Hey guys, over the past few months, I was trying to track down an ign timing problem where my ign timing had huge deviations on Map 2 on a JB4 with 93 octane, even when I added octane booster. Everyone kept telling me that some Stingers just can't handle the higher tunes as well as other, similarly modded Stingers. Physics told me that wasn't true, at least not to the degree I was seeing it. So, after testing a bunch of different things, I found the real issue.
TLDR: Make sure you're using genuine spark plugs and make sure they are in pristine condition and perfectly gapped when you install them.
DISCLAIMER: There IS a point where you absolutely need higher octane. Don't expect to push 19 pounds of boost without some seriously high octane or WMI. This post is specifically for people who aren't getting close to the results with a tuned engine that other Stinger owners with similar modifications are getting. I personally was able to shave another .3 to .4 seconds off my 0-60 times just by doing this. I went from an average of about 4.7-4.9 seconds with intakes and a JB4 on Map 2 with an AWD Stinger, down to about 4.4-4.5.
If you have a lot of deviation in your ignition timing when using 93 octane on Map 2 on a JB4, follow these steps to diagnose and fix it.
1. Take a closer look at your logs and see if it's specific cylinders that consistently have lower timing than the rest. For me, cylinders 3 and 4 (ign3 and ign4), were almost always the two cylinders deviating far from the rest. That told me there was a problem with those two cylinders specifically. I'll get into how to fix that in a moment.
2. If the deviation is sporadic such that sometimes ign2 and ign5 are much lower, then another time ign3 and ign6 are much lower, then a third time it's ign1 and ign3, then it is possible that you are getting gas for a bad gas station. Prime example, BJs gas says it's 93 octane, but it's not a "Top Tier" gas. I tried running a tank of that through my Stinger since it was literally about 40 cents cheaper per GALLON than the Shell station. Well, I found out that it was cheaper for a reason, my timing got awful after using the BJ's gas. So try a few different gas stations and see if that improves your timing.
3. If no other gas stations fix your timing issue, or you see that the ign timing deviation is consistently in the same cylinders, chances are very high that your spark plugs are the issue. To fix this, you need to replace your spark plugs with guaranteed, genuine plugs and make sure your gap them perfectly.
If you're getting the Denso plugs, which I use, the guaranteed genuine Denso parts seller is densoproducts.com. This is the website that Denso's technical support manager told me to order from if I wanted to be 100% positive that I was getting genuine Denso plugs. He specifically said NOT to order from RockAuto, Amazon, Ebay, or any other third party that isn't a major brand like O'Reilly's, AutoZone, or Advance Auto Parts. It's not that RockAuto, Amazon, or Ebay are guaranteed to be knockoff plugs, but the chances are high.
4. Once you have your new plugs, you'll want to gap them down to .022 (at least if you have the 6 cylinder Stinger. Not sure what the gap is supposed to be on the 4 cylinder Stingers). However, make sure you use a high quality gapper like the K-Motor Performance gapper from Amazon. This gapper has a rounded and polished tip that comes in contact with the top electrode of the spark plug to guarantee that you don't damage the spark plug when you're gapping it down. I used a cheap gapper on my first set of Denso plugs and it scratched the top of a few plugs, which is a huge part of why my timing was so awful.
5. To check your gap, I recommend a good set of oiled feeler gauges. Here's the set I bought. And to make sure you don't under gap the plugs, start with either the .023 feeler and gap it down until you JUST can't fit the .023 feeler in anymore. Then test the .022 feeler to make sure that one still fits.
6. If you reduced the gap too much and need to open it back up, DON'T grab it with pliers and open it back up, these can scratch the electrode. Instead, use a coin style gapper with a hole in it that's meant for opening the gap on spark plugs. Note, don't use the edge of the coin, because that will scrape against the electrode. Insert the top of the spark plug through the hole and pry it open. I'll see if I can find a video of this to demonstrate what I mean.
7.Disconnect the negative terminal of your battery (found in the trunk under the spare tire). This is done to reset what your ECU learned for ign timing. Your battery needs to be disconnected for at least 30 minutes in order for this to work. I tried 24 minutes once and it didn't work, 34 minutes did the trick for me. Basically, this forces your ECU to use the exact same ignition timing on all cylinders when accelerating hard for the first few pulls after reconnecting the battery. If there are any issues, the ECU will adjust timing and you'll see variations again. If there are no issues, you'll end up with almost no deviation in your timing.
8. Before you take the old plugs our of your Stinger, take a look at your logs again and see which cylinder consistently had the highest ign timing. Take that spark plug out first and measure it's gap with your feeler gauges. I'm going to guess it's gonna be right on .022, at least that was the case with me. This is what told me that .022 was the best gap to use. Note that the only mods on my car are the JB4 and DIY intakes. If you have more bolt-ons than I do, your optimal gap may be different than mine. Definitely let me know what gap is optimal for you guys along with a list of your mods. That'll likely be pretty helpful for the community in general.
9. If your optimal spark plug gap is different than mine, you can re-gap your plugs to match that optimal gap.
10. Install the new plugs.
11. Reconnect the negative terminal of the battery.
12. Start the car and let both the coolant AND oil get up to temp before ripping on it.
13. Go get some logs and see how your timing looks. Over time, you may start to see some slight deviation, but very small deviations could be a result of simply having one plug gapped a bit more or less than the rest. If you notice that one cylinder is consistently getting lower than the rest by a full degree or two, you could pull out just that plug and double check the gap. You should also check it for damage while you have it out. If the gap is off, regap it, if it's damaged, replace it.
I'll get some logs showing my timing before and after changing my plugs, as well as any other valuable pictures I can put together a bit later, but I figured this would be a good start.
Good luck with fixing your timing issues and happy tuning!
