Just changed oil pressure switch, and now oil light comes on, and other things.

[Mike Brennan]

Well the next easy step is to clean out the MAF. There are lots of tips on how to do that check the FAQ here or on Saab Central
Then take this last post, it's all you need, and put it up on SAAB Central. There is a bit more exposure there. I know what your problem is I just cant remember the fix. I'm pretty sure it is the TB. You also need to get the code numbers and post them

[nordwulf]

Joby, any luck with this issue?

[Joby Comstock]

Joby, any luck with this issue?

No. It's becoming a time vampire.

The engine is running rich, the plugs (NGKs) are fouling with carbon (not oil), the car hits a low idle or almost stalls when decelerating, and when it's hot at the lowest ebb of that deceleration, the oil light comes on, and the low idle/stall issue gets worse. It may be idling a bit rough when sitting still with the car in Drive, but a lot of cars do that. Twice it's thrown a P1110 code (Charged Air Bypass Valve), but both times I found a broken or loose vacuum line, and neither fixed the other symptoms. Otherwise, it seems to run and sound fine, and it idles smoothly unless it's just coming off a higher rev. The turbo, I think, is working right--no gauge, but I hear it, and it's got a lot more acceleration than a regular four cylinder.

I've cleaned the MAF (twice) and throttle body, replaced most of the 4mm vacuum hoses (I couldn't get to the ones that disappear into the fire wall, but I think they are the heater), changed plugs, checked compression (strong), and so far nothing, although I do think it runs a bit smoother. And as I mentioned before, I changed the air and fuel filter when I got it--both of them were beyond filthy, and probably the originals.

So, I don't know if it's hose related, sensor related, ignition or fuel related (but since it doesn't do it at regular speed, I'm thinking it's more likely air flow or some sensor), and I still don't know for certain the oil pressure isn't a bit low.

One more thing; on the highway the mileage is great, up over 30 or 33, but around town it's closer to 20, or even 18. Not that I'm driving it much. On the drive here from New York I had one tank of gas measure at 37 mpg. So it seems to mostly have problems at slower speeds and when it has to make a lot of quick adjustments. So that sounds like sensor or air intake to me. But that's just a guess.

Anyway, I'll play Symptom Bingo a little longer, and start replacing what could cause all the symptoms. So far I'm thinking temp sensor, CAB valve (since that's the one error code I've gotten), and the Turbo Bypass Valve with a thousand names. Could the latter two make it run rich? I mean, enough to carbonize a spark plug in less than fifty miles?

[Joby Comstock]

How would I know if the ECM was bad? I mean, if the idle is too low, or the MAF is bad, or I'm running rich, I should be getting error codes, right? And the ECM controls the fuel/air mixture and idle speed. The plugs are covered in carbon in less than fity miles, so why am I not getting error codes?

[kraichle]

Hi Joby, did you ever figure out your problem? Just curious because I'm going through low oil pressure work myself. I have a couple reasons I believe low oil pressure is causing your idle problems. Seems like one of the first things to show symptoms of low oil pressure is the lifters. On several different vehicles I've witnessed low oil pressure causing starvation to the lifters and then galloping idle. I instantly noticed a tappet noise once the idle got down low enough where my oil light started to flicker. Once the flicker started so did the tappet noise. The ECM is smart enough to know that the idle shouldn't be that low so it tries to compensate by raising the idle, but once the idle increases a little so does the oil pressure and then the lifters are functional again and it over shoots the target rpm. The ECM then decides to bring it back down and so comes down the oil pressure, and the cycle repeats. I have a 2004 Town and Country which also has a characteristic oil starvation problem and it does the same thing on cyl #2. You can hear the tappet noise when the idle eventually settles down then the ECM compensates and it goes through the whole cylcle. You can hear the miss in the exhaust too. Although this one is not a pretty. It turns out the cam lob is supposedly wearing down and eventually the engine will hatch out. Just my luck... My sons car also had a similar experience. He doesn't check his oil regularly as he has a leak (wrecking my freakin driveway) and one night he came home from work saying he was having problems keeping his car running at stop signs. He said he had to keep his foot on the gas. I went out to take a look at it. Knowing I'd been telling him to check his oil for the past month, I had some suspicions, not sure why, but when he started it I could hear the lifters banging away and told him to shut it down before he wrecked something. I checked his oil and there wasn't anything on the stick. I think we put in about 4 quarts out of 5 and started it up and it ran fine. Not sure how much life he took out if it, but it's a Camry and seems to take all the beatings he dishes out to it.

