Date: Tue, 02 May 2006 18:05:18 GMT From: Paul Halliday <pjghnospamyonder.co.uk> Subject: Re: 1985 900 Turbo - APC question
in article jw-8F1EFC.17083301052006nospam.verizon.net, jw at jwnospamet wrote on 01/05/2006 22:06: > In article <1146454771.755166nospaml.amnet.net.au>, > "Michael" <mvedernospamh.net.au> wrote: > >> Dave. >> >> I agree that apc works great.. repair procedure.. >> >> apc has several sensors of which makes it work correctly. > > Thanks again, all. I'll probably just start by taking a close look at > the APC to determine, based on the input and pix here and elsewhere, > whether it's something I can adjust. Will keep in mind the input about > the aftermarket swap. I'll try to post with results! Feel free to follow up with questions based on what you find. Really, APC is not difficult to troubleshoot. If it's not the usual handful of things, like stuck brake switch, bad grounds or the APC box shorting due to it being full of rain water by all means fit an aftermarket controller. Personally, I would advise renovating APC. While this may not be complete, this is the order I would check things: 1. Press the brake. Does the solenoid valve on top of the radiator click? Yes? Continue. No? Fix that. Usually, this is just a bad ground. Just double-check that your brake lights are not stuck on, too :) 2. Pull the multi-plug off the APC box, spray over with WD-40 and re-fit a couple of times. Clean again and re-fit. Better? No? Continue. Yes? Great. Feel free to check the ground on the APC box. Pin 5 (or rather the connection on the multi-plug that connects to pin 5) should have continuity to the chassis. See <http://www.nospam/phpBB2/viewtopic.php?t=150> for an inventory of the function of all the pins. If you're electronically minded, rig up the knock sensor LED to facilitate troubleshooting the knock sensor. 3. Remove the power to the APC solenoid valve, connect a known good pressure gauge to the intake manifold, find a long road and floor it in 4th. Note the maximum pressure reached. It should be 0.35 bar or thereabouts. Too low a pressure will give a poor max boost, which might feel like a failed APC system. Still bad? 4. Check the power to the knock sensor. You'll find this under the intake runners. No power/not connected and you'll get basic boost. Better? Yes? Fix the knock sensor wiring. No? Continue. 5. If you can reach, are inclined and the power is definitely good, unbolt the knock sensor from the block (and wrap in padded cloths) and go for a drive. Better? Your engine knocks. No? Continue. 6. Is the charger okay? Remove the vac pipe from the APC solenoid to the wastegate. Connect a pressure gauge, find a long road and slowly raise the boost to around 0.75 bar. If it won't make that boost (we already checked the wastegate, remember), then the charger is poor. 6. Beyond that, come back with more questions. Paul 1989 900 Turbo S http://saab.go.dyndns.org/