TLDR: Make sure you're using genuine spark plugs and make sure they are in pristine condition and perfectly gapped when you install them.
DISCLAIMER: There IS a point where you absolutely need higher octane. Don't expect to push 19 pounds of boost without some seriously high octane or WMI. This post is specifically for people who aren't getting close to the results with a tuned engine that other Stinger owners with similar modifications are getting. I personally was able to shave another .3 to .4 seconds off my 0-60 times just by doing this. I went from an average of about 4.7-4.9 seconds with intakes and a JB4 on Map 2 with an AWD Stinger, down to about 4.4-4.5.
If you have a lot of deviation in your ignition timing when using 93 octane on Map 2 on a JB4, follow these steps to diagnose and fix it.
1. Take a closer look at your logs and see if it's specific cylinders that consistently have lower timing than the rest. For me, cylinders 3 and 4 (ign3 and ign4), were almost always the two cylinders deviating far from the rest. That told me there was a problem with those two cylinders specifically. I'll get into how to fix that in a moment.
2. If the deviation is sporadic such that sometimes ign2 and ign5 are much lower, then another time ign3 and ign6 are much lower, then a third time it's ign1 and ign3, then it is possible that you are getting gas for a bad gas station. Prime example, BJs gas says it's 93 octane, but it's not a "Top Tier" gas. I tried running a tank of that through my Stinger since it was literally about 40 cents cheaper per GALLON than the Shell station. Well, I found out that it was cheaper for a reason, my timing got awful after using the BJ's gas. So try a few different gas stations and see if that improves your timing.
3. If no other gas stations fix your timing issue, or you see that the ign timing deviation is consistently in the same cylinders, chances are very high that your spark plugs are the issue. To fix this, you need to replace your spark plugs with guaranteed, genuine plugs and make sure your gap them perfectly.
If you're getting the Denso plugs, which I use, the guaranteed genuine Denso parts seller is densoproducts.com. This is the website that Denso's technical support manager told me to order from if I wanted to be 100% positive that I was getting genuine Denso plugs. He specifically said NOT to order from RockAuto, Amazon, Ebay, or any other third party that isn't a major brand like O'Reilly's, AutoZone, or Advance Auto Parts. It's not that RockAuto, Amazon, or Ebay are guaranteed to be knockoff plugs, but the chances are high.
4. Once you have your new plugs, you'll want to gap them down to .022 (at least if you have the 6 cylinder Stinger. Not sure what the gap is supposed to be on the 4 cylinder Stingers). However, make sure you use a high quality gapper like the K-Motor Performance gapper from Amazon. This gapper has a rounded and polished tip that comes in contact with the top electrode of the spark plug to guarantee that you don't damage the spark plug when you're gapping it down. I used a cheap gapper on my first set of Denso plugs and it scratched the top of a few plugs, which is a huge part of why my timing was so awful.
5. To check your gap, I recommend a good set of oiled feeler gauges. Here's the set I bought. And to make sure you don't under gap the plugs, start with either the .023 feeler and gap it down until you JUST can't fit the .023 feeler in anymore. Then test the .022 feeler to make sure that one still fits.
6. If you reduced the gap too much and need to open it back up, DON'T grab it with pliers and open it back up, these can scratch the electrode. Instead, use a coin style gapper with a hole in it that's meant for opening the gap on spark plugs. Note, don't use the edge of the coin, because that will scrape against the electrode. Insert the top of the spark plug through the hole and pry it open. I'll see if I can find a video of this to demonstrate what I mean.
7.Disconnect the negative terminal of your battery (found in the trunk under the spare tire). This is done to reset what your ECU learned for ign timing. Your battery needs to be disconnected for at least 30 minutes in order for this to work. I tried 24 minutes once and it didn't work, 34 minutes did the trick for me. Basically, this forces your ECU to use the exact same ignition timing on all cylinders when accelerating hard for the first few pulls after reconnecting the battery. If there are any issues, the ECU will adjust timing and you'll see variations again. If there are no issues, you'll end up with almost no deviation in your timing.
8. Before you take the old plugs our of your Stinger, take a look at your logs again and see which cylinder consistently had the highest ign timing. Take that spark plug out first and measure it's gap with your feeler gauges. I'm going to guess it's gonna be right on .022, at least that was the case with me. This is what told me that .022 was the best gap to use. Note that the only mods on my car are the JB4 and DIY intakes. If you have more bolt-ons than I do, your optimal gap may be different than mine. Definitely let me know what gap is optimal for you guys along with a list of your mods. That'll likely be pretty helpful for the community in general.
9. If your optimal spark plug gap is different than mine, you can re-gap your plugs to match that optimal gap.
10. Install the new plugs.
11. Reconnect the negative terminal of the battery.
12. Start the car and let both the coolant AND oil get up to temp before ripping on it.
13. Go get some logs and see how your timing looks. Over time, you may start to see some slight deviation, but very small deviations could be a result of simply having one plug gapped a bit more or less than the rest. If you notice that one cylinder is consistently getting lower than the rest by a full degree or two, you could pull out just that plug and double check the gap. You should also check it for damage while you have it out. If the gap is off, regap it, if it's damaged, replace it.
I'll get some logs showing my timing before and after changing my plugs, as well as any other valuable pictures I can put together a bit later, but I figured this would be a good start.
Good luck with fixing your timing issues and happy tuning!
here that talks CDN fuel. I'm pretty sure Terry has looked at quite a few Map2 Shell 91 logs including one of mine and has said it looks good. He has also looked at a number of Chevron 94 logs which don't look so good. But what I'm experiencing on my current tank of Shell 91 is definitely "not good". Next time I'm in the States I thing I'll pick up some Boostane and give that a try.
