Sputtering at Idle

[Hobo]

Two days ago I came out of a store and my 94 LE Sedan 4 Cylinder wouldn't start.
It would turn over but not start. After trying for a while it finally started and I drove it around the parking lot and it died again.

I had it towed home and last night I put on new Plugs, Wires, Distributor cap & rotor.
Started right up. I drove it around and everything was fine.

This morning I'm driving to work and I stop at a stop light. The car is idling and then suddenly sputters for a second. A few seconds later it sputters again.
I drive on and at the next red light it does the same thing. I put it in neutral and the sputtering goes away.

At the next light it's doing it again and when I put it in neutral it sputters but not as often as when it's in Drive.

Any ideas?

For the last few years I've had a rough idle when stopped at a light and it's in drive. If I put it in neutral the idle smooths out.
I'm going to try cleaning the throttle body tonight.

I have a 47 mile drive home and don't want to get stranded.

[ghettosled]

like what you are planning, number one on the list would be clean out the throttle body and idle air control valve. this is the most common problem to what you are experiencing.

[Hobo]

OK, I followed the tutorial and cleaned the thottle body & spray a lot of the cleaner into the hole that goes to the IAC (Idle air control valve).

Didn't help.

Here are the symptoms: when the car is cold it idles very smooth in park & neutral.
It it's in drive and I have my foot on the brake the car vibrates.
After I drive the car a while and it warms up the car starts to sputter when in drive with the foot on the brake. The tach jumps around between 500 & 1000 rpm. If I put it in neutral the tach jumps to 1000 rpm and idles smoothly but after a couple of seconds the tach starts to drop to around 800 rpm and the car starts to sputter again and the tach jumps around.
I can rev the engine and it revs real smooth.

Is this a bad IAC valve?

[Mister_Perkins]

Originally Posted by Hobo

OK, I followed the tutorial and cleaned the thottle body & spray a lot of the cleaner into the hole that goes to the IAC (Idle air control valve).

Didn't help.

Here are the symptoms: when the car is cold it idles very smooth in park & neutral.
It it's in drive and I have my foot on the brake the car vibrates.
After I drive the car a while and it warms up the car starts to sputter when in drive with the foot on the brake. The tach jumps around between 500 & 1000 rpm. If I put it in neutral the tach jumps to 1000 rpm and idles smoothly but after a couple of seconds the tach starts to drop to around 800 rpm and the car starts to sputter again and the tach jumps around.
I can rev the engine and it revs real smooth.

Is this a bad IAC valve?

Tach jumping sounds like a vacuum leak. Check the condition of the PCV Valve and the rubber tube that connects to the Intake. If its cracked, replace it. A new PCV Valve will run you about $5.00 - $10.00.

Grab the throttle body cleaner and spray it all over the intake manifold and behind the valve cover (covering the injectors). See if it idles up or bogs down.

If no progress, check the Fuel Pressure before the Filter, and also with the fuel filter installed. Check the condition of the fuel pressure regulator also.

[Hobo]

I should clarify about the tach jumping.
It holds steady until it sputters. Then it bounces in sych with the sputtering.

All the classic symptoms of a sticking IAC valve that I've read about but my attempted cleaning didn't help. I was thinking of removing the IAC valve for a better cleaning.

Anyone done that before?

[Mister_Perkins]

Yup:

5sfe IAC Removal (lots of pictures)

[Mike Gerber]

In addition to what has already been done and the more thorough cleaning you will be giving the throttle body and checking the fuel pressure, also check the coil inside the distributor for being in spec and for cracks. You will need a digital volt/ohmeter and the specs from any manual to do this. Also remove the coil and inspect it for hairline cracks. There is a common problem with the coils as they age and/or these cars rack up lot's of mileage.

Mike

[Hobo]

OK, I got sick of having this problem & had my mechanic look at it today.
I just got off the phone with him.
He diagnosed it as a bad Crankshaft Pickup Sensor.
It's located in the distributor so he's replacing the distributor.
I'll pick it up in a day or two.

[Hobo]

Picked my car up tonight.
RUNS GREAT. Problem solved.