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Discussion Starter #1
2 weeks after recieving my new GTO in February I removed my MAF and cut out the dividers with a hack saw removed the screen and trimmed the wire holder. I proceded to smooth the opening and epoxy the holes left from the trimmed wire holder. I spent some time and I thought I did a good job. I have done this to my 1994 LT1 Caprice and 1996 Impala SS with no problems. I also removed the air box and fitted a K/N cone filter I ordered for $35.00 to the end of the MAF. Everything seemed fine until several days went by and and I started to get lean codes 1701 and 1704. I cleaned the sensor wires w/alcohol mentioned on another thread but the codes kept coming back. I reinstalled the air box and reset the codes agian but they still kept coming back. I carried the scan tool with me and every couple of days I would reset the codes. I was not going to buy a new MAF as they are very expensive. Anyway........I got tired of reseting the codes so I just left them in with the check engine light on. The car seemed to run fine. Several days went by with the check engine light on then it went off and stayed off for several days. It went through 4 cycles of off then on for about ten days then it stayed off. It has been off now for 6 weeks with no signs of trouble. I never reset the codes still stored.

Question? Has the computer finally adjusted itself to the modified MAF or did it just get tired of storing the codes? Performance seems fine as I can smoke the tires through third gear from a standing stop speed shifting at 6000 rpm. (I have a m6) Car seems faster than when new.
 

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After you modifed your MAF and before you started your car again, did you reset the PCM, either by pulling the fuses or disconnecting the negative lead of the battery? I believe the PCM will "learn" quicker from a reset. (Don't ask me, I'm no expert, but I had NO trouble after installing the High Flow Induction. I reset the PCM before restarting the car.)
 

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When I changed my MAF I had the same problems with the SES light going on. The car seemed like it had more power and was a lot faster. Once I cleared the light and the code with my scan tool, the light never came on again. ITs been a month and now It doesnt feel like I have the power that I feel it once had.
 

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Discussion Starter #4
I never reset the PCM before starting the car with the modified MAF. I just started reseting the codes when they appeared. It seems the PCM needed more time to learn the modification. I don't have access to a dyno so I can't prove the car has more power but it feels strong. I'm afraid to reset the codes that are stored now as they may start coming back on. Should I just leave it with the codes stored in? The check engine light has not come back on.
 

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Discussion Starter #6
I guess I would like to see some before and after dyno numbers. Also some long term dyno numbers and some numbers with the codes stored (1701 and 1704) and the check engine light on. Then some more numbers after the PCM has been reset. I have never seen anybody doing this extensive testing on MAF modification or aftermarket MAF's. I here lots of talk but not much proof. The car would have to be completly stock other than the MAF changes to mean anything.
 

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You MAF is constantly learning even after a PCM reset. All a PCM reset does is reset everything to base tables and allows for a more thorough adaption after a modification.

Remember, while the MAF may be mechanically identical to the one on a 94 LT1, the software driving it is infinitely superior and with OBDII, is more sensitive to such an altercation.

A MAF measures two variables, one is the quantity of air being injested in pounds/hour measure. Secondly, it measure the speed with which that incoming air is flowing at in hertz. Removing the screen is one thing and rather trivial, but by removing that center vane you have altered how the air is funneled across those thermistors and as such it is inaccurately measuring. The placement of those thermistors are precisely placed for air to be funneled past due to that vane. Removing it in effect leaves a large amount of air to get by that necessarily isn't being accounted for, effectively leaning it out.

OBDII is light years ahead of OBDI.
 

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The MIL may not be viewable on the DIC but how about what is actually stored? How do your fuel trims look?

I'm assuming we can put in a Z06 MAF? they go for a decent price, and are OE descreened. Anybody know if you can put one in a goat?
 

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AS long as you buy the pigtail adaptor for it. The ZO6 MAF has the IAT sensor inside the MAF itself and we have a separate sensor.
 

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Money/time facture improves your performance

have you ever noticed after you spend hours and hours hand waxing your car with tender loving care, it runs better?? Without actual dyno proof, I doubt it is running any better. I wouls suspect a fuel economy reduction of some kind. the grids are there to channeling air, not for restricting it. I will not believe it until I see some actual proof. I am not criticizing you fir making the attempt to make the engine better. sounds like you did a very clean job of it. But after hours and hours of work........

