Coil pack
Thread Starter
Teching In
Joined: Jun 2006
Posts: 44
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From: Houston
Car Was missing, stalling out and was also backfiring at low rpms as wells as high so i put a scanner on it all the sensors looked normal except the car was running rich. I also noticed that cylinder 1 and 3 were misfiring the most. 3 was missing the most. So I pulled off the coil pack on 3 and tested the resistance and it was 74.4 ohms. I pulled all the rest of the coil packs off and tested them they were all geting close to 70 ohms except for cylinder 2s coil pack which was 59.7. I bought 2 new coil packs and tested them they both read 57.4 ohms. I replaced 1 and 3 with the new coil packs after i did this i started the car up I noticed the difference right away the engine had stoped shaking around and the car was almost idling like it usualy does. I took the car for a test drive and noticed that there was no longer any backfires at all in the low rpms. The only time the car backfires now is under really heavy load like when i tired to floor it. I also noticed that the car dosnt want to die at stoplights anymore do you guys think i should go ahead and replace the rest of the coil packs since they were all really close to the ohms resistance of the cylinder that was missing the most? Oh and sparkplugs and wires are brand new so thats not it.
Originally Posted by BigFrosty
Car Was missing, stalling out and was also backfiring at low rpms as wells as high so i put a scanner on it all the sensors looked normal except the car was running rich. I also noticed that cylinder 1 and 3 were misfiring the most. 3 was missing the most. So I pulled off the coil pack on 3 and tested the resistance and it was 74.4 ohms. I pulled all the rest of the coil packs off and tested them they were all geting close to 70 ohms except for cylinder 2s coil pack which was 59.7. I bought 2 new coil packs and tested them they both read 57.4 ohms. I replaced 1 and 3 with the new coil packs after i did this i started the car up I noticed the difference right away the engine had stoped shaking around and the car was almost idling like it usualy does. I took the car for a test drive and noticed that there was no longer any backfires at all in the low rpms. The only time the car backfires now is under really heavy load like when i tired to floor it. I also noticed that the car dosnt want to die at stoplights anymore do you guys think i should go ahead and replace the rest of the coil packs since they were all really close to the ohms resistance of the cylinder that was missing the most? Oh and sparkplugs and wires are brand new so thats not it.
Next thing "plugs and wires are new so thats not it". New aint good. Especially if you just changed them, and now you got a problem. There's too many possibilities of a plug wire not on all the way, a cracked plug, etc to blame it on the coils. Besides, what terminals are you ohming across to get your readings? If you know what terminals to check across, why dont you know what the resistance should be?
And what in the scan data told you the car was running rich?
And what would lead you to believe that bad coils would make it run rich?
Thread Starter
Teching In
Joined: Jun 2006
Posts: 44
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From: Houston
I tried to go to the dealer they didnt even kno the specs. And about pluges and wires the problem was goin on before i changed plugs and wires and was still there after no change at all. But when i changed the two coil packs it made a huge diff i couldnt even make it down the street before. Now after i changed them the car almost feels like normal except under heavy load then it backfires. Oh and it was a snap on scanner i used i think its the coils because its not the plugs or the wires and there is unburned fuel goin into the exhaust causing backfires which would explain the rich condition and would point to not enough spark to burn the fuel.
Last edited by BigFrosty; Feb 18, 2007 at 04:04 PM.
I would say with confidence your problem is not coil related. Like I said before, do you even know what terminals to check the resistance across? That being said, testing primary or secondary resistance really will only tell you something if the coil is either open or shorted. You are barking up the wrong tree.
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Originally Posted by BigFrosty
I tried to go to the dealer they didnt even kno the specs. And about pluges and wires the problem was goin on before i changed plugs and wires and was still there after no change at all. But when i changed the two coil packs it made a huge diff i couldnt even make it down the street before. Now after i changed them the car almost feels like normal except under heavy load then it backfires. Oh and it was a snap on scanner i used i think its the coils because its not the plugs or the wires and there is unburned fuel goin into the exhaust causing backfires which would explain the rich condition and would point to not enough spark to burn the fuel.
