I changed my ignition coil on my 1994 Chevy k1500 tbi 350 because I tested the old one and it tested to be bad so I changed it.. I started the truck and it ran like absolute crap the rpm gauge was going all over the place and then it died. So I thought the new coil was bad so I swapped it out for a new one again and it does the exact same thing.. but if I put my old coil I believe to be bad back on it runs good besides the misfires and stutters I have.. anyone have a clue what’s happening I’m lost..
Ignition coil issues?
- Thread starter MrobsMan
- Start date
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What "new" coils are you installing?
What testing did you do to determine the "old" coil was "bad"?
As usual for misfires and stutters:
What is the fuel pressure?
How old are the rest of the "tune-up" items--plugs, plug wires, cap 'n' rotor, PCV valve, fuel filter, air filter? How old is the O2 sensor? When was the initial timing checked? When was the electronic timing advance checked? EGR checked? Cranking compression tested?
Connect a scan tool, look for "codes" but also look at the data stream--verify EVERY sensor and computer output.
What testing did you do to determine the "old" coil was "bad"?
As usual for misfires and stutters:
What is the fuel pressure?
How old are the rest of the "tune-up" items--plugs, plug wires, cap 'n' rotor, PCV valve, fuel filter, air filter? How old is the O2 sensor? When was the initial timing checked? When was the electronic timing advance checked? EGR checked? Cranking compression tested?
Connect a scan tool, look for "codes" but also look at the data stream--verify EVERY sensor and computer output.
The whole fuel system is new.
does it matter where the icm points to? On mine it points to the passenger side.
"New" doesn't mean "works right". I didn't ask if it was new.
What is the fuel pressure?
That's not correct, but it shouldn't matter if the ignition timing is correct, and the wire harness isn't stressed. "I" would fix that because it would make me crazy to look at it being out-of-position.
What "new" coils are you installing?
What testing did you do to determine the "old" coil was "bad"? How old are the rest of the "tune-up" items--plugs, plug wires, cap 'n' rotor, PCV valve, fuel filter, air filter?
How old is the O2 sensor? When was the initial timing checked? When was the electronic timing advance checked? EGR checked? Cranking compression tested?
Connect a scan tool, look for "codes" but also look at the data stream--verify EVERY sensor and computer output.
So i changed the distributor and now it’s running fine with the new coil. I found out my egr was bad and thats why it was running lean. So here’s where we are at. I’ve got the timing set at 6 degrees advanced I’ve got a 14 psi fuel spring tbi spacer injector pod spacer I shaved the air horns off the bores, brand new injectors new fuel pump and it’s running a hair rich I believe.. now it did start to clear up when I bumped the timing up and let it run I haven’t had a chance to drive it just yet so I hope I fixed the hesitation/ misfire issues.. hopefully it’s not gonna run to rich with the higher psi spring.. although the pump is a stock tbi pump so it shouldn’t run to rich cause the tbi pumps aren’t high pressure.
Watch out for the pinging now....Why did you go 6*? Just curious..
I bumped it to 8 and it started pinging so I backed it down 2 degrees and the pinging went away. I bumped the timing because it has a bigger cam and it seems to run better advanced
Thanks...
Under a load when driving might affect things a bit too I'm guessing.....
The cam is pretty mild if you used a big cam the map sensor is probably having a fit from the loss of vacuum at idle.. the cam I have is supposed to either no affect vacuum or increase it apparently.
