2015 Nissan Versa Note 1.6 fries #4 coil
Friends,
There may be some kind of a mis-triggering event, in my opinion, on this Nissan as it has toasted four coils, all on cylinder #4 and in a very short length of time. After replacing the coil there is no misfire. It has only a P0304 code when it toasts the coil.
Ray Yergeau has one known-good waveform on IATN. Though these don't exactly match his waveform as far as highs and lows on the two cams, I've got no cmp codes of any kind so I'm reluctant to say that's a problem. The history on the vehicle is unknown at present. Any thoughts? I'm doubtful the transistor would “latch” in the “on” condition so I'm putting a bad ECM down the list of likely causes. A shorting wire could cause it but there is no obvious signs of wire damage.
Check your engine grounds. Several years ago I got a Nissan in the shop that melted a coil several times. After another shop replaced the coils multiple times, plugs and a PCM I found the ground from engine to radiator support disconnected. Seems the radiator was replaced and that little ground strap was never re-installed. .
felipe jay is correct ..same here I had seen this issue with a bad ground before check your grounds im sure u will find a bad one hope it helps .. I remember I had like 1 v drop on the groundd or less so ddint really aim at that direction quickly
Agree with the others. On this engine check V drop on the coil ground. Use your scope to check it. Also could have a slightly restricted injector causing it be lean in the cylinder stressing the coil.
If the ground doesn't pan out, check your CKP/CMP waveforms closely. I had a Chrysler 3.3 that would melt one coil out of the three on the coil pack. Chrysler's of that era had "windows" in their flywheels that triggered the CKP. This one had a slight dent in it from a recent trans overhaul. The dent was slight enough that depending on how expanded or contracted everything was from engine heat…
Tom, that's where I was going with the waveform, and specifically because of the same experience as you with mis-triggering caused by a faulty input. I'm having trouble connecting the dots with a ground-side volt drop increasing current flow. Voltage drop by definition is going to reduce, not increase current flow, and why always the same coil? Would that not affect all four coils equally, if it…
In my particular case (a V-6) there were three sets of four windows on the flexplate for the CKP to see, but only ONE set had the dent near it. It appeared to me that in my case the computer was only confused PART of the time during crank rotation, and at that point of confusion it just elected to do nothing with the coil that was due to be fired, because it didn't see what it was told to look…
You could check the coil signal from the PCM, and see if it's holding the coil on too long when compared to others. Also, make sure it's OEM coils, and not some el-cheapo AM piece. Nissans have ben fussy for years when it comes to coils. I've had several where the AM coils would cause a no-start, even after replacing only one coil… If the signal is grounded, the coil will not fire. If the…
Tim- I agree a broken ground would inhibit current flow and not burn up a coil. A loose ground on the other hand…..disaster. BTDT diag.net/msg/m6rjifpcu6…
Very similar to the BMWs that fry the ECM when the coil grounds are loose, or left off…
Hey, Tim, my thoughts as well. I have not scoped the trigger signal as I'm anticipating I will see it's turning the coil on too early. If it turned it off late, I ought to have a misfire right away as the timing would be off. Coils used have been Hitachi (which I think but am not sure is OE) and Napa Echlin which is typically a reliable brand on coils, anyway, in my experience. The fact that…
Phil- The on/off is handled by the coil itself. The PCM only sends the command. The coil itself is the actual controller. If the PCM commands off( the trigger signal) that doesn't mean the coil will turn off, particularly if it's malfunctioning.
Phillip- see my reply to Tim. My experience with this issue is in the comments section of Bernies case study I linked.
Interesting case for sure. Similar to my above post where a seemingly unrelated ground put enough drop on the circuit to cause overheating and eventually melting the coil.