Just as a side note, I NEVER check coil resistance. Using an oscilloscope, I can "see" if a coil is bad.
And, a misfire, and unburned fuel in the exhaust is NOT a rich condition.
A misfire and unburned fuel in the exhaust elevates the hydrocarbon levels, but not CO (carbon monoxide). "Rich" by definition is high CO, caused by an A/F mixture numerically lower than 14.7:1.
Elevated levels of HC is NOT a rich condition. It is more in line with a lean miss. You cannot, with your scanner,tell if its a rich condition.
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Originally Posted by BigFrosty
I guess i could take the new coil packs back then what if i take them off and it starts acting like it did before i put them on?
Most of this stuff is beyond the capability of even the best do-it-yourselfers.
No offense, but it takes real training and expensive equipment to diagnose and repair something like this quickly and effectively. Something that may have you totally stumped, I can probably find in minutes flat. Not braggin, thats just the way it is.
Thread Starter
Teching In
Joined: Jun 2006
Posts: 44
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From: Houston
Yea i took it to HPE and the guy told me the same thing to try changing the coil packs. He hooked a scanner up to my car aswell and looked a the sensors for awhile and didnt find anything out of the ordinary. Also my teacher told me to try changing the coil packs after we showed him the data from the scanner and told him what the car was doing. So i did what they said but i only changed 2 of them and it made a huge difference. 2morrow when i go to conleys ill see what the scanner says now and see if they cylinders i replaced the coil packs on are still misfiring.
Originally Posted by BigFrosty
Yea i took it to HPE and the guy told me the same thing to try changing the coil packs. He hooked a scanner up to my car aswell and looked a the sensors for awhile and didnt find anything out of the ordinary. Also my teacher told me to try changing the coil packs after we showed him the data from the scanner and told him what the car was doing. So i did what they said but i only changed 2 of them and it made a huge difference. 2morrow when i go to conleys ill see what the scanner says now and see if they cylinders i replaced the coil packs on are still misfiring.
To properly diagnose a coil problem, or any ignition problem for that matter, you need to use an OSCILLOSCPOE. Anything else is a guess.
If your teacher is teaching you to randomly change parts without a proven DIAGNOSTIC STRATEGY, perhaps he needs a teacher!!!
Ask him if he knows how to use/read an oscilloscope. Ask him what he sees, doesnt see in the scan data that leads him to faulty coil packs.
Thread Starter
Teching In
Joined: Jun 2006
Posts: 44
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From: Houston
There is virtually nothing in scan data to lead you to faulty coil packs. With the exception of an open coil driver circuit code. And even that can be caused by an open in the wiring. The only thing scan data will show you is a misfire code. And that can be caused by a coil problem, or a plug problem, or a wire problem, or an injector flow problem, or a compression problem. See where I'm going with this?
To properly diagnose a coil problem, or any ignition problem for that matter, you need to use an OSCILLOSCPOE. Anything else is a guess.
If your teacher is teaching you to randomly change parts without a proven DIAGNOSTIC STRATEGY, perhaps he needs a teacher!!!
Ask him if he knows how to use/read an oscilloscope. Ask him what he sees, doesnt see in the scan data that leads him to faulty coil packs.
To properly diagnose a coil problem, or any ignition problem for that matter, you need to use an OSCILLOSCPOE. Anything else is a guess.
If your teacher is teaching you to randomly change parts without a proven DIAGNOSTIC STRATEGY, perhaps he needs a teacher!!!
Ask him if he knows how to use/read an oscilloscope. Ask him what he sees, doesnt see in the scan data that leads him to faulty coil packs.
Last edited by BigFrosty; Feb 19, 2007 at 06:16 PM.
TECH Enthusiast
Joined: Mar 2004
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From: Australia
Originally Posted by BigFrosty
Dude thx for nothing Mr.years of experience the car is back to normal the misses are gone thx to the new coil packs WHICH WAS THE CAUSE OF THE MISFIRES! and the backfiring is gone thx to a repaired exhaust leak. And you dont need and osilloscope to find an ignition problem all that thing is is a DMM with a graph on it! That is only good if you need to see patternes of sensors.
