Bad mpg too

JF1957 · December 20, 2006

I replace my AC Delco plugs whit some Bosch platinum (no +2 or +4) and I notice a big difference on my fuel consomption, not on the good side lol. The pre set adjustement of the Bosch was about ,040 and I reajust them at ,060 like Chev said. Do you think that it can be the cause of my problem ? If it so I'll replace them whit the original one.

Question #2 Did anyone have a 1999 burb c2500 ? I would like to know how many spring leafs you got back there.

Regards

C & A s Dad · December 20, 2006

We do not sell Bosch plugs so I am not familiar with the electrode. However, if they are made like the other plat plugs, you have likely damaged the center elctrode while you were gapping them. Most plats are not supposed to be re-gapped due to the high probability of damage.

Just a thought.

Giant · December 20, 2006

I hope this is not a hijack.

But i also have the same question pretty much. My plugs are old, but the engine runs fine. Could brand new plugs help fuel economy? or is that only when they start to miss and the engine run rough that new plugs will make a difference? Also, will adding non stock wires (the preformance ones with the bigger cores/lower ohms) harm/help the engine with OE plugs?

I'm going to be putting on new plugs and wires here in a bit. I'm putting on AC delco platinums for the plugs, but wasn't sure if moving to a better set of wires would make a difference at all.

thanks

95Sierra2500 · December 20, 2006

It doesn't really matter what TYPE of Bosch plugs you use, they're garbage. I've never seen a GM vehicle that will run properly on Bosch Platinums, +2s, or +4s. I would suggest using at least Autolite plugs, NGK's, or AC Delcos. I wouldn't run Bosch plugs in my lawnmower, and I'm convinced it'll run on anything.

Hammer2785 · December 20, 2006

I tried the Bosch plugs and will agree to them being absolute garbage. I only ran them for 6000 miles and my milage was down and performance down. I just replaced them with ACDelco and improvement was immediate. Also the CarQuest dealer said that the ACDelco are factory gapped at .040 and are supposed to be there and GM has changed the specs even on my 2000 from .060 to .040

C & A s Dad · December 20, 2006

Robert, I replaced my plugs and wires about 6 weeks ago and went with Taylor Power Volt 8.2s. I did this primarily because I wanted Red wires and the Taylors are highly thought of. As far as perf. I can tell no difference in the seat of the pants. It does idle as smooth as warm butter. I can tell you that I have an Interceptor scan gauge that contains a HP calculation feature. Before the plugs and wires I had two runs, one at 298 and the other at 301. After the plugs and wires, I am at 309. I cannot say for sure the wires and plugs did this. The first run was on a 70 degree day and the second run with the new plugs and wires was on a 50 degree day. Either way, it runs great on the Taylors, they are great quality and look good under the hood.

David, you are right and your CARQUEST store advised you correctly. The AC plugs are pre gapped at .040 and are not to be re-gapped. NGKs are still gapped at .060 for some models and also are not to be re-gapped. My '02 model came from the factory with NGKs and that is what I replaced them with. The plug had NGK and the NGK # on one side and AC Delco and the long Delco # on the other side.

BTW Thanks for your business with CARQUEST. I have worked for them for 18 years.

Haulin' 8.1 · December 20, 2006

I just wanted to add a third professional opinion that Bosch Platinum plugs are garbage. I've never seen them work right. Many times when something comes into the shop with those plugs, they are the problem.

For fuel milage all you need is enough voltage to jump the gap at light load. If you don't have misfires now under WOT then lower resistance wires aren't going to help you at part throttle any. The thicker insulation is better protection though.

Vernon

pwall · December 20, 2006

I can tell you that I have an Interceptor scan gauge that contains a HP calculation feature. Before the plugs and wires I had two runs, one at 298 and the other at 301. After the plugs and wires, I am at 309.
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Sorry, not to hijake this thread, but....

C & S s Dad: have you calibrated the scan gauge for the HP or just using the default? I'm wondering if the default is good, or do I really need to take to it to a dyno to figure out? Thansk!

az'03Silverado · December 22, 2006

It doesn't really matter what TYPE of Bosch plugs you use, they're garbage. I've never seen a GM vehicle that will run properly on Bosch Platinums, +2s, or +4s. I would suggest using at least Autolite plugs, NGK's, or AC Delcos. I wouldn't run Bosch plugs in my lawnmower, and I'm convinced it'll run on anything.

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I've run them in several GM cars/trucks and they ran just as good as the originals. I didn't loose any MPG or performance. I had them in my '98 S-10 for about 50,000 miles without a bit of trouble. Also, my brother runs the +2's in his Alero and hasn't lost any performance. And he's at about 60,000 miles on 'em. I'm getting ready to put a set of +4's in my Silverado in a week or so. I'll give a report.

Oh, the gap on these is pre-set so re-gapping will ruin them.