ok, im talking about a 91 3.1 firebird, but im sure this applies to all speed density systems. first of all, is the little sensor that screws into the air filter can (stock) the spped density sensor?

1) if that sensor is broken (not sure if its working or not, but the plastic around the actual metal 'sensor' is physically broken, so i'll assume its not working) ...what symptoms or reactions could i expect that to cause??

2) would placing that sensor outside of the filered air stream (say for uise with a non-stock air filter setup) have any negative affects? i mean, does it measure the air speed or just the temperature?

thanks,
evan

 

Not real sure about the little engines, but if it is in the filter housing I do believe it it the inlet air temp sensor, not the MAP. MAP should be bolted onto the plenum (or near it) with a small tube that goes to a vacuum port on the plenum.

 

right...ive been on the search boards....its the MAT (manifold air temp) sensor. i know where the MAP is.

so any symptoms of a busted one??

thanks

 

Poor fuel economy, hesitation, stumbling, lack of power (these also can be caused by inlet air sensor and coolant temp sensors).
Do a search on MAP's, someone once posted a chart for resistance check that corresponds to a specific vacuum. ie check resistance at no vacuum, apply vacuum (so many in/ HG) and check again, more vacuum, check again, etc.

 

hmmm thanks morley.

would it neccesarily throw any codes?? mine has not, but i have a feeling that doesnt matter, does it??

i have a feeling im gonna end up replacing this thing, arent i? usually i would do it anyway, but darn holidays!

 

In my 91 Formula I was tracking down all of the symptoms I mentioned, it never set a ck eng light but when I replaced the MAP sensor it improved. The final fix was the coolant temp sensor, that made all of the problems disappear (along with getting rid of the Multec injectors)