hi

Seen some posts regarding the "service engine soon" light,
and responses to checking MAF. My lights been on for months
and while i'm restoring it i'd like to try and fix.

thanks for the help

john

 

MAF....Don't know what it stands for....maybe Manifold Air Flow, something like that. On the FI cars, it's in the intake tubing...it's got a filament inside it that usually vibrates when air passes by it, which gives the computer an idea of how much air flow there is, so it can use the proper air-fuel ratio. It's a common failure item it seems. Easy to replace, a tad pricey though. If your car runs crappy, an easy way to tell if it's an MAF problem is..disconnect the MAF. If it's an MAF problem, disconnecting it makes it run better again usually. I'd be careful doing that though, I think I heard somewhere that disconnecting it while it's getting power could short it out or something....but I don't remember.

 

Since you are pretty new to the boards just thought i would let you know that adding a little information about your car will help people diagnose your problems, not being a jerk just letting you know. As far as MAF it is a Mass Air Flow sensor and it measures the amount of air coming into an engine to determine the amount of fuel needed. It is a 3 wire sensor in the intake tract of fuel injected cars. As Nixon said it does this via a filament inside the sensor but it actually applies heat to the filament not uses vibration. Some people make modifications to this sensor in the name of performance but their effectiveness is a whole different arguement. Furthermore do you know how to check the codes in your car via the service engine light? Sorry this got so long but I kept getting more topics as I went. Hope this helps -John

 

The Bosch MAF (TPI) has 4 wires and a heated wire element.
It sounds like the both of you are describing the Delco MAF (which I think was used on the v6 cars only).

The only way to determine the problem associated with the SES light coming on, is to pull the codes.

 

I own a V6 and normally only visit the V6 boards, so I'm definitely describing the V6 MAF... And I don't know a lot about MAF's because my car doesn't have one....I've got an MAP. And ***..I dont know why I didnt remember what MAF stood for....it's later than I thought apparently!

 

I was describing the TPI Bosch unit with heated wire but I may be mistaken on the number of wires. I was trying to lead hime to pulling the codes but thanks for the MAF clarification.

 

Don't overlook the possibility of a bad relay. The MAF is controlled by 2 relays, one for power and one for burnoff which cleans the hotwire. Either one will cause an SES light to trigger. If one is bad change them both. Unless it was dropped of physically damaged all in all they are pretty reliable devices. Pricey is not the word, the OE is close to 450 bucks. Try the relays first!

 

thanks for the MAF info, I had no idea what it meant.

BTW I have a 92 rs/305/tbi all stock 180,000 mi, GM rebuilt tranny
and i'm finishing up suspension/front end rebuild. no longer a daily driver just trying to restore to showroom condition ++

some good info here, ill try and pull the codes as mentioned and diagramed by "Vader", i pulled down the pdf. i'm sure i'll be back with more questions.

thanks again
john

 

you can check your computer codes manually by finding the diagnostic connector under the drivers dash. its pretty easy to spot. short the a and b terminals with a jumper wire turn the key to on and the engine off. the service light will flash a code. for example if a code 12 comes up. the light will flash once pause then flash twice. it repeats all codes over and over. im not sure of the code number for an Maf. that youll have to look up

 

I'm wanting to say Code 34 for an MAF but I could be wrong... FYI, the terminals referred to are the upper right and the one to the immediate left of it. Although..I don't see how those would be a and b exactly..I haven't checked out the labeling for it lately.