The banner above is an advertisment - if it asks you to download software, please ignore.
Site News - 3/26 M Car Covers (by State of Nine) | 12/12 Make Amazon Pay Saabnet!
Date: Thu, 31 Jul 2003 10:01:12 +0000 (UTC)
From: "Saabtech" <saabtechnopsamnnect.com>
Subject: Re: Mixture problems and lumpy idle


It works like this: The cold start spray valve gives a initial extra squirt of fuel when the starter is cranking the engine and is controlled by the thermo time switch which is controlled by coolant temp. Mixture settings between cold and normal temp are controlled by the warm up regulator which is sitiuated on the side of the head by the thermostat housing being temp sensitive and also has a electrical connection working on a bimetallic strip which increases the amount of fuel pressure returned to the tank thus reducing the fuel pressure at the injectors and therefore making it run leaner, The auxillary air valve deals with the extra air to go with the extra fuel. If the warm up regulator goes tits up you can have a situation where the engine runs too lean at cold or too rich at hot or is ok at cold or hot if compensated for by adjusting the mixture. On turbo models the vacuum/pressure hose on the side of the regulator decreases the fuel pressure returned to the tank while on boost to increase the pressure at the injectors thus making it richer whilst on boost, The regulator being faulty would possibly be the cause of knocking on boost as the return pressure is not being adjusted accordingly. HTH Tom, Saabtech. "Paul Halliday" <pjghnopsamyonder.co.uk> wrote in message news:BB4DC7F0.80F6%pjghnopsamyonder.co.uk... > in article bg8ckm$lu9il$1nopsam52899.news.uni-berlin.de, Grunff at > grunffnopsam.com wrote on 30/07/2003 13:10: > > > Paul Halliday wrote: > > > >> Am I going the right way about this? The Haynes says to set the idle first. > >> Am I doing this right? It then says to set the mixture correctly by > >> measuring the exhaust gas. Is there something I can buy to check this? I > >> have no cat, so I presume I can measure the gas at the rear of the car at > >> the exhaust outlet. > > > > As Carl says, check the cold start injector - they sometimes > > leak. Remove it when the engine is hot, see if it dribbles. > > > > Have you cleaned out your idle control valve (by the thermostat > > housing)? If not, remove it, empty half a can of carb cleaner > > into it, followed by a generous amount of WD40. You will see > > lots and lots of soot coming out. > > > > Have you cleaned out the throttle body + butterfly? Again, lots > > of carb cleaner followed by a bit of oil. > > Do I understand this right? > > If the cold start injector is not running at all then while the car is > warming up it won't be rich enough. This will explain the poor RPM at cold > idle and occasional stalling when when the outside weather is a bit muggy. > > If it is over running (running all the time), then I've set the mixture too > lean to compensate when warm and the same outcome as above will be so? > > It all seems to have started since I had the dump valve fitted and my > throttle housing replaced for a 16V version to accommodate the dump valve. > I've ruled out the dump valve leaking by plugging up the pipe. Perhaps my > garage were over-zealous with the cold start valve gasket sealant :) > > I'll have them check it out when it's next in - I ended up burning myself > when I last bled the coolant, so spraying petrol all over myself from a > leaking injector seems a really bad idea :) > > I do clean out the PCV, idle control valve and throttle body with carb > cleaner the day before doing an oil change. I do a Wynns engine flush (to > get the remaining crap out) and oil change about every 3000 miles. Sparks > and leads are checked at this time as well. I've recently checked over the > rotor arm, cap, leads and plugs when I had that "wobble at 2000 RPM" > recently, so I know that's all okay. > > Thanks for the help guys, > > Paul <--- Contemplating that petrol fiasco now I've had a beer :) >

Return to Main Index
StateOfNine.com
SaabClub.com
Jak Stoll Performance
M Car Covers
Ad Available

The content on this site may not be republished without permission. Copyright © 1988-2024 - The Saab Network - saabnet.com.
For usage guidelines, see the Mission & Privacy Notice.
[Contact | Site Map | Saabnet.com on Facebook | Saabnet.com on Twitter | Shop Amazon via TSN | Site Donations]