Not dismissing the ground problem as a possibility Jay, but I think you will agree that it would have to be confusing the PCM causing it to modify the dwell/timing signal as a volt drop on a ground should REDUCE current flow, not increase it, and it seems pretty strange that it would always affect a single cylinder. Stranger things have happened. I'm just very puzzle that there is apparently no…
Confirm signal wire not shorting to ground somewhere on the harness. Had a Ford 3.0 that the coil harness rubbed through on VC bolt with extended pin (unused - did not have plastic retainer covering it)
Agree. It’s been a few years so I’m fuzzy on the exact details but it was only one coil melting(not sure of cylinder) and no misfire until coil failed.
Flip the cops, and see if there is an OEM one on the vehicle, and use it, instead of the AM replacement. You're only gonna have a few minutes (from what you say, I'm assuming you would be ready to catch it) to get results. And, then you're shutting it down. But, if it's happening immediately, the scope shot should tell all. A temp gun aimed at the coil can be real helpful to save it from…
I have to modify this as I have now found out the melted coils were happening on both 3 and 4. I'm still confounded somewhat as to the loose ground but am guessing that under certain conditions, perhaps charging system current might have been finding its was to the coil ground, though I'm baffled as to how, and why it cannot be seen on a current probe test.
Hi Phil, Sharing a thought, the ECM will typically modify coil dwell time upward if it believes that the system voltage is low. So theoretically, if the ECM‘s sensed supply voltage is far less that what the actual supply voltage is at the coils, you could end up with overheated coils.
I was thinking the same thing, Scott. However, I can't see any difference in the waveforms before and after tightening the ground wire. Just to be sure I had no other volt drops, I scoped the coil ground and the engine block ground after the strap was tightened. They are good (attached). My thought is that perhaps while the car was being driven, something was happening to the dwell which I…
I'd want to log the Control Module Voltage PID while the vehicle was in operation to see if we're on the right track or not.
Sort of, but since this takes some time to manifest, I was proposing a long data recording (I see I wasn't really clear on that) to see if indeed the supply voltage was indicating a problem or not. I see that he found a loose body to engine ground strap so I'll wait and see if the problems resurface. Monitoring that PID while other loads cycled on and off (fans, lights etc) when the ground was…
Scott How would a long data recording change anything? The engine was misfiring at the voltage you see, right from startup. Are you suggesting that the PCM is using a learned voltage memory for adjusting dwell time? Not quite sure what you're looking for. There are some questions concerning coil control left to be answered and I've already made rough notes on how to do it and illustrate it…
Are you saying that this recording included the time from start up with a new coil until it melted?
Nope. There are seven frames with the full global (applicable) PID list, so a rough amount of time on the screen is maybe 1-2 minutes. I would say it is unwise to monitor voltages and wait to burn up one or more coils to prove a theorized fault. We could drive it around and look for voltage changes, but why not just test the theory? After all, we all know how “intermittent” stuff is and how…
Lower voltage=lower current/dissipated heat … lower current +longer On time = no net energy difference??? Ohm’s law??
Yes, understood. However, if the available coil supply energy was greater than what the ECM thought it was, the ECM would increase the dwell time to compensate. This could lead to an overheated coil.
Yep get that. So in that case we’d b looking for resistance in the PCM Voltage sense circuit giving false info on system V, and from the response of longer dwell commanded at the coil we could see an overheat condition … theory is great Scott .. one to keep in mind. Thank u! … back to this specific case, we have no indication I believe of an under Voltage report to PCM leading to increased dwell…
Alex It is about heat rise in the coil, not heat from the current.
Phil- as I mentioned earlier, actual coil on/off is handled by the coil itself.(power and ground are constant and it has a built in transistor) In this capture, the red trace is the trigger and the yellow trace are the coils. As you can see from the 9A peak, thats when the PCM is commanding the coils to fire, the “humps” in between those peaks are the coils still firing, even though there is…
Rudy as I mentioned earlier, actual coil on/off is handled by the coil itself.(power and ground are constant and it has a built in transistor) Your capture shows the PCM controlling dwell time. What you see in the coil, is the power-stage which is controlled by the PCM. Very common control which Phil is very aware of. His concern is that excessive heat is being generated from excess dwell time…
You had time to respond Phillip, have you checked the V drop yet ?? lol jk.
