JimRockford

I have a stock 1990 Camaro 305 v8 tbi. One owner (prior to me) all original. The original ignition coil failed after 30 years. I replaced it with a brand new delco one I got online last December. Worked fine for about 5 months,then I got a rough idle,and it bucks/misses periodically when accelerating. Lifted the hood,heard zapping,found the problem,it was sparking from the base of the ignition coil electrode shaft across to the metal transformer looking section of the coil itself.
I tried putting brand on a brand new spark plug wire,still the same issue exists.
I ordered a replacement coil and put it on today and it’s doing the same damn thing!. This was a brand new ac delco coil,in its original box.

The spark is not coming from the metal part of the electrode,it appears to be coming from the base of the electrode where it’s coated in plastic and then jumping directly across to the metal center core of the coil itself.

Im at my wits end with this thing. Can TWO coils be bad in a row? Both are ac delco brand new in the box. What else would cause this?

JimRockford

The part number of the coil I am using is BS3005. Ac delco

henryd3

iTrader: (128)

Isn't that strap that mounts it to the intake manifold supposed to be grounding it? And is that working properly?
Wild guess?

BOOT77

I'd check your grounds like mentioned. Spark will jump if the resistance is too high, ie plug gap too big, bad wires/rotor/cap/phasing.

JimRockford

Can you show me a photo of the grounding strap? I don’t see anything like that and the car has not been messed with prior to me,to my knowledge.

JimRockford

There are two connectors that push into the top of the coil and the high voltage cable that comes off the top of the electrode and goes to the top of the cap. It was my understsanding one of the wires on connectors was a “ground”
It doesn’t do this all the time,It does it when it feels like it. The cap and rotor were replaced maybe 6,000 miles ago. I realize everything’s made in China these days,but why would a cap,rotor go bad that fast?
If the plugs/wire were bad why would the car still idle smoothly for 30 seconds or more at a time without missing and why would that cause high voltage to arc across the coil itself? Usually the engine would just miss.I’ve had lots of cars and have never seen this issue. But they were all older cars without these types of coils.

i just don’t want to do the “shotgun method” and just start replacing every part in the ignition system until I fix it. I was hoping someone here would tell me most logical,common cause of this,and if someone here has even actually seen this exact issue before and what they did to solve it.

i would think if it were plugs/wires it would do this ALL the time and not sometimes idle smooth as glass and run fine. But I could be wrong

can someone tell me where these ground straps are? All this has are two metal brackets that mount the coil to the intake

JimRockford

Here’s a photo of the spark jumping

JimRockford

Can someone please take a photo of this ground strap that’s been mentioned? This car doesn’t have anything like that,and the coil was original to the car when I originally replaced it,and I didn’t lose any parts.
when I researched this on another thread it was stated there was NO ground strap used on these coils as the coil itself is sealed in an insulated plastic and resin housing.

GeneralDisorder

iTrader: (1)

The spark is going to follow the path of least resistance - you have a problem with the cap and rotor, or one/more of the plugs and wires most likely. The arcing from the coil to ground is happening because that HUGE gap is still lower resistance than firing the plug(s) that have higher resistance through the cap/rotor/wire/plug combo.

The logical next step for you is a visual inspection starting with cap and rotor. Wild guess: you will find the rotor button melted into the cap.

There is no ground strap on the coil. I just replace the coil (and distributor) on my 91 Formula and there is no such beast.

GD

Tootie Pang

iTrader: (2)

When was the last time you did your plugs?

