bad MAF?

[JD1964]

We just had gotten the LT1 swap running sweet and then it cut out on the road. Circumstances resulted in having it towed home.

Went though the usual diagnosis, good fuel pressure, checking all the values in the ignition related stuff. Could not pin anything down and I was just about to consider a failed opti. But then I randomly decided to unplug sensors one at a time to see if anything happened. Well, it starts and runs with the MAF unplugged. Plug the MAF back in with the engine running and it will die after a few seconds. It had not thrown any codes, but obviously there is now since I unplugged the MAF it's running in limp mode with MIL on and fans running, but no codes prior to point me in any direction.

So, is this good evidence the MAF is the actual culprit? Got 12v to the pink wire at the MAF connector with KOEO.

If it needs a MAF, should I stick with AC Delco or is there a better choice? I see Delphi too. Looks like the Delco units are reman and the Delphi are new.

[steveo]

unless you have badly torn the boot between the maf and throttle body, you probably have a dead maf or busted wire. you could probably just get another maf from an auto wrecker if you wanted a quality one

[JD1964]

unless you have badly torn the boot between the maf and throttle body, you probably have a dead maf or busted wire. you could probably just get another maf from an auto wrecker if you wanted a quality one

Cool thanks. I just did some cross reference at Rock Auto and it looks like some other GM vehicles use the same MAF. B and F bodies pop up now and then in the yards near me but it looks like some of the GM trucks and SUV's use the same MAF. Tahoe, Suburan, Yukon, K trucks, C trucks, Express vans, this should be easy.

Edit: Just checked one local boneyard inventory online and they have 7 of these vehicles in stock. At least one is bound to have a Genuine GM MAF on it. I think they run about $25

[steveo]

there may be other mafs that fit but have different calibrations. if you've already tuned to the fbody maf thats what you should get. the bbody maf has a different calibration too.

[JD1964]

there may be other mafs that fit but have different calibrations. if you've already tuned to the fbody maf thats what you should get. the bbody maf has a different calibration too.

Interesting. At Rock Auto they show cross reference to other vehicles that share the F body MAF part number and you are correct, the B body LT1 cars are not included in that list. But interestingly, Vortec, LT1 and LS engine equipped cars and trucks are included under the same part number. So, the MAF we just bought came from a 2001 GMC Savana van and its compatible with the 1994 Z28. Heres the listing at Rock Auto and if you click on the part # 2133457 on the AC Delco line you'll see the cross reference vehicles.

Even more interesting is this. We just went and got the used MAF before we took the suspected bad one out of the wagon. Low and behold we discovered the screen had caved in and shorted the sensor. Pulled the screen out and the thing fires up and runs like it should. So now I have a spare MAF which is just fine.

On the screen idea, I now have a screenedMAF and an unscreened MAF. Is there any benefit in running unscreened in my application? The only mods on this LT1 are 1.6 roller rockers, 52mm TB and long tube headers.

Here's the pic of the caved in screen. Damn I should have just checked that initially on the side of the road. Could have just driven home.

[steveo]

But interestingly, Vortec, LT1 and LS engine equipped cars and trucks are included under the same part number.

just because a chinese knock off universal maf sensor says it works with 100 different vehicles, because their only qualifier is that it fits/starts/runs doesn't mean that all 100 vehicles actually have the same maf sensor with the same calibration curves.

rockauto is great for finding cheap parts but not necessarily the right way to ensure fitment of a critical sensor like a maf. they run cross reference chains to universal fit stuff and back in both directions to ensure the greatest amount of bottom-of-the-barrel cheap parts show up in the list.

a vortec or LS1 maf is definitely not the same with regards to airflow vs hz output and if this is a car you're actually tuning you need to totally recalibrate to that new maf

[steveo]

Is there any benefit in running unscreened in my application?

no, but again, will throw off your calibration a bit. we've always figured that screen is probably there to reduce turbulance for more accurate readings (which doesn't make a huge difference in reality, but make sense from a design standpoint) and to stop crumbling peices of that air filter you haven't changed in 200,000 miles from ending up destroying your maf wires