2000 Silverado misfire cylinder 3-thoughts?

Guys, first off thanks to the knowledgable folks that post to this forum like Ian and Doc and others- ya'll helped me before and now I've got a new gremlin.

Truck was running fine, started it up this morn, moved it forward about 10 feet into the garage, and proceeded to swap out a right front stereo speaker.

Finished the installation, started the truck to hear the stereo, and damned if I don't have the 'check engine soon' light on. Light is on steady until I drive it a little and then the light starts blinking. Truck was running rough, like I was down one cylinder (5.3 L v8). Ran down to autozone, plugged in their diagnostic machine, and got back a report of a misfire on cylinder 3 (actual error was a 'POS-303' or something like that then the machine flashed 'misfire cylinder 3' - saw it with my own eyes so it's not the technician messing with me). I've got 52k miles, just recently refreshed my K&N (bought before reading this newsgroup's opinion), last fuel filter at 30K, Mobil 1 changed religiously, premium gas only, etc. Only thing I haven't done is the PCV valve and the sparkplugs.

I'm trying to think what would cause a misfire on 1 cylinder. Either no gas or no spark or a combo of the two. I made sure the wiring harness for the injector and plugs were tight, wire looks good. Haven't yanked the plug itself yet as I'm waiting for the head to cool. I went ahead and bought 8 new plugs and hope to God this fixes the misfire. Gapping them to .060 and will install in about 30 minutes...

The sales rep sold me Delco 41-932's, which from my silverado manual are recommended for the v6 only with 41-952's for the V8. I called back autozone telling them they sold me the wrong plugs and they said the 932s are the regular platinum while the 952's are the double platinum and that the 932's are fine with my truck.

So, several questions-- if plugs don't fix my misfire, what else can I check? Secondly, are 932's ok or should I really find 952's? Lastly, if the condition is corrected with plugs, will the warning light go away or do I have to reset it somehow? Thanks for the help everyone.

Chris

Reply to
Chris
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Hi!

Take that K&N off and see what happens. My dad used one on his '94 before he became "informed"...and that truck (4.3 V6) didn't like it one bit. It never missed but the only time that the SES light has come on was when the K&N was installed.

William The Guesser

Reply to
William R. Walsh

Chris,

Could be a bad plug, bad plug wire, bad coil for #3 (only if you have DIS, if distributor ignition ignore that one), dead injector, stuck injector.

I'd check thing out before I started throwing plugs and such at her. At 52k miles she's not even close to the time for a tune up. Here's what I'd do:

  1. Disable fuel delivery by yanking the appropriate fuses.
  2. Pull the plug wire for #3, stick a long screwdriver in the boot (rubber handled!), and then ground it while someone cranks. Should be a fireworks display.
  3. If you have spark from the wire, replace the plug. If no spark, test #3 circuit further upstream until you find where the spark is stopping.
  4. If spark checks out ok, it's gunna be a fuel delivery problem.

Doc

Reply to
"Doc"

Reply to
Chris

OK next piece of weirdness- I was changing plug #3 while some of you replied, and yes I have spark, and after replacing just #3 she's running much better. Old plug doesn't show any obvious damage and doesn't appear to have all that much carbon on the electrode (at least it doesn't look like the old plugs on my MGB when I was running her rich)... So-- after changing one plug, the truck runs much better but I still have the service engine soon light. The only difference is that before the plug change, after a few minutes of driving the SRS light would blink. Now, after the change w/ the new plug the light isn't blinking- it's just on steady. Again, truck seems to be running fine now, not stumbling all over itself like it was when it was down 1 cylinder. Next suggestions? Does the blinking vs. steady light mean anything to anyone?

Chris

\"Doc\" wrote:

Reply to
Chris

Disconnect the battery for 2-3 minutes to delete all stored codes. Fire her up, let her reach full running temp before you drive anywhere to let the PCM relearn everything. Next time it sets a code, get it read at Autozone ASAP. Nuking the old codes will make sure when you have it re-scanned you're only getting current ailments.

Doc

Reply to
"Doc"

Whoa....

Before you do this, make sure you have the radio un-lock codes, as odds are, you (the OP, not Doc) have a TheftLoc radio in the dash.

