weird CEL this morning

[Beez540]

I fired up the car this morning (pretty damn cold out)... and after the usual couple seconds of rough idle it smoothed right out....let it warm up a bit, went inside to grab something. When I got back in the car it was idling where it usually does (right around 500) but maybe just a bit lower and slightly rough and a check engine light popped on.

I lightly tapped the throttle and the light goes away... idle comes back down to what it was doing and the light comes back... I tap the throttle lightly again (just a blip, not even above 1k) and the light goes away.

Idle now sits perfect at 500 and the light never came back.


ONE NOTE: left my lights on at work last thursday... had to jump it. The engineers at work let me use the battery charger for the station vehicles, and the amperage the batt. was drawing didn't go down significantly after 4+ hours of charging.

Sound like it's time for a new battery? but wouldn't I get a batt. light and not a CEL?

[Beez540]

anyone encountered this before? anyone?


anyone reccommend a good brand of battery or where to find one?

[Alexlind123]

I had a CEL for about a half second yesterday after i started it up and backed the car out of its cozy garage into the frigid cold. I think it might have something to do with the weather...personally im not going to worry about the time it happened to me unless it happens again or stays on for longer than a half second. Chances are the old o2 sensor doesnt like the sudden change from warm carage to frigid air too much.

[shogun]

Recharge the battery complete and most probably the CEL is gone.
But also check the charging voltage of the alternator when engine runs in idle and at abt. 1.500 RPM.
Alternator could also be the problem. Voltage regulator?

[Beez540]

thanks for the ideas... I've been needing to invest in a battery charger for awhile anyway.

[Jay 535i]

This occasionally happens to me, too. Only when it's very cold outside. Once the temp gauge reaches the first tick mark, the problem doesn't return. I don't worry about it.

[632 Regal]

intake leaks? The M-60s have a slight issue with that in the cold.

[Incantation]

shouldn't the idle be 800?

[Traian]

Ya, my M60 idles at nearly 800 when cold. Anywho, I had a similar problem and it turned out to be a vacuum leak, as Jeff said. Throttle body gasket was it for me.

[Beez540]

shouldn't the idle be 800?

I wondered about that... but since I've had the car it's cold idle is slightly above the 500 line (probably 600 - 700), and after it warms up it sits right at it or slighly lower (even looks like 400 - 450 at times). The idle doesn't feel or sound quite that low, and it's generally very smooth.

[632 Regal]

I ordered the front plate gasket for mine today, thats the last gasket that I didnt replace.

Ya, my M60 idles at nearly 800 when cold. Anywho, I had a similar problem and it turned out to be a vacuum leak, as Jeff said. Throttle body gasket was it for me.

[Jon K]

thanks for the ideas... I've been needing to invest in a battery charger for awhile anyway.

Make sure you get a slow charge/ trickle charger with auto shut off.

Its just a GUESS that its your battery. I am not sure if the E34 would throw a CEL for low voltage, but if you rev'd and the light went out, ie. the alternator surges a little and throws some volts out, that could be it. However, it could also be a vacuum leak post-maf. Check your codes. It could even be the O2 sensor not responding in the cold. It really could be anything.

As for a battery, Autozone 49D.