MISFIRE

Hello Gents, I have a concern that's been plaguing me since I can remember. I've had this ever so slight misfire (around idle 800-1k RPM) it was bothering me but, not really as bad because it didn't affect performance. I recently replaced my MAF sensor not long ago . before shortly after (I think) I developed a CEL and it gave (I forgot what CODE) low input for my MAF. I have no idea how to troubleshoot that issue.. . Long story short. I have unhooked my battery and reset my CEL and it has yet to come back on but, I now have a misfire at around I wanna say mid RPM band (I lost a race against an F-150 from the dig and it sadden me)That misfire is not only annoying but, its somehow affecting my performance and shift points because I find myself having to hit the gas a little harder than usual (I usually NEVER go WOT because I don't find it necessary) and I feel like the car feels sluggish. Any input is GREATLY appreciated, as you guys have helped me more than you know it through these 3 yrs of owing my RIV!

A scan tool will tell you which cylinder(s) is misfiring. Start there. If it is 2 cylinders and they are companion cylinders (1-4, 2-5, 3-6), suspect that coil. Most misfires are bad wires and/or plugs.

Thanks for the quick response! When you say scan tool do you mean OBDII? Because at the moment my CEL is not illuminated. I had all AC DELCO PROFESSIONAL SERIES. Long story short two of my boots ripped off changing my plugs!! So, instead of buying those same wires I ended up buying a cheap replacement kit. But to me it seems the problem started when my MAF was going out and ever since that code was thrown (Low input P0102 I think thats the one) I get the misfire mid RPM and if I really get on it It doesn't affect the Lower range at all.

9ty7rivi wrote:

Thanks for the quick response! When you say scan tool do you mean OBDII? Because at the moment my CEL is not illuminated. I had all AC DELCO PROFESSIONAL SERIES. Long story short two of my boots ripped off changing my plugs!! So, instead of buying those same wires I ended up buying a cheap replacement kit. But to me it seems the problem started when my MAF was going out and ever since that code was thrown (Low input P0102 I think thats the one) I get the misfire mid RPM and if I really get on it It doesn't affect the Lower range at all.

Yes, the OBDII, you need a scan tool to read the misfire monitors. The computer will keep track of each cylinder and list how many misfires there are. If it happens often enough, it will light the CEL. Might just be those cheapo wires. Go to Autozone and let them scan the car. Find out which cylinders are misfiring. It will misfire when the load is high. Have you looked at the price of Delco wires? The Delphi set are 26.79.

http://www.rockauto.com/en/moreinfo.php?pk=1323689&cc=1022050&jsn=409

LARRY70GS wrote:

9ty7rivi wrote:

Thanks for the quick response! When you say scan tool do you mean OBDII? Because at the moment my CEL is not illuminated. I had all AC DELCO PROFESSIONAL SERIES. Long story short two of my boots ripped off changing my plugs!! So, instead of buying those same wires I ended up buying a cheap replacement kit. But to me it seems the problem started when my MAF was going out and ever since that code was thrown (Low input P0102 I think thats the one) I get the misfire mid RPM and if I really get on it It doesn't affect the Lower range at all.

Yes, the OBDII, you need a scan tool to read the misfire monitors.  The computer will keep track of each cylinder and list how many misfires there are.  If it happens often enough, it will light the CEL.  Might just be those cheapo wires.  Go to Autozone and let them scan the car.  Find out which cylinders are misfiring.  It will misfire when the load is high.  Have you looked at the price of Delco wires?  The Delphi set are 26.79.

http://www.rockauto.com/en/moreinfo.php?pk=1323689&cc=1022050&jsn=409

+1 on the wires.

Mismatched coils will also cause a misfire eventually, if you have an SC you have to be sure to get the SC coils, they look the same as the regular ones but they are not.

Thanks for all of the input. I honestly didn't think they were that cheap because I've always opted for the OEM option on just about everything I buy for the car. I purchased those wires 3 years ago when I first bought the car. Anyways, unfortunately I'm guilty of having mismatched coils and, could you please further explain on the coils difference between the coils (Albert)? I finally had my CEL come on right after I left work! I went and got it scanned and it indicated a vacuum leak (code P1441) and, said that it was either the canister purge solenoid or fuel tank pressure sensor. Is there a way to test and see if either is out? Again, any input is greatly appreciated! I've have invested plenty of money into this car and don't plan on letting it go anytime soon!

