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#1 |
Registered User
Join Date: Aug 2010
Location: Ventura
Posts: 151
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89 S10 4.3 misfire
Hello all, recently my friend bought a 89 S10 with the 4.3 and 700r4 for $800. "Running" and driving. It has a decent misfire at idle, engine shakes abit. It has close to 180K miles. Engine starts fine, no ticking, no smoke out of the exhaust. Oil looks fine, cooling system is fine. No engine light. So far we have changed the O2, fuel filter, wires and plugs, coolant temp sensor, changed the dizzy (gear was worn and shaft had some play), replaced EGR valve, cap and rotor. Triple checked firing order. Base timing with with timing connector unplugged set at 0. When accelerating from a stop the mis is more present. Any ideas or direction would be appreciated! Thanks
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1990 Chevy Suburban v2500 1990 Chevy/Geo Tracker LSi 4x4 2Dr 1996 Chevy/Geo Tracker LSI 4x4 4Dr 2011 Chevy Silverado Crew Cab LT 1991 Nissan 300zx SlickTop |
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#2 |
The Engine Whisperer
Join Date: Sep 2006
Location: Ohio
Posts: 770
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Re: 89 S10 4.3 misfire
Have you checked the coil? I had a pretty gnarly miss at idle on my truck and it turned out to be a bad coil.
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#3 |
Senior Member
![]() Join Date: Aug 2013
Location: Northern Santa Barbara County, California
Posts: 2,678
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Re: 89 S10 4.3 misfire
Try rebuilding the TBI, the diaphragm in the fuel regulator leaks on these and clean out the IAC orifices. It is really easy, the hardest part is getting the diaphragm screwed down while holding the spring.
Here is the kit: https://www.autozone.com/fuel-delive...82053_821751_0 YouTube: https://www.youtube.com/results?sear....3+tbi+rebuild |
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#4 |
Registered User
Join Date: Aug 2010
Location: Ventura
Posts: 151
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Re: 89 S10 4.3 misfire
I've taken the throttle body off and checked, its not ripped. Haven't replaced the coil on the truck. Last night we did a compression test. Cylinder 2 and 6 have 120 psi. Cylinder 5 had 150. Cylinder 1 and 3 had about 135. I think the engine is toast.
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1990 Chevy Suburban v2500 1990 Chevy/Geo Tracker LSi 4x4 2Dr 1996 Chevy/Geo Tracker LSI 4x4 4Dr 2011 Chevy Silverado Crew Cab LT 1991 Nissan 300zx SlickTop |
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#5 |
Registered User
Join Date: Aug 2010
Location: Ventura
Posts: 151
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Re: 89 S10 4.3 misfire
Took the MSD coil off my Suburban and tried it on the S10, no change.
__________________
1990 Chevy Suburban v2500 1990 Chevy/Geo Tracker LSi 4x4 2Dr 1996 Chevy/Geo Tracker LSI 4x4 4Dr 2011 Chevy Silverado Crew Cab LT 1991 Nissan 300zx SlickTop |
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#6 |
Registered User
Join Date: Aug 2010
Location: Ventura
Posts: 151
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Re: 89 S10 4.3 misfire
Compression readings
Cyl 1 - 130 - Wet 140 Cyl 2 - 135 - Wet 155 Cyl 3 - 120 - Wet 130 Cyl 4 - 150 - Wet 160 Cyl 5 - 140 - Wet 150 Cyl 6 - 125 - Wet 130
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1990 Chevy Suburban v2500 1990 Chevy/Geo Tracker LSi 4x4 2Dr 1996 Chevy/Geo Tracker LSI 4x4 4Dr 2011 Chevy Silverado Crew Cab LT 1991 Nissan 300zx SlickTop |
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