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Discussion Starter · #1 ·
i have a 2003 s-10 with the 4.3 with about 80k miles and last weekend when leaving work i started it up and it had a little bit of hesitation/sputtering. i turned it off and turned it back on and it ran like normal. it happened one other time during last weekend and this time when i turned it on for the second time it didnt stop the hesitation and threw a code and caused the ses light to flash until i got to higher rpms and it smoothed out. so i drove it in the parking lot i was in and it seemed to only do it at idle or low rpms. but then after a few minutes of driving it stopped and ran fine... i went about normal day to day things all week with no issues but yesterday morning it started again, and does it every time it starts, but still only at idle or low rpms, when at highway speeds or above 1800 rpms it seems to run fine... i did get it scanned and the code was the P0305 (cylinder 5 misfire). i checked the plugs and the cyl 5 plug was very burnt looking compared to the others, so i changed all of them for good measure. and then upon starting it up, it seemed to have fixed the problem, so i turned it off and cleaned up, when i turned it on to head home it started again after driving for a few minutes at a stop sign... i did notice the smell of gas when sitting still at idle.. has anyone else run into similar problems or have any insight on what to check next, other than the obvious plug wires which i plan on changing tomorrow if i get off work in time, sorry for the long write up and thanks in advance for any help in figuring this out.
 

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Sometimes I'm mean...alot
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First thing always... check your fuel filter and fuel pressure! More problems are fixed by replacing dirty or clogged fuel filters than any other single repair.
 

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Discussion Starter · #4 ·
i will be changing the plug wires and checking the fuel filter and pressure tomorrow after work, but i did notice the gas mileage seems to have gotten worse, any other insight on this situation?
 

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drives a LSX zr2
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i will be changing the plug wires and checking the fuel filter and pressure tomorrow after work, but i did notice the gas mileage seems to have gotten worse, any other insight on this situation?
alot of times oxygen sensors will cause your gas mileage to drop and for a vehicle to have a somewhat rought idle.
 

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Discussion Starter · #6 ·
just wanted to post up for anyone else with a similar issue.. i got it working the other day and runs like a champ now! it ended up being a bad injector but now it runs great, idles smooth and starts right up.
 

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Did you do the mfi conversion with new injectors? My truck sputters some under heavier acceleration like half throttle and I'm thinking this may be my problem too. Just put new oxygen sensors in which helped get rid of or lessen the light throttle hesitation but still sputters out the exhaust during heavy acceleration so it doesn't run quite right, but it clears up and runs perfect under full throttle.
 

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Discussion Starter · #9 ·
How did you figure out that it was the injector? How can you check them on a 4.3?
well it threw a code for the misfire and a friend who was a mechanic told me it could be several things.. it was due for a tune up anyway so i changed the spark plugs and wires, and that didnt help the problem. then i checked the distributor cap and rotor, those both had some decent corrosion so i changed them and it still did it, the coil was good, and the fuel filter was new, so i was left with the possibility of a bad injector so i went ahead and got a new one. now it runs like a dream.
 

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Discussion Starter · #10 ·
Did you do the mfi conversion with new injectors? My truck sputters some under heavier acceleration like half throttle and I'm thinking this may be my problem too. Just put new oxygen sensors in which helped get rid of or lessen the light throttle hesitation but still sputters out the exhaust during heavy acceleration so it doesn't run quite right, but it clears up and runs perfect under full throttle.
http://www.s10forum.com/forum/f107/scpi-to-mfi-upgrade-kit-324166/

i didnt even know there were two different styles of injection on this year truck/motor until i saw that thread, one parts store sold the scpi injector and it was the only one listed for my truck, but another parts store listed only the mfi injector.... so i bought both and returned the one i didnt use, my truck uses the mfi system.
 

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I just ordered the MFI spider from amazon for only $173!!! While I was looking at it the price went down $40 lol. This is much cheaper on Amazon than GM Parts direct at $253 and one on ebay for $243. FJ10565 is the Delphi part number, just put that number in the Amazon search box. Also got the intake manifold gasket kit for $19. I hope this makes my truck run all good and better gas mileage to help pay for it. Today I got about 15 mpg highway with two people, two dirtbikes and 32" tires.
 
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