DANIELEK

Does anybody know if it does? And if so where are they located?

Just trying to help a friend.

Thanks.

tpi_roc

I went out and looked in my grand am but all I could find was a GM V8 and weird chevy logos and something about it being a camaro

DANIELEK

hahaha

tpi_roc

The general direction of technology is computers with both Maf and Map sensors...

I honestly dont know why, never made sense to me other than redundancy (in case one fails)


But anywho, being a 96 its quite possible it has both. By then GM was using both for 3 years and they're always a lil behind

Vader

Yes, somebody knows.

No, there are no relays.

Power for the MAF sensor is derived from the PCM ignition power circuits (pink wire). The black/white wire is the power and signal ground, and the other wire (usually tan or green) is the proportional FM signal to the PCM. And there is no "burn-off" feature on the newer GM (Hitachi-type) MAF sensors, since they use a thick-film sensor instead of the failure-prone hot-wire, like the older Bosch-style sensors originally used in our cars. because of the lower power requirement and no burn-off cycle, there is no need for a relay.

That's why I push the Wells replacement MAF for ThirdGens - since it is a clone of the Hitachi-type with a dummy load resistor in place of the burn-off input to fool our older ECMs into thinking there is a successful burn-off cycle. They're ALMOST idiot proof - but there's always that one, bigger idiot....

Incidentally, why do you ask? Your friend didn't try to "improve flow" by removing a screen, did he/she? (See above)

Vader

Oh. BTW - the newer systems use a MAF and MAP to gather more data about the engine load and operation. The more sophisticated programming uses both inputs to monitor both momentary load AND rate of change - somewhat like an S-D system with a MAF to verify the "guesstimated" load and factor the fuel trim even better. The outcome has the advantages of both systems, but is also superior to both.

tpi_roc

Mafs will always be an airflow restriction, which negates their positive benifits.


Theoretically calculated Load Via Maf and Via Map should still be linear to each other other than like tip in conditions, where the map might get the vacuum pull but the maf not get the air flow.

DANIELEK

Thanks to both of you about the info.

No Vader, she did not remove any screens. She does't even know what K&N filter is.

It is just that her car just acts up while driving like my did and it turned out to be faulty power/burn off relays for the MAF.

Thanks for the info though.

Vader

Any error codes / MIL lamp on?

And as for the MAF being a restriction, tell that to the Indy and F-1 mechanics. They're using DFI and are very picky about sensing air flow. Guess what THEY use to help get 800HP out of a 4-cylinder...


Incidentally, I fail to see how a MAF, with 7.67 in² free flow area can be considered a restriction to the throttle body, which has only 5.33 in² full open area.

tpi_roc

Looks good on paper doesn't it.


Mike davis swapped ecm's and instantly pulled a quicker time with SD

Now mafs way of measuring is a good thing, but i garuntee that F1 racers aren't bomb'n around the track with a stock bosch fbody (or grand am) MAF sensor.

DANIELEK

Yes her car is showing SES light but we don't know what the code is.

I think it is MAF related because when the car is cruising then all of the suden it feels like it is not getting any fuel for a second or two and then the SES light comes on and after that the car drives normally but she says it is not responsie anymore (i am thinking Limp Mode or something like that)

It only happens while cruising on the highway not idling. After several days the SES will disappear and come back in few days after.

Thanks for help guys.

tpi_roc

Daniele

Have you tried pulling codes yet? it sure beats guessing at sensors, your problems you're having could be from endless sources.

DANIELEK

How do you retrieve the code without hooking it up to some kind of a scanner?

Our car it is easy just groung two pins but her car, who knows.

I give up. I can't help her......!!!!

Vader

Yup. Sad, isn't it? We've got almost twice the displacement of most of the F-1 engines, yet Bosch and GM decided to design the system to handle 1/3 the air flow. Short of changing to an OBD-II PCM or getting really creative with some extra sources of air at WOT, we're really stuck to working with S-D for power. It's sad because it took a bunch of amatures and weekend tuners to fully release the potential of the system. Imagine what we (the amatures and tinkerers) could do to open up the LS1s.

As for the '96, it IS an OBD-II system, so there are no real practical restrictions on what the PCM can measure as air flow. And yes, to retrieve error codes you'll need to connect to a scanner or laptop/PC with scanning software. I use Auto-Tap, but you can also get a dedicated scanner to do the same kinds of things.

And the newer MAF sensors typically don't come and go like the hot-wire type. They just fail. I'd start diagnosing some of the other possibilities, like electrical connections, fuel tank seal, spark plugs, plug wires, and coil packs (you could be getting cylinder misfire errors), filters and vacuum hoses, PCV, etc. Inspect all the easy things, and if you don't find anything obvious, get your hands on a scanner. There is no way to reset the DTCs without a scanner, and some of the cheaper ones won't even do that.