white heat

How can a spark plug give you almost 10 more hp? I can see the vehicle running at optimum performance but not actually adding more power, if that makes sense.

jaden78

I bought a set of these and I'm considering returning them.
I've had them 2 weeks and I'm having troubles with the engine sputtering some when idling. They said to go through an entire tank to let the engine adapt to the new plugs. I've done that and its still sputtering when idling. I'm off to check the gap, but so far I'm not impressed. They also recommended unplugging the nuteral battery terminal to speed up the computer adapting to the new plugs.
Hope this helps and if anyone has any suggestions please let me know.

Hib Halverson

It is possible, but under some very unusual circumstances, for a plug change to make a 10hp difference with a 3.5L engine.

But...that would never occur in the 2.0, 2.2 or 2.4 in an HHR unless the engine was had a significant performance problem before the plug change.

I've read the SAE Paper Pulstar cites on its web site and in my opinion, the plug works much like a mini CD ignition system. In theory that could improve performance, but in practice, in an everyday situation with the plugs installed in an engine that was already running well, you're unlikely going to see that large a performance change.

My understanding is that product is double the cost of some of the best iridium-tipped plugs and may not last as long. If you're going to spend serious money on plugs, I'd go with something like a Denso Iridium Power plug at perhaps half the price.

The acid test for the HHR cited in the first post would be to simply stick the stock plugs back in and see if the driveability problem goes away.

As for the engine computer "learning" about the plugs, if any adaptation the engine controls make isn't done by the end of a full tank of fuel, there isn't any more change to be made. But, you can quickly determine that by take the car to a service shop having a TECH2 and have a tech. use it to reset all of the fuel trims and other parameters that adapt. Drive the car a tankful of gas and see if things get better...but...I doubt they will.

Lone Ranger

Always good to hear from you, Hib. Your spark plug Tech Tip from over on Corvetteforum.com is in my archives (I used to be active on CF).

To the original poster: the OE plug in the HHR is an iridium tipped part, no need to look to after market-- you've already got a really well engineered spark plug in there, courtesy of Chevrolet.

Everything about my HHR's powertrain is staying stock. The stock air intake system is superior to the after market air intakes that draw warm or hot air directly from within the engine compartment. As mentioned, the stock spark plugs are superior to after market brands. Even the stock bottom end on the Eotec is reported to be good up to about 400hp.

Snoopy

Hib....interesting comments.

Have you, by chance, read some of the performance car forums. Those people are having "nightmares" with the electronics and this plug.

Opinion ?????

JoeR

Hib, I know I've given you a hard time when some of your posts appear to be a paid promotion, but I agree with what you said above.

And, Lone Ranger, THAT post is well informed and accurate, too.

In reality (not advertising hype), if the proper air/fuel mixture is in the combustion chamber, heck, you could put an antique flint lock mechanism from a musket in there. If fired at the proper time.... BOOM!! The A/F could care less what ignited it, as long as it is reliable and timed properly.

Hib Halverson

Actually, the OE plug is an "ACDelco" which is made by Denso. Typically, Delcos like that are Denso's "OE type" iridium plug in the Denso, 16 heat range.

Typically, I replace the OE Delcos with a 20 heat range plug from Denso's, aftermarket, "Iridium Power" line. I have IT20s in our 04 Vette, our 01 Camaro and our 99 Blazer and I have IT22s in our 95 Vette. Now, I haven't done that with our HHR, yet, because it was quite a while before Denso released the ITV20 for the Ecotec and then it was several months before I obtained as set. They're sitting out in the shop along with a Green Filter waiting for the next time I schedule the truck in for service. Actually, I'm going to continue to hold off a bit longer because my understanding is that Flowmaster is just about ready to release their cat-back exhaust for HHR and I want to do all the work at one time.

