Check engin light.....

[Levarp21]

Howdy ya'll,

I own a '90 Prelude Si with 247,000 miles on it. Up until now I have only had minor issues with it; recently I started getting the check engine light either after accelerating from a dead stop (rather quickly) or after 20 or so mins of running at 65mph. Any reason as to why this may occur. Your help is greatly appreciated.

[spiffyguido]

What code is the ECU throwing?

Here is a guide to find out the code:
viewtopic.php?f=4&t=706

[Levarp21]

Its weird, I get one long flash (-), 4 short flashes (-,-,-,-), and 3 fast flashes (--,--,--)

[spiffyguido]

Is there a lengthy gap between any of these codes? I wonder if what you're getting is two separate codes.

Sounds like one of the codes is 14, which is the EACV valve. I had the same code on my Prelude two summers ago, and it also popped up after a long blast down the highway.

The behavior I got was that my car would bog if I didn't keep my foot in the accelerator at least a moderate amount. Do you get this behavior?

[Levarp21]

Yeah, The first one comes one (_), a second later I get the 10 code (_____), followed by the 3 code (__,__,__) followed by what seems to be another 3 quick burst (_,_,_)

[spiffyguido]

That almost sounds like 3 separate codes. Code 1, Code 13 & Code 3. Which is Oxygen Content A, Atmospheric Pressure Sensor and Manifold Pressure Sensor respectively.

I'd love to see a video of this flashing. It's hard to make sense of the flashes. Is this the PK2 ECU? See the sticker on the side.

[Levarp21]

Thanks Spiffy, thats what I was afraid it would be. After reading up on it the AP Sensor is built into the ECU, which means get a new one. The other parts seem to be easy enough to find, where can I send the video once I get it?

[spiffyguido]

Don't panic and go get an ECU just yet. Start with seeing if you can get the MAP sensor to stop throwing a code.

If the video is under 20 MB, send it to forumadmin@preludedriver.com. Better yet, upload it to youtube and post the link so others can see.

[Levarp21]

Thanks Spiffy, I will get the video tonight and upload it ASAP. A quick side note: I began having the "rough idle" issue this past week. Once the car warms up the idle bounces between 500-1k, not revving too high but will not stay stable.