Best spark plug?

What is the best spark plug for a 06 h3? My 3 has about 87k miles on it and it's running like crap. I think it's the spark plugs. The engine stutters alittle bit when I first turn on the car in the morning and when I floor I get no acceleration. What is the best spark plug you guys recommend?


Sent from my iPhone using Tapatalk

Ac delco iridiums...

digglesworth said:

Ac delco iridiums...

Click to expand...

X2 on the AC Delco Iridiums

I've been using the Autolite XP Iridium Plugs in both my H3's (3.7L & 5.3L) absolutely zero issues with them. I've been using Autolite's for years and I've never had a single issue with them. Whatever you do stay the heck away from those Bosch 2x/4x Plugs.... They're horrible and can cause misfire faults as quickly as 3K.

X3 on the AC Delco iridium

Sent from my SM-N900V using Tapatalk

X4 on Delco

I'd also clean your MAF and Throttle Body along with changing your plugs. They're "supposed" to last to 100K, but it won't hurt to replace em.

Best4x4 said:

I'd also clean your MAF and Throttle Body along with changing your plugs. They're "supposed" to last to 100K, but it won't hurt to replace em.

Click to expand...

My steering wheel shakes when my car is at idle do you think a dirty MAF might be causing it?


Sent from my iPhone using Tapatalk

Or is it just a bad motor mount


Sent from my iPhone using Tapatalk

the maf on my brother's camaro got dirty from the K&N being over-oiled and it just acted like it couldn't accelerate at certain points in the RPM range. shaking at idle might be that it's idling at an RPM that's too low. i think. maybe.

With the delco did you guys notice any performance gains? Or a noticeable difference compared to the stock ones


Sent from my iPhone using Tapatalk

poweraidon said:

With the delco did you guys notice any performance gains? Or a noticeable difference compared to the stock ones


Sent from my iPhone using Tapatalk

Click to expand...

I think the truck is tooooooooo big, heavy and brick wallish to feels any improvements, esp on an I5. Ive changed my spark plugs and didn't feel anything, except a slightly better idle.

You need to clean the MAF first, use stock AC Delco plugs if you change those. You will notice problems by NOT using the stock plug. A dirty MAF will cause the symptoms you have, its something you should regularly clean anyway.

Non OEM Plugs work fine. Both my H3's are proof of that lol. Zero issues :roll:

It's not the brand, so much as making sure to use the same type/temp, and gapping them properly.

When I was doing my tune up's on both H3's I was going to go with the OEM Plugs. Problem was not a single auto parts store had them in stock... The plugs I am using (Autolite XP Iridium) are easy to find so in the event of a breakdown on the trail or highway a replacement won't be hard to find.

http://m.autozone.com/autozone-mobile/en/parts/AC-Delco-Iridium-Spark-Plug/_/N-jo09tZ8gctd?id=922007

These ones will work right?


Sent from my iPhone using Tapatalk

Yep those will work. I do find it funny that the "OEM" AC Delco branded plugs are "Made in Japan", more than likely they're just rebranded NGK's.

Change your plugs, clean the throttle body (removing it completely), clean the MAF sensor, and check the air filter. Nothing like a good tune up. I'd also throw some lucas, chevron, seafoam, or royal purple fuel injector cleaner in the tank.

Best4x4 said:

Non OEM Plugs work fine. Both my H3's are proof of that lol. Zero issues :roll:

It's not the brand, so much as making sure to use the same type/temp, and gapping them properly.

When I was doing my tune up's on both H3's I was going to go with the OEM Plugs. Problem was not a single auto parts store had them in stock... The plugs I am using (Autolite XP Iridium) are easy to find so in the event of a breakdown on the trail or highway a replacement won't be hard to find.

Click to expand...

It's good to hear you've had good experiences with non-OEM plugs, but it's well known there have been more than a couple folks over the last few years on various Hummer forums that have reported negative results with some brands of plugs other than OEM in the GM I5 engine.

