New owner w/ an '82 needs help - running rich no idle

[Burningmustard]

Had a great day today cruising with the spider on my 5yr anniversary until we were headed home.

All of a sudden the car started to miss and was running real rich, and would not idle. At stop I had to keep my foot on the accelerator to keep it from dieing. we made it home but it was quite tricky. now I must put my foot on the accelerator to start it .

Would this be a common problem or am i going to have to diagnosis this one myself. Any help would be great.

It seems like this is either a computer issue, or a fuel intake valve (?) staying wide open. Now that I think about it, the car might have been running rich before, but didn't cause any issues. Any leads would be great.

Also, I am in Kansas City, so a recommended KC repair shop would be helpful as well

Thanks guys.

Zach

[rlux4]

Couple of questions for you Zach, so we get a starting point for diagnosis. How many miles on your car? Do you know if the injectors have ever been cleaned?
The ECU is most likely not at fault, it's pretty basic (just responds to input and completes ground circuits) and they are very bullet proof, but it could be responding to a faulty sensor. Most of the sensors are not so critical that if one went bad it would cause the car to run that poorly. All except the temp. sensor in the coolant "T". If it's bad, your car will run very poorly, if at all.
I ask about the injectors because if they don't shut off completely when the signal stops (the ground is opened), the constant pressure in the fuel rail would cause fuel to continue spraying.
Ron

[So Cal Mark]

you could have a leaking pressure regulator, a leaking injector including the cold start injector, a failed temp sensor or connection or even a failed thermo time switch. Or, a sticking air flow meter

[jfrawley]

Check the connection on the air flow meter or the meter itself. Sounds like the way my '82 ran when the connection at the air flow meter came loose.

[launieg]

Although you say it is running rich (how do you know this?), it could also be ignition. My 81 FI ran like that for a couple of days until I realized that I had a slightly loose connection on the coil. Check all the ignition connections anyway, is my recommendation.

[Burningmustard]

Thanks for the quick replies, the car has 110K and I just got it and I don’t really know what has been done previously.

A couple other items I noticed this morning, from everyone’s suggestions.

Mass Airflow Meter

In an attempt to do some diagnostic, I unhooked the electrical connection to the Mass Airflow Meter and started the car. The car ran about the same when it was connected, maybe a little worse.

This would lead me to believe that the Mass Airflow Meter may be at fault.

I believe the AFM can also control the Fuel Pump. I also noticed that once I let the car die (by taking my foot off the accelerator) I hear a noise from the back. This appears to be the fuel pump. The fuel pump will run until I turn the ignition to the off position. If I turn the ignition back to the on position w/o trying to start the car, the fuel pump begins to run again.

***Edit to add*** If I unhook the AFM and turn the ignition to on, the fuel pump does not run.

Any other ways for me to determine if it is the AFM?

Thanks everyone.

[So Cal Mark]

first, you have an Air Flow Meter, not a Mass Air Flow Sensor. They operate on completely different principles. Without a lab scope or digital mulitmeter, your testing of the AFM will consist of determining if the flap sticks in any part of its' travel. There is a switch inside the AFM to control the fuel pump, but it doesn't affect the operation of the AFM in any other way.
You should download a version of the Fuel Injection Diagnosis manual, otherwise you're going to spend lots of time throwing darts and hoping to hit something

[Burningmustard]

Thanks Mark. After digging around this site for a while, I had a good feeling that my airflow sensor flap was stuck open, and sure enough it was.

I will now include a 10mm wrench in my trunk tool kit.

Thanks everyone.

[Brian]

Unfortunately, if your AFM was stuck, this may not be the end of your troubles. Why was it stuck? Was the flap binding inside housing? With your fingers, you should be able to move that flap through it's whole range, smoothly and with no contact with the housing. The position of that flap tells the computer what the engine is doing and if it sticks someplace then the computer is getting erroneous information and will try to compensate.

If your sticky spot is minor, you could try polishing it with some emory cloth but keep in mind that the more material you remove the more error you are introducing. Again, the flap is telling the computer how much air the engine is using and it is very precise. For this reason, you also need to make sure that the big hose is connected and sealed properly and has no cracks. If either of those conditions exist, then they are allowing unmetered air into the system.

Keep an eye out for a good used AFM.

"Been there and done that"