flickering engine codes in the datastream

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Joined: Sun Sep 09, 2012 7:07 am

flickering engine codes in the datastream

Post by schwad »


I'm seeing codes flash for a fraction of a second as I monitor my ALDL datastream. Wondering if this is normal behavior, or possibly a faulty ECM, or possibly just a problem reading the datastream (i.e. not real codes). Here's some background...

My car (1992 Oldsmobile 88 Royale LS, 3.8L) was stalling suddenly while driving on the road. In monitoring the datastream I saw that code 42 was set (though the check-engine light was off), indicating a potential problem with the electronic spark timing (EST). Everything else looked clean (to my untrained eye). I took my car to the shop expecting them to diagnose a loose/broken wire between the ECM and ignition coils. To my surprise, they decided the ignition coils needed replacing (despite the fact I had them replaced 1.5 years go, so I wouldn't expect them to be bad). To their credit it hasn't stalled since, but now I see other problems. After I got it back from the shop, I saw that the code 42 was still set. (They disconnected the battery during service, which should have cleared the codes, but I'm guessing code 42 reset while driving home?) Worse that that, all kinds of codes would flicker with the engine running, each on for a fraction of a second.

I disconnected the battery for a few hours to reset everything again. I ran the engine for 20 minutes after that, and everything looked great -- no codes, flickering or otherwise. But since then, the flickering codes have started up again. I have noticed that the flickering codes tend to be associated with the ALDL connection occasionally flashing something like "Data Connection Error" in red (instead of "Logging" in green). (This is not stored in the log, since it is not part of the datastream itself; you have to see it in TunerPro as it happens.) The connection problem and flashing codes don't happen at the same time; rather, they are interspersed. But I think I've seen that when there are no connection errors for some period of time, there are no flashing codes either.

An acquaintance mentioned that flickering codes could be associated with the ECM relearning its proper settings, as it constantly tries new parameters. Is this true? If so, I won't worry about it. (But it has been happening for at least a dozen drives now.)

If it's likely a faulty ECM, then I will need to replace that so that it doesn't damage anything else.

Thanks for any advice.


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Post by aloma45 »

Hey you have Oldsmobile 88 Royale LS, 3.8L!! That was the most popular 1992 oldsmobile models. My cousin bought this at that time. I also wanted to buy this but my father didn’t give me money. Now I am planning to buy a latest Oldsmobile cars for my son.

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