The Iridium Power Densos are not an OE product so they have a few design features common to high-perfomance plugs, most importantly a slightly smaller diameter center electrode and a U-shaped side electrode. I use the 20 heat range because the 16s are used from the factory as a hedge against "pre-delivery fouling" during the truck's life between when it's made and when its delivered. None of my vehicles ever see regular starts without warm-ups so there's no need for a heat-range choice that considers pre-delivery fouling. Plus you've got a relatively heavy vehicle and a small engine which means I run it at WOT a fair amount, compared to my cars with larger engines. My guess is my 2.4 is going to like a 20 heat range better.

That said, I do not suggest a 20 heat range for HHRs which see starts without warm-up (ie: short trips) nor trucks which are never driven hard and never get "rev'ed-up".

Few dealers care about Magnuson Moss. Typically, it's up to the customer to "enforce" it and few have the tens of thousands of dollars necessary to file a suit in Federal Court. If a dealer voided a warranty due to a spark plug change you'd end up at least having to talk with Chevrolet's district service rep. You could cite Magnuson Moss and he/she might overturn the dealer's decision. That said, it would be highly unusual for a dealer to do that because of a plug.

I can only speculate, but since what I read in their SAE Paper suggests to me that inside the plug is what amounts to a CD ignion amplilfier, I'll guess that the plugs are creating an RFI issue with the engine controller. The ECM is mounted just to the left of the engine in an HHR which puts it unusually close to the plugs...I say "unusually" meaning different from what many of us are used to from older cars which had ECMs back on the firewall or in the interior. Engine-mounted powertrain controllers are the way the OEs are going because it reduces the complexity of wiring harnesses and improves durability, but they might be susceptible to RFI from a spark plug that emits more of it than the plug originally designed for the engine.

I've addressed your hard time in another thread. I'm starting to think you follow me around on this site claiming I'm a shill.
I've been active on the automotive Internet for ten years, so it should be no surprise that this is not the first time someone has suggested such a thing.

Because I feel you are misguided in your opinion on this issue, I'll restate what I said in another forum: In the last six months, I made four posts (not including any posts to this thread). Two of them listed a brand name. One of those four was a product review. In another thread you suggested that "all" I do is post promos. The evidence does not support that suggestion.

I submit that your "hard time" lacks fairness. Further, in my opinion, you should research a member's past posts before you express such beliefs.

IF this web site had a product review section, I would post reviews there and not on the site's forums. I even asked the owners of this site back in 2007 about a review section and never received an answer. With the software they're using, which many forum sites WITH review sections use, I believe it would be easy to add that feature.

All of the products I review are tested by myself on my own HHR or, in the case of non HHR-specific products (say, a tool or a car care product), I might test them on my other vehicles. Some of the products are supplied as review samples. Some of them I purchase. I am not paid by product vendors to review products on the Internet.

I will continue to post my reviews of HHR-related products on this web site until it's owners ask me to cease the practice.

Hopefully, this statement clears up any misconceptions chevyhhr.net members have about my product review posts.

Lone Ranger

Did Delphi stop making AC spark plugs?

Hib Halverson

Tough question.

I *think* it did, but I'm not sure.

I do know that GM has sourced some spark plugs from Denso since the early 00s starting on V8s. Whether it gets them all from Denso or not, I can't tell you.

To be honest, I think it's a good thing because the Densos--even its OE-type iridium plug--is a better design that the last of the ACDelco double plats which were made by Delphi. Iridium has most of the durability benefits of platinum but has less resistance. From an electrical standpoint, that's a plus.

Lee3333

Back in 9/06 Mike SoCal did a comparison test using Autolite APP 5263 plugs. Compared to the factory Delco, they improved 0 - 60 times by .8 seconds and 1/4 mile times by .53 seconds. All done back to back on the same road on the same day withing minutes of each other. His factory plugs were fairly new, so that was not an issue. Times were computed with a G-Tech timer, and even if you argue that it may not be accurate (which it is supposed to be) as a comparative tool it shows the Autolites to be better.

Can not figure out why-same heat range as the factory plugs. But, between the Autolite plugs, CGS intake, IMCO muffler, and TuneTime computer calibration my HHR should do the 1/4 mile in 15.8 seconds, and that was tested on the entrance ramp to the LIE with a slight curve and uphill climb.