Date: Fri, 2 Apr 2004 15:42:54 +0000 (UTC)
From: "Tomnospamtech" <>
Subject: Re: Intercooler heatsoak, and peak boost lower.......

"MeatballTurbo" <> wrote in message > In article <c4jj2q$2jdc6o$>, > says... > > MeatballTurbo wrote: > > > > > During the colder weather, boost peak was on the edge of red, dropping > > > back only a little. > > > > > > Yesterday, it was peaking at 3/4 yellow, dropping back to 2/3rd yellow. > > > Plugs were changed in the last 8k miles, had an oil and filter change 3 > > > weeks ago, airfilter is clean. Leads haven't been changed, but there was > > > no signs outwardly of them cracking. changed the rotor and cap about 8- > > > 9k ago just before I did the plugs. > > > > > > That's a big difference for such a small temp difference I think. Is > > your timing spot on? > > > > > Should be. Timing chain was changed about 5 months ago, so they should > have checked the cam and ignition timin when they put everything back > together. > > When the rad fan kicked in yesterday, on the way home, and stationary > for a while, before the temp fully dropped, it was peaking at 3/4 and > dropping to half, even bigger peak dip, and even bigger drop between > peak and stable. But after a while driving, yesterday, and this morning, > it was pretty close to what I'm getting now. > -- > The poster formerly known as Skodapilot. > I don`t think that the ambiant temp variation is the cause of your problem, It sound like the apc has defaulted to base boost, the easy way to tell is to disconnect the apc solenoid, [The round thing with three hoses on it above the rad] and then see if max boost returns, if it does then the apc is at fault, If not then look at the dump valve and its hose, Check that the wastegate acctuator diagphram is holding pressure, [you can use a bike pump to gently apply pressure and make sure that the rod to the turbo stays put until you release the pressure]. If the apc is at fault try it with the knock sensor unscrewed from the block and suspended out of the way but left connected, \\\if pinking occurs then lift of the gas straight away. There is a fairly common problem when the brake light switch is faulty or not correctly adjusted, when the brakes are applied it sends a signal to the apc to knock the boost off, this can happen even if the brake lights do not come on. You can check the apc acctuator by dissconecting the hose from the inlet manifold[the one that goes to the boost gauge] and plugging the hole in the manifold, run the engine at over 2000 rpm and apply pressure to the hose with the pump, as you approach the red bit on the boost gauge the apc solenoid should start to chatter. Also check the earths under the rad. Keep us posted and let us know how you get on, Regards Tom.

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