another simple thing to rule out if you haven't already...
Is the throttle body clean? The idle-air adjustment is a little brass needle valve. If the small passageways in the TB are blocked with crud, you won't get any air through there even when you open up the needle valve. You can pull off the rubber duct from the air filter & see if you feel some suction at the small holes inside the TB bore just outside of the throttle plate. One hole for the idle-air and the other for the cold-start air (FITV).

 

Jim / PAhonda,
I checked all the wire connections to those components that you mentioned and they are all in the correct place. However, I didn't see a ground wire mounted to the top of the intake manifold. I did see two ground wires though. A small one that is mounted right behind the power steering pump to the frame and a larger one by the motor mount.
As far as the TB, it didn't look all that bad so I cleaned it while it was still mounted. I checked for vacuum from the larger hole and it has plenty vacuum. Now on the brass Idle air adjustment screw. I've made several adjustments with it in and out and it changed the performance of the motor so it more than likely isn't stopped up but you know better than I.

I took the fuel rail off and cleaned the ERG passages and they were clean and open. and like I mentioned earlier my ERG valve is new.

 

G101 is between the upper intake manifold and the brake fluid reservoir. I attached a picture to show the location.

 

If the idle air screw made a difference, then it's probably back to the vacuum leaks that PA suggested. That brass screw has an O-ring around it which seals air from coming around the screw as well as gives it some friction so it doesn't move by itself. But it sounds like you might have a bigger vacuum leak than that.

I forgot which hole is which in the throttle body. The one that takes air for the cold-start (FITV) should NOT have suction after the car warms up. That's supposed to suck air during a cold start & then gradually close off to nothing when the engine warms up.