Fuel pressure regulator, dyno tuning
Thread Starter
Racer
Joined: Nov 2002
Posts: 320
Likes: 0
From: Bradenton Florida
Fuel pressure regulator, dyno tuning
Im thinking about a fuel pressure regulator and getting my car dyno tuned at
a local shop called fast forward for 180$. anyone have any experience with
the regulator or the dyno tunning-timing, air fuel, ext.
a local shop called fast forward for 180$. anyone have any experience with
the regulator or the dyno tunning-timing, air fuel, ext.
Burning Brakes
Joined: Aug 2000
Posts: 984
Likes: 1
From: Cincinnati OH
Re: Fuel pressure regulator, dyno tuning (C4kid94)
Here's a related question I've been wondering about (sorry if this is common knowlege, I'm not clear on this one)...
When WOT, the ecm goes into PE mode and disregards the O2 sensors. Question I have is does the ecm still look at the BLM's in PE mode? I know the ecm will learn and "undo" any fuel pressure changes for non-PE open loop operation by altering the BLM values over time. If the BLM's are still used in PE mode, this will nullify any fuel pressure changes over time, if not, then it would be a useful tuning tool. Can someone enlighten me on what really happens in PE mode?
Thanks
When WOT, the ecm goes into PE mode and disregards the O2 sensors. Question I have is does the ecm still look at the BLM's in PE mode? I know the ecm will learn and "undo" any fuel pressure changes for non-PE open loop operation by altering the BLM values over time. If the BLM's are still used in PE mode, this will nullify any fuel pressure changes over time, if not, then it would be a useful tuning tool. Can someone enlighten me on what really happens in PE mode?
Thanks
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Fuel pressure regulator, dyno tuning (Vince Ivanc)
On an OBD-1 system, like in my L98, at WOT the ECM looks at BLM cell #15 which always has the value 128 and the INT is set to 128.
So the O2 sensor readings cannot effect the A/F ratio at WOT.
So the O2 sensor readings cannot effect the A/F ratio at WOT.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Re: Fuel pressure regulator, dyno tuning (65Z01)
On an OBD-1 system, like in my L98, at WOT the ECM looks at BLM cell #15 which always has the value 128 and the INT is set to 128.
So the O2 sensor readings cannot effect the A/F ratio at WOT.
So the O2 sensor readings cannot effect the A/F ratio at WOT.
- If the BLM numbers are less than 128, it will use 128 as part of the base fueling equation
- If the BLM numbers are greater than 128 (PCM adding fuel), it will use that number...i.e the PCM will error on the side of a rich mixture vs being too lean
When tuning part throttle, the idea is to have BLMs slightly less than 128 so the PCM consistently uses 128 as the base when entering PE. This makes WOT fueling "consistent"
OBD II is similar although "BLM" is expressed as Long Term Fuel Trim (LTFT) with 0% being the equivalent of 128.
:cheers:
Melting Slicks
Joined: Jan 2002
Posts: 2,784
Likes: 3
From: Atlanta GA
Re: Fuel pressure regulator, dyno tuning (65Z01)
On an OBD-1 system, like in my L98, at WOT the ECM looks at BLM cell #15 which always has the value 128 and the INT is set to 128.
So the O2 sensor readings cannot effect the A/F ratio at WOT.
So the O2 sensor readings cannot effect the A/F ratio at WOT.
