2000StreetRod
Moderator Emeritus
- Joined
- May 26, 2009
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- Greenville, SC
- Year, Model & Trim Level
- 00 Sport FI, 03 Ltd V8
This is the first of several posts relating to my replacement of the stock 55mm MAF sensor with a 90mm Ford Racing F150 Lightning MAF sensor (P/N # M-12579-L54). When forum members learned of my intentions, several expressed a concern that the end result would be lacking in airflow resolution. I was also concerned since I've heard that there are only 30 entries available in the PCM table that stores the MAF sensor transfer function related data. There was also concern expressed about a lack of throttle resolution with the LMAF coupled to a 75mm racing throttle body. I was less concerned about the much larger than stock throttle body because the airflow control at a slight throttle opening has much more resolution than the airflow control at a moderate throttle opening.
To increase the probability of a successful modification I engaged the talents of James Henson of Henson Performance. I purchased an SCT X3 Power Flash from James and emailed him a list of my modifications that included a Spectre high flow cone air intake filter and 4 inch diameter inlet tube until just prior to the throttle body inlet. In just a few days James emailed me a first cut evaluation tune. I must admit that while I had heard good things about Jame's tuning talent I was expecting the first attempt to be pretty rudimentary since James (nor myself) have any first hand knowledge of the condition of my engine with 150,000 miles on the odometer. I was pleasantly surprised in the overall driveability of the tune. There are just a few minor driveability issues to resolve and then we can proceed with performance tuning.
As far as the throttle control issue is concerned, in my opinion it is unwarranted. I admit that the accelerator is more sensitive than before when contolling the engine speed when the gear selector is in Park or Neutral. However, the IAC valve is very capable of keeping my idle speed at the new tune setting of 750 rpm. And frankly, I can't think of any valid requirement for me to precisely control the engine speed with the accelerator when Park or Neutral is selected. However, this may be more of an issue for a vehicle fitted with a manual transmission. With the gear selector in Drive and load on the engine, I have no difficulty maintaining a desired vehicle speed.
As far as the MAF sensor airflow lower resolution is concerned, I have not noted any significant expansion of the A/F ratio from stock. I believe the 90mm LMAF is rated up to 54 lbs/min of air flow and my stock SOHC probably never drew more than 25 lbs/min. I installed a wideband A/F ratio meter prior to switching to the LMAF so I would be able to compare A/F ratios before and after. When in closed loop the PCM continuously varies the A/F ratio from rich to lean and back so resolution becomes less important. Also, I've read that the LMAF was designed to improve the transfer function resolution at lower airflows.
You may be wondering why did I spend the time and money to perform this modificaiton if there is no significant difference in the driveability. There are two reasons. The first, and most important to me, was to determine if reducing the airflow resistance by increasing the diameter of the intake system would increase fuel economy. The second was to determine if inceasing the diameter of the intake system would significantly increase performance. Both determinations will be accomplished thru future testing and will be reported in this thread.
As a side note, I find the sound of rushing intake air as much or more exhilarating as a loud exhaust and it doesn't aggravate others in the vicinity!
To increase the probability of a successful modification I engaged the talents of James Henson of Henson Performance. I purchased an SCT X3 Power Flash from James and emailed him a list of my modifications that included a Spectre high flow cone air intake filter and 4 inch diameter inlet tube until just prior to the throttle body inlet. In just a few days James emailed me a first cut evaluation tune. I must admit that while I had heard good things about Jame's tuning talent I was expecting the first attempt to be pretty rudimentary since James (nor myself) have any first hand knowledge of the condition of my engine with 150,000 miles on the odometer. I was pleasantly surprised in the overall driveability of the tune. There are just a few minor driveability issues to resolve and then we can proceed with performance tuning.
As far as the throttle control issue is concerned, in my opinion it is unwarranted. I admit that the accelerator is more sensitive than before when contolling the engine speed when the gear selector is in Park or Neutral. However, the IAC valve is very capable of keeping my idle speed at the new tune setting of 750 rpm. And frankly, I can't think of any valid requirement for me to precisely control the engine speed with the accelerator when Park or Neutral is selected. However, this may be more of an issue for a vehicle fitted with a manual transmission. With the gear selector in Drive and load on the engine, I have no difficulty maintaining a desired vehicle speed.
As far as the MAF sensor airflow lower resolution is concerned, I have not noted any significant expansion of the A/F ratio from stock. I believe the 90mm LMAF is rated up to 54 lbs/min of air flow and my stock SOHC probably never drew more than 25 lbs/min. I installed a wideband A/F ratio meter prior to switching to the LMAF so I would be able to compare A/F ratios before and after. When in closed loop the PCM continuously varies the A/F ratio from rich to lean and back so resolution becomes less important. Also, I've read that the LMAF was designed to improve the transfer function resolution at lower airflows.
You may be wondering why did I spend the time and money to perform this modificaiton if there is no significant difference in the driveability. There are two reasons. The first, and most important to me, was to determine if reducing the airflow resistance by increasing the diameter of the intake system would increase fuel economy. The second was to determine if inceasing the diameter of the intake system would significantly increase performance. Both determinations will be accomplished thru future testing and will be reported in this thread.
As a side note, I find the sound of rushing intake air as much or more exhilarating as a loud exhaust and it doesn't aggravate others in the vicinity!