OrangeBird

iTrader: (1)

A side note here on "carbon tracking"

When a high voltage spark jumps in a place it isn't supposed to like that , it burns itself a nasty little path called a carbon track . It is literally just that , carbon from the ionization / burning associated with the unintended electrical path . When you rectify the original cause of the arc (The General's melted rotor being one great suggestion of where to look) you may find the coil still arcs and must be replaced due to the burned in carbon track . It literally etches itself along the path of the arc and spells doom for the coil . There are ways us electronics hobbyists can save one if the carbon track isn't burned too deeply in , but most of them are so burned in by the time a fix is tried that it seldom works . So follow The General and Tootie's advice , inspect closely your plugs , wires , cap & rotor before you put another coil into it , lest a fried rotor or something like that end up making it a coil twofer

JimRockford

Thanks General,the cap and rotor were replaced November of last year,probably 6- 10k miles ago. I have a complete set of new Delphi packard wires for the ignition but haven’t installed them as the others worked fine until this happened.
Supposedly the spark plugs were replaced before I bought the car,but I bought a set of new champion platinum made in USA spark plugs yesterday. Guess I will try installing them new. I will also inspect the cap and rotor,but I replaced that not long ago.

whats the best way to get at the plugs on this car?

JimRockford

Thanks for the advice. I am thinking this is probably plugs then,because the cap and rotor are new

GeneralDisorder

iTrader: (1)

You would be surprised how quickly cheap parts will fail. Also if the plugs and wires are old they could easily burn up the cap and rotor.

It's a complete system. Each component has an effect on all the others. And bad link in the chain causes high voltage and that causes heat and subsequently failure of the next weakest link.

GD

JimRockford

I have a new set of Delphi ignition cables and bought some champion platinum spark plugs. If the cap and rotor look ok I will reuse them,if they look bad I’m going to buy the standard blue streak cap and rotor with brass contacts this time.

can you tell me why the replacement spark plug wires don’t have 1-8 on them so you know where they go? They are made in the USA and say packard cable like the originals but don’t have numbers to tell which plug they go too.

also,can I get to all the plugs from the top of the car or is there a trick to this? The passenger side looks like it’s a huge pain in the ***

GeneralDisorder

iTrader: (1)

The typical method for wire replacement is to remove one at a time, find the matching new one (same boots, same length, etc), and swap them over - one by each. You can label them if you like.

As to plug access. I'm not totally sure.... I can say I've always done all mine from the top. But I probably deleted all the air injection stuff on my 86 before I did the plugs the first time. Now I have headers and shorty plugs so can relatively easily do them from the top. Haven't done them on my 91 yet that still has all that crap. But you should be able to do them from above.

GD

???

iTrader: (5)

honestly 2 bad coils don't surprise me. I had a buddy with a 4th gen that went thru like 5 in 6 months and then ended up with a good one that lasted till he sold the car years later. cheap auto part store junk. even the ac delco branded stuff, you'll notice some very cheap ac delco stuff on Amazon but it's not true oem, it's some lower line they have come out with.

plugs, wires cap and rotor is never a bad thing to change. especially those small caps, depending on climate I've seen them get crusty very quickly. normally our lower hp v8s don't really show it, but the turbo syclone and typhoon guys change those caps like underwear. boost taxes the ign system way harder and shows its flaws faster but they are still there.

JimRockford

So I just pulled one of the spark plugs to inspect it. It’s an ac delco R45TS,it doesn’t look bad,but when comparing it to the champion 3018 platinums I noticed the electrode seems to be longer on the R45TS.
i triple checked the plugs before I bought them to make sure they were correct for this application. Why is there a length difference and does it matter? I’m thinking maybe it’s the wires and not the plugs causing this,still have to check the cap and rotor. It could also be two bad coils as the other poster said.

JimRockford

JimRockford

Supposedly the plugs were replaced about a year ago. If this were a plug or cap or rotor issue why would the car run smoothly for minutes at a time and then just off and on when it wants to miss? Wouldn’t it be a full time deal?

JimRockford

Those things are never bad things to change IF they need changing,but there’s also no point in throwing away money replacing parts that aren’t bad and have plenty of service left in them though,hoping to fix a problem through process of elimination.

As I said previously,I replaced the cap and rotor last November. I haven’t driven it enough to wear those parts out,but I will inspect them since they are modern Chinese auto parts. I have new plugs and wires to put on,But supposedly the plugs were replaced last year,guess if it’s not those things I’m back to it being two bad coils in a row.

