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  #1  
Old 10th October 2008
hckydad1122 hckydad1122 is offline
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Default Cleaning The AMM

Hey All,

Question>>>......I own a 1989 900 T vert, determined by the state of CA to be a gross polluter. The HC and NO are quite high. I put a new cat in 2 years ago and it passed smog at that time with no problem. As I look for reasons for this, the water pump went out. I also found one vacuum hose on the AIC loose, and a few small vacuum leaks. I am installing a new water pump and thermostat this weekend. I cleaned out the AIC. As I am looking into the AMM, I see one wire that appears to look like the goal posts on a football field, with a post behind it about the same height. It has a plastic case and no adjustment screw. I have noticed that it appears quite dirty inside. I have some CRC spray, is it safe to spray this on the inside?
Thanks,
Mark
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  #2  
Old 10th October 2008
spg1 spg1 is offline
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Do not spray or clean the AMM with oil. You have to pull off the screens on each end and clean them along with the eliment inside with brake cleaner, Not carb cleaner eather, it has oil in it also.

Make sure it is brake cleaner and let it air dry first before plugging it in and starting the car. Check your spark plugs, and distributor cap also along with an oil change. Change your air filter if it needs it. One more thing, Clean the throtle body with "carb cleaner", and run injector cleaner in a tank of fuel if you can. Run High test gas while you are at it and make sure it is hot when you do a test. If the Cat is contaminated at all, it will fix it's self after about a week of driving with everything fixed and good fuel.
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Old 11th October 2008
hckydad1122 hckydad1122 is offline
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so its ok for me to spray everything inside and wires with the CRC Mass Air Flow cleaner?
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  #4  
Old 11th October 2008
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skucera skucera is offline
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I think you're on the right track. Vacuum leaks are the bane of every older 900. If in doubt, replace every vacuum line in the car at once, then continue your troubleshooting from there.

Also, you've replaced your oxygen sensor, right? They last only 45,000-60,000 miles under ideal conditions. Check for corrosion on the electrical connections for the O2 sensor as well.

Scott
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Old 11th October 2008
hckydad1122 hckydad1122 is offline
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tomorrow (sat) i will have everything cleaned and installed.. i am going to warm up the car and check the voltage off the black wire at the O2 sensor

Mark
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Old 11th October 2008
spg1 spg1 is offline
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Ya you should be safe. You didn't say that the CRC was for the AMM. CRC is mostly known for its oil around here where Im at. If you don't want to spend the big bucks for the saab O2 sencer you can get the Bosch part for an 5L mustang part # 13913. This is what I used on mine and It has worked great for the passed 5 years. You will have to splice in your plug though for that o2 sencer
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Old 11th October 2008
hckydad1122 hckydad1122 is offline
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one more quick question on the AMM
do i check the resistance on the AMM in the car or out?

since mine has no adj screw do i even worry about the ohms?

the wires look dirty unit looks dirty but wires dont look broken
any other checks i can do while i have the AMM out of the car?

Mark

Last edited by hckydad1122; 11th October 2008 at 11:15 AM.
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  #8  
Old 11th October 2008
spg1 spg1 is offline
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I would think you should be fine just cleaning it. You should see a differents in the cars performance. I may be wrong and there may be a check for it, I don't know.
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  #9  
Old 12th October 2008
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skucera skucera is offline
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I wouldn't worry about using chemical cleaners to clean your mass airflow sensor. Bosch hot-wire AFM's clean themselves by heating their sensor wire to 1000F briefly when you shut the car down. This self-cleaning is triggered by different conditions on different versions of the Jetronic or Motronic controllers. I don't know the conditions that trigger self-cleaning in the LH unit in our Saabs, but my BMW does a self-cleaning of its two AFM's if the engine has reached full operating temperature and if I have either run above 2500 rpm or if I recorded one full throttle opening since starting the car.

If the AFM is working at all, it is probably working fine. Did you read an OBD (Check Engine Light) error code that lead you to suspect your AFM? What code did you get?

I really think you're chasing the wrong problem with your fixation on your AFM. High HC and CO are symptoms of a tired oxygen sensor, and if you don't have a CEL error for "fuel mix adaptation" or something like that then I'm doubly sure. If you do have a CEL error for "fuel mix adaptation" then look for vacuum leaks in every vacuum hose in the car, even the one from the fuel tank to the charcoal canister.

Scott
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