Intermittent miss at idle.

Asked by Jan 24, 2015 at 06:04 PM about the 2004 Chevrolet S-10 4 Dr LS 4WD Crew Cab SB

Question type: Maintenance & Repair

2004  S-10 Crew Cab
4.3L
236,000 + miles
For months now I've been having a "miss" while at idle. Not a constant miss where the cylinder(s) have no fire at all. It is definitely a miss. Sometimes when stopped at a traffic light or stop sign it's worse than other times. Never has set a code until recently.(PO303) There are other codes I need to mention in a moment.
I have been reading a lot of info on the fuel injection systems on this vehicle but cannot be certain it is the fuel injection.
Things I have done to "fix" this problem are...
Replaced distributer cap and rotor. (old ones didn't look bad to me)
Replaced air filter
Replaced AIC
Cleaned MAF sensor
Fuel pressure regulator leak down test. (passed with flying colors)
Replaced bad alternator just today.
Noticed that the coolant overflow tank was empty and topped off. Radiator was replaced in the last 6 months and there are no external coolant leaks.
Engine oil does not smell of gas but I will double check that.
Also another intermittent problem and probably related is that sometimes it is very hard to start in the morning for the first time of the day. More frequently after it has sat for a couple of days without running.
Fuel pump was replaced a couple of years ago by a Chevy dealership.
Catalytic convertor replaced less than a year ago and pre-cat was removed. The muffler shop said G.M. only used the pre-cats for a couple of years and that I really didn't need it.
List of codes stored currently in the PCM
p0420
p0507
p0303
p0102
Thanks for any advice,
Jeffrey

5 Answers

665

You'll probably need a compression test but before you go for any more expense, try this: This worked for my 97' S-10 & my 2000' Xtreme...All I did was add a bottle of "Fuel Injector/Carburetor Cleaner" to my gas tank from the Dollar Store. Also, check/change the inline gas filter? I found this YouTube video for you as well: https://www.youtube.com/watch?v=OZOLEgmy2BE Hope this helps.... Let us know !

1 of 1 people found this helpful.
665

https://www.youtube.com/watch?v=OZOLEgmy2BE

Hello Debo13, Thank you for your reponse. Couple of things Ushould ad, I have done the fuel injector cleaner a few months ago with no improvement but I have purchased another bottle to try again. I have noticed the "miss" problem is much worse if I let the truck move under it's own power WITHOUT touching the gas pedal. Fuel pressure test was 62 pounds max and 58 pounds minimum with just the key on and with the engine running. Leak down test was 62 pounds dropping to 58 pounds. Which was a duration of over 15 mins. Fuel filter was replaced at least 5 years ago. Spark plugs and wires were also replaced at least 5 years ago. I really don't believe I have a spark plug or wire issue because it would have a miss at all rpm's but I will check them and do a compression check. When accelerating it seems to pull strong and normal. No misses or stumbling that I can feel. Jeffrey Sent from my iPhone On Jan 25, 2015, at 10:07 AM, CarGurus wrote: Hello JeffnFranklinTn, A CarGurus user (DeBo13) answered your question: "Intermittent miss at idle.". They wrote: "You'll probably need a compression test but before you go for any more expense, try this: This worked for my 97' S-10 & my 2000' Xtreme...All I did was add a bottle of "Fuel Injector/Carburetor Cleaner" to my gas tank from the Dollar Store. Also, check/change the inline gas filter? I found this YouTube video for you as well: https://www.youtube.com/watch? v=OZOLEgmy2BE Hope this helps.... Let us know !" View answer | Mark answer as helpful | Mark as best answer | Stop following this question Take care, The CarGurus Team About CarGurus: CarGurus LLC is an online automotive community that strives to connect those "in the know" with those on the hunt for new and used automotive information. CarGurus - Where anyone can find and share automotive knowledge. Go to CarGurus | Unsubscribe | Change Settings | Contact us CarGurus LLC, 1 Bow Street, 4th Floor, Cambridge, MA 02138 Copyright © 2006-2015 CarGurus ® LLC All Rights Reserved.

Sorry for the copy and paste mess up in my last post. Okay new info....I hear a sound I've never noticed before. Leaning over above the engine I hear something that sounds like it's coming from under that plastic cover or "plenum cover" if I got that correct. It sounds like a light "scraping" noise(best I can describe it) and it stops whenever the engine "misses/stumbles" it's not loud and you can't hear it with the hood closed but it is definitely there. Like I said, I've never noticed this sound before and I've had my head under the hood of this trick many,many times. Jeffrey

Compression test results 1. 160 2. 160 3. 155 4. 160 5. 155. 6. 160 The tester I used was a loaner from Autozone and the seals on it are not in the greatest of shape. So I imagine the results are a little better than what was indicated. I went ahead and installed new spark plugs. Which was a smart thing to do because the "miss" is gone. All of the old spark plugs looked great. In fact, too clean if ya ask me.(Wish I could post a pic) I disconnected the battery for awhile so that all the stored codes would be erased. So far, the SES light is staying off. I still don't know what that noise is in the plenum however. Jeffrey

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