Hi, I have a ’99 S-10 4.3L Chevy Blazer. When I purchase the blazer I had a check engine light on with an Oxygen Sensor Error. I did not fix it right off, because the mechanic said it wouldn’t affect my car other then maybe fuel economy.

After a few months of owning it, I started it up and it was “shaking” while idle and at a low speeds. This continued to occur, but only after I use the car from a cold start and then shut it off and let it sit for 30-120mins and then start it again.

Symptoms:
“shaking” = misfiring.
Only occurs when the car is used and sits for a short while and then is started again

Error Codes:
P0300 – Random/Multiple Cylinder Misfire Detected
P0410 – Secondary Air Injection System Malfunction
P0172 – System Too Rich (Bank 1)
P0174 – System Too Rich (Bank 2)

Things Tried:

I brought the car to the mechanic and he replaced the regulators thinking this would help (this did help with the Oxygen Sensor Error, but didn’t fix the misfiring). The mechanic said he didn’t know why it was misfiring and he could not fix it.

So, then I brought it to the dealer. They looked at it and were able to recreate the symptoms, but all they did was switch the spark plug wires and they said that seemed to fix it. They also used some “industrial strength” Fuel injector cleaner. This worked for a few days, but it just started again.

I have looked into the P0410 Air Injection System replacement pump, but this doesn’t seem to be the problem. Maybe I am wrong.

Please any help from experienced mechanics or users who have had these symptoms I would greatly appreciate it.

Jason

Ever replace the cap and rotor?

Isn't there also a problem with some air pumps filling with water?

I don't know if they can just be removed and drained. Oddle enough my Blazer doesn't have 1 on any more :lol2:

What Brand of Spark plugs does the truck have in it right now and what is the gap on them? Also has the truck ever had a FULL TUNE UP done on it?

If your 99 has no sec air pump see if it was removed because if so you will always have the SES light on. See if the exhaust manifolds each have the check valve/hose/tube out the front or a plug. As to rough running what regulator, fuel pressure and if so what were the pressures off and running - specific psi required of 60 off to start and 54 min running. Could be many things as dirty or stuck injector poppet, sensor such as MAFS (clean it), EGR, turn-up needed, check the plug wire resistance, etc. Here's the sec air injection fix info:
http://www.automotiveforums.com/vbulletin/showthread.php?t=564664&highlight=sec+air+injection

I had a similar problem, it ended up being a non visible crack in the distributor cap. I ended up replacing the cheaper Advanced Auto part with a higher quality (and more expensive) top shelf NAPA Gold cap. That took care of the problem and it's been running great since the problem was fixed.