Moved MAF now car SUX
05-23-2016, 09:29 PM
#1
Safety Car
Thread Starter
Moved MAF now car SUX
So I moved my MAF from right at the throttle body down to the Vara Ram, and lost 4-5 tenths!! WTH!! Car felt faster after my new forged short block... Moved my MAF to make room for other "mods" now I'm slower...
Is it really cuz I moved the MAF? Went from 11.0x to 11.55 , no other changes to my set up....
Is it really cuz I moved the MAF? Went from 11.0x to 11.55 , no other changes to my set up....
05-24-2016, 02:42 AM
#3
Le Mans Master
Member Since: Aug 2005
Location: CA.
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St. Jude Donor '13-'14-'15
Absolutely this will happen---Whenever you alter the MAF from the stock location either further away from the T-Body or closer --you change the way the MAF reads airflow--
This affects many things---If your car is an automatic you can damage your trans without re calibrating your MAF after a re-location---As the trans uses the MAF load to set the line pressure of your trans
Most important--Typically moving the MAF further away than stock will make it read lean and the ECM will add a % of fuel at P/T to compensate in order to achieve the Stoich AFR of 14.68 via the fuel trims--- HOWEVER if at P/T the engine is lean--then the ECM will add that same % correction at WOT as a lean safety---If you have a rich condition the ECM will never subtract fuel at WOT with a negative fuel trim and they will lock on "0" again as a lean safety---
If the fuel trims go beyond + or - approx 20% you will get a lean or rich code---If you are not getting a code then chances are it is just below +20%
Adding 20% at P/T is no big deal--But again as a lean safety at WOT as I mentioned it will also add that same 20% at WOT as well--making your engine pig rich--lazy--and down on power---
If your tuner tuned your engine to run a safe 12.60 at WOT and the ECM is adding that 20% at WOT you end up with a WOT AFR of a horribly rich 10.08 !! That's the AFR of a boosted engine !!!
You need a retune to get all your P/T fuel trims to be "0" or slightly negative---This is an easy fix for any tuner using a data logger---Then you will not get any additional enrichment caused by a positive fuel trim---or have a need to relocate your MAF
This affects many things---If your car is an automatic you can damage your trans without re calibrating your MAF after a re-location---As the trans uses the MAF load to set the line pressure of your trans
Most important--Typically moving the MAF further away than stock will make it read lean and the ECM will add a % of fuel at P/T to compensate in order to achieve the Stoich AFR of 14.68 via the fuel trims--- HOWEVER if at P/T the engine is lean--then the ECM will add that same % correction at WOT as a lean safety---If you have a rich condition the ECM will never subtract fuel at WOT with a negative fuel trim and they will lock on "0" again as a lean safety---
If the fuel trims go beyond + or - approx 20% you will get a lean or rich code---If you are not getting a code then chances are it is just below +20%
Adding 20% at P/T is no big deal--But again as a lean safety at WOT as I mentioned it will also add that same 20% at WOT as well--making your engine pig rich--lazy--and down on power---
If your tuner tuned your engine to run a safe 12.60 at WOT and the ECM is adding that 20% at WOT you end up with a WOT AFR of a horribly rich 10.08 !! That's the AFR of a boosted engine !!!
You need a retune to get all your P/T fuel trims to be "0" or slightly negative---This is an easy fix for any tuner using a data logger---Then you will not get any additional enrichment caused by a positive fuel trim---or have a need to relocate your MAF
05-24-2016, 04:51 PM
#4
Safety Car
Thread Starter
Thanks for the reply and explanation.....I moved the MAF about 15" further away from the TB ..... Car stall a lot etc..... Down 5 mph and about 5/10 on the quarter mile.....needs to be there now though with the system I just added.....gonna get my "tooner" all over it 