Its just like the guys who put on low end exhaust systems that sound good, and therefore must and in their mind run better. But I have seen some dyno numbers on some sport utilities that actually showed a reduction in hp

dms
 

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All pshychological. :D
 

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CMNTMXR57 said:
All pshychological. :D
The improvements due to de-screening the maf or due to waxing?
 

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Both really.

Descreening your MAF won't net a notciable HP gain. What it will net you is increased throttle response due to the screen removal allowing increased air speed/air speed change across the thermistors as the air won't need to be straightened before going across them as when the screen was there. Otherwise, it will ingest the same volume of air regardless! A screen removal won't (or minimally) increase the lbs/hr intake reading, just the change in frequency from the air speed.

Waxing/polishing, while leaving a mirror smooth and non-sticky surface won't increase performance either. It more or less manifests confidence in the happy attitude you have after just shining the beauty up. Now, I'm sure perhaps that at Mach3+, aerodynamic resistance may start playing a factor into the equation, not at 55 though.
 

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CMNTMXR57 said:
Both really.

Descreening your MAF won't net a notciable HP gain. What it will net you is increased throttle response due to the screen removal allowing increased air speed/air speed change across the thermistors as the air won't need to be straightened before going across them as when the screen was there. Otherwise, it will ingest the same volume of air regardless! A screen removal won't (or minimally) increase the lbs/hr intake reading, just the change in frequency from the air speed.


Waxing/polishing, while leaving a mirror smooth and non-sticky surface won't increase performance either. It more or less manifests confidence in the happy attitude you have after just shining the beauty up. Now, I'm sure perhaps that at Mach3+, aerodynamic resistance may start playing a factor into the equation, not at 55 though.
So, would you say that the increased throttle response is worth taking the screen off?
 

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MAF Performance

The only way to obtain increased performance from an aftermarket MAF is to put it on just before you race. You will note an improvement. However after your 3rd or 4th run; the PCM will have corrected back to a stock configuration.

You can have the HP MAF programmed into your PCM and it will perform on a constant.

Also I just received an e-mail from one of the techs at LS1 Speed. I was trying to decide on mail order tuning or on the dyno. I had mentioned I was installing aftermarket ported MAF ends. He advised that because the stock tuning was so close; the aftermarket MAF ends would make it more difficult to tune and they are not necessary.

I also contacted my mail order tuner; Bryan Herter from Pa. He is infamous regarding his Impala SS tunes. He agrees with LS1 Speed. The ends are not necessary and complicate a HP tune.

slick50
 

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speed_demon_freak said:
When I changed my MAF I had the same problems with the SES light going on. The car seemed like it had more power and was a lot faster. Once I cleared the light and the code with my scan tool, the light never came on again. ITs been a month and now It doesnt feel like I have the power that I feel it once had.

What probably happened is you leaned out your fuel mixture and it gave you more hp. Now the cpu has learned to add more fuel back to your mixture and the hp gained from being lean is now gone. I may not be correct but thats what I think happened.
 

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I had asked MTI if they still sold polished MAF ends and they told me they no longer sell or recommend altering the MAF as it will lead to detonations. They have completely stock MAF on their high powered engines. This conversation took place two days ago.
 

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The type of MAF on these cars samples 100% of the air coming in.Most MAFs only sample 15% of the air passing though.When you took out the screen and support bar you changed the speed at which the air passes.The MAF was not calibrated less these parts.The MAF is now telling the PCM that there is less air going in because of the slower flow speed. This is what causes your lean codes.I have built and tuned many LS1s with stock MAF that make over 500HP.
 

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MAF Ends

CMNTMXR57 said:
...Removing the screen is one thing and rather trivial, but by removing that center vane you have altered how the air is funneled across those thermistors and as such it is inaccurately measuring...
I have installed the MAF ends from Tbyrne. There is no screen and no "vanes". I have not gotten any codes or SES light. The car seems to be running fine. The MAF ends look great.

Have I screwed up the MAF calibration with the MAF ends? What are the short term and long term risks of an uncalibrated MAF? Is there a way to "re-calibrate" the MAF in my car?
 

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The MAF is the black plastic center portion with the thermistors.

The ends have the vanes. Having the non-vaned ends it will run lean due to the extra air not being metered. You aren't hurting anything per-se. You may notice some extra grunt at first, but soon it'll re-learn and comepnsate as much as it can.
 
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