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Discussion Starter · #1 ·
Hi, this is really a follow on from an earlier post and am absolutely stumped over this problem now, how to solve it.

Have been working on this and still not firing :x .
First step was to follow instructions re. set up TDC and noting the nearest distributor pole to the rotor contact.
At that stage...
1. I set the flywheel position to 0 degrees (is this correct?...perhaps 14 degrees BTDC ? as in Bentleys re. ignition timing)
2. The rotor arm was pointing down to bottom left (say the 7 o'clock position, when viewed from the drivers seat) so accordingly I set lead/cylinder 1 to that pole and set the others in order from there.
Does that position sound right?
3. The engine did not fire, it vaguely 'spat' once.

Just to say, before this service the engine ran perfectly.

Following this failure I checked a number of electrics armed with my new multimeter and Bentleys.

1. Battery at full charge; spark at plug visible but not familiar enough to gauge stength; fuses OK.
2. Coolant sensor, throttle sensor, AIC, ign. coil, rotor arm impedance all OK
3. Re ignition amplifer there are 2 tests. One test was fine but the one that tests (I think) power to coil from amp that involves connecting the meter to Ign. Coil Terms. 1 & 15 the test failed. The reading with ign ON was to be 6V initailly and meant to fade to 0V in 2~3 seconds, it did not, the actual reading was 3.2mV which was continuous.
So, in some respects this could point to the ign. amp but I am confused the the presence of a spark at plug. Also, surprised that it would fail so abruptly.
Having said that would the high and oscillating idle (behaviour when last firing) be indicative of a failing amp?

Next and latest move...
1. I set the flywheel to 14 degrees, just to give a try though it naturally did not effect postion of rotor to pole from before.
2. Just a vague spit, akin to mis-fire but not continuous, cranking over healthily.

At this stage to do anything more seems pointless, (almost damaging!) and prefer not to rush out to buy replacement amp without greater certainity about what is really the cause of all this...the mind is fused...HELPPP!
 

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When you set TDC the flywheel will afford two (2) opportunities - one is true TDC, the other is 180 degrees off (remember - otto cycle - the crank rotates twice for each rotation of the cam(s)) - I suspect you've "discovered" this on your own;) . Bring your flywheel around to where you've set TDC then go another rotation, note the position of the rotor, re-do your HTL's accordingly and you might just find joy!:cheesy:
 

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It sounds like you're 180 degrees off; i.e. you have the rotor pointing at #3 instead of #1.
Swap the wires around so that #1 is 180 from where you describe the rotor pointing (#1 is at1:00 O'clock).

If you have spark (it spits), the amp is OK.
 

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Have you put the spark plug wires onto the distributor as per bentley? Bentley is wrong!
 

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The reading with ign ON was to be 6V initailly and meant to fade to 0V in 2~3 seconds, it did not, the actual reading was 3.2mV which was continuous.

In troubleshooting my intermittant stalling I tested two ignition amps--both tested the same as yours has. My car runs smoothtly--I think I've fixed the intermittant stalling--so I suspect the Bently's book is wrong on this also.
 

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Discussion Starter · #6 ·
Thanks a million :) ,
Steve, Jim...it seems I have made, yet another, discovery :p ... 1 fly rotation = 2 cam rotations news to me ;oops: .
But should that be set to fly at 0 degrees or 14 (or whatever best) degrees??

Actually looking forward to tomorrow now to try this out.

900t...well I did think of following Bentleys re position of #1 but did not persue that, but will look at that again to see what you mean.

Banman...that's sounds reassuring...will post how things go
 

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I've only screwed up the cam timing about 1/2 the 10 times or so I've had a head off ;oops:
 

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finbarr said:
... 1 fly rotation = 2 cam rotations news to me...
It's the other way around; 2 flywheel rotations = 1 cam rotation.
Since you aren't changing the relationship between the flywheel and the cam/rotor, it doesn't matter where the flywheel is when you move the plug wires.
Get it running, set the timing with a light.
 

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??? this car is a 1993 900i?


2.1l n/a? or 2.0l n/a?

I was under impression that the timing was not adjustable....(sorry Jim)....


You can have the flywheel at 0 TDC,...... but, is it cyl 1 or cyl 4 on TDC of the COMPRESSION stroke?

Sorry, just to confirm......

have you established that the crank pulse is functional? ie: the crank pulse sensor? Is the fuel pump turning on during the start process?
 

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Discussion Starter · #11 ·
its running !!

What a blissful sound after 12 weeks otherwise unservisable (from when I started replacing the rad that is).
Fanastic and many thanks!.

Rodentmaster…yes its a '93 900i and is 2.0l
The set-up with engine running is with fly at 14° and the cyl. plug ?1 located in the 1 o'clock position on the distr. cap when viewed from the driver's seat. The situation was as Steve + Jim indicated that I had "discovered" that there are 2 TDCs and I had set up on the wrong one. So I moved the plugs 180°. But I take Jim's point "Since you aren't changing the relationship between the flywheel and the cam/rotor, it doesn't matter where the flywheel is when you move the plug wires."
And no, I had not got round to checking the crank pulse~sensor or fuel pump.


About the ignition amp, as Banman pointed out, there does seem to be a misprint in Bentleys concerning the voltage values. Also as 900t mentioned Bentleys wrongly shows plug?1 at 11 o'clock rather than 1 o'clock.
 
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