I was doing some testing, and during an extended WOT pull under heavy load, my CEL started flashing. I immediately lifted off the gas pedal, but heard nothing odd, and the car was otherwise driving fine. The flashing CEL went away roughly 10 seconds after it first showed up, and has not come back since.

- Car is not making any weird noises.
- Car has zero symptoms of damage.
- Car has been VTEC'd to redline after the incident, with no problems (but not under the same load).

Anyone know why the CEL would flash, and then go away?

 

probably emissions related, and intermittent, some emissions codes will come and go without being stored. I think anything that could be problematic would be stored. It could be as simple as a gas cap. Just a guess as something like this is hard to decipher.

 

Bump, any help? =/

 

When you say no stored codes, do you mean that you hooked up a scan tool and looked for stored codes, or just that the CEL is off? Even after the CEL is off, a scan tool can pull the code, and even pull freeze frame data, which could reveal the cause of your problem (for instance, if the Engine coolant temp sensor intermittently cut out, the ECM would see -40 degrees F and would thus dump waaaay too much fuel)

A flashing CEL means you are damaging the catalytic converter, specifically running extremely rich.

Don't reset the ECM via pulling the fuse or the negative battery cable because this will delete the stored code and freeze frame data.

 

Flashing CELs with no stored codes usually means a misfire. It's flashing because the misfire was happening at that very moment.

 

Pretty sure if you connect it to a scanner you will still pull a code.

 

Exactly. You're most likely misfiring if its flashing a while and then going away after 10 seconds.
There are too many reasons to list as to why this would happen- just research them
but this has happened with my s2k and others I know at WOT while datalogging with an aftermarket ECU
so i speak directly from experience.

 

Facts.

OP let's start with the basics. Pull your plugs and give them a once over. Are they old? How old? How is the condition of them? White, Tan, Black??


If they pass inspection, we will move onto ignition coils. Now this is a tough code to diagnose without a datalog because, like said above, the misfire was happening right then and went away.

Do you have an aftermarket ECU?

 

I'm using a Flashpro, tuned by Shawn Church of Church Automotive Testing.

I'll take a look at the plugs when I have time later today. They are about 10k miles old now. OEM plugs.

Only breather mods are test pipe + tune.

 

So look what I found...

VSA + ! light came on today too.