9ty7rivi wrote:

Thanks for all of the input. I honestly didn't think they were that cheap because I've always opted for the OEM option on just about everything I buy for the car. I purchased those wires 3 years ago when I first bought the car. Anyways, unfortunately I'm guilty of having mismatched coils and, could you please further explain on the coils difference between the coils (Albert)? I finally had my CEL come on right after I left work! I went and got it scanned and it indicated a vacuum leak (code P1441) and, said that it was either the canister purge solenoid or fuel tank pressure sensor. Is there a way to test and see if either is out? Again, any input is greatly appreciated! I've have invested plenty of money into this car and don't plan on letting it go anytime soon!

Good luck with that CEL.

The coils for the SC put out more power than the ones for NA. But many aftermarket suppliers say their coils wound for NA will work on SC engines. They are right, to a point. They put out different amounts of power (different spark intensity) and it is enough to tell. If everything else is good but coils are mismatched, the engine will lope a bit. If the mismatch is bad and/or there are other issues then you see the problem you have. Add to that any issues at all with the wires and you're kinda hosed.

I had a wire fail while traveling, and it made a coil fail (it was the #4 wire). Mechanic at a Firestore installed an aftermarket coil and instead of selling me a set of wires, told me to go buy an OE set and popped a wire on from his 'salvage' bin (off an SC Bonneville that was in earlier that week for wires, this was 1 of 2 salvageable ones on that car)-- he and the other mechanics at this particular Firestone moonlight from other local car dealers, at that Firestone they kept serviceable parts that people did not want for use in 'emergencies' so they could get other customer's cars on the road more effectively... what he said was my other wires tested good and they were not gonna sell me a set of wires to chase one, but I really should replace them all when I got around to it. Bottom line it was a Sunday and they got me on the road for a 300-mile drive, no CEL no issues...

I went to the GM dealer at home, after a couple-three weeks, bought new wires, put them on... What I thought I noticed was a slight lope at idle. I mean, you had to be OCD to make it out, although it was enough of a lope that you could not balance a nickel on my idling engine - you could get it to stand but it would fall after a few seconds. No big deal... However, on this board, I learned that used SC coils from a junkyard were a better choice than about anyone's aftermarket except maybe Denso, because the aftermarkets were almost all wound for the NA engines (not the other way around). So I used a meter to measure the primaries and secondaries of my coils. The new one did not match the other two. So I picked up a set of SC coils off a Park Ave that someone had junked. Maybe 105K miles on the engine or some such. Measured them at home, they matched the SC coils I already had. SO... I swapped one of the junkyard SC coils for the "new" one. Instantly, the Lope was GONE I mean it was a "so I am really not crazy" moment. And I then balanced a nickel on edge, on the idling engine (and still can).

What I learned is that the SC and NA coils really do, no kidding, put out different spark intensity and it really does make a difference.

albertj wrote:

9ty7rivi wrote:

Thanks for all of the input. I honestly didn't think they were that cheap because I've always opted for the OEM option on just about everything I buy for the car. I purchased those wires 3 years ago when I first bought the car. Anyways, unfortunately I'm guilty of having mismatched coils and, could you please further explain on the coils difference between the coils (Albert)? I finally had my CEL come on right after I left work! I went and got it scanned and it indicated a vacuum leak (code P1441) and, said that it was either the canister purge solenoid or fuel tank pressure sensor. Is there a way to test and see if either is out? Again, any input is greatly appreciated! I've have invested plenty of money into this car and don't plan on letting it go anytime soon!

Good luck with that CEL.

The coils for the SC put out more power than the ones for NA.  But many aftermarket suppliers say their coils wound for NA will work on SC engines.  They are right, to a point.  They put out different amounts of power (different spark intensity) and it is enough to tell.  If everything else is good but coils are mismatched, the engine will lope a bit.  If the mismatch is bad and/or there are other issues then you see the problem you have.  Add to that any issues at all with the wires and you're kinda hosed.

