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Old 09-27-2010, 08:27 PM
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My 98 z28 had an ses light on so i took my car to auto zone so they could run the codes and i got all the o2's sensors but i changed those and it said i was running to lean.
i was just wondering what could cause this?
my mods are a lid, ls6 intake p&p throttle body and maf.
Old 09-27-2010, 08:28 PM
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should i get a tune i dont plan on getting headers or anything else for a long time.
Old 09-27-2010, 09:49 PM
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I would say you PP MAF is the problem. Don't touch those things. They are good for 500HP and don't need porting even though it makes it faster because it is leaner. Sure if you lean your motor out to 14:1 it will go .2 faster in a 1/4 but your motor will be shot in no time. Let me explain...

A stock ECU knows how big the MAF is, so air will flow through the sensor at a certain speed and then the engine makes calculations to get the A/F to 13:1. Now when you PP your MAF the air actually moves slower over the wire sensors because it has more room and the ECU doesn't know the MAF is bigger. (Think of it as if you take a river and narrow it it becomes quick and rapid but if you widen it, it slows and flows easily and slower.) So now that the air is moving over the MAF slower the ECU thinks there is less air coming in then what actually is so it reduces fuel to engine leaning it out. So when your ECU is thinking its adding less fuel and making the A/F right its actually leaning it our because the motor is getting more air then what is being seen. Sure a PP MAF makes a car faster in the 1/4 mile but it is a lot harder on the engine with out a tune. Get the ECU tuned to see the bigger MAF or get a stock MAF back in.
Old 09-27-2010, 10:04 PM
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Originally Posted by araber89
I would say you PP MAF is the problem. Don't touch those things. They are good for 500HP and don't need porting even though it makes it faster because it is leaner. Sure if you lean your motor out to 14:1 it will go .2 faster in a 1/4 but your motor will be shot in no time. Let me explain...

A stock ECU knows how big the MAF is, so air will flow through the sensor at a certain speed and then the engine makes calculations to get the A/F to 13:1. Now when you PP your MAF the air actually moves slower over the wire sensors because it has more room and the ECU doesn't know the MAF is bigger. (Think of it as if you take a river and narrow it it becomes quick and rapid but if you widen it, it slows and flows easily and slower.) So now that the air is moving over the MAF slower the ECU thinks there is less air coming in then what actually is so it reduces fuel to engine leaning it out. So when your ECU is thinking its adding less fuel and making the A/F right its actually leaning it our because the motor is getting more air then what is being seen. Sure a PP MAF makes a car faster in the 1/4 mile but it is a lot harder on the engine with out a tune. Get the ECU tuned to see the bigger MAF or get a stock MAF back in.

yeah i got it in like a package deal so i just said what the heck but i didnt look into it. (now i know that was a mistake) but if i get a tune do you think that will fix it?
Old 09-27-2010, 10:22 PM
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Ya you need to talk to a guy who actually tunes whether he can do it with out a dyno tune or reflash the MAF. Call some of your local shops to see what they say they can do. Shops that have been around a while will have many tunes saved with mods just like your that they can do for you with out a full dyno tune for now.
Old 09-27-2010, 10:36 PM
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Originally Posted by araber89
Ya you need to talk to a guy who actually tunes whether he can do it with out a dyno tune or reflash the MAF. Call some of your local shops to see what they say they can do. Shops that have been around a while will have many tunes saved with mods just like your that they can do for you with out a full dyno tune for now.
yeah there is a shop like 30 minutes away im thinking about going to he said he could do a full dyno tune for 250 because i dont plan on doing any other mods for a couple of years.
Old 09-27-2010, 10:57 PM
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Wow thats a deal compared to what dyno tunes are going for around here. Anywhere from 400-600 bones.
Old 09-27-2010, 11:31 PM
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Originally Posted by araber89
Wow thats a deal compared to what dyno tunes are going for around here. Anywhere from 400-600 bones.
yeah thats why i dont mind getting a full dyno tune. do you think i should get the full tune.
Old 09-28-2010, 06:58 AM
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Its up to you really. With a full tune they can tune it for 93 octane reduce the torque management at low RPMs and smooth everything out. Also with a full tune you have piece of mind that your car is running right. I have a friend who did it on his intake only GTO and he gained a little in the quarter mile, so there is some power benefit from a tune, if you have a good tuner.
Old 09-30-2010, 02:00 PM
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i have this same problem but i am stock all my o2's dont work and i also have sims after the cat




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