For the '95 in the sig:

I have been chasing a slightly shaky idle, poor gas mileage, and rich smelling exhaust for a while now.

I started out by changing wires, cap, rotor, and plugs. When I took them out, #1 and #2 were darker than the rest and seemed a bit oily. They were Autolites.

The new plugs I have in there (about 500 miles on them), #1 and #2 are darker than the rest again (they are Bosch Plats given to me by a friend).

I just changed them out to Motorcraft Plats and put in a new O2 sensor.

Any thoughts? Could the EGR be dumping too much exhaust gas in there fouling #1 and #2? I removed the IAC and it looked fine inside- cleaned it anyway. Have not removed the EGR yet.

Thanks,

 

Pull your codes and do the injector balance test that the code reader does.

 

No codes- 111 for KOEO & KOER.

 

A machanic buddy once told me not to run platinum plugs in a motor with higher miles on it . This is because a very small wiff of oil will start to foul them ,you won't get a proper burn after that. That was when I was having a plug color problem on my old motor so I stopped using them. True or not I do not know-just his opinion.
Check your fuel presure. Maybe bad/dirty injectors. Do a compresion test.

 

Fuel pressure KOEO: 38psi

Fuel pressure KOER: 30-31psi fluctuating

Fuel pressure vacuum disconnected: Increased 10psi



Cylinder compression (dry): all 180-190psi

 

My '93 5.0 with E4OD has exact symptoms you have. When I pulled the codes (using the jumper/dash flash method) I get 33 and 133. I've checked the EGR, EGR Position Sensor, and TPS which all came within spec. I replaced the MAP and it had no effect so I took that back. I had originally thought the rough idle was cheap aftermarket iginition components a shop had installed so I replaced with all Motorcraft parts (cap, rotor, wires, plugs). When I pulled the old plugs I noticed that on cylinders 2 thru 7 they were a whitish grey, but the plugs in #1 and #8 were brown/tan.

Usually my rough idle isn't too noticable until the engine reaches operating temperature. And, it gets worse as the air temp increases. Sometimes the RPM drop to 500 and the engine lopes badly. You can also hear a slight miss until about 2000 RPM and when accelerating from a stop I can feel a shimmy between 1400 and 1900 RPM that worsens under load. I know the shimmy is not the driveshaft because I replaced all U-joints and carrier bearing last fall trying to track down that problem.

The problem persists to this day and like many others, I refuse to just throw parts at a problem hoping to fix it. Is it maybe a timing issue? I don't have a timing light so maybe I should go to shop and have that checked?

The fuel milage isn't terrible, but I'm getting 15 mpg at best on the highway. That's a lot of $$ at $1.40/gallon!!

KJ

 

johnsonmtz:

Your "33 and 133" is actually "111 111 -1- 111 111" Those are pass codes for KOEO and continuous codes.

Your 15 mpg is standard- I am around 9-10. Your lope is probably related to a dirty IAC-never hurts to pull it off and clean it.

 

what is a IAC

 

Idle Air Control valve- sorry to use the acronym loosely.

I believe I have a slight pinhole in my EGR diaphragm. Does anybody think that could lead to cylinders 1 and 2 running rich?

 

The slight miss in the engine is usually present warm or cold. The loping & subsequent RPM decrease to about 600 RPM only happens when the engine is a full operating temperature and most often after you have run a constant speed for a few miles. It doesn't seem to appear as often in stop and go driving.

Does that sound like a dirty IAC? I'm beginning to think the timing is off. Unforutantely I've never set timing on anything and I don't have a timing light.

Maybe I should clean the IAC and take it to a shop to have the timing checked?

KJ

 

If a EGR diaghram leak is causing significant problems then I'm sure you would pick this up as a code. The diaghram leak would cause a mis-position of the EGR valve and then the position sensor would pick this up and throw a code (theoretically anyhow).

The EGR system tends to increase deposits in intake runners 1,2,5 and 6 which can significantly reduce airflow into these cylinders. If fuel injection remains the same then these cylinders will run rich. The O2 sensor should detect an overall rich condition and compensate somewhat but the end effect is that 1,2,5 and 6 will still be slightly rich and 3,4,7 and 8 will be on the lean side. To remedy, if this is the situation, you'll have to remove the upper plenum and clean with carb cleaner, oven cleaner, lacquer thinner or take it to a shop to have it boiled out. Also make sure that the engine is in top tune (O2 sensor etc.) to reduce future build-up. I'm not claiming that this is your problem for sure - just an idea.

Randy

 

That's the odd thing- no codes. I have pulled a vacuum with my MityVac and it seemed to hold on. But when I spray carb cleaner at the diaphragm at idle (no EGR), the idle changes some.

I am going nuts trying to solve this slightly shaky idle, rich exhaust smell and poor gas mileage that started right after a dealer from Iowa City worked on my truck (they worked on the exhaust manifolds and replaced a oil pan gasket).

 

sounds like they installed wrong o2 sensors, and they are telling the truck to run rich.....

 

They did not touch the O2 sensor (1). They resurfaced the one manifold that the EGR is attached to and they replaced the other.

 

Just a shot in the dark here, but could your intake or head gaskets be leaking a bit of water into those cylinders? I've had that happen with similar symptoms. If you put some stop leak in the radiator and it clears up, that would confirm. Just a wild guess...