9 replies to this topic

[kenhoeve]

I've noticed lately that my car is not running real smooth over 15psi. It's very smooth up until then, but it just feels a little rough when it is holding 16psi, which I can up to 5k rpm. I know that CA gas is crappy, so this may have something to do with it. I was in Utah a couple weeks ago, and after filling up and a ways down the highway, I stopped and turned and got some pretty bad misfiring in 2nd gear around 3.5k-4k rpm at 16psi. This hasn't happened since though. It's also pretty easy to tell that I'm pulling plenty of timing in 3rd gear at highway speeds.

All my ignition components have less than 15k, with less than 10k on the plugs. Running OEM coppers, at .028. What solutions should I consider? Lower the gap a little? To what? Or is an upgraded ignition the only answer?

I have a 17psi chip, and full 2.5" exhaust. Any thoughts?

[PyROTech]

gas could be the problem, i find from my bud-0-meter that higher octance fuel feels alot smooth than say some crappy mid/high

[turbor850]

lower the gap a little to .024 and see how it goes, if it still persists, then my guess is the craptacular gas (or the heat ?)

[RAzOR]

You said OEM coppers. Does that mean you are using the stock Volvo plugs or something that says it is "OEM". I had misfiring issues and the only way to begin to solve them was using the stock Volvo plugs at stock gap.

I've noticed lately that my car is not running real smooth over 15psi.  It's very smooth up until then, but it just feels a little rough when it is holding 16psi, which I can up to 5k rpm.  I know that CA gas is crappy, so this may have something to do with it.  I was in Utah a couple weeks ago, and after filling up and a ways down the highway, I stopped and turned and got some pretty bad misfiring in 2nd gear around 3.5k-4k rpm at 16psi.  This hasn't happened since though.  It's also pretty easy to tell that I'm pulling plenty of timing in 3rd gear at highway speeds.

All my ignition components have less than 15k, with less than 10k on the plugs.  Running OEM coppers, at .028.  What solutions should I consider?  Lower the gap a little?  To what?  Or is an upgraded ignition the only answer?

I have a 17psi chip, and full 2.5" exhaust.  Any thoughts?

Edited by xRAzORx, 29 October 2004 - 05:48 PM.

[pennybridge pioneer]

in socal i only run 91 from chevron, its the best stuff i've found yet. I'd say if you want to minimize your chances of hurting something look into lowering your intake air temps, i'd look into a bigger/more efficient intercooler, even though the stock one is pretty damned decent....

maybe just a more powerful coil would help, but again the stock coils are very good.

but see i had this concern too with regards to the speedtuning 17psi chip, because that's like the upper range of the 15g without having complete control of the tuning, and i'm pretty sure the speedtuning 17psi chip is for 93 octane gas (is there a different one for cali 91? someone clarify?) I'm worried that due to the nature of the "off the shelf" chip, its just dumping fuel in and the spark is just backing off as intake temps rise. The extra fuel will cool the charge slightly, but too much will make it bog. Could this be what's happening? maybe it has nothing to do with your ignition?

[kenhoeve]

lower the gap a little to .024 and see how it goes, if it still persists, then my guess is the craptacular gas (or the heat ?)

i'll try .024, maybe .026 to see what happens. Not heat, I live by the coast. The misfiring happened when it was in the upper 50's. Definitely pulls harder when temps dip into the lower 50's though. And it's usually around 70 here.

Pennybridge, I think you're right. Probably a combination of 91 fuel, which I always run, and the off the shelf tuning at the edge of the 15g's limits, throw a little spark issue in at high PSI and there you go. I've wanted to go Upsolute and just dyno a couple times for some time, but it is a bit of a pain. If I had a dyno nearby, different story.

[kenhoeve]

Pull the plugs, they will tell all.

argh! of course. didn't even think to diagnose.

[JESSEXC]

Crap, my car is doing the same! I use only 93 octane,spark plugs one degree colder and water injection set at 10psi. At 16 psi It sounds like turbo flutter? Now here is the strange thing. It doesn't do it all the time