That leads to the question, which of these two would seem to be the greater gamble: 1) zero percent problems by using OEM plugs, or 2) hoping you pick the right 'other' brand to avoid scattered issues that many of them have been known to induce?

I agree with you, but at the same time I disagree.

Way to many variances are involved. When these people complained about using non OEM Plugs (which aftermarket plugs are designed to match) did they install them and gap them correctly? Did they get the proper P/N: or plug? If the engine has 100k (life of the OEM plugs) did they also replace the coils, boots, or center coil spring? Just changing the plugs won't fix the problem if the coils are old and can't provide the proper amount of spark to the new plugs. I've found that 99% of online reviews are mixed at best. Forum results would be more reliable, but once again it goes back to the specific rig the plugs were installed in and the condition of the rest of the system. Spark plugs are the simplest part of a modern day ignition system. The PCM, various sensors, and coils do all the truly hard stuff. All the plug has to do is spark.

The plug does however have to meet OEM specs. Using the wrong temp plug or gap is where you're going to have issues. Since our OEM AC Delco's are made in Japan I wouldn't hesitate to use NGK's in my H3's.

As far as me running Autolite XP Iridium's in both my H3's. I didn't just pick that plug out of the air. I've been using them in my Jeep's for years without a single failure or defect. A plug is a plug and as long as it matches the OEM Spec's the only difference is going to be the box it came in, and the name on the plug.

The only time I've ever induced a problem via spark plug was when I dropped one.

^^Do a search on some of the Hummer forums. The I-5 is sometimes particular about what type of 'spark' it likes. Never heard of anyone having issues with the OEM specified plugs though.

That being said, I have read instances in which folks put in new plugs and then immediately do a Seafoam or other fuel treatment and still report having run-idle issues. Personally, I'd avoid using a super concentrated fuel system cleaner right after plug change to avoid fouling those brand new plugs.

I'd never put new plugs in and do a seafoam treatment thru the intake. It "could" cause the brand new plugs to fowl. Now if adding a fuel treatment to your tank gives you issues you've got other problems.

The 3.7L is an inline engine and they'll always run rougher (vibration wise) vs say a V8. Just two totally different setups. Easy to see the difference in a 3.7L vs a 5.3L. From broken motor mounts to torn up manifolds. Inline engines vibrate more.

I read a few threads and they never clarified if they had bad coils, boots, the wrong plug, wet coilpacks from a leaking hood louver, or the dreaded head issue related to misfires. Very very very easy to get the wrong boxed plug or completely wrong part from the kid behind the counter.

So far I guess I'm a rebel lol. I've used pretty much everything on my H3's that hasn't been OEM, like brake pads, rotors, oil sending unit, variable valve timing sensor, waterpump, thermostat, fan clutch, idler pulley, spark plugs, CV Axles, spark plug boots (5.3L), silla radiator, transmission filter/gasket, and a K&N air filter (with a prefilter). My H3's run great, zero issues and honestly after my initial tune up's after buying them I haven't spent any time under the hood except for a 10min oil change.

Nothing wrong with OEM stuff, but plenty of aftetmarket name brands work just as well if not better.

I know this is a well beat down subject..but here goes anyway

30,000 miles ago I replaced the plugs with AC Delco Iridium 41-103..But over this last year, I had a weird little stumble in the engine idle every so often..I replaced every sensor on the engine with no improvement...Also I've noticed over the past year that cold starts in the morning would come with almost a misfire on start up or a hic-up sometimes, but not every time, but would start and settle out immediately..Of course I had the fuel pump and pressure regulator checked, all seemed normal...So finally I resorted to changing out the plugs again...I went this time with NGK Iridium IX (4344).(Gapped at .046")..Checked out for over a week now and not a single issue as like before the change...seems the response and acceleration is better now too.


Just thought I'd share here

Note: All 5 of the AC plugs appeared clean and non-fouled..

Yep I am a fan of NGK as well. Both my LR's are running them and great plugs! Both NGK & Autolite have performed flawless in my rigs.

My engine runs better without spark plugs.

:thumbs:

Ryan