I changed my plugs to BPR8ES gapped to 0.28 only 3 weeks ago. Yesterday I got P0303 cyl 3 misfire for the first time on these plugs, my car bucking and losing power on the missed fires. I've been having a hell of a difficult time tuning my idle and cruise trims because my LTFT constantly creeps to max (12) at any karman below 150hz.

I'm wondering if 8ES might be too cold for my setup? I mistakenly thought 9ES was the coldest plug for heavily modified drag strip DSMs...but I think I'm supposed to have 7ES with my mods. I pulled a plug out a couple weeks ago and it had fuel all over it. Could that have ruined it, considering my really rich idling problems?

7`s in the winter 8`s or 9`s for race use only

How much boost are you running? Doesn't really matter about your setup (other than that it should support whatever boost you're running). I'm assuming you're under 25 psi but more than 18. BPR7ES's should be good for you.

I'm at 19psi on T28. I intend to get up to 22-23 once I get tuned. But if it doesn't matter, why does the tech guide on routine maintenance show 6ES for stock to mild mods, 7ES for moderate mods, and 8ES for heavy mods...it means relative to boost levels then?

As for winter...there is no such thing in Florida. Tomorrow I'll be going to 7ES and see if I run better, thanks for the quick advice.

Yeah switch to the 7's only running 19 psi & daily driving will foul those 8's quickly. Even at 22-23 the 7's should/will be fine.

Rice Over Wheat said:

But if it doesn't matter, why does the tech guide on routine maintenance show 6ES for stock to mild mods, 7ES for moderate mods, and 8ES for heavy mods...it means relative to boost levels then?

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It's relative to cylinder temperatures. The cooler the plug, the faster it will dissapate the heat. If the plug is too hot, it will turn into a glow plug and you'll start pre-igniting. If the plug it too cool, it will foul out. You should probably just stick with the 6's until you get to 23 psi, but the plugs are so inexpensive it doesn't really matter.

The 8's are more of a "race-only" plug for DSMs, because normal daily driving would never get them hot enough to prevent fouling.

I agree. The misfire problem is definately you plugs getter fouled. I would switch back to at least some 7's, maybe even to 6's. The 7's should be ok but if you still have problems go to the 6's.

That clears up a lot, thanks everyone. I'm going to go down to 7s and see if that helps things. I'm thinking this may be contributing to my tuning problems. I'll update on how it goes.

So lets i'm running 33psi, what should the gap be on 8es? Here is where I get lost, because i'm still on 7es I have them gap @ .20 @ 33psi. Would like to move to the 8es but don't want to play the guessing game with the gap.

Thanks,
Marc

Is there a reason you have the 7's at only .20?

brute said:

Is there a reason you have the 7's at only .20?

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Yeah, I couldn't imagine why Marc has his 7s gapped at .20" (unless he made a typing error). What I think Marc meant to type was that he currently has his 7s gapped at .020", but we will assume that is what he meant.

Marc, I can't think of a reason to have your spark plugs gapped that close. If the plugs aren't working out for you even at .027" or .026" (or at the other end of the spectrum, .030" or .032"), then you should upgrade to 8s.





EDIT:

Marc, if you could fill out your profile a lot more, that would be great. Just considering the numbers you are putting down at the dyno, and your timeslip, you definately are in the category of "heavily modified" DSMs. So go get some 8s, gap them appropriately, and take it for a spin. They should work just dandy for you.

If he's running 33psi on a stock ignition you'd need a pretty small gap to avoid spark blowout. I run mine .028 at 25psi since I have a DIS-2, but I don't understand the big deal about colder plugs. I use stock heat range Autolite 63's and don't bother with NGK's. Keith (92awddsm) and I both swear by them and you pick them up at WalMart.

The correct thing to do is run a WOT pull, shut the motor off and pull the plugs to read them. The first two threads are the key to a good heat range reading. If the plugs are too cold, they'll be black, if they're correct, they'll be a light tan and if they're too hot they'll be white. Everyone has a tendency to run plugs that are on the cold side when they don't need to. It's a great way to foul them under non open loop conditions and hamper performance the moment you go WOT.

Keep in mind that reading plugs should be done in the absence of boost leaks and in the presence of an efficient A/F. If the A/F is too rich or there are boost leaks, it will throw the reading off. Tuners in the 60's and 70's used to jet their carbs by simply looking at the plugs and reading them for timing and correct heat range. I'm amazed at how many modern tuners ignore this when it'll tell you just about everything you need to know. Unless you have a full out race car, I don't much see the point in going more than one heat range colder. I've used NGK 7's and 8's with both projected and non-projected tips and neither of them improved knock. All they did was load up more under closed loop driving. Run a pull, yank 'em and give them a read.

