Let's play: Good Coil Pack, Bad Coil Pack
12-24-2008, 04:59 PM
#28
And the winner is...
Hymee 
After two days in the dealer shop, they thought that had it fixed. After the first day they said it would be the coil packs, and were going to replace them. Went back for the 2nd day, and they told me it was the MAF, and it had been fixed.
Result - Car wouldn't start. When I got it started it wouldn't run.
So I spent the next 1.5 hours helping them trace the fault and fix it.
In the end, you wouldn't believe what it was. One of the wires on the MAF sensor harness (loom plug side)was broken inside the insulation about 5 mm from the terminator. Depending on how the wire was sitting at the time, the MAF was sending the correct signal to the ECU. As soon as there was a itsy tinsy open circuit (or high resistance I guess) it would go high voltage on the MAF and the PCM would see that as more air = more load = dump in more fuel = way too rich = misfire.
The funning thing is that is the first thing (the MAF) I checked when I was diagnosing using my sCANalyser. I noticed when it was misfiring, the MAF was peaking, and reasoned that the sensor might be fouled with some contamination, causing the hot wire sensor to draw the wrong current. It works by trying to maintain a constant temperature on the hot wire. So I unplugged the MAF back then, pulled it out and cleaned it. Put it back in and it was all good. For a couple of weeks. So then I put a new MAF in from a buddy, and all was good again... for a couple more weeks.
So it was the wire going loose all the time!
I helped the guy splice a new short length of wire and another pin onto the loom, and now it is sweet. Thanks Mazda for fixing it for me.
Put that one down to experience!
Cheers,
Hymee.
After two days in the dealer shop, they thought that had it fixed. After the first day they said it would be the coil packs, and were going to replace them. Went back for the 2nd day, and they told me it was the MAF, and it had been fixed.
Result - Car wouldn't start. When I got it started it wouldn't run.
So I spent the next 1.5 hours helping them trace the fault and fix it.
In the end, you wouldn't believe what it was. One of the wires on the MAF sensor harness (loom plug side)was broken inside the insulation about 5 mm from the terminator. Depending on how the wire was sitting at the time, the MAF was sending the correct signal to the ECU. As soon as there was a itsy tinsy open circuit (or high resistance I guess) it would go high voltage on the MAF and the PCM would see that as more air = more load = dump in more fuel = way too rich = misfire.
The funning thing is that is the first thing (the MAF) I checked when I was diagnosing using my sCANalyser. I noticed when it was misfiring, the MAF was peaking, and reasoned that the sensor might be fouled with some contamination, causing the hot wire sensor to draw the wrong current. It works by trying to maintain a constant temperature on the hot wire. So I unplugged the MAF back then, pulled it out and cleaned it. Put it back in and it was all good. For a couple of weeks. So then I put a new MAF in from a buddy, and all was good again... for a couple more weeks.
So it was the wire going loose all the time!
I helped the guy splice a new short length of wire and another pin onto the loom, and now it is sweet. Thanks Mazda for fixing it for me.
Put that one down to experience!
Cheers,
Hymee.
12-24-2008, 05:04 PM
#30
Those are the ugliest kind of electrical gremlins to trace 
I have run whole bypasses around the harness to diagnose and fix a few things before. Never could see the fault on a scope..but a new wire fixed it...go figure
Engine compartments are not nice to wiring harnesses.....
I have run whole bypasses around the harness to diagnose and fix a few things before. Never could see the fault on a scope..but a new wire fixed it...go figure
Engine compartments are not nice to wiring harnesses.....
02-20-2009, 03:35 PM
#31
:( traded in my 8
This sounds similar to the problem I 'think' I have with the harness that plugs into my Throttle Body.. Thanks for the ideas...
mkztg
mkztg
Those are the ugliest kind of electrical gremlins to trace
I have run whole bypasses around the harness to diagnose and fix a few things before. Never could see the fault on a scope..but a new wire fixed it...go figure
Engine compartments are not nice to wiring harnesses.....
I have run whole bypasses around the harness to diagnose and fix a few things before. Never could see the fault on a scope..but a new wire fixed it...go figure
Engine compartments are not nice to wiring harnesses.....