I'm actually replacing the timing components (chain, gears, rails, etc.) because of my own fault. I use to have the attitude of "yeah I'll get around to changing my oil when I'm good and ready" It seemed to work fine with the earlier vehicles, Saabs included, but these later years don't tolerate attitude. My Saab, 2000 93, had the breather conversion done so it shouldn't have had any problems with slugging if I had changed the oil regularly, but I didn't. I think the color of oil after black is gray or something, cause that's what mine was. After I pulled the pan I noticed little shards of something fiber like which looked like it had chain marks in it from maybe a timing chain. I did the research and found that if you're starving your engine (Saab that is) of oil the first thing to be affected is the timing chain. So I did the stretch check and mine was past the recommend max. (16mm or more). After all said and done I probably could have got by with not changing it as it wasn't the worst thing I've seen, but glad I put the effort in pulling the timing cover off. Turns out the biggest joke piece of junk Saab came out with is the balancer mechanism. The chain was lose as hell slapping all over the place. There where wear marks on the cover and block, there were no teeth left on the actual balancer shafts. I had a hard time figuring out which was the balancer shaft and idler gear. The gear had the teeth, go figure. No wonder why everyone recommends cutting the chain cause you'll just end up with it snapping and hatching out you engine. The pieces of fiber in the oil pan came from the balancer chain guides. So it ended up being worth all the effort of removing the timing cover without pulling the engine. Sliding the engine/tranny over to make space, what a hassle.

Anyway, back to you story. There's one comment you made earlier that I picked up on, which I believe may be your problem. You mentioned something about an oil additive cleaner or de-sludger or something like that. When I get my vehicle back on the road again, I was planning on adding some automatic transmission fluid to help clean it up a bit, but am having second thoughts now that I've though about it a little bit after reading your scenario. It doesn't take much to plug up the stupid oil pickup screen on these year vehicles, and I believe that's might be what you did by adding the cleaner.

It also doesn't take much to carbon a plug up either like could happen at idle. Just leave a small engine on choke for a few seconds and pull the plug and bet you it's black.

You may have other problems, but I believe the underlying problem is low oil pressure.

I'm planning on adding an oil pressure gauge to my car before i start driving it. I'm also going to add gauges to the other Saab I have which falls into the 99-04 year where they f'd up the engine design. Oh, and my '04 Town and Country where they f'd up that engine too, but think it's too late for that one. Oh BTW, I bought the T&C that way and wasn't applying my oil change philosophy on it, must have been the other guy.

I've gone through about a dozen Saab so far and am thinking that maybe I should retire from them. My wife owns a Lexus RX300 and my son a Camry, both Toyota's, and I rarely touch them. If it wasn't for the safety factor of a Saab I probably would own anymore either, but that said, I started buying Saabs when my first daughter started to drive. Since then one of my daughters seems to like smashing them up, and has been in some pretty serious crashes where she's walked away. One where the policeman at the scene said he's seen accidents that didn't look half as bad and the people were dead.

So for as much as I despise working on these pieces of crap, I think I'll still own a few for a while till my daughters are out on their own and buy their own cars.

Oh, and one more thing don't get confused by what some think that their timing chain has stretched cause the TDC mark on the crank goes past the mark to line up the cam marks...Saab made it that way, go figure. Took a little research to find that little nugget of important info.

I'm just anticipating having to redo the whole effort (timing cover) cause my oil pressure isn't high enough and I need to replace the pump or something.

Anyone know what acceptable oil pressure readings should be???

[Joby Comstock]

I solved it, but I'm not sure how.

Basically, I took the pan off again, took off the valve cover, sprayed degreasers through every oil channel I could find. The only sludge at all was the light caked-on stuff inside the timing chain cover (the chain is less than a year old--the previous owner replaced it), and I cleaned it out. There was nothing wrong with it due to sludge, in other words. I then took an air hose and blew out all the oil channels. I then replaced the bearings, all of them--they weren't too worn, but one or two of them could have developed into a problem.

Basically, I cleaned out anything that sludge or silicone could have gotten into, and replaced the bearings, then reassembled. It took a while, but I had more time than money, and I had the use of a lift and compressor at work.

Since then it's run fine. No oil light, quiet engine. You may be right about low oil causing the erratic idle. Never thought of it like that. I've taken it on a couple of long trips (1200 miles each), driven it daily around town. It's still a Saab, so something new goes out ever week--right now I'm trying to get a rebuilt ABS computer and I have to pull the blower motor to change the brushes--but it's such a smooth car it's almost worth it.

[kraichle]

Thanks for the update.

I believe I'm going to have to head down that same path. I installed an oil pressure gauge, and found my oil pressure was great at cold around 60-80psi@2500rpm, but drops to around 20psi@2500rp and 10 or lower at idle when hot.

Did you pull the engine to do the bearings? It didn't look like you could do the mains with the interference between the ring gear and the bell-housing. I think I'll pull the engine anyway seems like i could have got my timing cover done quicker since the time spent tweaking my arms, hands and fingers into places they wouldn't fit into was longer than taking out the engine.

I work with a few gear-heads at a telecommunications company and they are trying to convince me to bore the block and do the rebuild right. Not that I don't want to do it right from my last learning experience, but really didn't want to put the extra cost into the pistons etc to do that.

Did you have the crank turned or did you just go with std bearings?

I'm also a little concerned about replacing the oil pump, which also requires a new timing cover too.

Someone said that you can even replace the pump with older one that has more capacity or something like that. Might be something i'll look into more.

Wonder if anyone else has any feedback on how far to carry out a rebuild.

The engine doesn't knock or use any oil. Or at least didn't before I started to see the oil light flicker.

I found a forum where another Saab guy was having similar issues, but kept driving it and finally spun a bearing, so figured I'll probably get started on my little spring project before that happens.