I know, it was a joke lol. Although I now see the name says Phil's Probes. I can only assume this is the inventor of the tool sold by aeswave. I'm sure he is busy.
Yep, he invented the probes. I have a couple and like them. I don't want to embarrass him, but when he's not out teaching classes, he's seemingly always at a shop somewhere helping someone. I don't know where he gets the energy :-)
Hey Jim what scan data should he be looking at to diagnose this?…
Come on Rudy… I have never said that all one needs is scan data. I posted but one example of how I was using a scope over 20 years ago. Do you need more? I got them, but you will need a sub. I used them judiciously on systems far more difficult than what you face today without an internet help line. I bought an FW Bell current probe when they came out and had to travel to a printing store to…
What is your point Rudy? How about doing the work of making a coherent argument for your position, innuendo takes no thought. Otherwise you've just added noise to an important topic. BTW, would you have been interested in the mode 6 data? Or can you access it with your scope?
Just for my benefit and education, I can see how a bad ground might cause a cyl specific misfire if it were the ground for that cyl … ie low current and poor coil field build followed by poor/insufficient spark. However, I'm not seeing how that leads to multiple coil meltdowns on same coil??? Happy to be told;-)
It can happen if the ground path is only ‘mildly’ interrupted, causing a voltage that is too high in other parts of the circuit, especially if they all share a ground, or feed…it can instantly fry a module certainly, and cause slow-motion fails on other circuits.
The ground that I found in my situation was not specific to the ignition. It was the ground strap from radiator support to engine. I have to assume it was affecting multiple circuits but manifested in the melting of one coil Causing the customer concern when the coil melted.
Jay- My scenario was the same. The coil specific grounds were fine, but the ground on my core support was causing misfiring and my coils to melt….
Not uncommon with a ground fault. You power a circuit with a failed ground and it may find another ground path through another circuit/component to it's ground. i.e. turn signal ground is bad and you flip on turn signal and both turn signal dash display lights illuminate along with outside lamps. Hope this makes sense.
Honestly it just fascinates me the way this can happen … so that suggests to me that the coil gets fried not by its normal on/off current but by some predatory back feed current from some other component/s looking for a ground and finding it at least partially somehow thru a coil primary???? … If I were looking for a source I’d probably start with starter current and a body strap … just what u…
Well, Jay, Rudy, take a look at my video and you will see that it was indeed a problem. (Update: Having trouble uploading the video. I think I have to compress it.) I'm having to assume too, as I can't quite connect the dots. It also troubles me that at idle the coil current draw is so high at 12.5 to 13 amps. The AM coil that I used on #4 draws less amps and runs cooler. See related photos…
Phil- in your uploads, am I correct in assuming picture #4 is with a loose ground?
Trace 1 , amp clamp the power feed to all coils ( 20 amp scale ). Trace 2 ,trigger signal to coil 4. Trace 3 power to coil 4 . Trace 4, ground for coil 4 ( use 2 volt scale). You will get direction from 1 of these. You could also do a resistance check on the spark plug from the top to the center electrode. HTH
Here's a few Pico files if anyone is interested. I'm withholding judgement at present as I'm not positive the problem is solved, but initial results are encouraging. No melting yet. Latest coil installed is an Napa Echlin made by SMP.
Philip, In summary, what did you find as root cause? I understand you're not positive the problem is solved.
Hopefully, it was the loose ground strap. I can't exactly connect the dots but perhaps if I had driven the car with the scope attached I would have seen increased dwell. It was also suspicious that the coil power wire fuse had been changed from a 15 to 20 amp fuse, lending the idea that someone had previously found a blown fuse and “fixed” it by upping the amperage. It bothers me that the coils…
I must be dumb. I did not read which ground strap you found loose and tightened.
