Granatelli Mass Air Sensor Question

jthokie92 · May 12, 2005

Does anyone know if installing a Granatelli Mass Airflow Sensor to a Supercharged Engine will cause any problems?

I have a 2001 GMC Sierra w/ 5.3 engine with an ATI ProCharger P-1SC running about 8-9lbs boost. Also have a Comp Cams Camshaft, lifters, and valve springs and Edelbrock Ceramic Shorty headers.

Reason, Everything seemed to be working fine, till I added the Granatelli Mass Airflow Sensor and now getting the Check Engine Light. Forget the exact code, but said that sensors indicating a "Lean" condition.

Any ideas anyone?

Thanks....

May 12, 2005

I am not a supercharger expert but I think I would expect that. The new MAF will flow more air. Without reprogramming your fuel I would expect it to go lean. I know the computer can compensate but I believe once you add the supercharger you're outside the "compensation" capability for the pcm. Get the pcm reprogrammed and you'll probably be fine. Unitl then be careful, lean is bad

99Silver6.0 · May 13, 2005

It will lean it out. That mass air is a pile anyway. Spend your money on something else worthwhile.

Haulin' 8.1 · May 13, 2005

With that pile of mods the larger MAF was the straw that broke the camels back. Your fuel injectors can't flow enough fuel for all the air your using. Keep the MAF but take it off until you can install larger fuel injectors, which will require a custom tune.

jthokie92 · May 13, 2005

Thanks to everyone for your help. I removed the Granatelli MAS and put the stock unit back on for now. I was just hoping the new unit would help out with the throttle response, but when I put it on I really didn't notice any large improvements with all the stuff I've got put on already. It's running pretty good right now with the stock MAS. I still have to have the PCM tuned to remove the factory speed limiter and see if I can gain a few extra HP that way. Problem now is, since I've got the ProCharger installed, they strongly recommend against using any handheld programmers, said that it can mess up with the timing and cause major issues. I guess I have to figure out some other way to tune and remove the limiters... Any ideas on this one? Thanks again for all your help, I do appreciate the advice.

Indy · May 14, 2005

Thanks to everyone for your help. I removed the Granatelli MAS and put the stock unit back on for now. I was just hoping the new unit would help out with the throttle response, but when I put it on I really didn't notice any large improvements with all the stuff I've got put on already. It's running pretty good right now with the stock MAS. I still have to have the PCM tuned to remove the factory speed limiter and see if I can gain a few extra HP that way. Problem now is, since I've got the ProCharger installed, they strongly recommend against using any handheld programmers, said that it can mess up with the timing and cause major issues. I guess I have to figure out some other way to tune and remove the limiters... Any ideas on this one? Thanks again for all your help, I do appreciate the advice.

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Check the vendors on the side of this page. PCMforless and TBYRNE (Westers) both sell custom tuned PCMs.

jthokie92 · May 16, 2005

Thanks. I just took my GMC Truck to a Car Show this past weekend and put in on a chassis dyno. I tested 397.04 RWHP and took 1st place in the 8 cylinder dyno category. The only other competitors in the 8 cylinder class was a Kenne Bell Supercharged Mustang GT that tested 326 RWHP, A Naturally aspirated 92 Mustang GT with exhaust upgrades that tested 190 RWHP, and a brand new Chevy Silverado 2500 with the 8.1liter engine with only an exhaust upgrade that tested 215 RWHP. Needless to say I was pretty happy to finally know what my truck tested at after everything thats been done. 1st place in the 4 cylinder was a Turbo VTEC Acura with 299 RWHP and they only had 1 entry in the 6 cylinder category was a pretty much stock Chevy S10 Xtreme that got 160 RWHP...

May 16, 2005

If you don't have a custom tune already you are taking seriuos chances of destroying that engine. If you have a tune your limiters should have been changed at that time.

Do a full professional custom tune. If you're getting 397rwhp without one you are going to go well over 400 with Westers.

Get 'er done!!!

jthokie92 · May 16, 2005

Thanks for the info. I've already had that engine rebuilt with speed pro pistons and rings, comp cams camshaft, lifters, and valve springs. Edelbrock ceramic headers, b&m transmission shift kit and corvette servo, just need 3 more hp to get her over 400 mark. Highly recommend the ATI ProCharger though, made the biggest improvement. The replacement valve springs really help out in the redline rpm's keeping the valve's from floating. I hear the stock springs don't put enough pressure and can damage the engine if pushed to redline. I had to take the Granatelli mass air sensor off and put the stock one back on for now. It was causing everything to run too lean, which is very bad. I'll have to save up for larger fuel injector's and/or more powerful fuel pump. ATI ProCharger kit came with an inline fuel booster pump and fmu, but will probably need to put in larger injectors to feed more fuel into this beast... She's running really good now, but it's like an addiction. The sufferring with the thirst for more HP... Thanks again for your advice/input...

tmf6902 · May 16, 2005

and a brand new Chevy Silverado 2500 with the 8.1liter engine with only an exhaust upgrade that tested 215 RWHP.
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The 8.1 puts what??? 340 hp out at the flywheel......that's about 36% loss.....I though the allison was down around 30%??? d**n.....that's just embarrasing.

Haulin' 8.1 · May 16, 2005

397!!! Dude those numbers are Hella good. Congrats. I've got a Whipple coming for my big block. Hopefully I can keep up with your half ton LOL.

Vernon

jthokie92 · May 17, 2005

I remember looking up some info on my 5.3, the factory hp rating from the flywheel was 285, but somewhere I found that the factory rear wheel horsepower was down around 200 for a stock 5.3. I think the guy that had the 8.1 wasn't running it right on the dyno 'cause he had a manual transmission and was putting it up in 4th gear before getting heavy on the throttle. We kept telling him to keep it in 3rd and go to redline, but the guy wasn't too bright so I think he would have gotten some better numbers if done right. He only had a dual exhaust with no other work done, so I believe he could have gotten a little better but not terribly significant. I was told to put it in 3rd gear and then mash the throttle to redline and let it coast off afterwards, 'cause you want to stay out of overdrive. I put a copy of the dyno sheet in my garage section along with all the other pictures of my truck if anyone is interested. Just go to the garage section and look for my user id for my 2001 gmc sierra... I hope to do some other mods to break the 400 rwhp barrier. Some other great info on my ProCharger at www.procharger.com