Clogged IAB valve?

[NASCAR Mike]

94 SHO ATX

The engine starts very easily, doesn't stall at any speed, it just misses when I accelerate from 0 MPH to about 10 MPH. After 10MPH I have no problems at all. No stalling, bucking or pinging
of any kind. Just from dead stop starts do I have bucking or missing.

All of this just started without anything being done to the engine, except for a new timing belt, valve adjustment and new waterpump about 4 months
ago.

I have changed the valve cover gaskets including spark plug gaskets, new spark plugs (Ford double plats) and new spark plug wires (Ford Motorcraft).
Plugs and wires are completely dry.

I just changed the thermostat (B revision) and the TPS sensor but I still have the same problem. No check engine light is shown and my code scanner
comes up clear (111 code). I have cleaned the TB and the MAF wires. I sprayed carb clean on the engine while it is running and the RPM did not
raise so I don't think there are any vacuum leaks.

I think it's the IAB. Could this be it?

Thanks all.

 

[sdpatt]

The IAB or IAC valve controls only air flow and should not be able to create a misfire or stumble. A misfire without an EEC light is usually a secondary ignition problem. Have you checked for memory codes too? You said that you replaced the plugs and wires with the correct parts. Did the situation change at all after doing that? Might want to clean the MAF sensor filaments. I still lean toward a secondary ignition system problem.

 

[NASCAR Mike]

No memory codes. Everything is clear.

I cleaned the MAF wires with electric cleaner with no residue type.

The plugs were coated with oil thats why I changed the valve cover gaskets, plugs and wires. I disconnected the battery while I was doing this work so I know everything in the computer was cleared out. It didn't stop the problem of the missing.

I do not get any kind of miss at any speed above 10MPH. It pulls strong all the way to redline.

I only get misses from 0 to 10 mph.

What is a secondary ignition problem?

Thats why I am thinking its the IAB. Maybe the EGR? Uggghhh!!! headbang

 

[Off Road SHO]

The secondary ignition is the spare one that all SHO owners keep in their trunk for emergencies. Just Kidding.

That is the high voltage side of the spark, from the coil packs to the spark plugs and engine block ground.

The primary side is the low voltage part that comes from your DIS and computer.

Tom

 

[NASCAR Mike]

Off Road SHO:
That is the high voltage side of the spark, from the coil packs to the spark plugs and engine block ground.

The primary side is the low voltage part that comes from your DIS and computer.

Tom

OK. So how do I check this?

 

[Off Road SHO]

Well I could jump ahead 10 years and say "when I was young we were so tough that we would just hold onto a spark plug wire and the frame of the car to test for spark voltage" blah blah blah. Actually that's what little brothers are for.

You could start by measuring how much resistance each of your plug wires have with a good VoltOhm Meter. Don't know what the risistance should be, but if you check them all and one is not like the others, you've either got one bad one or five bad ones.

Spark plugs: Of course you have the right ones installed. AGS32PP Motorcrafts. Check for correct gap; .042 to .045 IIRC. Insert a plug into a plug wire boot and have lovely assistant crank over engine while you hold plug threads against the grounded manifold plenum. Should get highly visible spark.

Tom