NoEmissions84TA

iTrader: (1)

Please don't be offended Jim, but why are you so adamant about not changing the cap & rotor?
NEW does not always mean GOOD! A spark plug can LOOK good and never fire - or intermittently.
The rotors for the small body distributors commonly arc out to the center mounting post (carbon tracking as OrangeBird describes in post 11). Yet the rotor LOOKS good. When you finally solve this, I think you will learn this.

GeneralDisorder

iTrader: (1)

I've changed quite a few spark plugs over the years that looked fine, but were internally damaged in such as way as to completely or partially malfunction. Remember they have resistors inside them. Things can be cracked that you can't see.

Age of the components has nothing to do with logical problem solving. You must let go of those crutches. Approach the problem as if you had no bias - no idea how old anything is. Test, verify, then replace. Getting hung up on "I just replaced that 6,000 miles ago!" will not solve this problem for you.

GD

JimRockford

First off,I’m not “adamant” about not changing the cap and rotor. Please,don’t put words into my mouth. you can’t read my mind and don’t know what I’m thinking so please don’t presume to.
You also don’t know the cap and rotor are indeed bad,you are making an assumption without any first hand knowledge and could be right OR wrong..

I appreciate the input people have given me here to try and troubleshoot this. All I said was that I replaced both the cap and rotor last November and was just wondering/asking why it would just suddenly become defective when it worked fine and I haven’t even put 7,000 miles on the car since then And it still runs smoothly sometimes and then sometimes it acts up and the coil arcs. If the cap/rotor were bad wouldn’t it just run like crap all the time?

The forums are for discussion. That’s how people learn by asking. There’s nothing wrong with questioning things and trying to understand the “why” of something better.

if you recall,earlier in the thread someone was telling me there was a ground strap on these coils when there is no such thing. This is the Internet,not everyone here knows what they are talking about. You get both bad and good advice and it’s up to you to ask questions and figure out which is which.

When I got this car it would thump in the back going over a bump or pothole. I had one person insisting it was bad coil springs. (The car had only 90k miles) They were wrong. The 30 year old shocks were completely shot. I replaced fhem with OEM delco units and it’s like new again. No more thump even over huge speed bumps.

I’ve dealt with mostly 50’s and 60’s cars before and never had this issue. I change the parts,like points,condenser (this car doesnt have those) cap and rotor,etc at the necessary intervals. I’ve rebuilt carbs,changed fluid/filter on trans,and do all the routine maintenance.

These third gen cars have hei coils,ignition control modules,fuel injection,computers and all kinds of crap older cars don’t that can act up in ways I’m not used to. I don’t claim to be an expert on them. I’ve had other third gens and never had this problem before with them. This is a new one to me.

I understand what you are saying. Yes,new parts can and do sometimes fail,but I did inspect the cap and rotor this afternoon a little while ago and didn’t see any abnormal wear or carbon tracing,the “button” in the cap also wasn’t burned,worn down or melted. Can it still be bad and look fine?

If you’re replying with something constructive that’s fine,but making condescending remarks like “when you finally solve this i think you’ll learn this” comes off a little arrogant and rude. If you didn’t mean it that way I’m sorry,but that’s how it came off to me,but it’s hard to tell how somethings being phrased here.

What you don’t understand is that I’ve had people claiming to be “in the know” say stuff like this before “it’s definetly the coil...it’s defiently this,it’s surely that...and they are often wrong. I’ve changed the coil twice now,same thing. I had someone else insisting this wasn’t an ignition problem at all but a fuel problem,completely ignoring the fact that I mentioned the coil was arcing and it’s definetly ignition related. Lol.

Some people get their egos bruised if you don’t blindly accept something as truth and dare to ask questions. I don’t understand that. Nobody is perfect,nobody is always right and nobody knows everything. There’s too many variables. I’m sure glad I didn’t waste money replacing the rear springs when the problem was only shocks.

To repeat,I inspected the cap and rotor as per “General Disorders” instructions and the button isn’t melted,burned or worn down,the rotor center contact looks fine as well and I don’t see any burns or carbon traces and it’s not burned through.

So what if I change it and it doesn’t solve it? Then I guess you’ll learn it isn’t always the cap and rotor? Right? Lol.