Cheers,

Andy

7's gapped at .028 on the stock ignition work fine for me at 26psi.

Andy, when you check your plugs after a pull how long can you drive in closed loop before it will effect what you see on the plugs? ie can you drive a couple minutes to get home, or can you drive a min or two at the track to return to the pit area or do you need to shut it down at the end of the brakeing zone to get a proper reading?

Daren,

I'll put it like this. The sooner you can shut it off the better. The more you drive around in closed loop, the more it can skew the readings. The best case scenario is on a dyno since you're locked in one spot, but I wouldn't get too crazy about it. Install a fresh set, warm the motor, run it for a pull and shut it down as soon as you can. It'll still be good enough to get a good reading.

andymoraitis said:

Daren,

I'll put it like this. The sooner you can shut it off the better. The more you drive around in closed loop, the more it can skew the readings. The best case scenario is on a dyno since you're locked in one spot, but I wouldn't get too crazy about it. Install a fresh set, warm the motor, run it for a pull and shut it down as soon as you can. It'll still be good enough to get a good reading.

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Thats what I figured, thanks Andy

I pulled my 8s and put in 7s. Here's a pic of one of the 8s, only 3 weeks old. Bit fuzzy in close up but how does this look? According to my trims I have a very rich condition at idle and cruise below 150 hz. There's a lot of black soot on the first 2 threads. According to Andy, they're too cold for me.

You're right, typing error, I meant .020... I was blowing the spark at 31psi with a gapping of .024 with my Twin Fire ignition system... Pull the Twin Fire off, went on stock ignition gapped down to .020 the car pull all the way through. Then turn up the boost and ran out of intake manifold <---Stock 1g... So now looking forward to getting a SB intake manni and some 8es.

Rice,

Those are definitely way too cold. Check for boost leaks and install the 7's so we can have a look at those. The 8's are fouled silly...

All four looked like that. The car seems to be running pretty good on the 7s. No misfires yet after a few pulls. At daylight I'll pull one and take a pic for comparison.

If you have reason to fear melted/broken side electrodes (I've lost a couple motors to this), you can stick to the more typical 7 heat range but make the move to non projected plugs. I ran non-projected 8s in the EVO with a maxed out stock turbo and a 75 shot. They would give me some minor cold idle issues after 3-4 weeks of use. The non-projected 7s last as long as I would expect them to (I change them with each 2500 mile oil change at the latest) and looked just as good even after some super lean nitrous passes. No signs of overheating the side electrode. I've made some passes that would have almost certainly tossed a motor based on personal experience, but these plugs look the balls. I think the lack oif projected tip is worth more than the change in heat range with what I have seen.

There also seem to be no negative side effects to runnin non-projected plugs in these cars, so running some BR7ESs is cheap insurance and should probably become standard operating procedure, IMO.

Could the Bpr8es cause starting issues? I finally fired my car up yesterday and it started without any issues. After about a couple of minutes of running I realized that I didn't fill it up with coolant so I shut it off filled it with coolant and attempted to start it again, the car wouldn't start without pressing on the gas pedal.

Running without coolant for more than 20-30 seconds is not a good thing, IMO. I don't know how long a "couple minutes" is in this case, but if it turns out to be just the plugs you'll be lucky. If these plugs were just installed, they are not going to be the cause. Mine took more than a "couple weeks" to give me issues. And the car would start fine, just miss a cylinder here and there and stumble a bit if I started driving while it was still on cold idle enrichment. If those plugs were in there for some length of time it's possible it's just a coincidence that they started acting up at the same time as the coolant-less idle ####ery.

Been running a couple days now on the 7s and many hard pulls, no misfires and the car is running much better. 8s were definately too cold for my mods.

The funny part is i have at least 10 sets of BPR8ES' sitting here (no joke) that my buddy who has a low 10 sec 2g (140 mph traps) gave me. He switches plugs after every pass and he has no use for them so he just gives them to me but i'm sure they are overkill so ill just keep staring at them for now

I run 7s in the car and it feels great. I ran the non projected plugs for a lil bit and ended up going back to the projected cause i needed new plugs and i had a set sittng here. However, the car felt great on them too so i plan on grabbing a set and switching back and forth and logging to see which ones work best in my car.