1998 Chevy Silverado #2 cylinder misfire

Tiny
WKNOEPP
  • MEMBER
  • 1998 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 38,000 MILES
I had an engine fire. Replaced the engine wiring harness, VCM computer, plastic parts. Used harness and computer. Relearned security and started. DTC is misfire #2 cylinder. Need relearn Crank position sensor. Replaced Dist. Cap, rotor, plugs, wires. Still missing. Compression tested OK. Made harness and manually cycled each injector to watch for fuel pressure drop. All fired. Checked Green/black and pink wire from red computer harness plug to injector feed plug. (Good)Question is could whatever fires #2 injector in the computer be bad and all the others work fine? At my whits end with what to try next. Any syggestions on what else to look for. Ignition/coil module? No miss before replacing computer.
Wednesday, September 24th, 2008 AT 5:42 PM

5 Replies

Tiny
BLACKOP555
  • MECHANIC
  • 10,386 POSTS
It getting spark on cylinder 2, if so its getting reference to fire. Check for power going to it key on and a negative pulse when cranking.

Let me know what you find. With all other injectors disconnected does 2 get pulse?
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Wednesday, September 24th, 2008 AT 7:10 PM
Tiny
WKNOEPP
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If by refrence to fire you mean the coil/module is OK? As far as unhooking the other injectors its a vortec SFI so you really can't unhook other injectors. With my test harness they have power to them and when I ground each wire they fire. I do have power to the pink wire with the key on and the Green/black wire is a completed circuit to the computer. (Ground for #2 injector)
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Wednesday, September 24th, 2008 AT 8:32 PM
Tiny
BLACKOP555
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I mean refrence to fire as in they vehicle should be getting a refrence to the injector to fire on #2, if there was no spark then it may be related to no pulse.
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Wednesday, September 24th, 2008 AT 9:13 PM
Tiny
WKNOEPP
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OK. So the #2 injector should be firing. Only thing left would be a weak spark. It is firing according to my timing light but when I put a plug on the #2 plug wire, start the truck, and ground the plug the spark looks weak. Not the bright blue I'm used to with points and condensor. This has the external coil with ignition module and heatsink attached. Since the wires are good I'm guessing weak coil? Module must be good since engine runs? Not sure why only #2 comes up misfire on DTC.
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Thursday, September 25th, 2008 AT 9:44 AM
Tiny
BLACKOP555
  • MECHANIC
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Use a spark tester that can read out hte voltage of the spark and compare it to others. USE A SPARK TESTER!

Have you checked the compression on that cylinder?
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Thursday, September 25th, 2008 AT 5:42 PM

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