needsize

Since I bought my z28 a year ago, its been plagued by problems, mainly running like crap, really noticeable when its hot out. The places I took it to replaced all kinds of stuff trying to figure it out, distributor, all plug wires, etc, about $2500 worth, and it kept coming back.
Last place I took it to guessed at the mass air flow sensor, and disconnected it, and it it actually ran better, but I could still smell gas coming out of the tailpipes. I need an e test this year, so want to replace the part, but the $320(canadian) they quoted me for the part seems a little high, not to mention all the parts sites I looked on dont have this part for my year(1994). Anyone know where a good online place would be to find one, aftermarket would be cool as any boost in hp is good to me?

2000GTP

Granatelli is the only aftermarket MAF supplier that I know of and I would stay away from those. Just replace it with another GM piece. Maybe one of these guys can get you one at a cheaper cost: http://shbox.com/1/4th_gen_tech2.html#Dal_and_Jason Another idea would be to check the classifieds section on here, plenty of people sell used MAFs in good working order for around fifty bucks.

needsize

thanks for the ideas, I was thinking about staying away from aftermarket anyway as I am afraid it might not pass the e-test with one

2000GTP

The aftermarket MAF shouldn't be an issue with passing your emissions testing. They can, however, create tuning and driveability issues and do not live up to the results that they are advertised as producing.

BTC

I'm not sure how much shipping would be to Canada, or how the exchange rate might come into play, but Dal & Jason have great prices.

needsize

I am guessing that the gas smell coming from the tailpipes is from the MAF, and I cant see it passing emissions testing with that going on. I do notice it seems to affect the drive though, when its cold out, its smooth and pulls hard, when its hot out, seems to hesitate and not drive as well.
If I hadnt of bought in the winter last year, I would have caught this before paying for it

OBE1 95Z28

With the MAF unplugged, the PCM uses speed density mode to determine air/fuel ratio. This won't be as accurate as a MAF, hense your air/fuel ratio is off.

Sinister_Z

Where abouts are you in Ontario? If you are anywhere near Waterloo, I can give you a better price on it...$263.30 plus tax. Also, if you aren't close...Delco has a reman unit available from the GM store nearest you...part #19112572 retail on it is $282.00...might take a couple of days to get...but another option...oh, and the Delco one has a $45.00 core charge where as the GM one has no core...let me know if I can help.

shoebox

You need to quit guessing and wasting money. A datalog on your car would probably tell you everything you wanted to know about what is going on. There may be nothing wrong with your MAF at all.

BUBBA

I doubt that that it is your maf---and if it is get one from a junk yard and if you can't find one there, perhaps someone here would cost one out for you at a bone yard and ship it to you for cost. Right guys?

But as shoe mentioned, stop thowing parts at and find out what the computer says.JMHO

BUBBA

Might have a bad 02 since the car is almost 13 years old.

Injuneer

Speed-density is a method of calculating mass air flow from the temperature and pressure. Still uses the same A/F ratios that are programmed into the PCM. There is nothing inherently inaccurate about speed-density, until you start modifying the engine in ways that affect volumetric efficiency. Even with small changes to VE, the PCM should be able to make minor adjustments to the long term fuel corrections to eliminate the effects of the inaccuracy.

needsize:

How long did you drive it after you disconnected the MAF sensor? Is it possible you didn't wait long enough for the long term fuel corrections to respond? If they are screwed up because of a faulty MAF sensor, you either need to reset the PCM (pull "PCM BAT" fuse for 30 seconds), or drive it for a while.

OBE1 95Z28

Injuneer, help me understand. If this is true, then why would GM use a MAF at all? I doubt they're using the MAF to allow you to modify you car. The MAF is extra expense as the temp and pressure sensors are there with a MAF based car anyway.

In this article by Car Craft: http://www.carcraft.com/techarticles...uel_injection/

They state: "In a perfect world, virtually all street-performance engines would use Mass Air, due to its superior accuracy and greater tolerance for engine changes" They're confirming your statment about about making engine changes, but they are also stating superior accuracy.

needsize

I had the car for 4-5 months before the MAF was disconnected. I had it at two different shops, and on the computer both times, and nothing came up, they said the problem was that it wasnt having the problem when it was in their possession, as it didnt run like that 100% of the time. The first shop found things that needed to be done, the distributor was seized, one of the plug wires came apart when he was taking them off, some idiot even used silicone to seal parts of the engine as well, I think around the oil pan, and a few other places I cant remember.
One thing I forgot, there is way too much pressure in the gas tank, the one garage said he could hear the pressure whistling out when the car was parked in the shop, and when you take the cap off, you can hear it. I guess its a sealed system, no vented gas cap, so the part of the tank that is supposed to vent pressure is blocked. My last one was an '86 trans am, so much easier to work on, so I am having problems figuring out with the higher tech engine. At times I drive it with the cap loose, and its better, but still not 100%, so I dont think thats the only problem.
Sinister, I am in brantford, so pretty close....I did find a MAF at the place 2000GTP mentioned for 140 american plus shipping

Injuneer

MAF is more accurate because it doesn't care what the VE of the engine is. Speed-density needs the VE accurately programmed in a table, so the PCM can look it up, based on RPM and engine load. Its not easy to develop the VE tables.... the factory does a lot of dyno time establishing this. But, given a proper tune, speed-density is every bit as accurate as MAF. Its when you start to modify things that speed-density falls down.

Similarly, MAF will be faulty if the calibration table in the PCM is not correct. That can be affected by something as simple as changing the shape of the air duct feeding the sensor.

Neither system is perfect.