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, Mon, 30 Oct 2023 18:31:34
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Hi Reed,
My EFI basics are: in boot, below spare tyre well, remove fuel filter and back plow it into white paper, or just replace it ( same as VW Type III – 68-72 VW fastback )
My 2 cents:
The issue you noted are likely one dramatic over fueling issue. 1 is suspect is a split rubber vacuum boot in the full manifold vacuum line,
This full vacuum line runs from top of intake plenum, 5" behind the throttle body. there on intake manifold is a brass elbo, where a 2 ft white plastic tube with two rubber connect tubes at either end.
IF either rubber splice connector split, EFI - ECM thinks very low throttle manifold vacuum MEANS or tells the ECM that the engine is at full throttle.
Location MAP sensor: the manifold pressure sensor sits atop the left under bonnet inner fender, aluminum barrel shape, elect connection with 4 wires ( all of them white wires ) and black cover cap on one end. The vacuum port is along the engine facing side too.
input from Manifold pressure sensor is the most vital signal to ECM with the BIGGEST influence on engine mixture. if vacuum leak here, or hose puled loose, idle is terrible and plugs do foul.
additional EFI throttle switch settings and then other fuel tests:
VIP: idle and throttle switch ( one and the same component) on EFI is key to set up throttle and throttle switch.
1. remove air cleaner, with carb cleaner on rag, clean throttle plate bore and brass throttle disc.
2. slacken throttle cable 1/4"
3. on throttle housing: there is a stop locknut seen for mechanically keeping throttle plate just a wee bit open. This is called “ mechanical air setting “
So to re confirm and to verify is best by RESETTING mechanical air : loosen 8MM throttle plate “stop screw” lock nut 2 turns up PLUS ALSO *** loosen throttle switch ( 2) screws so that throttle sw is free to move. "to an fro"
screw up Phillips throttle mechanical stop screw until: actual throttle flap in throttle housing closes fully ( visual w air cleaner still off ) no gap seen brass disc and aluminum throttle bore. It may stick.
then screw down Phillips mech stop screw until you see throttle disc just move ( life away from fully closed) FROM that point of throttle disc just opening…, screw screw down 270 degrees ( 3/4 turn)
this is it: THE "mechanical air only" baseline setting: Tighten 8mm little throttle stop lock nut. ( Note: 3/4 from closed throttle disc IS set up for ALL saabs efi CIS or LH until 900’s to 1994 and 9000's
4. next to set EFI throttle switch: WITH key on, AND w eng OFF, move throttle switch in its adjusted slots “ forward till one "click " is heard. lightly set the 2 throttle sw screws, TEST by opening throttle a bit 1” , then slowly lower / close throttle disc, and listening for 1 ( one ) clicks as your engine now reaches mech air throttle stop setting. You just indexed throttle sw “off/home” with throttle mechanical air setting – great. Rest of testing throttle switch is w key on and no running, slowly open throttle and you will hear 20 clicks. Yes this is throttle disc open position info now going to EFI ECM
Note : there is NO CLICK in return travel letting throttle disc close on this test – That’s normal
Note: one click when disc is full closed ( mech air flap setting ) you may need to tweak throttle sw adjustment few times.
Some other tips
to get some idea of injector open duration in milliseconds.. just a basic hand held Volt meter ( digital fluke ) with pos and neg probes inserted in one injector on its backside under wire boot ( injector still plugged in. will give idea of amount of fuel injected. works great on LH cars too.
idle warn is .2V-.3V at Idle, then if engine cold: Idle injector reads .6 V > 40F, flipping throttle open briefly you will see 1-2 V
VW trained 1971 and 1972 including EFI and Saab dealer tech 1977 onward where servicing 99 pre 1975 car EFI issues were common.
May this information fix your 99 drive ability and fowling and idle problems Don
posted by 174.19.117...
, Mon, 30 Oct 2023 18:31:34
, Fri, 3 Nov 2023 15:24:03, Sat, 4 Nov 2023 06:30:46
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