Thread Starter
Racer
Joined: Nov 2002
Posts: 320
Likes: 0
From: Bradenton Florida
Re: Fuel pressure regulator, dyno tuning (C4kid94)
ya well anyway, what kind of gains can i expect with the A/F ajusted, timing
ajusted, and anyother tunning he can do. As for the 180$ the guy just said it
incudes him tunning my car, so i dont kno what that involves but its a well
known shop and they kno what there doing, they have a TT Ferrari, TT
Corvette that makes 1200hp there right now.
ajusted, and anyother tunning he can do. As for the 180$ the guy just said it
incudes him tunning my car, so i dont kno what that involves but its a well
known shop and they kno what there doing, they have a TT Ferrari, TT
Corvette that makes 1200hp there right now.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Re: Fuel pressure regulator, dyno tuning (StealDads67)
I think Im missing your point.... So doing a AFPR on our L98 the compuer will not learn over time and compansate for it.... Or it will?? Because I am about to get one and wondering if it is worth it or the computer will fix the car to run where it wants to.... Thanks
At WOT, o2 sensor feedback isn't used. If fuel pressure is decreased during part thottle to the point the BLM goes above 128 (adding fuel to correct a lean condition), you'll actually end up richer at WOT since the power enrichment table assumes a BLM of 128 in the base fueling equation. When combined with already rich WOT factory programming, in most cases you'll lose power.
The AFPR is a way of adjusting WOT A/F ratio vs actual programming changes. Problem is, without a wide band o2 sensor, tweaking the fuel pressure is a akin to throwing darts and praying you get lucky. The engines tended to be rich from the factory. How rich will vary, especially if the car has mods, how many or few miles, etc.
On an otherwise stock car, I wouldn't spend the $
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Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Re: Fuel pressure regulator, dyno tuning (C4kid94)
ya well anyway, what kind of gains can i expect with the A/F ajusted, timing ajusted, and anyother tunning he can do. As for the 180$ the guy just said it incudes him tunning my car, so i dont kno what that involves but its a well known shop and they kno what there doing, they have a TT Ferrari, TT
Corvette that makes 1200hp there right now.
Corvette that makes 1200hp there right now.
Unless he's reflashing the PCM, there is no base timing adjustment on a '94. If he's charging $180 for a true "dyno tune"...actual programming changes to the PCM, use of a wide band o2 sensor, etc...you're getting a hell of a deal. Most charge $400 & up. Usually for that price, simple adjustment of fuel pressure for best performance is what you get.
He may have a TT Corvette, but that doesn't mean he can tune an LT1. Specifics can vary by year and what works on an L98 may not work on yours (and vice versa).
Melting Slicks
Joined: Aug 2000
Posts: 2,009
Likes: 1
From: Springfield MO
Re: Fuel pressure regulator, dyno tuning (96GS#007)
I agree with 96gs#007 completely. If he isn't going to flash your computer you are getting ripped. Around here I can get 3 pulls for 100 bucks with wideband.
Thread Starter
Racer
Joined: Nov 2002
Posts: 320
Likes: 0
From: Bradenton Florida
Re: Fuel pressure regulator, dyno tuning (C4kid94)
Basicaly i just want to get my car dynoed, but at the same time i can get some tunning done, im looking for doing anything major.
Melting Slicks
Joined: Jan 2002
Posts: 2,784
Likes: 3
From: Atlanta GA
Re: Fuel pressure regulator, dyno tuning (C4kid94)
Around here I think the price is about 125 with wideband for 3 pulls... no chip or tuning.... except a litle turn of oour AFPR if you wish.....
I gotta get my car on the dyno with the nitrous and see how its working.... I think I have to much fuel... But im not lowing the jetting on the fuel side until I get the dyno and wideband readings
I gotta get my car on the dyno with the nitrous and see how its working.... I think I have to much fuel... But im not lowing the jetting on the fuel side until I get the dyno and wideband readings
Melting Slicks
Joined: Aug 2000
Posts: 2,009
Likes: 1
From: Springfield MO
Re: Fuel pressure regulator, dyno tuning (StealDads67)
I would dyno it and get a baseline for future reference. If all of your mods are listed in your sig, I would bet that it's pretty close to where it needs to be
Melting Slicks
Joined: Jan 2003
Posts: 2,167
Likes: 0
From: What did the 5 fingers say to the face? SLAP!!
Re: Fuel pressure regulator, dyno tuning (AS84)
Around here I can get 3 pulls for 100 bucks with wideband.
