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Discussion Starter #1 (Edited)
I have an annoying problem that is re-occurring on my 95 LT1. Recently had a ICM go bad based on a "No Start" issue that came up and troubleshooting chart directed me to replace the ICM. I have also been running the MSD 8226 Coil for probably 5+ years without issue til this "no start" happened. Before buying a new ICM, I have a spare (stock) Coil/ICM assembly from another setup that I was able to bolt on and the car and it fired right up. So it sure seemed like the diagnosis was right, a bad ICM.

I purchased a new Delco ICM and installed it (with HS paste) on the same bracket with the MSD coil. The car started right up and ran for about a week or 2 til one morning went to start....and she just cranked and would not fire....DAMN!! Same issue as before and just took a few minutes to bolt on the spare coil/ICM and she started right up again. I suspect I have another bad ICM but these things aren't cheap ($90 on Amazon).

I started to wonder if the Coil itself could be taking out the ICM and found some info out there that suggests this is possible. What do YOU think in this scenario....could the Coil cause the ICM to get fried? Just on a hunch, I decided to replace the coil with another MSD 8226 but looking at this 1 review and the pictures of what this guy found when cutting open, the MSD Coil sure does not give me a "warm and fuzzy" feeling. So instead, I just ordered a new AC Delco Professional coil for about $39 and think this is the better way to go. So again, assuming here that the MSD coil took out a brand new ICM.....does this sound possible and do you think it's best to just stay away from the MSD part?? But check out this review on the Amazon Site for the MSD #8226 Coil and let me know your thoughts. Look at the 1 Star Review from "DYI Man" and the pictures he included. This review is what drove me to get the AC Delco part over another MSD.

https://www.amazon.com/MSD-8226-Blaster-Ignition-Coil/dp/B00062YYVS/ref=sr_1_1?gclid=EAIaIQobChMIm_Xhw7K14wIVjbjACh3Hww1GEAAYASAAEgIzDPD_BwE&hvadid=177548346152&hvdev=c&hvlocphy=9007343&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=12028324809786843491&hvtargid=aud-648278611385:kwd-1581460228&hydadcr=12275_9726162&keywords=msd+8226&qid=1563146130&s=gateway&sr=8-1#customerReviews

I also have a Under Load, under power miss that I suspect is a bad wire and will be replaceing the wires with some from taylor that I just got. It almost feels like it's running on 7 Cylinders and just seems sluggish in upper RPM's. Hope to get her running well again soon.
 

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V.Good write-up. I've read more than once on here to replace IC and ICM as a set. Call it scientifical, or just urban legend/old wive's tale, but cost v. confidence tilts me to replacing together. And another ENTIRELY subjective insight = car mags since the '70's have been hawking brightly colored and way more attractive aftermarket ignition parts compared to their oem counterparts. But I collected repeat cases where neighborhood friend's running problems got traced to their aftermarket distributors and ignition coils. While I always weighed in at least a small potential for improper installation or fitment, the excess cost over stock steered me just make sure of good maint. of stock stuff in those areas. What's interesting is for the past near-20 years on this forum I've picked up on numerous cases of the same thing for elec. gremlins, - especially regarding your brand in question and the other popular one. Sure, ACD and Delphi and other 'used-to-be-trusted' reps keep sliding, but for the revs most of us run I've never felt ignition is the weak link on a sbc.



Sorry, just a long way of adding support to your diagnosis and suspicions. And I know you know about the dozens of documented "off-idle miss" issues that just may be contributing to your under power problems.
 

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Since it only took 2 weeks to fry it, i think using the $39 coil is a good throw parts at it test. You will know soon if your replaced coil was the issue.

-ALF out...
 

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IMHO ICM can effect coil and vise versa. The coil may test fine cold (ohms) but that won't show a broken wire inside the wrap

Also take a GOOD look at the wires & ground terminal on DS head at ICM/coil

I tried ordering the AC Delco ICM from Amazon...they won't ship to CA (customer service did not know why). Got it at RA
 

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In the old days with points I expect mechanics would be able to see a coil going by how bad and how quick the points contacts burnt out.


