This is topic New MAF & injector's - need advice. in forum Tech Talk at Northern California Ford Owners  .


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Posted by SmokinLX (Member # 1684) on :
 
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?
 
Posted by JohnB (Member # 969) on :
 
Raise the fuel pressure, then raise the idle to where you want it.
 
Posted by SmokinLX (Member # 1684) on :
 
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.
 
Posted by Jeff S (Member # 371) on :
 
Why is your fuel pressure lower now? Are you still running a chip?

[ September 23, 2008, 04:34 PM: Message edited by: Jeff S ]
 
Posted by F8LSN8K (Member # 7080) on :
 
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.......
 
Posted by forced331 (Member # 1270) on :
 
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 ]
 
Posted by SmokinLX (Member # 1684) on :
 
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] . I am still running the SCT chip.
 
Posted by SmokinLX (Member # 1684) on :
 
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 [Confused]
 
Posted by SmokinLX (Member # 1684) on :
 
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.
 
Posted by Jeff S (Member # 371) on :
 
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 [Confused]
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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