Flowing 1422Hz of Air/Hitting Fuel Cut?

[4G63dsmpwr]

I did two passes the other night and kept track of how many HZ my AFC was seeing. The most it saw was 1422 (my lower section is removed). I thought fuel cut on a 1G MAF was around 2000 so why would I be hitting it if I never see more than 1500? Is there anything else that could cause this? Thanks

 

[4pistons]

If turbulence was causing it to lose counts you'll get fuel cut. Are your lower honeycombs removed or did you hack the lower section off? I think I saw somewhere that if the HZ was too low compared to injector pulse width or rpm the ECU shuts things down. This may be the result of hacking it too much. I'm not positve on this though. You might want search for 1G MAF hacking info.

Rick - '91 GSX

 

[4G63dsmpwr]

I removed the entire lower section, not just the honeycombs. It only happens when its really cold and I'm running 18lbs of boost. For example, during the day it could be fine and then at 11 o'clock when it cools down it will hit it in 3rd gear, every time I open it up at WOT. I think when its colder out it dumps more fuel into the engine b/c even though the same amount of air is flowing through the MAF its denser, right? My AFC settings are all around +38, does this have anything to do w/it?

 

[Silent2g]

welcome to fuel cut
i see a 2g mas in your future

 

[fast_talon]

Yeah once you get the 2G MAS, you will say to yourself... "Why did I wait so long??"

 

[4G63dsmpwr]

ok thanks guys

 

[BatmanGSX]

You can't hack a 1G MAS "too much". Maybe too much for your setup but not to a point that will cause it to malfunction. Hacking the 1G is a good first step before going to a 2G.

Remember, the MAS uses a thermistor to check air temps. 1400hz at 30F is a lot different than 2000hz at 90F. As it gets colder you are likely to have either overrun or fuel cut problems sooner. If you are running anything over stock boost on a cold day you can hit fuel cut pretty easy.

Figure out how to hack your MAS. If you have no luck then try a 2G MAS. I wouldn't go to a 2G unless you also go to larger injectors. For now, removing the lower chamber by grinding it out with a dremel should be pretty good. Also add a 10K potentiometer in series with the the line that has the thermistor (little resistor looking thing).

Your trouble should be cured for as little as $1.50 rather than $100 for a 2G MAS and harness. If you are pulling in only 1400hz you just don't need a 2G MAS yet. Save your cash for later.

 

[pneumo]

All good. You can also get away with lowering the correcion on the AFC by 1 or 2% since it's cold and the car is slightly less likely to knock. That will push the fuel cut threshold slightly higher. Just keep an eye on the EGT's, knock and timing.

 

[KenTSIII]

Also if you have the MAF hacked alot... & have the AFC richened up alot to compensate... you'll hit fuel cut alot sooner. The richer you have to set the SAFC the sooner you'll hit fuel cut. If you haven't already.. you might want to get some 550s & lean the SAFC out accordingly. Then you shouldn't have any fuel cut issues at all. I used to have the EXACT same issues.