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Author
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Topic: New MAF & injector's - need advice.
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SmokinLX
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Member # 1684
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posted
 
 
Just swapped out My 42's for some 50's & also changed up mass air meter's & both are 80 mm pro m's that are calibrated for sc. Now the fuel pressure is lower "which makes some sense to Me" but the idle has dropped down a couple hundred rpm's and obviously it is running rough at idle. I have tried clocking the maf and it helped but still having low idle problem's. Now should I just raise the idle or fuel pressure or both. Where would You guy's start?
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Dont claim power if ya cant mile per hour. 10 second AOD
Posts: 4388 | From: East Bay | Registered: Aug 2002
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JohnB
Tech Moderator
Member # 969
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posted
Raise the fuel pressure, then raise the idle to where you want it.
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1965 Shelby Cobra
1993 Cobra
2012 F150 Raptor
2020 GT500
Posts: 6523 | From: Orlando FL/Redding CA | Registered: Mar 2002
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SmokinLX
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Member # 1684
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posted
quote:
Originally posted by JohnB:
Raise the fuel pressure, then raise the idle to where you want it.
Thank's John, I will give it a go tomorrow.
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Dont claim power if ya cant mile per hour. 10 second AOD
Posts: 4388 | From: East Bay | Registered: Aug 2002
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Jeff S
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Member # 371
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posted
Why is your fuel pressure lower now? Are you still running a chip?
[ September 23, 2008, 04:34 PM: Message edited by: Jeff S ]
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'90 Mustang LX: 8.53 @ 157.92 w/ 1.33 60' on DR's
'10 ZR1: FOR SALE
'14 E63 S: RENNtech ECU
'04 Gallardo: UGR TTG
Posts: 2121 | From: San Jose, CA | Registered: Aug 2001
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LQ9SN95
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Member # 7080
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posted
quote:
Originally posted by Jeff S:
Why is your fuel pressure lower now?
i could be wrong but im thinking its because the fuel pressure was set for the 42lb injectors and since he swapped to 50lbers its now lacking fuel since the injectors are bigger and need the fuel set higher to compensate.
just a theory. again i could be wrong.......
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Lq9 swap
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Trick flow heads
T rex cam
Posts: 8031 | From: Fresno, Ca | Registered: Sep 2006
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forced331
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Member # 1270
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posted
Pull the sparkplugs out to see if there is fuel not burning on the plug, could be a leaking injector? Try that if all above info doesn't work.
[ September 23, 2008, 04:46 PM: Message edited by: forced331 ]
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1992 Ford Mustang LX (Original Owner)"Titanium Frost" 331stroker S-Trim, 5spd
2014 Ford Mustang GT- daily driver
Posts: 1154 | From: Sonoma County | Registered: May 2002
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SmokinLX
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Member # 1684
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posted
quote:
Originally posted by Jeff S:
Why is your fuel pressure lower now? Are you still running a chip?
I don't know why it is lower but it dropped from about 40 to 37-38 ![[Confused]](confused.gif) . I am still running the SCT chip.
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Dont claim power if ya cant mile per hour. 10 second AOD
Posts: 4388 | From: East Bay | Registered: Aug 2002
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SmokinLX
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Member # 1684
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posted
quote:
Originally posted by F8LSN8K:
quote:
Originally posted by Jeff S:
Why is your fuel pressure lower now?
i could be wrong but im thinking its because the fuel pressure was set for the 42lb injectors and since he swapped to 50lbers its now lacking fuel since the injectors are bigger and need the fuel set higher to compensate.
just a theory. again i could be wrong.......
Thst is what I was thinking but with JeffS's response I am thinking that it should'nt drop
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Dont claim power if ya cant mile per hour. 10 second AOD
Posts: 4388 | From: East Bay | Registered: Aug 2002
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SmokinLX
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Member # 1684
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posted
quote:
Originally posted by forced331:
Pull the sparkplugs out to see if there is fuel not burning on the plug, could be a leaking injector? Try that if all above info doesn't work.
I will adjust the fuel pressure & reset, and clock the MAF again if needed. It does'nt smell like it is running much "if any" richer than before but We will see what happen's when I adjust the fuel pressure. I have been going lean on the top end on the dyno & was hoping it was the injector's "I have a 255 intank & 255 inline" but if I am still having problem's I will have to upgrade the fuel system and get it retuned.
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Dont claim power if ya cant mile per hour. 10 second AOD
Posts: 4388 | From: East Bay | Registered: Aug 2002
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Jeff S
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Member # 371
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posted
quote:
Originally posted by SmokinLX:
quote:
Originally posted by F8LSN8K:
quote:
Originally posted by Jeff S:
Why is your fuel pressure lower now?
i could be wrong but im thinking its because the fuel pressure was set for the 42lb injectors and since he swapped to 50lbers its now lacking fuel since the injectors are bigger and need the fuel set higher to compensate.
just a theory. again i could be wrong.......
Thst is what I was thinking but with JeffS's response I am thinking that it should'nt drop
Your fuel pressure definitely should not drop from changing injectors/MAF. Is your idle vacumn the same as before the swap? Are you refering the to fuel pressure with the vacumn line disconnected or connected?
I'm not suprised that your car is running rough after the swap since you have a chip in your car and your computer is still setup for the 42's injectors/MAF.
What lines/rails are you running?
[ September 24, 2008, 12:08 AM: Message edited by: Jeff S ]
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'90 Mustang LX: 8.53 @ 157.92 w/ 1.33 60' on DR's
'10 ZR1: FOR SALE
'14 E63 S: RENNtech ECU
'04 Gallardo: UGR TTG
Posts: 2121 | From: San Jose, CA | Registered: Aug 2001
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