Spark Blow out and Fuel Economy

I'll try to do a weekly WOT start or stint on the highway to check this. If you don't do that, you won't notice the blowout until it's too late.

Newb here. How do you tell? Hesitation?

Spark blowout is felt as serious power drops at higher RPMs while under WOT but the car performs fine otherwise. As the spark plug gaps continue to grow the "high" RPM drops closer and closer to cruising speeds of 1800 - 2500 RPM. It usually is first noticeable above 4000 RPM and then progressively at lower engine speeds.

Careful, it may not be blowout.. I thought I was having blowout for the longest time and it ended up being my coil boot arching on cyl 1 causing a misfire and cel. Just my experience with this type of problem.. I changed my plugs prob 5 times, they would be fine for about 1,000-2,000 miles then it would start to "shutter" again.

Same for me WhitenBright. Had a rip in a boot causing "blowout like sputters". Either way, if you start feeling the blowout sputtering, check the general area of the coilpack / plugs.

basicly in a automatic, the car wont go past 4000 rpms, and then shifts to the next gear

obermd said:

If you start to notice spark blowout during WOT it's time to take care of your plugs. I wasn't able to get to my spark plugs for three weeks and I noticed my daily commuting fuel economy dropped by about 10%. Even though I don't drive in WOT that much the plugs weren't igniting the fuel as well and I was leaving unburned fuel to go into my exhaust system.

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Well the good news for the EPA, your catalytic converter is consuming those HC"s, but maybe not for you if you have to replace it.

Don't have to get nitpicky on the cause for a failed spark, blowby, excessive gap, excessive carbon on the center electrode insulator, poor connectivity, shorted turn in the ignition coil, poor connectivity to the ECU, water in the fuel, etc. All cause for a misfire, even dirty fuel injectors, or a dirty air filter.

Just tells you, its time to look at it. Check mine every 15K miles because I already know misfires will occur after this time. Always has, always will as long as we are pouring carbon in the fuel.

cdb09007 said:

Same for me WhitenBright. Had a rip in a boot causing "blowout like sputters". Either way, if you start feeling the blowout sputtering, check the general area of the coilpack / plugs.

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I'm experiencing what I think to be spark plug blowout, but I JUST checked the plugs, gapped them all to .028, and they are the BKR7E plugs that everyone raves about here. What now? Also, if it matters, I have a 2015 Eco 6MT with about 7,500 miles on it.

The world of sparkplugs is as varied as the people using them.... There are what is considered generally accepted best practices. as indicated above.

one thing to think about, perceived spark blowout and misfires could very well be the ECU responding to knock detection and it's movement the spark timing, which at times can be a significant loss of power with a slow return to normal.

ssnscruzeeco2015 said:

The world of sparkplugs is as varied as the people using them.... There are what is considered generally accepted best practices. as indicated above.

one thing to think about, perceived spark blowout and misfires could very well be the ECU responding to knock detection and it's movement the spark timing, which at times can be a significant loss of power with a slow return to normal.

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Spark blowout and knock detection feel different. Knock detection feels like pulsing in the throttle and doesn't impact engine speed. Spark blowout is a longer power drop and can actually limit engine speed in more severe cases.

These are the times where I wish I had the genius to be able to parse and compile data via automatic software. I have 8000 Km's of data logging running on Denso TT IR's gapped at .045".

I know that I get misfires, knock retards, and I expect them and have recorded them, but I am able WOT to 5000 RPM (very rare that I do, or go past) I currently feel the most power loss during knock retards. Pulling up a 8% hill @ 100 Kph @ 1900 RPM is also WOT just without the acceleration of speed part. sometimes I feel and see misfires, knock retards but not always.

I seems what you are describing is what I felt in my OLDS Achieva quad4 when I hit the rev limiter in third gear years ago.

For the most part I am stock, except for the plugs..... which may or may not be the same as the other guys, but adds a few more what if's.

Engineer that said to gap the plugs at 65 mils was smoking crack when the HEI ignition system came out, misfires like crazy, also the very first year the catalytic converter came out that was very profitable for GM. They sure didn't last very long with misfires, lots of raw gas in there. Ha, starting to get paranoid, want to sell me more cats and made a very stiff law to buy one.

I stayed with the standard 35 mil gap, first vehicle with a cat was a 73 Fleetwood, put over 200k on that car, zero cat problems, much better fuel economy and performance.

Kid's new Kia Soul said 45 mils, they are also smoking crack with those super tiny coils on plugs, would get lost in my pants pocket. Has an MT, really had to hit the gas to prevent stalling the engine,not good on the clutch. Gaped those at 30 mils, what a difference, also picked up around 5 mpg.

Cruze with a bit more intelligence says 28 mils, believe me 25 mils works a lot better.

So why is everyone saying .028" gap when ALLdata and many other threads on here state .032"-.035" is actually correct?

1988gmc355 said:

So why is everyone saying .028" gap when ALLdata and many other threads on here state .032"-.035" is actually correct?

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Your AllData information is out of date. Read the following two threads for why:

http://www.cruzetalk.com/forum/10-g...cial-statement-regarding-spark-plug-gaps.html

and

http://www.cruzetalk.com/forum/34-gen1-1-4l-turbo/46833-new-copper-spark-plugs.html

XtremeRevolution, with the assistance of over 100 CruzeTalk members, determined there was a problem with the spark plugs in the 2011 and 2012 Cruze. He got GM to take a second look at the spark plugs in the Cruze and their response is in the first link above. The second link is my measurements and calculations supporting GM's response.

obermd said:

Your AllData information is out of date. Read the following two threads for why:

http://www.cruzetalk.com/forum/10-g...cial-statement-regarding-spark-plug-gaps.html

and

http://www.cruzetalk.com/forum/34-gen1-1-4l-turbo/46833-new-copper-spark-plugs.html

XtremeRevolution, with the assistance of over 100 CruzeTalk members, determined there was a problem with the spark plugs in the 2011 and 2012 Cruze. He got GM to take a second look at the spark plugs in the Cruze and their response is in the first link above. The second link is my measurements and calculations supporting GM's response.

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Fair enough, I just joined a few months ago, I am not understanding then what is correct now for OEM ACDelco plugs for gap and real world life in miles?

I am not interested in playing the copper plug game, I have a 350 TBI powered 95 GMC K1500 to play that game with.

Set your spark plugs to 0.028" regardless of type. Replace them when the gap reaches 0.038".

I had blow-out the other day at just .032". These cars are ridiculously picky. The recommendation for .028" to just set and leave is a good one. No use in futzing around with it.

I will be gapping them back to .028" then, I currently have 73K on the car, so will need new ones in 20K or so anyways.

1988gmc355 said:

I will be gapping them back to .028" then, I currently have 73K on the car, so will need new ones in 20K or so anyways.

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At this point if you're going to regap them I'd go ahead and purchase and use new plugs. Take a look at the lower two sections in my copper plugs post. I go into the gap growth calculations based on the OEM plugs there.