Rough Idle - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sider68 · 07-28-2003, 10:38 PM

I took my son,s 81 GMC pickup with a 250 in line six in to get certified and safety checked.It has 75,ooo miles on it.I asked the mechanic to tune it up as it had a very slight miss to it,but lots of power.He changed the distributer,rotor and plugs.Now it idles rougher than before.The mechanic claims those motors were always rough running.What should I do now as I don,t want to cause any damage driving it like it is?I heard those engines were very long lasting and dependable.

bigd65 · 07-28-2003, 10:49 PM

sounds like the mechanic neds to be SMACKED.

seriously, check all the plug wires and make sure they are firmly snapped to the plugs as well as the distributor cap. then you may want to check the firing order or even the adjustments on the cab. its reall hard to tell if not looking at it. also check all vacuum hoses and make sure one hasnt been pulled loose or even cracked for that matter

r0lf- · 07-28-2003, 10:56 PM

They are rough as hell idling engines. Thats just the motor.

They are torqey little suckers especially. You might think something is wrong with the motor but its not, you'll get used to it. Thats kinda what makes the motors so cool!

Russell · 07-28-2003, 11:02 PM

My whole truck shakes when it idles, the engine is in perfect running condition, so I think that chances are it is fine. Definitly gives the truck a very powerful sound and feel...

Low83 · 07-29-2003, 02:13 AM

Possible Vacuum leak ???

sider68 · 08-01-2003, 10:48 PM

:p RUSTY I know you are back and will have an answer

**old Rusty C10** · 08-01-2003, 11:01 PM

check the ignition wires sometimes they screw up after being moved etc. also a cheap cap or rotor can cause a problem but sometimes it is just the motor but being it ran better before the mechanic messed with it, id tend to say he touched something wrong

sider68 · 08-01-2003, 11:10 PM

He replaced the cap and rotor but not the wires.There were new spark plugs in it.Should I replace the wires?

Nvbowtie · 08-02-2003, 03:57 AM

If you had a plug wire tester I would do that first,

I made the mistake once of replacing all my wires at tune up and it started missing off and on, took to two shops, and then broke down and took to GM dealer,

I paid 199.54 for them to find and replace a bad plug wire that was new, but had a internal break, talk about being pissed !!!!!!!!!!!!

maineiac · 08-02-2003, 09:36 AM

If he replaced the cap and rotor did he touch the timing too? Could be he set it up to wrong settings also if he used a generic cap and rotor half the time they are not worth the cheap plastic they are made out of check it and see if it is carboning up on one plug or another. I have bought two trucks now that had "engine " problems to find out that they had the firing order wrong.
Steve

07-28-2003, 10:38 PM	#1
sider68 Registered User Join Date: Mar 2002 Location: newmarket,ontario,canada Posts: 936	Rough Idle I took my son,s 81 GMC pickup with a 250 in line six in to get certified and safety checked.It has 75,ooo miles on it.I asked the mechanic to tune it up as it had a very slight miss to it,but lots of power.He changed the distributer,rotor and plugs.Now it idles rougher than before.The mechanic claims those motors were always rough running.What should I do now as I don,t want to cause any damage driving it like it is?I heard those engines were very long lasting and dependable.

07-28-2003, 10:49 PM	#2
bigd65 Registered User Join Date: Mar 2000 Location: Clute, TX. Posts: 1,935	sounds like the mechanic neds to be SMACKED. seriously, check all the plug wires and make sure they are firmly snapped to the plugs as well as the distributor cap. then you may want to check the firing order or even the adjustments on the cab. its reall hard to tell if not looking at it. also check all vacuum hoses and make sure one hasnt been pulled loose or even cracked for that matter __________________ 2004 Silverado Crewcab 1972 Chevy Monte Carlo 2017 Chevy Tahoe

07-28-2003, 10:56 PM	#3
r0lf- Hotwheels? Join Date: Dec 2002 Location: Pleasant Hill, CA Posts: 1,145	They are rough as hell idling engines. Thats just the motor. They are torqey little suckers especially. You might think something is wrong with the motor but its not, you'll get used to it. Thats kinda what makes the motors so cool! __________________ 1978 Money Pit - CUSTOM DELUXE!!!!

07-28-2003, 11:02 PM	#4
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	My whole truck shakes when it idles, the engine is in perfect running condition, so I think that chances are it is fine. Definitly gives the truck a very powerful sound and feel... __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap) Last edited by Russell; 07-28-2003 at 11:07 PM.

08-01-2003, 11:01 PM	#7
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,310	check the ignition wires sometimes they screw up after being moved etc. also a cheap cap or rotor can cause a problem but sometimes it is just the motor but being it ran better before the mechanic messed with it, id tend to say he touched something wrong __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

07-29-2003, 02:13 AM	#5
Low83 Registered User Join Date: Aug 2002 Location: Porterville,Ca. Posts: 118	Possible Vacuum leak ???

08-01-2003, 10:48 PM	#6
sider68 Registered User Join Date: Mar 2002 Location: newmarket,ontario,canada Posts: 936	:p RUSTY I know you are back and will have an answer

08-01-2003, 11:10 PM	#8
sider68 Registered User Join Date: Mar 2002 Location: newmarket,ontario,canada Posts: 936	He replaced the cap and rotor but not the wires.There were new spark plugs in it.Should I replace the wires?

08-02-2003, 03:57 AM	#9
Nvbowtie Registered User Join Date: Jul 2001 Location: Laughlin, Nv. USA Posts: 700	If you had a plug wire tester I would do that first, I made the mistake once of replacing all my wires at tune up and it started missing off and on, took to two shops, and then broke down and took to GM dealer, I paid 199.54 for them to find and replace a bad plug wire that was new, but had a internal break, talk about being pissed !!!!!!!!!!!! __________________ www.unlimited2u.com/chevy Bill 1980 Chevy C-10 Silverado 1988 Chevy Blazer Tahoe

08-02-2003, 09:36 AM	#10
maineiac Registered User Join Date: May 2003 Location: South Carolina Posts: 104	If he replaced the cap and rotor did he touch the timing too? Could be he set it up to wrong settings also if he used a generic cap and rotor half the time they are not worth the cheap plastic they are made out of check it and see if it is carboning up on one plug or another. I have bought two trucks now that had "engine " problems to find out that they had the firing order wrong. Steve

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