With the variables of heat and speed diagnostics would be hard. You could patch a current meter into the ICM power line and see if a suspect coil was drawing more current than a new one.(@set RPM and temperature) A logging oscilloscope might show more. But economically a new coil and ICM and a inspection and cleaning of contacts and wires is probably the best way to go.


I have two old Honda twin motorcycles with factory capacitive discharge ignitions. The process is about the same. Replace the coil if the CDI module fails. Ford moved the ICM off the fender and into the PCM while Chevy (same time 1990s) put it on the engine. These parts should be OK with engine bay heat but reality seems like there is a problem.


One mod I never get around to is running a ground wire from the ICM/coil ground to the main ground on the other side of the block.I see many old cars with added ground wires to main components like voltage regulators windshield wiper motors, and ignition modules.
 

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Discussion Starter #6 (Edited)
Thanks for the input guys and really hoping it's just the Coil that went and not the new ICM too. Mad at myself for not replacing the Coil with the ICM.
Once I get the new Coil, I'll try to swap out the MSD coil and use the New-ish ICM and cross my fingers. Hate to think I got to buy another ICM but I wont trust my 25 YO Spare setup for the street but it's nice to have a diagnostic spare on the shelf.

I'll let you know what happens and will most likely look at my Plugs and replace all the wires. I've noid checked all 8 injectors and they are all pulsing. I need to get a stethoscope and listen to each injector too but they are fairly new Accell replacements, could be 1 is not working. I also checked for arcing near the plugs and under the car in a dark garage and didnt see anything. So I dunno, could just be a dead plug or wire?

Background/symptoms - Car was running like a top after the new injectors and then the car wouldn't start about 8 months ago. Lots of family, jobs and other stuff and I finally get her fired up with new ICM. Take it on a test drive and notice the lack of power and something must have went bad just from sitting for 8 months I guess. I would best describe it as under power thru all RPM's, but when she upshifts and I keep the throttle steady "under load" I really feel power drop off and car starts to shake slightly until I give it more throttle to compensate. The shaking stops but she is still under power. I just think there is a cylinder down for some reason and a plug read may reveal a lot. MSD Wires have been on the car for many years and were moved over from my old L99 so it's time for new wires anyway.

BTW - Someone mentioned the 4 Ground Rings on the Coil Assembly Bolt. I did check these and cleaned them up again and they're fine. had to re-crimp a terminal on 1 of those wires a while ago that the original ring had broke off.
 

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4Door...when I had a plug arc (stumble under load) I also looked and could not see the arc.....until by chance I was under the car with engine running and could hear it and finally found it. #6 plug wire had the stock heat shield over boot and arc was between boot & shield making it VERY hard to see

I have Magnacore plug wires. Very nice but not the cheapest wire set. Got them from Lingenfelter
 

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Discussion Starter #8
I heard those little Metal shields can be problematic. I have a set of Taylor Thunder-Volt wires to install and will ditch the metal shields and instead use Cloth Heat covers on the ends of all 8 wires that slide over the plug boot.

Is there a way to check for a bad Spark Plug on the work Bench? I will vissual them but wonder if they go bad, do they break internally and I could just check them with a meter.
 

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RE: wires and the metal insulators. I've put in Taylor on 3 B/D's at slightly larger than oem (I think I get 7.5 or 8mm?), whatever size they still fit the keepers. I reuse the metal isolators at all original locations. No issues with fit on the boot or clearance to manifold, not even with closer bends of headers.
 

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I also have a Under Load, under power miss that I suspect is a bad wire and will be replaceing the wires with some from taylor that I just got. It almost feels like it's running on 7 Cylinders and just seems sluggish in upper RPM's. Hope to get her running well again soon.
Have you tried a timing light on all the spark plug wires? You might get lucky and see a miss at idle. I have some clear inline adapters that light when the plug fires. There is also a inline tester that lets you set a spark gap and watch it.


