I have an “88”, 5.7, TPI with MAF. I was battling a code 33 problem. I did the usual troubleshooting and everything was good but the code 33 kept coming up. Thanks to thirdgen and its members I found out that the computer is set for an error threshold of 45 grams at about 2000 RPM.
Anything above that and the ECM condemns the MAF. I invested in a cable and laptop. I found with all the mods I have done to the engine it is demanding about 65 grams at about 2000 RPM. So I sent my EPROM in to have the threshold raised to 100 grams and the code 33 has not come up again. Does anybody know if 100grams is to high?
Hopes this helps somebody.

 

I guess I should mention that “grams” is referring to the Mass Air Flow sensor flow rate per second. Also code 33 is the code for high air flow at the Mass Air Flow sensor.
My point is if you know your MAF sensor, relays, wiring and ECM are O.K. And you have modified your engine (i.e. bigger runners, higher compression or aftermarket throttle-body) it could be the engine is demanding more air than a stock set up. If the EPROM has not been adjusted for this then the code 33 will keep coming up.

 

No, no problem at all in changing that diag parameter. Good job on figuring it out too. I'd say that 100g/sec should be OK. If concerned then try 85 g/sec and see what happens. You are really looking for enough of a difference that would signify a MAF problem.

This same error number 33 comes up on SD cars (MAP high) once the cam gets a bit on the big side. With the overlap and duration the manifold pressure goes up accordingly and boom: DTC 33.

RBob.

P.S. nice '68