You made an educated guess at the problem, and it worked. What he was stating was the CORRECT method. "All roads lead to Rome" as they say, and Im glad it worked out for you. However, you discredit this forum and its contributors with responses like this.
Did he say it WASN'T the cause? No. Did he say it was? Maybe.
Don't bother posting if you can't take the advice on offer, or...
You obviously have no clue what an oscilloscope is. And did you ever think the coils may have had a few bad connections? I have seen more electrical problems cured by UNPLUGGING AND PLUGGING STUFF BACK IN. just like you did with your COIL PACK REPLACEMENT. what do you think happened to cause several coils to go out, all at he same time?
A GRAPHING DMM IS A TOTALLY DIFFERENT TOOL. AND IF YOU DONT THINK USING A SCOPE IS THE PROPER WAY TO DIAGNOSE ANY ELECTRICAL PROBLEM, INCLUDING IGNITION SYSTEMS, GOOD LUCK IN SCHOOL.
For that matter, just unplugging and replugging the plug wires on and off the coils could have fixed it. You are nothing more than a PARTS CHANGER, and our occupation needs LESS OF YOU, NOT MORE. LEARN HOW TO DIAGNOSE.
AND TELL ME WHERE IN YOUR SCAN DATA YOU SAW BAD COILS
A GRAPHING DMM IS A TOTALLY DIFFERENT TOOL. AND IF YOU DONT THINK USING A SCOPE IS THE PROPER WAY TO DIAGNOSE ANY ELECTRICAL PROBLEM, INCLUDING IGNITION SYSTEMS, GOOD LUCK IN SCHOOL.
For that matter, just unplugging and replugging the plug wires on and off the coils could have fixed it. You are nothing more than a PARTS CHANGER, and our occupation needs LESS OF YOU, NOT MORE. LEARN HOW TO DIAGNOSE.
AND TELL ME WHERE IN YOUR SCAN DATA YOU SAW BAD COILS
Originally Posted by MNR-0
Steady on bloke! The advice offered is sound and free. You go pissing on it like he is useless or something.
You made an educated guess at the problem, and it worked. What he was stating was the CORRECT method. "All roads lead to Rome" as they say, and Im glad it worked out for you. However, you discredit this forum and its contributors with responses like this.
Did he say it WASN'T the cause? No. Did he say it was? Maybe.
Don't bother posting if you can't take the advice on offer, or...
You made an educated guess at the problem, and it worked. What he was stating was the CORRECT method. "All roads lead to Rome" as they say, and Im glad it worked out for you. However, you discredit this forum and its contributors with responses like this.
Did he say it WASN'T the cause? No. Did he say it was? Maybe.
Don't bother posting if you can't take the advice on offer, or...
Your Discredit For A Tool As Important As A Scope Is So Ignorant Its Unbelievable. You Really Have No Clue. A Scope Is One Of The Most Important Tools There Is. Far More Superior To A Scanner. The Ability To Use And Understand One Seperates Techs From Really Good Techs. Before You Qwack Off About What A Scope Is, Why Dont You Learn A Little About Them. Like Maybe How To Turn One On.
Thread Starter
Teching In
Joined: Jun 2006
Posts: 44
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From: Houston
I PROBABLY BEEN DOIN THIS STUFF SINCE HIS MOMMA WAS WASHIN HIM IN HE SINK.
Originally Posted by BigFrosty
Yea and you suck at it which is sad i never said the scanner said the coils were bad dooshbag. Whatever the cars back to normal and thats all i care about so you can keep posting on this thread for all i care have fun. Besides in a few years ill have your job anyway ur only geting older
AS FAR AS MY AGE, I CONTINUOSLY UPDATE MY EDUCATION, YOU SHOULD TRY THE SAME. MAYBE FIRST START WITH SIMPLE SPELLING LESSONS.
Thread Starter
Teching In
Joined: Jun 2006
Posts: 44
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From: Houston
Oh and another thing i never hated on the scope i just said its not needed to find igniton problems. Besides most Electrical problems can be solved witn a DMM and a good wiring diagram. I think your just blowing this way out of proportion im sry if this lil old lube tech made the MASTER TECH of ls1 tech mad.