MAF screen removal: just lost 2 HP...
Thread Starter
Melting Slicks
Joined: Jul 2001
Posts: 3,284
Likes: 3
From: Southwest Florida
MAF screen removal: just lost 2 HP...
Well, I just did a before and after dyno run using Road Dyno and it indicates that I lost 2 HP by removing the MAF screen. The car was tested before/after and each test was within an hour of the other. The tests were performed on the same stretch of road with the car in the same operating conditions (temp, etc) and the same weather conditions.
I'm not sure what that dip is in my curve either at about 4,600 RPM. I suspect the knock sensors might be cutting the timing back momentarily in that range. I'll have to check into that.
Removal of the MAF screen was a real PITA compared to doing it on the f-body. I was cursing endlessly at those little rubber grommets that hold the whole intake on. :mad I also had to destroy the screen getting it out. It didn't appear to have the big C clamp holding it in like the LT1 MAF did.
Anyway, FWIW... I guess it's possible that the computer needs to get used to the change too. The car is completely stock except for a K&N filter in the stock airbox.
Mike
[Modified by mchaney, 4:30 PM 8/3/2001]
Burning Brakes
Joined: Feb 1999
Posts: 933
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From: Santa Clara Ca
Re: MAF screen removal: just lost 2 HP... (mchaney)
I suggest you monitor the PCM and see what your fuel trims look like.
You may find your running too lean and also getting knock esp at the higher RPMs. Also look at the timing for you may find its a bit low.
You might rerun the same test after you get some more miles for the PCM to retune for the incrreased airflow changing the trims.
John
You may find your running too lean and also getting knock esp at the higher RPMs. Also look at the timing for you may find its a bit low.
You might rerun the same test after you get some more miles for the PCM to retune for the incrreased airflow changing the trims.
John
Thread Starter
Melting Slicks
Joined: Jul 2001
Posts: 3,284
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From: Southwest Florida
Re: MAF screen removal: just lost 2 HP... (Vette-Racer)
Sorry. Gotta plead ignorance on that. What's a PCM relearn? I thought you just had to drive it for a while. Is there a specific procedure?
Mike
Mike
Thread Starter
Melting Slicks
Joined: Jul 2001
Posts: 3,284
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From: Southwest Florida
Re: MAF screen removal: just lost 2 HP... (Speed-Racer)
Sounds like you are probably referring to Home Dyno, which is the software-only version, instead of Road Dyno. In any case, you can email me provately at mchaney@ddisoftware.com. Just be sure to include your full name so I can look you up in the registration database. Then I can send you the latest version.
Mike
Mike
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Race Director
Joined: Mar 2000
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From: Palm City Florida
Re: MAF screen removal: just lost 2 HP... (mchaney)
Dude, get real. 2 hp is Mice Nuts! If you farted in the car during the Dyno you could have gained or lost 2hp
Stay with it. Get the BPP MAF ends with Air Foil and a MAFT. Then tweak it with autotap till she screams!!!! :D
Stay with it. Get the BPP MAF ends with Air Foil and a MAFT. Then tweak it with autotap till she screams!!!! :D
Racer
Joined: May 2000
Posts: 279
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From: Windsor Ontario Canada (lakeshore township)
Re: MAF screen removal: just lost 2 HP... (mchaney)
If the car is newer than the 2000 model year I was told you shouldn,t take the screen out. What year of vette do you have? Mine is a 2000 FRC and I gained between 3 & 5 HP. :cheers: ;)
Thread Starter
Melting Slicks
Joined: Jul 2001
Posts: 3,284
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From: Southwest Florida
Re: MAF screen removal: just lost 2 HP... (pld)
Mine is a 99. Also, there was no farting during the dyno run. I did eat a sandwich between runs though and forgot to account for the extra weight. :lol: Seriously, I do realize that 2 hp is negligible. I can't make any conclusions on whether screen removal is good or bad based on that alone. Also, the car didn't have a chance to relearn when I did the "after" test so I plan to retest once it has been driven a bit. I'm more concerned with the dip in the curve at 4,600 RPM than 2 hp. I may have to try desensitizing the knock sensors a little because knock retard is the only thing I can think of that would cause a dip like that.
Mike
Mike
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From: Riverview FL
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Re: MAF screen removal: just lost 2 HP... (pld)
No screen here...took it out when I installed the Vortex... 
Instructor
Joined: Oct 1999
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From: Corona CA
Re: MAF screen removal: just lost 2 HP... (SRitger)
As I understand how the C5 PCM works. Any time you make changes to the intake system you need to drive the car at normal speeds for 50 to 100 miles to allow the computer to relearn (adjust the fuel LTRIMS). Removing the MAF screen allows more air to flow which leans the mixture. The PCM uses feedback from the O2 sensors at normal (not WOT) operation to dial in the A/F ratio by adjusting the LTRIMS. The PCM then calculates and sets the mixture required for WOT. If you dyno right after removing the screen, the PCM bases the WOT mixture on the previous LTRIMS which will under estimate the amount of fuel required at WOT (it will be too lean). If your car was running on the rich side, you could see an improvment, if you were lean allready you will probably see a decrease in performance. At WOT the PCM runs open loop, which means that it does not use feedback from the O2 sensors, it uses the calculated values from a table.
Re back-to-back runs: A 2 to 3 HP difference is insignificant; it falls within the precision limits of the dyno.
Re back-to-back runs: A 2 to 3 HP difference is insignificant; it falls within the precision limits of the dyno.
Safety Car
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From: Murphy TX
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Re: MAF screen removal: just lost 2 HP... (mchaney)
I would be cautious about desensitizing the KS. If it's real knock, you want to isolate the cause(s) and eliminate it rather than ignore it. Fooling with the KS themselves only makes sense if you're fighting really determined false knock.
I agree with Mello, you want to be looking at what's happening with your timing and what not, particularly around that dip.
I agree with Mello, you want to be looking at what's happening with your timing and what not, particularly around that dip.