So driving to work the other day my "Service Engine Light Soon" Light flashed about 10 times, then went away. I took it to Autozone the same day, and they didn't find any codes (Not sure if 02 blazers store codes). I did notice the temp gauge was at about three quarters in the parking lot, when usually it is at about half. I bought a jug of antifreeze just in case, and went home. I have not had any overheating problems since then, either idling at a light or while driving. About a week later, at the very same spot on my way to work again, it flashed, but temp was normal. It flashed a few times then went away like before. A flashing light indicates a misfire condition, so I shut off my radio to listen to my engine, and it sounded fine. My coolant is a little low, but I am stumped. Maybe after I top off the coolant I'll check the plugs? I have no idea why a service light would flash a few times then go away. Maybe it just misfired once for some reason? The spot it happened at is on a flat spot at the top of a big hill if it matters. A rapidly flashing service engine light means a misfire condition on these trucks, correct?

 

When you check the plugs also look carefully at the leads and the coil.

 

Its not a constant misfire and that is why your not seeing a code stored.
Flashing check engine light is a misfire that is only happening under certain conditions. One possibility could be a sticking valve.

 

Now I'm nervous, what could cause a sticking vavle, and how can I fix it?

I did replace the fuel pump and filter back in March, could it be a lack of fuel pressure?

 

Well, If it is a sticking valve the right way is to have the heads re-done...What causes a sticking valve? There are a host of things ie; Engine got to hot, mistreatment of the engine, like not changing the oil or letting it get low. Just to name a few.

 

Topped off my Coolant yesterday.
I've always changed the oil regularly, and it seems like the previous owner did the same (no gunk on dipstick or oil cap). It never had any serious overheating problems I know of beside the time I described where it got a little hotter out of nowhere. The guage still wasn't in the red though. What else could cause a temporary misfire besides a stuck valve? When I find time I'll check the plugs and see what they look like.

 

You might also want to try a fuel injector cleaning as well. Whenever I encounter a misfire situation, I always check to make sure the big 3 are good. Fuel, spark, and air. Also make sure your plug wires and distributor cap/ rotor are in good shape. Doesn't hurt to be thorough!

 

There may not be stored codes, but there are probably pending codes. If your coolant level is going down, and you are also having what I presume by the flahing CEL, a misfire, I would start looking at Head gaskets. Could be a slight leak. You can do a hydrocarbons test with a block tester kit you can rent at autozone, and a compression test. Compression test will also tell you lots of things. Like a sticking/bent valve, bad rings, bad head gasket, etc.

 

So your probably not going to believe me, but the engine light flashed about fifteen times IN THE SAME EXACT SPOT I was twice before. This is the third time that it has flashed at that exact spot on the same road. It is not running rough or anything. The temp guage is normally straight up. This time it was just one mark hotter than normal. Can anyone think of a reason that my SERVICE ENGINE SOON light would My coolant is not going down, I just never topped it off all the way when I changed it. It was low, but not too low. I have since topped it off.
Can anyone think of a reason why my "SERVICE ENGINE SOON" light would flash three times in the same geographic location? Even if it's something crazy like my computer is acting wonky, and sending me false warnings.
Just to make sure I don't leave out any relevant info: each event was about two weeks apart. Each occurrence was with a warmed-up engine about 5 minutes into a 10 minute drive. Before leaving for work, I think I ran the truck previously, so the engine was started warm. I think every day was sunny and it was on the hotter side (80ish degrees). The spot that it occured was a relatively flat spot right after a large hill, about 45 MPH. Also, since I replaced the fuel pump with a Carter unit back in March, and ever since, the truck konked out once or twice. The fuel pressure may be low, but the fiel guage works better than ever.
I am really stumped. I haven't had much time to look into it with college, but maybe I'll rent a compression tester or something if I get time.

 

aliens. nuf said. (all kidding aside.. got a obd scanner? try to catch it when it happens)... I would suggest a fuel pressure test also... anything other then ac delco or delfi pumps usually don't last long.