And No,I’m not “offended”,but I do love how some people make absolute and definite diagnosises on a car they haven’t seen in person about parts they haven’t seen in person and haven’t tested to determine if in fact that specific part is indeed faulty..

It could be bad plug wires,It could be bad spark plugs,It could be another bad coil as the other poster mentioned. We are all just guessing here,right? We’re ruling out all the most common and logical causes. So why get confrontational if I ask questions?

In the “old days” people used to attempt to diagnose,locate and replace the actual part that was bad. A tv repairman didn’t replace every resistor,tube and capacitor in a television set until it worked again. You’d test the suspected components and replace the ones that were bad.Same thing with cars. Mechanics didn’t just replace every part in the system until they finally fixed the one that was bad.I’m not Thurston Howell the 3rd,I have other things to spend my money on. Lol. It’s funny how cavalier people are with someone else’s money.

FYI,I have ordered a brand new Standard Blue Streak cap and rotor today,so I guess I’m obviously not adamant enough about NOT replacing the cap and rotor,huh? Lol.

And as stated earlier,I already have new wires to put on and a set of new plugs I bought last year,and tomorrow I will have a new cap and rotor despite the old one looking ok. The only thing that I guess I will need is another new coil after I do all this so I don’t have to worry about arcing due to carbon tracing as another member pointed out.


The plug wires appear to be original to the car and when I replaced the cap last year two had some blue corrosion but I cleaned them up. I’m guessing the plug wires may be bad but I guess I will see when I replace them tomorrow if that solves the issue.

JimRockford

Moving forward,can anybody here tell me if I need to be concerned about the difference in the electrode length on the champion plugs I bought vs the old ac delcos in the car? I posted a photo above

GeneralDisorder

iTrader: (1)

Well almost for certain those Champion plugs are going to be a much higher heat range. I don't see them not functioning but I wouldn't be happy about the difference. I used some Accel shorty non-resistor plugs on my LB9 and as far as the electrode section is concerned they looked just like the AC Delco plugs I took out.

As a rule I haven't used a Champion spark plug in..... well since the last time I had to change a plug in a lawn mower and that's probably been 20 years. Mostly I run NGK's in everything but for the GM's I usually get AC Delco. But for my 86 Trans Am I went to the Accel shorty plugs for clearance on my Dyno Don headers. They work excellent for me.

GD

JimRockford

Thanks for the info and advice. I wanted to buy AC Delco plugs for the car,but they didn’t have a platinum version. I settled on the Champions because they were made in USA and platinum. the platinum plugs supposed to last much longer than the copper core plugs. Should I avoid any platinum plugs for this car then? I can go back and get the delco plugs tomorrow. Did the delco plug I posted look bad? All 8 look the same. I was told they were replaced before I bought the car.

Are autolite plugs good anymore?

GeneralDisorder

iTrader: (1)

I would just get the AC Delco plugs. The copper plugs should last about 30k. But appearance doesn't mean they are good. The stock plugs are resistor plugs so they have ceramic resistors inside that you can't see. These fail a lot more often than the non resistor plugs.

I have pulled plugs that looks absolutely perfect. But intermittently misfired. Unfortunately you can't go off looks.

GD

JimRockford

Thanks General,What effect would using my non resistor platinum plugs have? I ordered some of the R45TS plugs online. Can I use these platinum plugs though?

GeneralDisorder

iTrader: (1)

Well they *could* cause interference to electronics. Though I have no problem with mine. They might interfere with AM radio reception or the ECM, etc. I have had no issues. I wouldn't reccomend non resistor wires for anything with computers in it but plugs..... I haven't had an issue.

GD

JimRockford

Ok,thanks for the info. I assumed all the resistors did was prevent radio interference. I didn’t think it would mess with the computer.
im curious,have you ever run into this issue before where a car sparked across the coil like this?

