Bad Coil?

[BigT]

I've been having a surging problem after my HO upgrade. I thought it was a vacuum leak, but now I think it may be the coil. I went out to mess with the timing and guess what happened? While it was surging the timing light did not fire every rotation. Push on the throttle and it fires every time. Let it go back to idle and it starts missing again.

I think it could be the coil going bad. What do you think?

The module on the distributor is new and came with it from Rock Auto, but its a no-name brand. Could it be the module?

[gadget73]

random blink on the light would just indicate a misfire on #1. May or may not be related to the coil. Flaky wires, bad coil, bad connections to the coil, problems with the pickup or ignition module, low voltage, fouled plugs or a bad cap/rotor could all possible do the same thing.

also, the timing light is not supposed to fire every rotation. It goes every other

[DerekTheGreat]

Coils either work or they don't.. I fried the one on the GMC this weekend by letting the tach signal go to ground, ran just 20 minutes prior to that. Also, while it may not help you perhaps with Fords they also have to have their base idle speed set correctly. When we first got our GMC it would surge at idle so I rebuilt the throttle body, cleaned the injectors and put new gaskets all over. Truck still surged (it did run better though) but when I had the TB off I noticed someone punched the cap off the idle adjustment screw so I did some research and sure enough once I adjusted the base idle up (IAC closed & unplugged) the truck idled just fine.

[BigT]

random blink on the light would just indicate a misfire on #1. May or may not be related to the coil. Flaky wires, bad coil, bad connections to the coil, problems with the pickup or ignition module, low voltage, fouled plugs or a bad cap/rotor could all possible do the same thing.

also, the timing light is not supposed to fire every rotation. It goes every other

Everything is new except for the wires and coil. I have new wires, but they are cut to fit and plan on doing them later. As far as I know the coil should be firing every cylinder every time. Yes I only had it on the #1 cylinder, but it should fire every time, not every other time. My timing light is an old fashion type where it flashes only when it picks up a signal from the wire. No signal, no flash, no spark at the plug. Also, I could smell gas as the engine was stumbling. I will try the other wires after work today to see if there missing too. But in a nutshell, I'm not getting constant spark at low RPMs.

I will take a look at the coil connections. I've had bad wires before, but I didn't see any of them flashing to ground when I ran the engine in the dark. The ignition module does look cheap, but it's new and came with a rebuilt distributor. If the coil is not the problem, then I can try a new module.

The plugs are new E3 plugs. Cap and rotor are new too.

[turbo2256b]

Did you try hooking up the timing light to other wires

[turbo2256b]

Did you try hooking up the timing light to other wires. Autozone, Advance auto and such can test those modules

[BigT]

After work I will try the other wires. I did get a sense that more than one cylinder wasn't firing.

[turbo2256b]

E3 plugs are a bit of a joke only one tip will spark the cleanest and closest. Such plugs have been used for years in airplanes were the extra tips could mean cylinders firing as there is no place to pull over easly and replace plugs. Also platinum plugs in most older style engines dont work well because of the tip temperature

[BigT]

PowerNation...you've done me wrong! That's the only reason I got E3 plugs, because they praised them so much. I usally buy Autolites.

[87Topaz]

Autolites have been jokes for years. I would use OEM (on standard cars). Not sure what would work best in a HO upgrade but my guess it is not Autolites!

[BigT]

I know Autolite is owned by Fram now, but wasn't it a Ford product at one time? So when you say OEM, go back to Motorcraft?

[BigT]

I'm finding folks out there are having problems with their MSD coils. My MSD coil is about 9 years old. Could be my problem.

[DerekTheGreat]

I had two crap out on me in the Firebird, I keep an OEM one in the back as a spare now. Kinda sad. Also had one of their distributor caps fail on me. Perhaps try swapping out that TFI module to see if anything changes or even the entire distributor, could be that the PIP sensor is bad too. I highly doubt it is the coil but if that fixes the problem I'll eat humble pie with a side of crow.

[87Topaz]

YES! I would use Motorcraft plugs and coil unless someone here can verify an issue with your HO setup.

[gadget73]

4 stroke engines fire every other revolution. Its just how they work. On a V8, the coil fires 4 times per spin of the motor. Distributor will rotate 1/2 turn. You should see it blink in a steady pattern, but its not every rotation.



and yeah, boring Motorcraft plugs work quite nicely.