'93 214k rough start for 30 sec. or so

[Rupesy]

My Astro starts very quickly but idles really rough for about 30 seconds(pumping the pedal or reving it up during this phase doesn't seem to help). After that it runs great. I've posted before and someone suggested turning the key on for 10 seconds or so to allow the fuel pump to build pressure, but that doesn't seem to work. The spark plugs wires and cap are fairly new. Where should I start?

Thanks

[Blue Bowtie]

"Check Engine" light on? You might want to make sure the MAT/IAT sensor is plugged in. You could also clean the TB, and clean the IAC, but neither is easily accessible. Even testing fuel pressure is no easy task. Has the fuel filter been replaced lately? I'm just stabbing in the dark with no further input.

[Rupesy]

The "check engine" is on. Where can I find the MAT/IAT sensor? What do you use to clean the TB (assuming you mean throttle body)? What is the IAC and where do I find it? Fuel filter is a couple years old, but easy to change so I will go ahead and do that.

[Blue Bowtie]

If the "Check Engine" light is on after the engine starts, you need to retrieve the stored error codes. That will be the fastest route to solving the problem. It's realtively easy on a '93.

Locate the ALDL connector in the driver's footwell. Insert a jumper made for a short piece of wire or paper clip formed into a "U" shape between the terminals 'A' and 'B':



Turn on the ignition but DO NOT start the engine. Watch the "Check Engine" lamp. It should perform a series of flashes and pauses to display the error codes. The first code will flash three times, and will usually be a code '12'. This is encoded by one flash of the lamp, a brief pause, then two successive flashes of the lamp. Each code will repeat three times, so you should see a "Code 12" flash three times. Any other error codes will follow in numerical order, and each code should flash three times. After all codes have been displayed three times, the "Code 12" will again flash three times, then all other codes will follow as described earlier. This cycle will continue until the jumper is removed or the ignition is turned off.

After you have made a note of all error codes, turn off the ignition and remove the jumper immediately. If you forget to remove the jumper and attempt to start the engine with it in place, you could damage the ECM. For this reason you should remove it immediately.

Once you have a note of all error codes, check this file for the decoding:

GM Error Codes.pdf.

You'll need Adobe Acrobat Reader to open/print the file.