I'm not sure if this is the right section...but since I've noted the anomaly on my boost gauge I'll post it here .
When I first start up my car, after it has set long enough to get fully cooled, as it warms up the boost gauge bounces from about 18in/Hg to lets say about 14in/Hg. Some days are worse then others, but it only lasts until the coolant temp gets up to about 1/2 the normal operating range. What could be causing this? A sticky lifter? Bad valve spring/valve seat? If a valve isn't closing all the way it must not be open far enough to crash into the piston because I don't hear anything out of the ordinary. It's done this for quite awhile so I'm not to worried about it, but it's just something that I notice on a regular basis...it's not every time but probably close to 90% of every cold start. TIA
#74506, "RE: bouncey boost gauge." In response to Reply # 0
Does the rpm of the engine go up and down as vac flutters up and down? I notice too, until the motor is fully warmed up, that i get a idle surge. Its not bad, like 100 rpm at most, but vac doesn't vary 4 hg's, but maybe one or two at most. I notice too that my wideband A/F goes lean at the surge, then motor comes back down when it hits around 14.7:1. As it goes leaner like up to 15.7:1 or so, the idle increases just slightly, and the whole process keeps going until i've been driving for a bit until the motor warms up. It sounds like yours is a bit more extreme than this, so not sure there. Just check all of your vac lines everywhere, esp the ones that your boost gauge and all your turbo lines are connected to.
13.5 @108 MPH-2.2 60ft(stupid FWD!) S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential fuel injection) My webpage: http://eclipsed4evr.home.comcast.net -1998 Mitsubishi Eclipse RS-T- "Toy" -1992 Plymouth Laser Turbo AWD(SOLD) -2000 Honda CR-V(daily)
#74560, "RE: bouncey boost gauge." In response to Reply # 1
Originally posted by XtremeRS Does the rpm of the engine go up and down as vac flutters up and down? I notice too, until the motor is fully warmed up, that i get a idle surge. Its not bad, like 100 rpm at most, but vac doesn't vary 4 hg's, but maybe one or two at most. I notice too that my wideband A/F goes lean at the surge, then motor comes back down when it hits around 14.7:1. As it goes leaner like up to 15.7:1 or so, the idle increases just slightly, and the whole process keeps going until i've been driving for a bit until the motor warms up. It sounds like yours is a bit more extreme than this, so not sure there. Just check all of your vac lines everywhere, esp the ones that your boost gauge and all your turbo lines are connected to.
well...my rpm's do fluctuate a little. But the vac fluctuation is much more frequent. Like 2 bounces/sec. And 4hg's is the extreme side...most of the time it's like 2 maybe 3. What else is weird, is the days that's it doesn't do it...usually in the afternoon, it sits rock solid at 18in/hg and the days that it does do it my vac reading is more like 15 or 16 once it stabilizes. Oh well I'll check my vac lines and not worry about it until I have more cause to. Thanks for your thoughts Matt.
#74727, "RE: bouncey boost gauge." In response to Reply # 2
Mine bounced in vacuum also, my valve stem seals were worn out, I never replaced them when I did the rebuild. If your valve stem seals are worn out you'll start to notice a lot of carbon soot build up, like I remember my turbine housing used to be white now it turned black. Then there was carbon soot on my rear bumper and when condensation would come out of the tail pipe black water came out.
http://www.hadesomega.info -car specz and movies 95 Eclipse RS | 76' 280Z | 89' MR2 | 99 Neon | 91 Zephyr Who sez FF can't drift?
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