I had a wire fail while traveling, and it made a coil fail (it was the #4 wire).  Mechanic at a Firestore installed an aftermarket coil and instead of selling me a set of wires, told me to go buy an OE set and popped a wire on from his 'salvage' bin (off an SC Bonneville that was in earlier that week for wires, this was 1 of 2 salvageable ones on that car)-- he and the other mechanics at this particular Firestone moonlight from other local car dealers, at that Firestone they kept serviceable parts that people did not want for use in 'emergencies' so they could get other customer's cars on the road more effectively... what he said was my other wires tested good and they were not gonna sell me a set of wires to chase one, but I really should replace them all when I got around to it. Bottom line it was a Sunday and they got me on the road for a 300-mile drive, no CEL no issues...

I went to the GM dealer at home, after a couple-three weeks,  bought new wires, put them on... What I thought I noticed was a slight lope at idle.  I mean, you had to be OCD to make it out, although it was enough of a lope that you could not balance a nickel on my idling engine - you could get it to stand but it would fall after a few seconds.  No big deal...   However, on this board, I learned that used SC coils from a junkyard were a better choice than about anyone's aftermarket except maybe Denso, because the aftermarkets were almost all wound for the NA engines (not the other way around).  So I used a meter to measure the primaries and secondaries of my coils.  The new one did not match the other two.  So I picked up a set of SC coils off a Park Ave that someone had junked.  Maybe 105K miles on the engine or some such.  Measured them at home, they matched the SC coils I already had.  SO... I swapped one of the junkyard SC coils for the "new" one.  Instantly, the Lope was GONE I mean it was a "so I am really not crazy" moment.  And I then balanced a nickel on edge, on the idling engine (and still can).  

What I learned is that the SC and NA coils really do, no kidding, put out different spark intensity and it really does make a difference.

Tell me about it! It took a long time and money getting it off the first time. I had NO idea about the differences in the coil packs! That makes sense because before I changed one there motorwas smooth and, then after the first one I replaced I "thought" I noticed improvement in acceleration but, as time went on I too noticed a very faint "kick" at the idle  (OCD  ) and, also noticed my motor having the "shakes" still does! If that would solve my problem by charging the wires, coil packs and, finally get my AL104s I'll be more than ☺. I definitely appreciate a good story backing up ANY claim! on that note should I buy OEM or go with a junkyard?

Short answer: junkyard coils off an SC engine should be fine, just try to be sure they are OE -- look for the numbers printed on the tops that indicate which cylinder wire goes where.

Long answer: New or used as long as they are truly SC coils.  What I did was to buy all 3 (and the ignition module plate) from a nearby pick-n-pull.  They sold me the assembly for short money. I did well, all the coils tested good with a meter.  that's not always the case, point is just check with an ohmmeter to see that the resistances on the new-to-you coils match the resistances on your good SC coils.  If you are unsure, thing is you're OK if the junkyard coils match each other. Be sure to check BOTH primary and secondary, also check for primary-secondary shorts and/or leakage.   Context  -- Two of the 3 coil packs on my car are original, they have been in service for 19+ years over 330,000+ miles. The other one is a JY pull off a Park Avenue that had about 100 - 110 K miles at the time of the pull.

albertj wrote:

Short answer: junkyard coils off an SC engine should be fine, just try to be sure they are OE -- look for the numbers printed on the tops that indicate which cylinder wire goes where.

Long answer: New or used as long as they are truly SC coils.  What I did was to buy all 3 (and the ignition module plate) from a nearby pick-n-pull.  They sold me the assembly for short money. I did well, all the coils tested good with a meter.  that's not always the case, point is just check with an ohmmeter to see that the resistances on the new-to-you coils match the resistances on your good SC coils.  If you are unsure, thing is you're OK if the junkyard coils match each other. Be sure to check BOTH primary and secondary, also check for primary-secondary shorts and/or leakage.   Context  -- Two of the 3 coil packs on my car are original, they have been in service for 19+ years over 330,000+ miles.  

