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Discussion Starter #1
Hello guys, I have a '93 900 S 2.1 with running/idling issues. On cold start it starts and idles normally but after hard driving, or highway driving it will have an erratic idle and sometimes die completely. The issue doesn't come up on steady state cruising and I've driven for hours on the highway with no issue, but when I slow down for an onramp or exit ramp it will turn on the check engine light, burble and rev erratically and then usually idle at an extremely low speed, under 500 RPM, then die completely.

I've cleaned and tested the air mass meter , tested the ELCD valve for resistance (charcoal canister), replaced and tested the o2 sensor and preheater circuit, checked the coolant temp sensor for resistance, and used carb cleaner to check for vacuum leaks and found none. I pulled a vacuum hose while running and while it did idle worse, it still idled, leading me to believe a vacuum leak wouldn't cause the issue I'm having.

I've also pulled several check engine codes: 12223: AFR too lean, 12241: AFR fault, 12111 and 12112: Oxygen sensor self-compensating circuit problem (12111 means incorrect AFR while driving and 12112 means incorrect AFR at idle)

Today, I pulled the coolant temp sensor plug and drove it hard hoping to see if the issue wouldn't appear without the sensor, but I had the same problem with it dying at stop signs, and while parking.

Does anyone have any other suggestions or experience with this issue? I'd really appreciate any and all suggestions and help.
 

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check you hve'nt a vac pipe off, I had this happen to me the last couple of days, only happened when I slowed to stop at a junction, and it jsut cut out, lifted the bonnet toady to see what might be, and the vac hose from the car air divert line was off at the intake manifold, nipped 1/2" of old pipe off and refitted...wish fixes were always this easy lol
 

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From what is described, this reads very similiar to the experience I've had........which ended up being sorted by replacing the Air Mass Meter.
Regretfully, acquiring prime condition AMM units is increasingly challenging due to the scarcity of the parts.

There can be similar running issues which can be attributed to the quality of the grounds, power sources, wiring, fuel pump, spark, plugs, leads, etc., vacuum hoses, ECU (rare).......even manifold gaskets.......idle valves have been noted to give awkward driving issues!
From my experience, the exhaust probe will not improve the running issues.......it does however improve the air/fuel ratio feedback response to the ECU.
The ECU is adaptive.....it learns and fine tunes the engine as a running operation. It cannot mask a faulty component within the composite operation of the engine.
When you change a major item in the engine bay, the ECU needs approx 30 minutes of driving to adapt to the changed engine operation.
 

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I suggest two things: (1) checking timing. One method is to just turn the distributor cap very slightly (a degree or 2) counterclockwise - I read this in a post by Peva. If car runs better, then timing is off - and then you can set it appropriately with a timing light. Worked for me.

(2) Check fuel injectors to see if the seals are leaking. Do this by pouring a tiny bit of water around injectors (while engine is running). Change in idle means leaking injectors.

My car had similar symptoms, and had both problems - leaking injector seals - worse when engine was hot, not noticeable when cold. Timing affects idle (when warm), and also affects how quickly the car starts up.
 

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In factory - standard form, the timing on the 2.1l unit is not adjustable. Timing is based on trigger signal from crank sensor, mounted at crank pulley.
If the distributor is moved, the spark timing will not change but the relationship between the rotor tip and cap anodes will........potentially weakening the spark.
No Need to alter the distributor position.
 

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I suggest two things: (1) checking timing. One method is to just turn the distributor cap very slightly (a degree or 2) counterclockwise - I read this in a post by Peva. If car runs better, then timing is off - and then you can set it appropriately with a timing light. Worked for me.
I never said this about a car equipped with a crank mounted sensor. In this case moving the dizzy has no effect.
 

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I didn't think the status of the valve on the charcoal cannister had any effect on the behaviour of the electronics? Isn't that simply a valve to close or open the connection between the charcoal cannister and the intake manifold?

Craig.
 

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Discussion Starter #8
Thanks for the advice guys! I've done some more poking around, and it seems like the injectors aren't leaking and the AMM is fine, the filament glowed and everything, like it's the crank position sensor. I've ordered a new one, and plan on replacing it soon.
 

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From what is described, this reads very similiar to the experience I've had........which ended up being sorted by replacing the Air Mass Meter.
Same experience here - although I fixed mine by cleaning up the Air Mass Meter's connector, rather than having to replace the whole unit.
 
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