91 s15 jimmy 4.3 rough idle - The 1947 - Present Chevrolet & GMC Truck Message Board Network

wlf89 · 10-27-2017, 05:19 PM

i have gave it a complete tune up plugs,wires,cap,rotor. i cleaned the egr valve not as bad as i was expecting it to be. i replaced the iac valve few months back and that helped alot but it still idles rough has died a couple of times but not usually just a inconsistent idle. other day while tinkering with it i cranked it up with the air cleaner assembly off and it was running smooth as has in a long time , but when putting it back on and hooking the vacumm line up going from it to the throttle body it lowered rpms and started idling rough again. that line goes to a sensor on the inside of the air cleaner (thermal air temp sensor i think)? do yall think that could be my problem or likely something else? that sensor is $60 so hate to buy it if not needed. also doesnt ever throw a check engine light. also noticed looked like the oil pressure sender is leaking oil around the plug connection but dont think that could have nothing to do with it could it?

wlf89 · 10-29-2017, 08:09 AM

btt

68C15 · 10-29-2017, 08:17 AM

not really a sensor, but a thermal vacuum switch for the hot air riser valve so it can get warm air around exhaust manifold. Plug it off and move on with life

10-27-2017, 05:19 PM	#1
wlf89 69 c/10 lwb fleetside Join Date: Jul 2004 Location: saint joseph TN Posts: 195	91 s15 jimmy 4.3 rough idle i have gave it a complete tune up plugs,wires,cap,rotor. i cleaned the egr valve not as bad as i was expecting it to be. i replaced the iac valve few months back and that helped alot but it still idles rough has died a couple of times but not usually just a inconsistent idle. other day while tinkering with it i cranked it up with the air cleaner assembly off and it was running smooth as has in a long time , but when putting it back on and hooking the vacumm line up going from it to the throttle body it lowered rpms and started idling rough again. that line goes to a sensor on the inside of the air cleaner (thermal air temp sensor i think)? do yall think that could be my problem or likely something else? that sensor is $60 so hate to buy it if not needed. also doesnt ever throw a check engine light. also noticed looked like the oil pressure sender is leaking oil around the plug connection but dont think that could have nothing to do with it could it? __________________ 69 lwb fleetside 67 swb fleetside (2) 72 lwb fleetside 50 swb no bed 65 impala ss 65 1 ton flatbed

10-29-2017, 08:09 AM	#2
wlf89 69 c/10 lwb fleetside Join Date: Jul 2004 Location: saint joseph TN Posts: 195	Re: 91 s15 jimmy 4.3 rough idle btt __________________ 69 lwb fleetside 67 swb fleetside (2) 72 lwb fleetside 50 swb no bed 65 impala ss 65 1 ton flatbed

10-29-2017, 08:17 AM	#3
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	Re: 91 s15 jimmy 4.3 rough idle not really a sensor, but a thermal vacuum switch for the hot air riser valve so it can get warm air around exhaust manifold. Plug it off and move on with life __________________ Man rule #77...if you own a 67 stepside with a caddy 472 you will never be in danger of loosing you man card



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