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Re: My SAAB will idle, but stalls out when you try to drive Posted by Dana [Email]  (#2822) [Profile/Gallery]
(more from Dana) on Tue, 10 Aug 2004 13:16:56
In Reply to: My SAAB will idle, but stalls out when you try to drive, White Vampire, Tue, 10 Aug 2004 06:16:02 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I'll make a couple of assumptions of the start conditions....
The engine is cold..i.e. <115F
You gave it throttle within 2 minutes of starting...
During this time the cold injector will come into play during initial turn over and during any acceleration function. The emissions control unit should have locked a slightly increased 60/40 enrichment pulse rate into action and the warmup regulator has also increased enrichment by lowering its control pressure regulation to the fuel distributor.
Most likely Cause...lack of proper fuel enrichment during the warmup cycle (enough for acceleration)
Possible Reasons:
1. Thermo time delay switch is gone....when engine is cold, 40 ohms between the two temperature switch pins, 0 ohms between one pin and engine body, 40 ohms between the other pin and engine body. When engine >145F the 0 ohms becomes 40 ohms. Simple to test...switch is ~$64 Switch is located on top fo the engine right between the intake manifold channels. Has black plastic wire bar release connector plug.
Background.....cold start injector is getting power via hot/cold start relay for initial start but then cold start injector will work on manifold pressure impulse pressure switch (mounted under the fuel filter) for the first two minutes.
2. Impulse pressure switch is not working....vacuum tubing to intake manifold has rip/leak or come off. Switch contacts are not closing on short vacuum impulse. Switch is mounted just under the fuel filter..look for the vacuum tubing.
Background: The short impulse signal from this switch locks the emissions control to a richer mixture for a timed 2 minute interval. This makes the car more drivable during the first couple of minutes without stalling.
3. 115F engine temperature switch has failed open...located just below the thermo time switch it has two separate push-on wires attached. It opens at 115F increasing temperature. When below 115F it tells the emissions control unit to increase enrichment to 60/40 pulse rate. Easy to test after engine has warmed fully and when it is stone cold.
Background: This switch is a parallel function of the vacuum impulse switch above but has no enrichment time limit if the temperature of the engine is below 115F.
4. Warmup Regulator....changes the distributor control pressure which regulates gas supply pressure to the injectors. After about 104F increasing engine temperature it has no real effect so it usually has a very short control time. Control pressure will change from about 30 psig to ~47 psig as the engine warms. Test internal heater coil, pull electrical plug off, internal heater has 40 ohm resistance. New replacement varies from $58 to $190.
posted by 129.57.8...
, Tue, 10 Aug 2004 13:16:56 <-- Viewing This Message
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