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This is what a cracked coil pack looks like and what it does when it's bad.

57K views 36 replies 23 participants last post by  agm 
#1 ·
I was troubleshooting an issue with the car and found that several of the coil packs were cracked. I read a post where some members were not sure where to look for the cracks and what it would look like if the coil was in fact bad. The cracks are typically under the rubber boots at the tip. Mine were cracked from the tip under the boot almost all the way up the entire post. If your coil is cracked the spark will exit the side instead of the end of the post and ground out like this. I hope this helps out a little.

 
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#3 ·
Wow talk about good timing...
I just recently went BPU and with the turbo's boosting 16lbs at WOT my car is "hiccuping" so to speak. I've never experienced misfiring, does this sound like misfiring?
I suspect its my coilpacks because they werent in the best shape when I got the car serviced last.
 
#19 ·
Same here...
 
#12 ·
Stefan i having the same issue but from 1000rpms to 2500 rpms .if you find out what was your problem please let me know ,i will do the same....Thanks.....Omar
 
#6 ·
Yes the car breaks up starting at 16psi and the powerband goes flat. At first i thought the tps was the culprit but after testing i have ruled that out and went to the ignition system. I wont have the new packs until tuesday but i am a betting this is my problem as i have checked for boost leaks and found only two vac leaks wich have been repaired. All six of mine are shot just like this one.
 
#10 ·
I chased a misfire issue for many months and even drug my car 1100 miles to TX with a hit or miss, literally. I finally found out what the problem was, cracked coil packs and it was arcing on the head causing major misfire issues. I put new coilpacks in the car and had no other issues. It sucks too because all those people in TX and nobody offered any advice to what was wrong with the car or offered to help. It was a miserable trip for me due to car issues.
 
#17 ·
Just an fyi for everyone who is thinking of buying new coil packs. I just purchased six new forecast coil packs for $311 shipped and they work great. The car starts and boosts better than before! The parts have a one year warranty as well! I got them from partsgeek.com and If you spend 299 or more put the code save15 in to save 15 bucks! I tried to buy the beck and arnelys first but they are backordered for at least two weeks. The total for them was 292 shipped and you saved 10 bucks with the code save10 on orders over 250! If these packs last 50,000 miles i would have no replacing them again. I know guys say oem phr .....but who wants packs on their car with 100k on them....! I would rather buy these and have new packs on the car at 50k rather than run them up to 100k plus it would take an eternity for most of us to put 50k on our rides anyhow!
 
#21 ·
Weird,

I am chasing a similar issue on a friend's car. Inconsistent and random misfire at idle and consistent misfire at 5700-6k RPM, if under boost. Coils have 50k miles on them and ohm out acceptable per TSRM.

DP
 
#22 ·
Did you check the coils when hot? My coils ohm'd out at 1.2ohms piece. I thought it was strange that all of the coils were dead even but all were out of spec. Its very easy to see the arc. Just do what i did.
 
#30 ·
Both my friends had visible cracks.

I am well aware of that issue and it proved no resolution.

This isn't my first waste-fire supra w/DLI I have worked on or built.
Pull timing from the map if on a stand alone. Im giving you ideas. Im not sure what you have done already.
 
#33 ·
I think the aggresive knock tune that my tuner did is what save the engine .I did a compression test and leak down yesterday and everything was perfect
cyl 1 155 psi 5% leak
cyl 2 154 psi 4% leak
cyl 3 156 psi 5% leak
cyl 4 154 psi 6% leak
cyl 5 154 psi 3% leak
cyl 6 154 psi 3% leak

cause i beat the shit out of the car with a slight misfired .I race some vettes,mustans and one big hp diesel truck (got beat by the truck from a dig ,i want a rematch now lol)
 
#37 ·
back when my car was BPU i had an issue with the o2 sensor and in trouble shooting i bought new coilpacks and connectors and my car drove and revved noticeably smoother and that wasnt even where my problem was.

everything went better than expected even though it didnt fix my misfire issue.

so in my opinion you simply cannot go wrong replacing coilpacks. if they are 16 years old, etc.
 
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