Reply to
Neil Nelson

Disconnect the battery for 2-3 minutes to delete all stored codes. Fire her up, let her reach full running temp before you drive anywhere to let the PCM relearn everything. Next time it sets a code, get it read at Autozone ASAP. Nuking the old codes will make sure when you have it re-scanned you're only getting current ailments. Whoa....

Before you do this, make sure you have the radio un-lock codes, as odds are, you (the OP, not Doc) have a TheftLoc radio in the dash.

Reply to
Chris

Found a reference to this article but haven't found the full thing yet...

Silverado/Sierra 2000 Bulletin 000604006

SOME CUSTOMERS MAY COMMENT ABOUT THE SERVICE ENGINE SOON LAMP BEING ILLUMINATED WITH NO OTHER DRIVEABILITY CONCERNS NOTICED ON VEHICLES BUILT PRIOR TO THE VIN BREAKPOINTS MENTIONED IN THIS BULLETIN. *TT

Mine was one of the first 2000's off the line, so I'm pretty sure my truck would be within the VIN breakpoints. Anybody have access to bulletin 000604006?

Chris

Chris wrote:

Reply to
Chris

Silverado/Sierra 2000 Bulletin 000604006

SOME CUSTOMERS MAY COMMENT ABOUT THE SERVICE ENGINE SOON LAMP BEING ILLUMINATED WITH NO OTHER DRIVEABILITY CONCERNS NOTICED ON VEHICLES BUILT PRIOR TO THE VIN BREAKPOINTS MENTIONED IN THIS BULLETIN. *TT

Mine was one of the first 2000's off the line, so I'm pretty sure my truck would be within the VIN breakpoints. Anybody have access to bulletin

000604006?

Chris

/////////////////////////////////////////////////////////////

Chris,

Here it is. I don't think this is yer' problem. Get thee to Autozone and get the codes pulled.

Doc

Service Engine Soon Lamp On with DTCs P0141/P0161 (Reprogram VCM) #00-06-04-006 - (01/24/2000) Service Engine Soon Lamp On with DTCs P0141 and/or P0161 (Reprogram VCM)

2000 Chevrolet and GMC C/K Models (Silverado and Sierra) with 4.8 L or 5.3 L V8 Engine (VINs V, T -- RPOs LR4, LM7) Built prior to the following VIN breakpoints: Assembly PlantDivisionVIN Breakpoints OshawaChevrolet2GCEC19V8Y1226868 OshawaGMC2GTEK19T9Y1226878

Condition Some customers may comment about the Service Engine Soon lamp being illuminated with no other driveability concerns noticed. When investigating, the technician may find one or both of the following stored codes. DTC P0141 (HO2S Heater Circuit Bank1 Sensor2) DTC P0161 (HO2S Heater Circuit Bank2 Sensor2) Cause The engine diagnostic was not robust enough to account for variability in HO2S heater warm up time. Vehicle emissions are not affected by this condition. Correction Verify that the DTC is not the result of an inoperative component, or a related wiring/other condition. Reference the Service Manual diagnostics as needed. If no other conditions are found, the following service calibrations have been released to address this issue. Re-program the VCM with the appropriate calibration listed below. Old Cal P/NNew Cal P/NAssy Plant RPOVehicleEngine RPOTransmission RPOFuel/Emissions

93580099358082OSG1/2 Ton 2WD and 4WDLR4 4.8 LAutomatic M30NF2-NN8/NW7 (Federal Tier 1, Canada) 93580129358083OSG1/2 Ton 2WD and 4WDLR4 4.8 LAutomatic M30NN8 (Non-European Unleaded Fuel Export) 93580159358084OSG1/2 Ton 2WD and 4WDLR4 4.8 LAutomatic M30NC1 (California LEV) 93580409358085OSG1/2 Ton 2WD and 4WDLR4 4.8 LManual MG5NB6/NF2-NN8 (Nationwide and Canada) 93580429358086OSG1/2 Ton 2WD and 4WDLR4 4.8 LManual MG5NN8 (Non-European Unleaded Fuel Export) 93580189358087OSG1/2 Ton 4WDLM7 5.3 LAutomatic M30NF2 Federal Tier 1 93580229358088OSG1/2 and 3/4 Ton 2WD 1/2 Ton 4WDLM7 5.3 LAutomatic M30NN8 (Non-European Unleaded Fuel Export) 93580259358089OSG1/2 and 3/4 Ton 2WD 1/2 Ton 4WDLM7 5.3 LAutomatic M30NC1 (California LEV)

The calibrations listed are electronic calibrations and are NOT available from GMSPO. Calibrations will be available from Techline starting December

1999, on the TIS 2000 Disk 26 CD ROM.
Reply to
"Doc"

Whoops! Thanks Neil. I always forget about the damn TheftLoc as I never use it.

