[therealturbofan]

well, I just picked up a '92 900s today. The check engine light was on and the car felt really, really slow, but I didn't think much of it, I thought all non-turbo 900's were that slow.

The battery died on me, so I got a new one and installed it. awhen I started it up after the new battery, it was VERY unhappy. Coughing, sputtering, would die without giving it throttle and even with throttle would almost die, then zing up. After about 3 minutes, the check engine light came on again and it began to smooth out. After another couple minutes, it runs fine, but again, it seems like it's missing a lot of power.

before all this happened, I noticed that under acceleration it was inconsistent. Holding the pedal steady at, say 3/4 throttle, it would accelerate moderately, then get really super smooth but accelerate more slowly, then back to moderate acceleration. To me, it feels like the computer is pulling crazy amounts of timing.

what does this sound like to you guys? I was thinking of starting by replacing plugs and wires, then replacing the O2 sensor. But I'd really rather not blindly replace stuff!!

thanks so much in advance for your help! Sorry if this has been covered already, I couldn't find much on it!

 

[SteveTheFolkie]

If the CEL is on then check the codes - the light is telling you that something is wrong, the codes will at least point you in the right direction. My money is on an O2 sensor - but pull the codes. The instructions for doing so are somewhere around here - and it's not hard to do.

 

[therealturbofan]

ok... so... maybe I'm not using the correct search terms, but I can't seem to find those instructions!! ;oops:

Could somebody point me in the right direction? Has anyone else had this problem?

 

[peva]

You don't need to do a search, just look in 900 workshop FAQ sticky in this forum; http://townsendimports.com/Web/engine_folder/24codes.htm

 

[Jim Mesthene]

A '92 N/A will have the LH 2.2.4 adaptive Fuel System.
After Battery replacement, it could take up to 50 miles for the LH ECU to adapt. Intermittent Check Engine Light, and erratic performance is normal during the adaptation period.
Normally, Ignition problems won't set off the Check Engine Light, but it never hurts to check the Plugs etc. If your problems don't improve within 50 miles, as with all power-loss complaints, check Fuel Pressure at idle and while driving.

To me, it feels like the computer is pulling crazy amounts of timing.

An active imagination can enrich your life in many ways.

 

[Rodentmaster]

I would also suggest that the issue could be AMM based.

Either the AMM is dying.... or the plug is corrupted, corroded, dirty, poor ground wire/lead at the top of the head (near thermostat housing).

I must admit however, I would appear to be very fortunate in that when I have had to remove and restore the 12v, it runs quite well at first operation afterwards.......better after the 10 minute run.

Confirm the integrity and condition of all the major power trunks, alternator earth strap, and battery lead to and from the starter/alternator.

 

[therealturbofan]

Thanks for the replys! I appreciate your help.

More miles hasn't helped anything, so we're going back to diagnostics.

I tried to do the check engine thing as linked to above, but I don't know if i'm doing it correctly. If they added a couple of pictures to that how-to, it would make a world of difference... I'd be willing to provide the pictures when I have this all figured out if someone wants to post them...

Anyway, as per the instructions, I was digging around under the seat trying to find the described connector. I found the gray wire with red stripe, here it is going into the back of this panel thing (it's in the center of the picture, it's going into the same spot as a little blue wire):

it has a connector on the other side. so i plugged a wire into it, like this, to serve as my lead wire. It's the black wire with the little red connector:

I bought a little two-way switch from radio shack. I plugged the lead wire onto one side, and then used a wire with little alligator clips for the ground.

i tried following the instructions, but it's not going anything like the instructions say it should. my check engine light won't come on when the engine is off. of course, when i turn the ignition on, the check engine light is on along with all the other dash lights for about 3 seconds, but then they all shut off, so the instructions don't really apply.

Am i doing something wrong? Is this connected properly?

thanks in advance for your help. i hope ya'll can see that I'm really working at this, trying to figure it out.

 

[misu]

Wrong connection! You've connect it into some relay position! Test connector is separated, 10 wires connector (four positions along two longer sides and two more positions in center, around center locking mechanism), with four cables, what go into it. Check wiring diagrams and identify that connector carefully, with 100% sure it is, what you looking for. Or you can destroy something!

 

[Rodentmaster]

http://www.saabcentral.com/forums/showpost.php?p=1377942&postcount=28

Is this the socket you are looking for?

 

[Ezra]

I'm not sure how you're getting on with this - the thread Rodent kindly referred you to was a thread of mine.

The connector to read the codes was actually attached to the rear wing behind the driver's (USA passenger) seat - you have to lift up the back seat to see it. It is 'fixed' into the wing and is in the vertical plain, rather than horizontal as per the pictures in the post.

