86 Silverado Q's - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Chevelle454 · 05-26-2004, 08:53 AM

I am posting this for a friend.

Some days the 305 runs good, some days it runs like crap. It misses once in a while and lacks power(a lot). Plugs, wires, cap and rotor have all been changed. Timing is alright. Could it be a valve sticking, carb adjustment, or anything else? Could it be emissions, and if so, what could it be?

Also, what year did Vortec heads come out(305 and 350)?

Thanks in advance...

**Palf70Step** · 05-26-2004, 09:39 AM

Try new fuel filters,
Check fuel pump pressure/flow
Electronic choke may be working erratically

Sounds like what I was dealing with on the 82 and cjust took tweak and going through the carb/choke settings. I'm in the hot south, so most of my problems cleared up when I pulled the new electrical choke out and just ran it wired open all the time. Not sure how that would work up there since you folks only have a week or two for spring and summer.

Does sound like a carb issue though.

Chevelle454 · 05-26-2004, 09:58 AM

Thanks for the info. It has a new fuel filter. Any other ideas? A lot of Sea Foam has been run through the carb...

**Captkaos** · 05-26-2004, 11:32 AM

Quote:

Originally Posted by Chevelle454

Also, what year did Vortec heads come out(305 and 350)?

Vortech heads came out in 1996 and were stopped in 1998 but were offered in production until 2002 (with Vans from what I understand). The new redesign of the new generation engine ( LS1 motors) ended the production.

flip66 · 05-26-2004, 05:36 PM

Had that problem one time turned out to be control modual in the dist. check the wire goign to the modual the go bad too.

gldevall · 05-26-2004, 10:52 PM

I bet it is the stupid ESC, electronic spark control. Mine acted up on me and left me dead in the middle of a 4 lane hiway, twice. There is a way to bypass it, which I did. I think there is an article about this on Jeff's website. Look here http://www.73-87.com/7387garage/drivetrain/escrepl.htm

eagle23 · 05-27-2004, 06:42 AM

I second the module idea. I had an erratic idle-only misfire, would almost die like all cyl's cut out at once. Changed the module (and coil, too FWIW) and bingo! No misfire and stronger revving on a stock Goodwrench 350. I got mine from Summitt with their hi-po coil/module, but even a good stock replacement would likely do it, since you've largely ruled out fuel issues...though the pump is a possibility. Even if it were all three, they aren't real expensive (I think the '86 still has a mechanical pump?)

Could be the ESC as gldevall says, but since I don't have one I can't comment.

Brian

Chevelle454 · 05-28-2004, 08:12 AM

Again, typing for a friend...

Thanks for the ideas, I will try them out. Was the ESC on an '86? H engine 305 maybe?

Thanks

gldevall · 05-28-2004, 08:13 AM

Quote:

Originally Posted by Chevelle454

Was the ESC on an '86? H engine 305 maybe?

Thanks

Mine was an '86 with the 4.3 V6 and it had it.

SanitysBane · 05-28-2004, 02:28 PM

In regards to the ESC, all u have to do is disconect the knock sensor and it can't do anything. THats all i did for my truck, that and disconect the vacum sensor, which was unessesary.

05-26-2004, 08:53 AM	#1
Chevelle454 Registered User Join Date: Aug 2003 Location: MN Posts: 380	86 Silverado Q's I am posting this for a friend. Some days the 305 runs good, some days it runs like crap. It misses once in a while and lacks power(a lot). Plugs, wires, cap and rotor have all been changed. Timing is alright. Could it be a valve sticking, carb adjustment, or anything else? Could it be emissions, and if so, what could it be? Also, what year did Vortec heads come out(305 and 350)? Thanks in advance... __________________ 1972 C10 1972 C20

05-26-2004, 09:39 AM	#2
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 47,216	Try new fuel filters, Check fuel pump pressure/flow Electronic choke may be working erratically Sounds like what I was dealing with on the 82 and cjust took tweak and going through the carb/choke settings. I'm in the hot south, so most of my problems cleared up when I pulled the new electrical choke out and just ran it wired open all the time. Not sure how that would work up there since you folks only have a week or two for spring and summer. Does sound like a carb issue though. __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

05-26-2004, 09:58 AM	#3
Chevelle454 Registered User Join Date: Aug 2003 Location: MN Posts: 380	Thanks for the info. It has a new fuel filter. Any other ideas? A lot of Sea Foam has been run through the carb... __________________ 1972 C10 1972 C20

05-26-2004, 10:52 PM	#6
gldevall Registered User Join Date: Mar 2003 Location: Walker, LA Posts: 2,925	I bet it is the stupid ESC, electronic spark control. Mine acted up on me and left me dead in the middle of a 4 lane hiway, twice. There is a way to bypass it, which I did. I think there is an article about this on Jeff's website. Look here http://www.73-87.com/7387garage/drivetrain/escrepl.htm __________________ Gary -1986 SWB: lowered 4/6, SOLD!!! -Best 1/4 mile: 14.51 @ 91.01 MPH -2001 Pewter Tahoe, billet grill, Corsa Sport Cat-back, K&N FIPK SOLD!!! -2004 Z-71 Extended cab with a flowmaster, BDS 6.5", 3" BL, 35x12.5x18 Trail Grapplers on Pro-Comp 18x9 wheels Last edited by gldevall; 05-26-2004 at 10:54 PM.

05-28-2004, 08:12 AM	#8
Chevelle454 Registered User Join Date: Aug 2003 Location: MN Posts: 380	Again, typing for a friend... Thanks for the ideas, I will try them out. Was the ESC on an '86? H engine 305 maybe? Thanks __________________ 1972 C10 1972 C20

05-26-2004, 05:36 PM	#5
flip66 Registered User Join Date: Jan 2004 Location: Garland TX Dallas area Posts: 658	Had that problem one time turned out to be control modual in the dist. check the wire goign to the modual the go bad too.

05-27-2004, 06:42 AM	#7
eagle23 Active Member Join Date: Feb 2004 Location: Atlanta GA Posts: 174	I second the module idea. I had an erratic idle-only misfire, would almost die like all cyl's cut out at once. Changed the module (and coil, too FWIW) and bingo! No misfire and stronger revving on a stock Goodwrench 350. I got mine from Summitt with their hi-po coil/module, but even a good stock replacement would likely do it, since you've largely ruled out fuel issues...though the pump is a possibility. Even if it were all three, they aren't real expensive (I think the '86 still has a mechanical pump?) Could be the ESC as gldevall says, but since I don't have one I can't comment. Brian

05-28-2004, 02:28 PM	#10
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	In regards to the ESC, all u have to do is disconect the knock sensor and it can't do anything. THats all i did for my truck, that and disconect the vacum sensor, which was unessesary. __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer



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