I just have a quick question I've got a 99 Blazer 4.3 vortec two door two wheel drive what should my reading at 70 miles an hour be across my mass air flow..????

 

The airflow is not a constant at a given speed. Your best bet is measure at idle and then at a full load acceleration just before the shift from 1-2 gear.

George

 

0.6 at idle
14.1 at full load between 1st and 2nd shift

 

14.1 what? Grams per second? Tons per year?

 

Assuming that the unit of measure is lbs/min that translates to 4.5 g/sec idle and 107 g/sec full throttle shift. These are low. The GM spec is 6 g/sec min at idle although I have seen various reported values here in the 4's and 5's. The full throttle shift GM spec is 130 g/sec min and I have calculated the theoretical value at 170 g/sec in a new engine using a VE calculator. Les and I discussed this a while back and he reports 164 g/sec at his max throttle shift. So your values are low but the question is why? If the volumetric efficiency of the engine is poor then the MAF may be reporting correctly.


George

 

His full throttle shift data is actually 509 million pounds per year which is 231 kt/yr. At least we finally got off of dipstick length. Oh crap, I just brought it up again. lol.

George

 

Volumetric efficiency?? That is above my paygrade i think.. seems ive always had low readings on everything.. ive got a reman motor in her with around 14k miles. Im just wondering if i should take this pos maf back again and get ac delco..

 

I see it has to do with moving air in and out of the cylinders on internal combustion engines I'm reading a little bit more on it now

 

There is no one maf reading at a given rpm. The volumeteric efficiency speaks to the actual amount if air being moved compared to the theoretical amount for that cylinder volume, rpm, air density, etc. The 1-2 shift point at WOT is used because its a standardized way of seeing how your engine breathes and how that air volume is being reported. You plug the data into a VE calculator and you expect to see 70-90% efficiency for most healthy naturally aspirated garden variety engines.

https://www.otctools.com/ve

GM set the spec at a conservative 130 g/sec. You don't meet this spec so the question is:

Is the MAF malfunctioning/dirty?
Is the power and ground and signal wire all in top shape?
Is the PCM calculating the correct volume (the MAF outputs frequency)?
Does the engine/exhaust have mechanical problems?

All you know with your reading is that one or more of those things is faulty. Always check the wiring, connectors, power and ground to a suspected faulty senor. Do you have a recent compression test? Do you have the original MAF available to compare values?

George

 

Thanks for sticking with me GeorgeLG . I just replaced the maf on monday . Autozone/Duralast brand though. Id like to believe its ok but who knows...
i know after putting in the reman motor there were,i think it was 2 wires that looked broken due to engine being pulled w/ detatching them first. I have no clue where they go. Spoke of them before in a thread. Never came to a conclusion. Hell i drove around for awhile and didnt have my main engine ground hooked up at all..!! Just dangling there. I think i put it temporarily on a metal to metal bolt back somewhere in there. I really need to put it on the back of my head where it goes.. could the possibly broken wires go to the rear of the head also to be grounded? Gonna see if i can find the pics... Think i posted them b4.
Exhaust is a flowmaster Super 10 Series single chamber performance muffler. Just changed an O2 sensor for a po135 dtc . B1S1. I found a ebcm on ebay for 89$ prob gonna buy it today.. then maybe i can get my brake issue fixed.. i was under the impression that u could take ebcm off and brakes would work fine. You just would not have abs. My brakes do not work fine. Could be having bad parts issue with them as well.. i have went through 3 fuel pumps b4 finally getn a good one.. crazy