You are not dumb; this thread just got too long. Here's the video:
Does this car have the ground from the battery to body? Or does the main negative cable go to engine and this strap is the main engine ground? In your opinion would adding a secondary Ignition trace matter? compared to many here I’m a scope novice so maybe you can see something in the patterns provided that would make That redundant
Jay, there is no way to get a secondary pattern other than using a paddle on top of the coil, and that doesn't work too good with a module in the way. I didn't check where the negative cable from the battery connected. It may have been just to the body, which would add to the importance of the strap between the core support and the engine. It is strange that there were no other symptoms such as…
Dang, I wish I had looked at the negative cable, but I would bet it is on F16 (lower left rear of the block) along with the coil ground. I used the coil ground for my testing.
Phil- My Hitachi coils on my problem car ('17 Versa)were at 9A. One Import Direct coil was 13A. I swapped it out before I let the car go as I didn't trust it.
So… the F5 ground loose at RF engine (from rad core support). Ground diagram shows that F5 defined as alternator ground. Alt schematic shows alt control wire (pin 4) to ECM. ECM ground E15. This is the likely ground path for the alt if F5 was not good. Coils use ground F16 linked to F59. If schematics are accurate, you could load the alt and see if ground current changes significantly on E15 and…
All If you were working on this in the sun, dizzy from the sweltering heat, and using what is probably a 20 year old low end amp probe, what would you think of this waveform? Others captures were clean. I was thinking my probe was junk. Somehow I managed to pack the wrong probe :-) [edit] At the time it had a dead coil and ran like any other 4 banger with a dead cylinder.
My guess is people who regularly use a scope would recognize something is amiss in the circuit.( I regularly scope coils 4 or 5 times a week) I certainly did when I saw a similar capture on my problem vehicle. I didn't know exactly what the issue was, but I was fairly certain it wasn't the PCM.( because there was no change in dwell time) I was thinking it was some type of charging system…
from that waveform? I would think you had three different brands of coil that work, and one that doesn't. :-)
Hi Geoff To save time I'm going to wrap up multiple comments into one. I will be away for a while due to a procedure that I will be undergoing soon. So some of what I'm writing is addressing others points. Hope that is ok. It doesn't take everyday use of a scope to know what the possibilities are. Current anomalies in the circuit, external noise induced into the probe, or an internal probe…
Best of luck with the procedure, Jim. I have near zero experience with the old ignition scoping but with ignition and underutilized scan tool combined into one thought, I wonder how many guys take the car out of closed loop and/or use the add/subtract fuel functions while scoping sec. ignition patterns.
I miss having an ignition scope in the shop. I have all the leads to set it up on my scope but the two shops I work for keep me jumping around like a triage tech so I don’t get to “play” with it enough to get comfortable using as much as I should. And like this versa many cars it isn’t practical anyway. Ease of set up is a requirement for me And often, unfortunately with situations like this the…
Prayers for a successful procedure and quick healthy recovery Jim. Ground issues are likely some of the most elusive electrical issues a tech will deal with. Having a BSEE degree and 45 years experience has surely helped me. We often forget that the current has to exit the ground side not just come from a supply. If ground circuit F5 primarily supports the alternator, where does the alt find a…
Friends, I don't understand it, but the tightening of the ground strap between the cylinder head and the body/radiator support seems to have cured the coil burning. The customer has reported back that the vehicle is running well. The replacement coil is aftermarket and draws less current that the OE coils, runs 20 degrees cooler, but none of it explains what the relationship is between the body…
Philip, if you remove the ground from a component/load where does the current go that is being supplied? The answer will help you better understand your coil issue. Copied from above. If ground circuit F5 primarily supports the alternator, where does the alt find a ground path if F5 is loose/bad? The amount of current that the alternator ground path supports is more than most components under…
Hi Ted Philip, if you remove the ground from a component/load where does the current go that is being supplied? The answer will help you better understand your coil issue. I don't see that answering the question. If the current is still being provided, how does it increase through the windings and create heat? Here is how it was explained to me by an engineer who is involved with coil design…
Jim, it im not mistaken you mentioned previously about looking at scan data as well. Is it possible for you to give an explanation on it? Or let us know what we could look for? Thank you so much ahead of time.