Good luck - pulling the codes is much easier than I supposed, and really helped sort where my problems were. However, it was Rodentmaster's suggestion to swap in a known good AMM that finally sorted the problems AND this was after the incumbent had tested good for resistances and 'burn off'.

Ez

 

[therealturbofan]

ok, i'm making some progress on the code reading. I have it all rigged up, and i was getting the codes. quick question: are the codes always going to be 1 flash, and then three sets of flashes, finishing with one flash? I thought i saw a code that was 1-2-2-2-3... lol but maybe not.

I'll finish reading them and post what I find. Thanks again for all your help!

 

[therealturbofan]

ok, I finished reading the codes. Here's what I got, according to the chart on the link that was posted above.

1 2 2 2 3 -- air fuel mixture too lean
1 2 1 1 1 -- incorrect air fuel ratio while driving
1 2 2 4 1 -- this code didn't exist on that chart.

considering these codes... I think ima start by checking and replacing the fuel filter. I've noticed something about my car... Occasionally I catch the slightest whiff of fuel smell, but can't pinpoint where it is coming from. Not sure what to do about that...

also, does anyone have any idea what that last code means?

I'm goin to the junkyard today... Might come back with a few saab parts! My steering wheel jiggles, lol!

 

[900t]

Fuel filter a good idea for the smell, often they rust and start to leak when very old. I doubt it would affect your air/fuel ratio in the slightest however.

 

[Rodentmaster]

Been down this road..........

Obviously, check and replace any thing that you can, hoses, leads, spark plugs etc.....you think you can change it? change it................in the end I suggest you will not make too much progress until you change the Air Mass Meter.


I struck a bit of luck some months back with a wrecker that I really didn't expect to drive past...........asked what he had...sold me a AMM for $50! It has been a good unit to date............

 

[therealturbofan]

thanks again for your help, rode. You had the same codes, and it ended up being the AMM?

there's a non-turbo saab 900 at the junkyard about a block from my house, it appears to be about the same year as my car since it has the airbag in the steering wheel (which I believe was just '90 or '91 and up right?). Hopefully the car still has the AMM on it... Is there a way to test an AMM to see if it's good?

I also can't seem to figure out how to check the fuel pressure on this silly thing. But we'll see what I can find. I'll try the AMM first.

 

[Ezra]

I didn't pull the codes using the home made switch for a long time as I am not very electrically minded ;oops: When I did, I got the same codes as you and 1 more 'incorrect mixture at idle'. Using this forum and Bentley, I tested just about everything I could, and replaced most components with the exception of the AMM as this is expensive and had 'passed its test'. As detailed earlier I swapped in a known good one as a last resort and BINGO - no more CEL; as I had replaced just about everything I could, there was little improvement in engine performance but the blooming light was off, and that felt good after months of work.

To test the AMM
1. Disconnect the AMM from the air cleaner only. Leave it connected to the duct to the intake manifold and eave the wiring harness connected.
2. Start engine and run to normal operating temp. (It helps to have someone do this for you).
3. Rev the engine to at least 2500 revs and shut it off. Look through the front of the AMM at the hot wire. After approximately 4 seconds the wire should glow brightly for 1 second.
4. If the wire glows as specified, then the AMM and control unit are probably working as they should.

Let us know what happens.

Mine did as it should but was still the culprit.

Ez

 

[therealturbofan]

argh!! Went to the junkyard where I found the 900 of the same year as mine... And someone has already snagged the AMM. D'oh!! So... I'll continue searching. The guy wrecker was gonna sell it to me for $15 too!

I'll test the amm as specified... We'll see how it goes. But if yours passed the test and still was the culprit, I don't much see the point. I'll just replace it and see if there's a change. I figure if there's no change, then that's prolly not the problem. :/

ima fix this, I will.

 

[Rodentmaster]

Sadly, I don't think the glow test is going to assist you.........

As much as it is a 'test', the 'burn off' is principally designed to clean the wire.
It will not really inform you of the state of the sensitivity of the d.c. amplifier/driver in the housing...........all this glow test will confirm is that the wire to be physically intact.
The wire is meant to have a resistance of 1.00 ohm.
Two old AMM's I have, have the little 'loops' (where the hooks supports the wire) spot-weld broken.............the wire is 'still' intact but the resistance value has changed to 1.12 and 1.18 ohms........12% and 18% variance.
The AMM is not an adaptive process so the output will be 'out' if the wire resistance is out of spec.

 

[therealturbofan]

ya... I had kinda decided after my last post that I don't want to test mine, just gonna swap it out. Gotta check some other yards...

 

[KaMiKaZi_t0M]

Yea I have a Bad AMM, (or MAF in NG900) and it does the same thing when cold. I can floor it when cold, and it won't go ANYWHERE. After she warms up and realises the AMM is shot, cheesy, it fixes itself and is okay.

+1 on the AMM.