I would like to start off by saying THANKS for that VERY informative info as I have confirmed that myself this past weekend. I took your advice and went to a local "Pick and Pull". First off, I was not expecting to see ANY rivieras up there as I know how hard they are to find. But, I have located 5 rivieras in one location!! I am excited and saddened at the same time...Anyways. I was able to obtain all 3 coil packs and I know these motors are in about 80% of GM cars I still felt safer taking some from the exact same model. I even took my cheap DMM with me to confirm that they were in working order. I can say that as soon as I went home and changed coil pack #1 with cyl 1/4 I went out for a test run and sense I was feeling the misfire with increased throttle in the higher RPMs I went ahead and WOT(I hate doing this as I see no need) and, MAN DID IT FLY!! I almost forgot how fast it picks up since i've been having that misfire so often. Long story short. Stick with the GM coil packs as mister Albertj suggested.

This is just an FYI for people who read this thread later.  

Used GM coils are an inexpensive way to make the ignition work well if you're having issues and troubleshooting points to the coils/wires.    There's a reason why the Delco D576 (the OE coil for supercharged engines) costs so much, new... it puts out a lot of spark.  That's also why on the SC Rivi you have to use high-spec wires such as the Delphi, Delco, Taylor, Magnecor, etc. The higher-powered D576 coils tend to damage low-spec, inexpensive wires.  

If you'd rather get new ones, try this:
- Look at RockAuto.Com's ig coil listings for the '97 Riv, both NA and SC engines
- Don't get a coil that's listed for both applications, get one of the ones for SC only.  I think
 those would be...
 -- the Denso 6737103 (not the 6737102);
 -- the Delco D576 (neither the D535 nor the E530C)

There is another posting somewhere on this site showing a Taylor coil for this SC application, also.

When you click the part number for either of those two, on the SC listing, only the B-O-P SC applications come up. There's like 8 models on that list.  If you have an SC Riv, those are the coils you probably want - so for used coils you can pull them from any of those 8 models that have a supercharged engine--but like Terrance, you ought to take an inexpensive multimeter with you to the pick and pull, and test those things to make sure they're in spec. I forget what the resistances are but I think the secondaries were only a half-ohm or an ohm or so. Primaries run around 6-10 K ohms I think. Specs might be elsewhere on this site or in the FSM. Anyway...  If you click any other coil's part number, all the cars equipped with a range of GM V6 engines come up.  There's like 60-70 models, including GMCs, Chevrolets, Hondas and Isuzus.  Those are the coils you probably don't want and although they will run and not necessarily set a code, you'll get the stubborn mild (or worse) misfire.

Once you have a small fistful of the junkyard coils, you can re-test them along with the ones you have,  and put the three that are closest matched, electrically, on the ignition module and wire 'em up.

albertj wrote:

This is just an FYI for people who read this thread later.  

Used GM coils are an inexpensive way to make the ignition work well if you're having issues and troubleshooting points to the coils/wires.    There's a reason why the Delco D576 (the OE coil for supercharged engines) costs so much, new... it puts out a lot of spark.  That's also why on the SC Rivi you have to use high-spec wires such as the Delphi, Delco, Taylor, Magnecor, etc. The higher-powered D576 coils tend to damage low-spec, inexpensive wires.  

If you'd rather get new ones, try this:
- Look at RockAuto.Com's ig coil listings for the '97 Riv, both NA and SC engines
- Don't get a coil that's listed for both applications, get one of the ones for SC only.  I think
 those would be...
 -- the Denso 6737103 (not the 6737102);
 -- the Delco D576 (neither the D535 nor the E530C)

There is another posting somewhere on this site showing a Taylor coil for this SC application, also.

