I worked on the Saab a bit this weekend
AkioOhtori last edited by
Just a bit though.
I'm nearing the point with that vehicle that I need to just pay the local specialist to fix it. This would be expensive, but likely worth it. However... as I am the self-proclaimed 3rd best CIS mechanic in Tulsa, I figured I would give it another look. Any you know what? I found a problem!
To rewind for a second, my 1984 Saab 900 Turbo Sedan ( #Project Dumpster Fire) has been a pain in the ass since I lightly abandoned it for 12 years and have spent the last 4 or 5 (who remembers?) years fixing it. The latest problem is a lean running condition when I hit the gas that eventually sorts itself out, but is a major drivability issue.
This list of replaced components on this car is long. Looooooooong. So one of the last things to check is to see if I see an unacceptable drop in fuel "line" (post-filter, unregulated) pressure when I see the lean condition. I was unable to test this on the road for a variety of reasons, but it appears the fuel pressure is within tolerance.
I'm unclear as to why I thought to check the poorly named "cold start valve" but I did. The cold start valve doesn't just help with cold starts, though that is part of its function, it also corrects the AF ratio while the car is running and gives you an extra shot of fuel on sudden acceleration.
It also doesn't appear to be working.
Though it isn't clear to me why it isn't working.
After some investigation I proved the injector works, the fuel pressure to the injector is correct, the electrical connector appears to have signal, and if I manually fire the injector gas comes out. However with the car running, no gas?
First guess is the connector isn't making good contact with the injector. This is a little bit of a long shot, but certainly not unheard of. Next guess is I'm testing it incorrectly, somehow. Also unlikely as the system isn't complicated and my understanding is that injector pretty much fires all the time. Third guess is one of the many, many, many little mini-computers that run this thing have gone wonky, lost a ground connection, or accidentally been bypassed.
I feel like the third is the most annoying, most expensive, most complicated answer therefore must be the case.
Thinking next steps should be to:
- Try and tighten the electrical connection
- Maybe bypass the connector and run wires directly to the injector
- Haul out the oscilloscope and see what signal is getting sent to the injector
Unfortunately that is all I've got. I'll post an update when I actually track down the problem.
Random personal stuff
Despite making some good progress on some stuff, I feel like this has been a really unproductive weekend. I did a couple loads of laundry, mowed and seeded the lawn, and did some computer stuff that needed to happen but... I dunno felt like I mostly just fucked around? But not in a good way.
Oh as promised I got a robot vacuum for the office. We set it to work with Dog B in the office because we assumed he would attack it. He could care less. Later I was playing with it with Dog A in the office and he started stalking/attacking it (he is part cat). This was surprising as he is generally intelligent and chill, but also LIVED WITH US WHEN HE USED TO HAVE LIKE THREE FULL TIME ROOMBAS. So weird. Of course him nipping at the vacuum caused Dog B to charge in and pick a fight, so I had much scolding to do...
Oh yeah and vaccination update! My arm got super sore/immobile about 12 hours after the shot, but when I woke up the next morning I was through the worst of it, seemingly. No other side effects, but I did take a HARD nap about 4 hours after the shot. So far the 5G coverage has not improved, but maybe that transmitter comes with the second shot?
Think that is all I've got. I'm going to have a beer and go to bed, me thinks.
WhoIsTheLeader last edited by
@akioohtori Your battle with this Saab is legendary. It might even be kind of coming to an end. It being a ground issue somewhere in the electrics would be the most annoying possibility and, as you stated, is therefore probably it.
EssExTee last edited by EssExTee
@akioohtori Macco's Razor - the most annoying possible explanation is always the one it is
BritsnSwedes was MINIGTI last edited by
@akioohtori this is good oppo. my 85 Jaguar has some similar flavor of Jetronic and also has the cold start injector. I just got a cheap oscilloscope so it would be interested to wire that cold start injector up to it and see what signal it gets.
Supposedly the EFI board is potted and extremely reliable, so don’t give up hope yet.
annoying_salman last edited by
MM54 last edited by
@akioohtori Any progress is still progress, and it sounds like you're on the right track. I suspect pulling the connector and putting the 'scope on the plug to see if it's getting signal is the right route - if it's getting the pulses but not firing, something is very weird (perhaps the driver circuit would be bad) - if there's no pulses, then you can chase wires back until you find the computer!
Weekends are about the right balance of doing and relaxing. I find myself with the same feeling after a weekend of doing nothing - it was nice to relax but I feel guilty for "wasting" the whole weekend and not getting anything done. Similarly if I do some particular task all weekend, I feel guilty for "wasting" the whole weekend and not relaxing at all.
(I spent a bunch of time this past weekend troubleshooting an intermittent "runs perfectly and then doesn't and won't even try to restart" issue in an AW11 - much poking, testing, and diagnosing later it's 90% one of the pickups in the distributor crapping out when hot and stopping the position sensor signal to the ECU.)
AkioOhtori last edited by
if it's getting the pulses but not firing, something is very weird
Welcome to my life. I had a multimeter on it and at least saw the carrier wave frequency (though IIRC the spec is 70Hz and I would have sworn I saw 90Hz...), hence why I need to drag out the 'scope.
True that balance is good, but I feel like I've been too much "resting" (read: nothing) and not enough other stuff. I feel like working my ass off on side projects makes the drinking and watching TV justified haha