GeneralDisorder

iTrader: (1)

Yes - but it's usually related to bad tune up parts down-stream from the coil. Electricity is pretty simple stuff - it takes the path of least resistance - always and forever. So if the spark is jumping down the coil, then it's either easier than going through the cap/rotor/wire/plug, or there's a carbon track down the coil as Orangebird suggested. Honestly that's about the only two possibilities in general. Think about how long that spark is and how short the plug gap is by comparison. It should easily be able to go though the plug rather than out the coil like that. There must be a very high resistance somewhere down stream for it to do that.

GD

JimRockford

I agree,it must be. I know the wires are original to the car so I’m changing them right now. Then the plugs and then the cap and rotor after that it can only be another bad coil.

JimRockford

Inside of cap and rotor that I installed a year ago. No burns or wear

JimRockford

Does anyone have a diagram showing the plug wire order going onto the distributor? Some of the wire clips are hard to open

JimRockford

Fixed the problem today! I just wanted to say thanks to everyone who helped out with advice,especially “General Disorder”.

It turned out to be bad spark plug wires. I didn’t see any burns or cracks in any of them,but I guess after 30 years some of them had shorted. A couple of the contacts inside the boots had corrosion too which I’m sure didn’t help matters any.

It was time consuming getting the wires into the wire holder clamps on each side of the engine. And the last spark plug boots nearest to the firewall were a pain in the butt to get at to push the new wires on. I had to go underneath the car on the passenger side to get a good enough grip to push the last one on all the way.

So now I have an extra brand new blue streak cap and rotor for the future and a set of spark plugs too.
the car runs great now. No sparking across the coil and not missing!

GeneralDisorder

iTrader: (1)

The conductors inside the wires probably have cracks and thus really high resistance. They wouldn't be "shorted" as that would be a short path to ground and thus essentially zero resistance - in this case they were closer to "open" (maybe some were entirely open), and thus the resistance was approaching infinity rather than zero.

Glad you found the source and thanks for the kind words. Doing this every day for 20 years.... I like to think that diagnostics is my super power but really it's just that I do it 10 hours a day.

GD

JimRockford

Youre welcome. I really appreciate the input. The car runs incredibly well now,I don’t dread taking it out anymore. Sorry I misspoke and used the incorrect terminology about the wires. I just figured if the resistance reached the point where the coil spark was jumping across that huge cap to the core that maybe a wire or too were shorted. I had a mechanic tell me “wires never go bad unless they are burned or cracked”,he claimed to have a 67 Chevy with original wires. 🙄

by the way the wires I bought were Delphi brand and made in the USA with packard cable just like the originals on the car. The fit and work great.

GeneralDisorder

iTrader: (1)

The "mechanic" made the mistake of taking a single outlying example and creating a rule with it. Unfortunately there are about as many plug wire designs out there from the last 120 years of automobile and internal combustion engine manufacturing, as there are types of insulators found in and out of nature. Not all insulators and not all conductors break down at the same rate - so that he may have a lightly used set of 67 Chevy wires that still work, while I can show examples of cars from the 2000's that have worn out wires. Also bad plugs frequently damage wires because as the gap grows, more voltage must be generated by the coil to fire across the enlarged gap. So wires that have been subjected to long term operation in front of plugs with big gaps will break down their insulation faster, and heat up their conductors more, causing more rapid failure. As with most things - lifespan of the ignition components "depends" on many factors.

GD

JimRockford

That’s true. A lot of things today are made with cheaper materials than in the past,I know I have cars from 1957-1960 that had really bad looking plug wires when I got them yet ran amazingly smooth. I always replace them anyway though because I actually drive my cars like they were intended. I never got into the whole trailer queen/car show thing. The only fun of owning a car is to drive it and use it like it was supposed to be when it was new.

i pulled all the plugs on the Camaro yesterday and checked and set the gap at .035,but thanks for letting me know that plugs with the wrong gap can also damage the wires.

by the way,that same mechanic bragged he ran his cars with copper plugs for 60,000 miles and that I should never pay attention to the manufactures saying to change them every 10,000-20,000 miles. I don’t listen to that either,but it’s a perfect example of why you have to do your own research and not just blindly listen to anything someone tells you.

???

iTrader: (5)

so did you even get it running well again. what did it end up being?

Tuned Performance

iTrader: (92)

Full tuneup