02-20-2009, 06:28 PM
#32
Certified Mazda Tech
just as a random sidenote, i didnt read the whole topic, scanned it and just wanted to add in case it was missed, mazda no longer declares the white spot as a sign of coil failure. They've determined it as normal, and it's true ive seen perfectly working coils with massive white spots.
The only real way to know is to hook up a signal sensor of some type to it and watch as it fires.
kevin.
The only real way to know is to hook up a signal sensor of some type to it and watch as it fires.
kevin.
02-26-2009, 05:45 AM
#33
I don't buy Kool-Aid
Hymee
After two days in the dealer shop, they thought that had it fixed. After the first day they said it would be the coil packs, and were going to replace them. Went back for the 2nd day, and they told me it was the MAF, and it had been fixed.
Result - Car wouldn't start. When I got it started it wouldn't run.
So I spent the next 1.5 hours helping them trace the fault and fix it.
In the end, you wouldn't believe what it was. One of the wires on the MAF sensor harness (loom plug side)was broken inside the insulation about 5 mm from the terminator. Depending on how the wire was sitting at the time, the MAF was sending the correct signal to the ECU. As soon as there was a itsy tinsy open circuit (or high resistance I guess) it would go high voltage on the MAF and the PCM would see that as more air = more load = dump in more fuel = way too rich = misfire.
The funning thing is that is the first thing (the MAF) I checked when I was diagnosing using my sCANalyser. I noticed when it was misfiring, the MAF was peaking, and reasoned that the sensor might be fouled with some contamination, causing the hot wire sensor to draw the wrong current. It works by trying to maintain a constant temperature on the hot wire. So I unplugged the MAF back then, pulled it out and cleaned it. Put it back in and it was all good. For a couple of weeks. So then I put a new MAF in from a buddy, and all was good again... for a couple more weeks.
So it was the wire going loose all the time!
I helped the guy splice a new short length of wire and another pin onto the loom, and now it is sweet. Thanks Mazda for fixing it for me.
Put that one down to experience!
Cheers,
Hymee.
After two days in the dealer shop, they thought that had it fixed. After the first day they said it would be the coil packs, and were going to replace them. Went back for the 2nd day, and they told me it was the MAF, and it had been fixed.
Result - Car wouldn't start. When I got it started it wouldn't run.
So I spent the next 1.5 hours helping them trace the fault and fix it.
In the end, you wouldn't believe what it was. One of the wires on the MAF sensor harness (loom plug side)was broken inside the insulation about 5 mm from the terminator. Depending on how the wire was sitting at the time, the MAF was sending the correct signal to the ECU. As soon as there was a itsy tinsy open circuit (or high resistance I guess) it would go high voltage on the MAF and the PCM would see that as more air = more load = dump in more fuel = way too rich = misfire.
The funning thing is that is the first thing (the MAF) I checked when I was diagnosing using my sCANalyser. I noticed when it was misfiring, the MAF was peaking, and reasoned that the sensor might be fouled with some contamination, causing the hot wire sensor to draw the wrong current. It works by trying to maintain a constant temperature on the hot wire. So I unplugged the MAF back then, pulled it out and cleaned it. Put it back in and it was all good. For a couple of weeks. So then I put a new MAF in from a buddy, and all was good again... for a couple more weeks.
So it was the wire going loose all the time!
I helped the guy splice a new short length of wire and another pin onto the loom, and now it is sweet. Thanks Mazda for fixing it for me.
Put that one down to experience!
Cheers,
Hymee.
You know a few years back abbid had a issue with his maf. As I recall someone on here bought him one lol anyway if I recall right he had to replace the wires too.
I'm going to take a look at mine as I tend to clean it about ever month. After all its a desert out here.
02-26-2009, 05:46 AM
#34
I don't buy Kool-Aid
just as a random sidenote, i didnt read the whole topic, scanned it and just wanted to add in case it was missed, mazda no longer declares the white spot as a sign of coil failure. They've determined it as normal, and it's true ive seen perfectly working coils with massive white spots.
The only real way to know is to hook up a signal sensor of some type to it and watch as it fires.
kevin.
The only real way to know is to hook up a signal sensor of some type to it and watch as it fires.
kevin.
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