Is there a way to check for a bad Spark Plug on the work Bench? I will vissual them but wonder if they go bad, do they break internally and I could just check them with a meter.
Not with a normal multimeter unless they are a dead short. You could connect each plug to the coil and crank the engine. Connect each plug to a roto-tiller or lawn mower and watch as someone else pulls the cord. A little messing around and you could test the plug wires too.



You are sounding like you want to go back to pre 1950s where things were checked out instead of thrown out. I have seen coil checkers, spark plug checkers, spark plug cleaners, and distributor testers. Some would be not hard to make.


really hoping it's just the Coil that went and not the new ICM too.
You might be able to see it work with a 12V LED and crank the motor. You could compare it to a known good one by checking and comparing it's voltage out. Again a oscilloscope might show the issue better.
 

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Discussion Starter #11 (Edited)
RE: wires and the metal insulators. I've put in Taylor on 3 B/D's at slightly larger than oem (I think I get 7.5 or 8mm?), whatever size they still fit the keepers. I reuse the metal isolators at all original locations. No issues with fit on the boot or clearance to manifold, not even with closer bends of headers.
Got some work done tonight and got the DS wires/bracket off and was going to check the old wires and my DVM is dead. Figures...time to call it a night and will bring another from work.

Thought I kept a few of the old metal insulators, but forgot they were all removed. :surprise: The Taylor wires I got are 8.2 and the old MSD's are 8.5 and I use the MSD Wire Separators on stock brackets...the MSD separator lids pop off real easy. I'm going to open up the other hole on the DS Bracket cause that 1 bolt above the Motor Mount is a PITA. At least then I can put the bolt in almost all the way and DROP the bracket on the 2 block bolts. Will use some new stainless HW on the brackets to mount to block.

Have you tried a timing light on all the spark plug wires? You might get lucky and see a miss at idle. I have some clear inline adapters that light when the plug fires. There is also a inline tester that lets you set a spark gap and watch it.



Not with a normal multimeter unless they are a dead short. You could connect each plug to the coil and crank the engine. Connect each plug to a roto-tiller or lawn mower and watch as someone else pulls the cord. A little messing around and you could test the plug wires too.



You are sounding like you want to go back to pre 1950s where things were checked out instead of thrown out. I have seen coil checkers, spark plug checkers, spark plug cleaners, and distributor testers. Some would be not hard to make.



You might be able to see it work with a 12V LED and crank the motor. You could compare it to a known good one by checking and comparing it's voltage out. Again a oscilloscope might show the issue better.
Picked up 1 of these....

https://www.harborfreight.com/90-in-line-spark-checker-63593.html?cid=paid_google|*PLA+-+All+Products|All+Products|63593&utm_source=google&utm_medium=cpc&mkwid=sKE0GgBvZ|pcrid|327822404853|pkw||pmt||pdv|c|slid||product|63593|&pgrid=71439424048&ptaid=pla-296227499965&pcid=1688396772&intent=&gclid=EAIaIQobChMIxYuTj-664wIVD5-fCh0KTgvfEAQYBSABEgKLCPD_BwE

I love the "Briggs and Stratton" approach to testing the Plugs....didn't think of that. The plugs all look good except #6 plug looked a little too clean. I didn't see much brown compared to the other 7 plugs. They were all Dry and free of oil and will check gap later.
 

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Discussion Starter #12
partial Update

It's been HOTTER than BallSS lately but got some time on the car.

Driver Side - New Taylor Wires and Plugs installed on driver side....YES!! Forgot how fun (Not) these wires are to install.:frown2::frown2: I was already told by the Fam they heard my Colorful Language while doing just this side. If only the ABS brake lines weren't there it'd be soooo much easier. Checked the old MSD wires and 7, 5, 3 were all ohmed within spec....#1 wire? Ruh Roh, think I found the problem. :smile2:

The #1 wire had numbers in the Mega-ohms and jumped around if I moved the wire. A few times I got it to show 60 ohms but barely move the wire and it would jump back up to mega-ohms. I've had a dead wire before and to MSD's credit, they replaced it for free. But this entire set is pretty old and was on my original L99 and moved to this LT1, so it's time for a new set of wires. :wink2:

OK....on to the Passenger Side....Dun Dun Duuuuunnnn!! My goodness it's a tight area between the Block and Accessory Bracket and that Stock Clip behind the ABracket...FU!! Believe me...I considered leaving them alone after finding a bad wire on DS but I'm committed to installing these wires, just not looking forward to it at all. I removed the Tensioner and Balancer (replacing anyway) just for a little more room up front. Also removed the bolt that holds the Stock Bracket to the block so I could get to the Clip cover a little easier. And then after attacks from Flies and this damn HEAT, I decided to pack it in for now.

Temps in the upper 90's for days still and I got Yardwork ("Good Sweat!") and other stuff going on so may be a while til firing her up again.
 

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It's been HOTTER than BallSS lately but got some time on the car.

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Hey now...I resemble that statement :)

yeah the plug wire swap is....tedious, especially on PS

I know how hot it gets there on our visits to Q...humidity is the killer.

Remember dialectic grease is your friend on plug wire boot ends
 

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Discussion Starter #14
Hey now...I resemble that statement :)

yeah the plug wire swap is....tedious, especially on PS

I know how hot it gets there on our visits to Q...humidity is the killer.

Remember dialectic grease is your friend on plug wire boot ends
Sorry about that, didn't mean to tie your handle (name) into that comment, just something I say when it's HOT. This heatwave, I don't think the word "HOT" does it justice.....maybe Sweltering would be better.

Not much new to report on this Project...you know family stuff and this heat and everything else. I took my Grandson to a Monster truck Show (outdoors) Sat night and it was a Blast but it was HOT. Then it was the Pool yesterday but even that wasn't refreshing....the fricking pool water was 92*.

On saturday, I did get an hour or 2 on the car and got a good bit done on the Pass side of the car. I was looking at Ed Runnion's install again and sort of modified that a little. With the Balancer, Tensioner removed and the trans cooler lines tied off the bracket and tie wrapped to the side, I found it pretty easy to fish the wires into place. I just removed all 4 wires from the front, then once they were all removed, I managed to "feed" each wire through the opening (working from the front) without using a fish wire. I just got them to push thru the bracket/block area and then up over the compressor. They are all in place and I just got to fight with that 4 wire Stock Bracket behind the accessory bracket and get that mounted and think the rest will be fairly easy after that.

Hoping to get some time tonight and finish this project up and fire up the car for a test drive....we'll see.
 

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Misery loves company eh. Always gratifying hearing another's all-too-familiar PITA wire job, including recounting of all the familiar R&R details ;) Truth be told I don't mind that work since it's only "once every 15 years or after purchasing another one" of these tubs. Besides, it's a good chance to eyeball all the other goings-on underneath deserving some TLC. I was just working on the 80k black garage queen and noticed the orig wires and plugs. I hate to think it's still quite a few years before 100-120k to replace them with the opti tune-up. LOL



And ::Seinfeld:: What is it about the weather. ::Seinfeld:: Sat morning sweating after 10 minutes just walking around deadheading flowers WTF? Yesterday the pool is 91*, but now down to 87 -- but have to drain 4" after this morning's rain. At least 100% humidity and 65* is way preferable to 105 H.I. all last week. All just makes me 'preshee-ate first-responders utilities and outside trades a bit more.
 

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Discussion Starter #16 (Edited)
Passenger Side DONE!

Made some good progress and all downhill from here getting her buttoned up. Hoping all works and get it fired up tomorrow. That stupid GM Wire Holder behind the Accessory Bracket is a....

(Warning - Rated ARRRRR)


...but found a easier way that worked for me. 0:)>:) With Hand access a BIG need and being able to see, I just removed a few (easy to remove) items. In a nutshell while it's still fresh in the ole memory bank.

