JustinL

I had to put in some crappy and expensive petrocanada gas into my car and it made that exact same noise. I only put 1/4 tank in so I filled the rest up with good gas and presto... problem solved.

Justin

bavarian banshee

this morning, it was about 75ish, on my way to school. i jumped on it going around a corner and the boost built, and then... ping ping ping. i just filled up yesterday with name brand gas, i think it was cheveron, and it was cool this morning. i also have this vacuum hose that keeps popping off the evaporative emmisions vacuum pot. im assuming it blows off under boost because its not on tight. but if anything, i would think a leak like that would bleed off charge air, and make the mixture rich. it is a big hole though, with it on the vacuum pot, i pull just under fifteen inches of Hg, and with it off, i pull a bit under ten inches. quite a difference! i still dont understand why i would boost more though with a vacuum leak. if the wastegate got more pressure sooner, wouldnt it open faster, and bleed off more exhaust? or does it have to do with the cycling valve? my auto meter gauge says 15 pounds on full boost, though im not sure when it begins to fall off.

do you think playing with the fuel quality switch is worthwhile? i see i can add 6 percent fuel and take out 2.7 degrees of timing, at the same time. it is just covering up the problem though...

take care,
brian

Jeremy Himsel

Brian,

In AZ, Chevron is a poor quality fuel. Try putting unical or texaco in it especially since your running chips. I pulled my intake last weekend and found every hose or line under the intake was loose. I tightened everything and replaced a few and it made a world of difference. What kind of shape are your plugs in? How about your fuel filter? I'd stay away from the fuel quality switch if I could. This weekend I'm having an AC charging day at my place for a few people. If you want to stop by I'll take a look at it. I'd bet we can get it figured out pretty quickly.

alkemyst

Definitely check who you are buying your fuel from...Octane ratings are averages and sometimes 93 at the pump = 90 in your tank, when I had mustang GT's octane was important, whenever I used things like 7-11, Cumberland Farms, 'Mom and Pop', my car would run terribly....any of the big names like Shell, Mobil, Chevron, etc never caused me problems....however it really depends on your area and area suppliers.

Also older service stations I have found problems with (mostly water in the fuel and it could be fixed with one of those water removers at the auto parts store (isopropyl alcohol probably).)

Danno

"whenever I used things like 7-11, Cumberland Farms, 'Mom and Pop', my car would run terribly....any of the big names like Shell, Mobil, Chevron, etc never caused me problems...."

Yeah, avoid the Ultramar station that's about 1-2 exits south of the Laguna Seca exit on 101!!!