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Old 04-19-2012, 11:29 PM   #1
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Default 98 chevy pu miss

Hello everyone
new to this forum, hoping somebody can help. here goes.

I have a 98 chevy 2500 pu. w/ about 150,000 miles on a 5.7vortek.
started feelin a miss bout a week ago. changed plugs & wires. no help. A friend has a snap on diagnostic unit. showed misses on cyl. 4 & 8. but no other problems except some o2sensor activity. low activity i think it was, also the check engine lite is NOT on.
when im stopped at a light, it feels like it wants to surge forward. in neutral u can really feel the misses bad. when im driving i also feel it surging, or cutting out, and it has no get up and go.
my question i guess is, what else can make it miss like this. thinkin fuel injectors.but the snap on unit said they were ok. please help.
thanx, Bob
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Old 04-20-2012, 06:26 AM   #2
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I'm not sure about your particular engine, but does it have a distributor? If so, did you replace the cap and rotor when you changed the plugs and wires?
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Old 04-20-2012, 08:37 AM   #3
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you can inspect the rotor and cap but its likely the pos spider injector. what are your ltft'* and stft'*? whats your fuel pressure koeo and started at idle reved?
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Old 04-20-2012, 07:28 PM   #4
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As jwfirebird said, my 2cents is on the efi spider, more particularly the "poppets" in the ports.

The actual injectors are centrally located below the upper intake manifold - They "fire" (snap-on thinks it'* all good) and the pressure pushes the proper spring-loaded poppet open for that cyl. (go figure)

I recently replaced the whole mess with the Delphi (OEM) upgrade $180ish amazon
It moves the injector out to the port - bolt on & runs great

Oh, the $180ish was for my '98 sonoma 4.3V6 - yours is similiar.

And ditto on the "good" cap & rotor

luck,greg
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Old 04-20-2012, 07:31 PM   #5
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I'm leaning towards fuel since you said "o2 low activity & surge" in your description.

luck,greg
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Old 04-20-2012, 09:13 PM   #6
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I have a 98 same as yours i just up graded the spider assembly. It cost me 299 at Autozone.
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Old 04-20-2012, 10:06 PM   #7
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amazon has the v8 one for 250ish
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Old 04-21-2012, 10:16 PM   #8
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thanx everyone for your input. I didnt change the cap & rotor.but i inspected them.they seemed ok. so fuel. see i was hopin to not spend money on things that aint the problem, like i usually end up doin. let me check out the fuel sys. ill let u know
thanx again Bob.
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