* removed the Belt, Tensioner, Alty, Balancer Pulley (NOT the Hub), Starter and removed the Trans Line Holder (1 - 10mm Bolt) on the Bottom of the Accessory Bracket and pushed the lines toward the frame and tie wrapped them to "something?" to hold them over.

* Unplugged all of the Spark Plug boots and unclip the GM clips/lids and just pulled all 4 OLD wires out from the Front toward the rad.

* Used a marker to put numbers 2, 4, 6, 8 on BOTH ends of each wire to keep them straight when installing on the opti.

* Laying under the car, looking toward the engine, just feed/pushed each wire (plug end first) thru the Accessory bracket and up over the AC Compressor and just let them lay there. Having the Wheel removed for access into the Wheel Well area too.

* Now onto that "M**********R" GM Wire Holder. I found it a lot easier to loosen the Bolt at the Front of the Block and let the Wire Holder drop down a few inches. If you already connected the bottom 2 wires to the Opti, you'll need to remove those to get to the Bolt. Sooooo much easier to get 4 wires installed and get the Clip/Lid on. MAKE SURE the #2 wire which is pretty short, may need to be feed it back up over the AC Compressor. Then pushed the wire holder up while pushing the 4 wires over the AC Compressor and toward the back of the engine to the length they need to be. These Taylor Wires were Spot On in length and fit perfect. Then just tighten down the Holder Bolt.

* Then pretty much PnP and there are plenty of pics for the firing order.

* reverse install, Cross Fingers and Turn the Key all is hooked up right. :grin2:
 

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Discussion Starter #17
got it altogether and she fired right up and seems to be running normal again. I still have to swap the coil with the new ICM and see if the ICM got fried from the MSD coil. I'll do that later this week....didn't want to do too much at once and be chasing failure later.
 

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Relief. Always gratifying as well, hearing of another's successful PITA wire job. ;) Yours is pretty much my attack plan, with exception of not having ever removed the starter or trans line holder, or messing with the PS bracket. There are so few wire connection points (at least compared to the DS) that I just load up with good light and budget 15 minutes NOT snapping any of the affected keepers. But agree getting that alternator and its brackets out of the way sure helps.


BTW IDK if I were just too busy when that show was on or just didn't buy that station, but never got into it. But neat vid, and here's one caught my eye with similar themed title:
 

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Discussion Starter #19
Californication was on Showtime and think it ran about 7 Season's. Just love the unfiltered Hank Moody (Duchovny) on that show and his "don't give a crap" persona. I remember that "Biting Elbows" POV video and believe that's the same group that did the HardCore Henry movie....at least it seems like the same Genre. Never saw HC Henry though as I don't think I could sit thru 90 min of that POV stuff.

Anyway, back to the car. So I spoke a little too soon. While with the old wires (1 was dead) the car was maybe running at 75%. It would drive ok but as the trans would shift to the next gear and keeping steady throttle (under load) it would shake and seem under power until I gave it more throttle.

Now with new wires, it is much better but something is still not right. I'd say she's at about 90-95% power wise but still noticing slight hesitation and shake under the same "Load" type of driving. Again, no where near as bad as before, just not 100% right.

This all started when I suspect the MSD coil took out the ICM. I got a new ICM but think that coil took out the new ICM. I have a spare ICM/COIL from another motor that was sitting on the shelf for years and just threw that on there. I'm still going to replace the MSD coil with a Delco I just got and try the new GM ICM to see if it's actually toast. If it is, then I'll move that coil over to my spare setup to see if maybe the coil is weak and the old ICM good.

Just not sure what else it could be unless I mixed up wires on the driver side but think that would be pretty evident if the wires were wrong. Just driving me a little crazy trying to figure out this issue on a car that basically sat for about 8 months due to a fried ICM and now has these weird issues. I have a laptop and a cable just have not got the Scan software installed yet and tried this out. Maybe that may help diagnose the issue. Any ideas or how else to diagnose a problem like this?
 

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Discussion Starter #20
It looks like I cleared up my Coil/ICM issue and may have another area causing this "driveability" issue. I'll post up a new thread around this specific issue to see what other opins are.
 
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