Total power loss when floored

Army · Dec 9, 2008

Story: Didn't want to mess with the dang intake manifold to put in new plugs and wires. New wires and plugs are Granatelli zero resistence wires (green) and "E" plugs (multiple gap type) from Stylin' Concepts. My fav shop took 1.5 hours to do the swap, test drove it, and tossed me the keys. I didn't make it a block, when I tried to punch it, and............ nothing. Complete power loss as if no gas or spark is going anywhere.

Turned around and drove it into the shop. They hooked up the code readers (plural, multiple), and one said my truck thought it was in Colorado....... I'm in California. Hooked up a timing light to the wires, and all fired until the pedal was dumped, then nothing. They checked the MAF, and it tested out OK but they initially blamed it.

Pulled the heads, and noticed the slightest of peening around the valve seats, so they said there's your problem. I asked how that much damage could have happened in less than one block from this shop? Sent it to get ground anyway. The machine shop pointed out that the motor is well taken care of for 257K miles on it. I asked the fix it shop; wouldn't I notice the power slowly bleeding off over weeks or months, with maybe some smoke from the pipe?

Then one said the zero resistance wires ruined the coil. I pointed out that electricity works best with no resistance, unless you want a lightbulb. No, they said, the coil needs resistance to function best. They put the original wires back on....same problem, no power.

So, anyone have a clue? I have had absolutely no problems with this engine since new. Seems really weird that it would die all-of-a-sudden like.

mikepotts · Dec 9, 2008

is that shop charging by the hour? sorry i am drawing a blank.

Mirage · Dec 9, 2008

In a stock setup resistance IS needed because the spark plugs themselves are fairly low resistance. And yes, very low resistance in both the plugs and the wires could cause coil damage. (In the form of heat). Remember that the coil takes low voltage (12v) and turns it into somewhere greater than 10,000v to give you the arc across the gap of the plug. It does this using the resistance it sees on the output of the coil.

As to why they may only show bad when you floor it, it may be because with ) resistance on the output of the coil, you can't make a hot enough spark fast enough to keep up with the engines demand. Sort of like charging a capacitor, one you can never charge because it's being bled off as fast as you charge it. And the coil may be failing because of heat as well, the worst enemy of electronics.

Now I'm not familiar with your "E" series plugs, so I can't give you a definitive answer to your problem, but I would take a look at the resistance across the coil spark plug terminals and see what they read now to see if they have been damaged.

I am assuming here that you used the stock coils, and added 0 resistance wires and your performance plugs. This may not have been the right thing to do. Along with the performance wires and plugs you may have to go with new high performance coils. Ones that are made for 0 resistance wires. I know Accel makes some, and MSD does too. A little pricey, but they work great.

Hope this helps a little.

jdm90 · Dec 10, 2008

Well put Mirage.

Army · Dec 10, 2008

Thanks Mirage. That explains it much better than I understood it to be.

Seems I gotta shop for new coils then.

Mirage · Dec 10, 2008

Thanks for the support guys.

But don't just run out and buy new coils before checking the old ones out first. Also make sure the existing coils are mounted correctly. As others have posted here on the boards, a loose ground could also cause this type of problem.

Especially if you punch the gas and the spark drops out, my first guess would be a ground problem at the coil due to the vibration.

But in this particular case the coils themselves may be perfectly fine. They may just be unable to handle the low resistance from your plugs and wires.

Maybe try putting back on the stock wires and plugs, an see if the problem continues. (Again after checking he resistance of the spark plug terminal at the coil). If the the resistance is below spec (rarely do I find them adding resistance as they break down and being above 15k ohms) then I would say the coils are shot. And you might as well forgo this test and just buy new coils to match your new wires and plugs.

There is also a spec for the input resistance of the coil, but I don 't have the book handy so I don't know what it is for these particular coils. But I'd check that as well, as they can very well break down on the primary side as well.

I just tried looking at the Accel and MSD sites, and neither had anything for a 2.3l that was made for 0 resistance wires. But if you look around you may find something I missed.

Again, I hope this helps.

jdm90 · Dec 10, 2008

Mirage, are you referring to the primary side as the side with the electrical connection? If so, my Haynes manual states that it should be no more than 5 Ohms.

Earl43P · Dec 10, 2008

Thinking a bit outside the box....

Backprobe the TPS GY/W wire and move the throttle throughout its range while watching the DC voltage. I believe you only need the key in the RUN position, engine doesn't have to be running. Should see ~ .9 vdc with the throttle closed and go up toward 5v as you open the TB. I'd repeat this test with engine running too.

If the TPS voltage goes to zero at any point, I'd guess that it is shorting PCM-provided reference power to ground and killing the whole shooting match (spark) until that short goes away (I have no idea what occurs if TPS signal goes open, will engine run with it disconnected?).

I'd also unplug the WOT relay and try it again. Actually, I'd do that FIRST. It takes a LOT to blow the PCM power fuse (30A), but a shorted WOT relay coil COULD draw down power to the point of effectively killing the PCM functions.

I just can't believe a coil can work fine at lower rpms, then quit completely when rpms go above a certain point, let alone TWO coils failing in exactly the same way.

FWIW, they DID put the original wires back on, with no improvement. I'd suggest putting regular spark plugs back in, just to rule out the obvious. Might also eyeball the crank pulley for exceesive radial play at the rpm where it dies. I'm wondering if the crank bearings are bad enough to make it lose the crank sensor signal (I think if it were that bad, the seals would leak a lot of oil).

Army, clarify: Spark dies when the pedal is floored OR spark dies when it hits "XX" rpm.

If it is "when floored", I'd concentrate on TPS and WOT.
If it is @ "XX" rpm, I'd concentrate on plugs, (already did wires), coils and crank sensor.

Mirage · Dec 10, 2008

Yep, that's what I was referring to. 5 ohms sounds about right, on the primary side. If I remember correctly the secondary side (spark plug cable side) should read between 13,000 and 15,000 ohms.

Army · Dec 11, 2008

The spark dies only when punched. Slowly revving up seems to maintain it, but the mech never took it really high.

Thanks Earl, good tips.

Total power loss when floored

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