Doc

Reply to
"Doc"

"Chris" wrote

Service Engine Soon Lamp On with DTCs P0141/P0161 (Reprogram VCM) #00-06-04-006 - (01/24/2000) Service Engine Soon Lamp On with DTCs P0141 and/or P0161 (Reprogram VCM)

2000 Chevrolet and GMC C/K Models (Silverado and Sierra)

with 4.8 L or 5.3 L V8 Engine (VINs V, T -- RPOs LR4, LM7)

Built prior to the following VIN breakpoints:

Assembly Plant Division VIN Breakpoints

Oshawa Chevrolet 2GCEC19V8Y1226868

Oshawa GMC 2GTEK19T9Y1226878

Condition Some customers may comment about the Service Engine Soon lamp being illuminated with no other driveability concerns noticed. When investigating, the technician may find one or both of the following stored codes.

a.. DTC P0141 (HO2S Heater Circuit Bank1 Sensor2) b.. DTC P0161 (HO2S Heater Circuit Bank2 Sensor2) Cause The engine diagnostic was not robust enough to account for variability in HO2S heater warm up time. Vehicle emissions are not affected by this condition.

Correction Verify that the DTC is not the result of an inoperative component, or a related wiring/other condition. Reference the Service Manual diagnostics as needed. If no other conditions are found, the following service calibrations have been released to address this issue. Re-program the VCM with the appropriate calibration listed below.

Sounds like you need to verify "what" the code/s are.

Perhaps you will be fortunate and the software reflash

will cure your problems.

Ian

Reply to
shiden_Kai

Take your truck to Autozone and have the clear the codes. If you still have a problem the light will return.

Reply to
Sid Port

Okay, now I'm confused... This started out as P0303 code and the check engine (SES) light on, now you have the airbag (SRS) light on?

I don't see a relation between the two.

Reply to
Neil Nelson

Blinking indicates misfire condition can potentially damage the catalytic converter.

Reply to
DonW

The light will eventually go away after a few running/driving cycles. Or it can be cleared manually with a scanner.

My old '02 5.3 also threw this fit on me.

I went to start it up one morning. It gave it a half-hearted turn of the key, and it didn't light. I tried again, and it sputtered out. WTF? I turn it again... keep it going... and say f-it, and feed on some throttle.

It caught, but wouldn't stay running. I had to play with the throttle and restart it a few times. Eventually it settled down and ran perfectly fine. I pulled off and reset a "random multiple missfire" code.

I never did anything about it, and it never came back. I have no idea what it was, but this is the third story I've heard of the missfire-at-startup thing.

-marc

Reply to
Marc Westerlind

"R" is right next to "E" on the keyboard. I think he just has bad aim!

Doc

Reply to
"Doc"

Definitely bad aim, meant the service engine soon light (SES) :) So the story goes like this- pulled the plug (#3), replaced it with the

41-932, had the steady light, drove it about 5 miles to autozone this morning and on the way the SES light cleared out. Got there and plugged in anyway, and couldn't pull a code. Found 8 of th 41-952 original equipment plugs and pulled them all tonight and she's running fine, no warning lights. So the only other strangeness I have to add is that
  1. it's weird that two parts places (Vans and autozone) are seeing that the 952's being replaced by the 932's according to their ordering info. I had to look high and low for the 952 plugs recommended on all 99 and
2000 V8's because they seem to be on the way out...
  1. When I pulled my original plugs, I realized that they are Denso plugs. I've owned the truck since mile 10, and no one has done a plug replacement on it, so I have to figure it came from the factory like that. Anyone realize they used Denso's as original equipment? These also weren't gapped to .060 but something closer to .053 so I'm wondering if there was some hijinks on the line for the first few 2000's that rolled off and maybe this contibuted to a bad plug at 52k miles.

Thanks everyone for the time- no code now, smooth idle, no missing, problem solved.

Chris

\"Doc\" wrote:

Reply to
Chris

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