When you click the part number for either of those two, on the SC listing, only the B-O-P SC applications come up. There's like 8 models on that list.  If you have an SC Riv, those are the coils you probably want - so for used coils you can pull them from any of those 8 models that have a supercharged engine--but like Terrance, you ought to take an inexpensive multimeter with you to the pick and pull, and test those things to make sure they're in spec. I forget what the resistances are but I think the secondaries were only a half-ohm or an ohm or so.  Primaries run around 6-10 K ohms I think.  Specs might be elsewhere on this site or in the FSM.  Anyway...   If you click any other coil's part number, all the cars equipped with a range of GM V6 engines come up.  There's like 60-70 models, including GMCs, Chevrolets, Hondas and Isuzus.  Those are the coils you probably don't want and although they will run and not necessarily set a code, you'll get the stubborn mild (or worse) misfire.

Once you have a small fistful of the junkyard coils, you can re-test them along with the ones you have,  and put the three that are closest matched, electrically, on the ignition module and wire 'em up.

That sounds like a VERY good idea as I have no idea of the range of a "new" coil. I was basically just guessing as far as whats good or not with my DMM. I figured If the tested around 6100 OHMS than they were good enough because that was around the one I put in and I get not misfire mid range like I was getting before. Actually, I find myself going fast than I should be.

Don't obsess about the exact reading as long as they are not (1) open (2) shorted and they are (3) in a reasonable range and (4) each coil's primary and secondary measures about the same as the others. Again, the figure is somewhere in the factory manual. The secondaries on the "wrong" D535-type coil is higher, IIRC on the order of 4 ohms (again I think the real figure is in the fine manual).

If you want something to mess with, how about this: make *sure* your ignition wires and their terminals are actually good. One thing that has happened with mine - a terminal loosened over time (thermal expansion made metal lose it's temper) actually ablated away (evaporated). That caused a misfire that was not hard to find. At these voltages that is not a surprise. Pull the boots back and see that the wire is secured well, and when you click the terminals onto the coils or plugs make sure they are firmly gripping.

Other than that... well, sometimes I ask my spouse, when we're together and I am driving the Riviera, if it's wise that any vehicle this big really should move this fast.

Point of that is... time to move on to your brakes.

9ty7rivi wrote:

albertj wrote:

This is just an FYI for people who read this thread later.  

Used GM coils are an inexpensive way to make the ignition work well if you're having issues and troubleshooting points to the coils/wires.    There's a reason why the Delco D576 (the OE coil for supercharged engines) costs so much, new... it puts out a lot of spark.  That's also why on the SC Rivi you have to use high-spec wires such as the Delphi, Delco, Taylor, Magnecor, etc. The higher-powered D576 coils tend to damage low-spec, inexpensive wires.  

If you'd rather get new ones, try this:
- Look at RockAuto.Com's ig coil listings for the '97 Riv, both NA and SC engines
- Don't get a coil that's listed for both applications, get one of the ones for SC only.  I think
 those would be...
 -- the Denso 6737103 (not the 6737102);
 -- the Delco D576 (neither the D535 nor the E530C)

There is another posting somewhere on this site showing a Taylor coil for this SC application, also.

When you click the part number for either of those two, on the SC listing, only the B-O-P SC applications come up. There's like 8 models on that list.  If you have an SC Riv, those are the coils you probably want - so for used coils you can pull them from any of those 8 models that have a supercharged engine--but like Terrance, you ought to take an inexpensive multimeter with you to the pick and pull, and test those things to make sure they're in spec. I forget what the resistances are but I think the secondaries were only a half-ohm or an ohm or so.  Primaries run around 6-10 K ohms I think.  Specs might be elsewhere on this site or in the FSM.  Anyway...   If you click any other coil's part number, all the cars equipped with a range of GM V6 engines come up.  There's like 60-70 models, including GMCs, Chevrolets, Hondas and Isuzus.  Those are the coils you probably don't want and although they will run and not necessarily set a code, you'll get the stubborn mild (or worse) misfire.

Once you have a small fistful of the junkyard coils, you can re-test them along with the ones you have,  and put the three that are closest matched, electrically, on the ignition module and wire 'em up.

That sounds like a VERY good idea as I have no idea of the range of a "new" coil. I was basically just guessing as far as whats good or not with my DMM. I figured If the tested around 6100 OHMS than they were good enough because that was around the one I put in and I get not misfire mid range like I was getting before. Actually, I find myself going fast than I should be.