Angel It has been awhile, but I think my comment was about someone being concerned with system voltage over time and a “learned” correction (which I disagreed with). I believe most of our questions (concerning the ground) can be answered by reading articles on transformer heat and efficiency design.
Jim, I appreciate you sharing the engineers perspective. The question the engineer answered is not the question being dealt with here. The coil ground is not the root cause of the coils melting. It is apparently the alternator ground (F5) that is allowing alternator voltage/current to apparently back feed through the coils since it is not being sinked through it's own ground. I don't have data…
That makes more sense to me … but even so if the alternator ground path were backfeeding thru the coil windings and then thru the coil ground, the alt power/current would still be modulated by the coil on/off transistor and - barring an over voltage condition, which I don’t think is described here- the coils would power up and down as per normal but just with an alternate pwr supply????…
Ted I'm not following you on this, the coil primary circuits are open when not in dwell period. Primary amperage is pretty much the same before and after repairs. For those who commented earlier on amps and heat, increasing primary winding resistance increases heat transfer. (Ohms' law is not being violated) The F5 “alternator” ground is interesting since the case is ground zero. I've never…
After pulling up the schematics, it appears the ignition coils are grounded through grounds F16 and F59 on the back of the engine block. The engine block is grounded through the F4 connection at the alt to F5 body ground (found loose at the rad support). So… it could be low voltage across the coils causing the issue and NOT stray current trying to find a way to ground. Curious why only #4 burns…
Mine would burn #3 and #4. Never #1 or #2, which complicates the mystery.
“During operation, this will make the coil less efficient and create internal heating.” This a very interesting topic to me and to those who have stayed for the long haul. It’s the learning that matters… I think the phrase above from the engineer holds the clue and answer but needs better explanation. It was referring a “coil efficiency” affect under reduced current conditions due to high…
I got called to a shop today to diagnose a multiple melted coil issue. Coil #2 has been burnt multiple times. Today I went in, intakes taken apart for coil replacement. Load tested powers and grounds at coil. Trigger signal is not shorted to ground. Checked all 3 visible grounds I saw on inner fenders and the radiator one. Told him to put it all back together and ill test it then. I'm…
Mine was fixed by tightening the ground wire between the cylinder head and the radiator support. Go figure. I have no explanation but it worked.
Hello Phil and the rest reading on later. My vehicle in question was a 2016 Versa 1.6 that shop complained of burning up coil #2 multiple times. Asked if I could take a look at it. Everything I checked, checked out fine. Before this thread I didn't think an unrelated ground could cause an issue. I tested the ground F5 and will attach captures I took before and after. I thank you all for taking…
I must admit I’m struggling to understand the actually process by which a coil is fried … put me in the dumb basket, but surely any bad ground -while it may overheat the actual bad ground connection point - will affect the intended load by reducing current thereby reducing stress on the component, coil or whatever … has anyone ever heard of a bad ground blowing a headlight bulb as opposed to…
Good info Angel. Not clear how the Alt voltage drop impacted voltage potential across coils. Apart from coil current surge to ~10A in the beginning of the trace, it seemed to be the same as post repair of ~6A. I may have missed something. Would be interesting to see the voltage potential across coils from supply to coil ground with F5 loose/removed. Alex, I'll try to explain using a previous…
Thank you Ted, I can see why you choose an electrical engineering degree. It surely can be difficult to diagnose issues. I did not get a capture of the voltage feed to the coils or the ground directly at the coil. These captures we’re taken at first start up. I did a snap throttle towards the end to see if there would be any change and nothing. Shop owner states the car went 2 weeks without…