My daily driver 2000 2.2L/5 speed S10 now and then has a miss. Right above idle (1000-2500rpm give or take) it will miss under load. At idle and light loads it runs perfect. I have owned the truck since new, always maintained now with 217k. I thought it was wires since they has roughly 50k on them, but new ones did not change it. Plugs are fresh with maybe 1k miles on them. It has yet to set a SES light and no codes in the ECM. I have an Actron scanner that verifies the SES light works and no codes are stored.
I Checked the Primary and Secondary resistance of the coil packs hot and cold.
Spec for Primary Resistance = .35-1.50 ohms
Spec for Secondary Resistance= 5,000-10,000 ohms
After sitting in my house @ 74 degrees for nearly 20hrs I have:
Coil Pack 1/4
Primary = .4-.5 ohms
Secondary = 5,650 ohms
Coil Pack 2/3
Primary = .5-.7 ohms
Secondary = 5,710 ohms
Then I put them under the hood over night @ approximately 30 (or less) degrees for nearly 11hrs and I have:
Coil Pack 1/4
Primary = .4-.5 ohms
Secondary = 4,920 ohms
Coil Pack 2/3
Primary = .4-.5 ohms
Secondary = 5,030 ohms
So all findings have the coil packs showing spec resistance figures. I put them back in and the miss remained.
So I threw the new plugs in...she still missed. Kinda leaned towards a failing fuel pump...nope! Brand new fuel pump and filter installed. Blew all lines out with compressed air, no blockage.
Although it does run noticeably better with the new fuel pump, it is still missing. Overall the truck runs great now with all these parts and tune up pieces I have changed so I really feel the money has been well spent. But it still misses! BUT, not as often nor as severe as it was before the fuel pump. I am out of ideas at this point. I may throw in new coil packs as they are the originals and I do like to change coils on my vehicles every 100k or so, so it is overdue by my standards.
Original O2 Sensors. Scanner shows voltages are in spec for what they should be.
Swapped in known good coils off a friends truck that runs mint in all weather. Miss is still there!
Brand new AC Delco TPS... and the miss remains!
I just swapped in a good used set of injectors and fuel pressure regulator. Good used MAP sensor also installed and the miss remains!!! That rules out fuel system. Brand new pump, filter, good used injectors and FPR from a truck that had no miss and the truck runs the same... missing. Lines were all blown clear when pump and filter were swapped. Fuel rail was blown out during injector swap. I also put in a new intake manifold gasket as it had a small leak and I had to pull it to do the injectors anyway so I changed it. All brand new o rings top and bottom on every injector.
I plan to remove any/every ground I find under the hood and clean/grease/reinstall. Other than that I may put in a new crank and cam position sensor as they are fairly cheap enough.
Any ideas?? I have been chasing this since LAST January '09. I have driven the truck like this and put on roughly 10k miles. Still dependable, just misses. Gets good fuel mileage. 27-29 Highway.
I Checked the Primary and Secondary resistance of the coil packs hot and cold.
Spec for Primary Resistance = .35-1.50 ohms
Spec for Secondary Resistance= 5,000-10,000 ohms
After sitting in my house @ 74 degrees for nearly 20hrs I have:
Coil Pack 1/4
Primary = .4-.5 ohms
Secondary = 5,650 ohms
Coil Pack 2/3
Primary = .5-.7 ohms
Secondary = 5,710 ohms
Then I put them under the hood over night @ approximately 30 (or less) degrees for nearly 11hrs and I have:
Coil Pack 1/4
Primary = .4-.5 ohms
Secondary = 4,920 ohms
Coil Pack 2/3
Primary = .4-.5 ohms
Secondary = 5,030 ohms
So all findings have the coil packs showing spec resistance figures. I put them back in and the miss remained.
So I threw the new plugs in...she still missed. Kinda leaned towards a failing fuel pump...nope! Brand new fuel pump and filter installed. Blew all lines out with compressed air, no blockage.
Although it does run noticeably better with the new fuel pump, it is still missing. Overall the truck runs great now with all these parts and tune up pieces I have changed so I really feel the money has been well spent. But it still misses! BUT, not as often nor as severe as it was before the fuel pump. I am out of ideas at this point. I may throw in new coil packs as they are the originals and I do like to change coils on my vehicles every 100k or so, so it is overdue by my standards.
Original O2 Sensors. Scanner shows voltages are in spec for what they should be.
Swapped in known good coils off a friends truck that runs mint in all weather. Miss is still there!
Brand new AC Delco TPS... and the miss remains!
I just swapped in a good used set of injectors and fuel pressure regulator. Good used MAP sensor also installed and the miss remains!!! That rules out fuel system. Brand new pump, filter, good used injectors and FPR from a truck that had no miss and the truck runs the same... missing. Lines were all blown clear when pump and filter were swapped. Fuel rail was blown out during injector swap. I also put in a new intake manifold gasket as it had a small leak and I had to pull it to do the injectors anyway so I changed it. All brand new o rings top and bottom on every injector.
I plan to remove any/every ground I find under the hood and clean/grease/reinstall. Other than that I may put in a new crank and cam position sensor as they are fairly cheap enough.
Any ideas?? I have been chasing this since LAST January '09. I have driven the truck like this and put on roughly 10k miles. Still dependable, just misses. Gets good fuel mileage. 27-29 Highway.