Coil Problem - ZR-1 Net Registry Forums

Locobob · 10-21-2016

So my car was running a little rough and progressively got worse so I did some testing. Initially I thought it was a fuel issue but after checking a few things I decided to ohm the plug wires through the coil packs. All were in the 15K range except the 8,5 coil which was OL. Pulled the plenum and here is the 8,5 coil. Lots of corrosion on the #5 tower, not sure what would cause this, all the other towers were nice and clean. All the plug wires ohm'd out good.

Paul Workman · 10-21-2016

Quote:

Originally Posted by Locobob

So my car was running a little rough and progressively got worse so I did some testing. Initially I thought it was a fuel issue but after checking a few things I decided to ohm the plug wires through the coil packs. All were in the 15K range except the 8,5 coil which was OL. Pulled the plenum and here is the 8,5 coil. Lots of corrosion on the #5 tower, not sure what would cause this, all the other towers were nice and clean. All the plug wires ohm'd out good.

Corrosion = mouse or meeses (if you prefer!)

Young1 · 10-23-2016

That mouse is not prostate challenged to pee up the insulator boot! I shall give him due credit.

Sent from my iPhone using ZR-1 Net Registry

XfireZ51 · 10-23-2016

Bob,

How does the #5 plug look? The question in my mind is whether the corrosion caused the misfire or is there a misfire in #5 resulting in the corrosion?

Locobob · 10-23-2016

Quote:

Originally Posted by XfireZ51

Bob,

How does the #5 plug look? The question in my mind is whether the corrosion caused the misfire or is there a misfire in #5 resulting in the corrosion?

The plugs all looked good

XfireZ51 · 10-23-2016

So 5 was firing as good as the others then?

Locobob · 10-23-2016

Quote:

Originally Posted by XfireZ51

So 5 was firing as good as the others then?

I doubt it considering I had an OL OHM reading from the #5 wire to the #8 wire. But I didn't see anything too awful at the plugs, they were all intact and had proper gaps.

Locobob · 10-23-2016

Ugh, and now I'm having more annoying issues. The throttle appears to be hanging up sometimes. Won't rev down on coast down occasionally and sometimes the idle is a little high, both cured by a blip of the throttle. I pulled the airhorn and checked the throttle blades, cleaned up the IAC and reset the TPS to .54 (it was slightly low at .52). Don't see any issues when manually manipulating the throttle, it appears to snap shut just fine every time. Hmmmm

Locobob · 10-29-2016

Well the problem is back, apparently the coil was not the root cause of the problem as wires 5 and 8 through the coil are once again OHMing at OL

Locobob · 10-29-2016

The #5 spark plug looks a little cleaner than the others. It tested good on the multimeter, no sign of ground leaks and the center electrode was within the same OHM spec as the others.

10-21-2016	#1
Locobob Join Date: Jan 2004 Location: Portland, OR Posts: 1,057	Coil Problem So my car was running a little rough and progressively got worse so I did some testing. Initially I thought it was a fuel issue but after checking a few things I decided to ohm the plug wires through the coil packs. All were in the 15K range except the 8,5 coil which was OL. Pulled the plenum and here is the 8,5 coil. Lots of corrosion on the #5 tower, not sure what would cause this, all the other towers were nice and clean. All the plug wires ohm'd out good. __________________ Robert ZR-1 Net Registry Oregon State Director 91 ZR-1 #431 Black/Black LPE 368 Last edited by Locobob; 10-21-2016 at 05:31 PM.

10-23-2016	#3
Young1 Join Date: Sep 2016 Location: Ocala, FL Posts: 898	Re: Coil Problem That mouse is not prostate challenged to pee up the insulator boot! I shall give him due credit. Sent from my iPhone using ZR-1 Net Registry __________________ Steve Young 1991 ZR-1 Quasar Blue Metallic/Black #729 Second Owner 1991 ZR-1 Dark Red Metallic/Black #2040 SOLD 1990 ZR-1 Dark Red Metallic/Saddle #1670 SOLD Double your happiness.....complain half as much.

10-23-2016	#4
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,708	Re: Coil Problem Bob, How does the #5 plug look? The question in my mind is whether the corrosion caused the misfire or is there a misfire in #5 resulting in the corrosion? __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX

10-23-2016	#6
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,708	Re: Coil Problem So 5 was firing as good as the others then? __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX

10-29-2016	#9
Locobob Join Date: Jan 2004 Location: Portland, OR Posts: 1,057	Re: Coil Problem Well the problem is back, apparently the coil was not the root cause of the problem as wires 5 and 8 through the coil are once again OHMing at OL __________________ Robert ZR-1 Net Registry Oregon State Director 91 ZR-1 #431 Black/Black LPE 368

10-23-2016	#8
Locobob Join Date: Jan 2004 Location: Portland, OR Posts: 1,057	Re: Coil Problem Ugh, and now I'm having more annoying issues. The throttle appears to be hanging up sometimes. Won't rev down on coast down occasionally and sometimes the idle is a little high, both cured by a blip of the throttle. I pulled the airhorn and checked the throttle blades, cleaned up the IAC and reset the TPS to .54 (it was slightly low at .52). Don't see any issues when manually manipulating the throttle, it appears to snap shut just fine every time. Hmmmm __________________ Robert ZR-1 Net Registry Oregon State Director 91 ZR-1 #431 Black/Black LPE 368

10-29-2016	#10
Locobob Join Date: Jan 2004 Location: Portland, OR Posts: 1,057	Re: Coil Problem The #5 spark plug looks a little cleaner than the others. It tested good on the multimeter, no sign of ground leaks and the center electrode was within the same OHM spec as the others. __________________ Robert ZR-1 Net Registry Oregon State Director 91 ZR-1 #431 Black/Black LPE 368