Need help deciding on Maf, Injectors and Fuel pump for 1998 GT!

John1998

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Hello, the setup I'm building now is a 4.6 2v PI swap with PI Intake Accufab 75mm TB, JLT cold air intake, BBK Long tubes, Catted BBK H pipe, Flow master 44 series, I'm running the stock PI cams. I was thinking on getting 24 lb/hr injectors with Walbro 255 Pump and a Stock replacement MAF for a 1998 GT from either Delphi or Hitachi, question is do I even need the 255 pump? and would Upgrading the MAF to a larger one be worth it? I know the stock 19 lb/hr injectors might be high on the duty cycle so thats why I was going to go to 24 lb/hr. The car is planned to be dyno tuned with an SCT tuner as well! Appreciate any input or opinions, thanks!
Oh its also going to have an EGR delete and be tunned for 93 pump gas!
John
 

apsmith49921

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You can upgrade the maf and upgrade to 24lb injectors. I dont see the need for the 255 pump. Without forced induction the stock unit should be fine

Also if you need an 80mm maf I have one collecting dust I'd get rid of.

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Silver95bird

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a 2003-4 maf is less of a restriction and includes the IAT on the extra 2 pins if you like a tidy engine bay.

bigger injectors IMO isnt really necessary but you can if youd like.

the FP is a nice upgrade to do now if you decide to go supercharged later.

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ttocs

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your in no way stressing the 19lb injectors now. I took a weighted (I think that is the term I am looking for) maf on my car to a dyno when I got heads/cam installed the tuner made a face as though I was causing him pain. He explained how the maf works in that it sends a different signal than it really should to the ecu so that the ecu, which has all the tables for the stock maf/injectors, will hopefully work with the new gear. He said it was like going on a diet by doing nothing more than changing the scale you weigh yourself on and look you just lost 10 lbs... To do it right you really need to get tune after and your really not far enough into the motor to justify the price of a tune/chip. If your planning on heads/cam/boost later then these are things you will want but at the moment do not need. I would put the maf on the list of things that I keep an eye out for to pick up used but the injectors personally I would wait till there was a black friday sale or something where you can pick them up for %10-20 off. If you want to do heads/cam again keep your eyes open and its amazing what can fall into your lap. I knew I wanted to go supercharged so when I found one that had only had the huffer taken out of the box to oogle before they put it back and then wrecked the car. I got it all complete NIB for $1k off the new price.
 

John1998

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I see, I’ll just stick with a stock style pump then I guess I should have said I got the car as a roller with no motor or trans and I’m trying to piece together everything I need atm, it’s just gona be a fun knock around daily driver that I want that is very reliable. It sounds like the later style maf that has the IAT incorporated in the maf sounds like a good idea and when you say weighted maf you mean one that can be bought that is “calibrated” to a certain injector lb like I see some bbk mafs that are for like 24 or 36lb and oh yes the dyno tune is going to be done AFTER I get this thing together I just hear a lot of people say a stock 1998 ecu tune won’t really run a PI swapped car that well. I did a lot of research and everyone says something different and get kinda confused lol, so I might just stick with stock maf with the 24 injectors because atm I have no injectors so I figured why not step it up for later plans but then it’s like how am I gona drive this thing with a stock maf and 24lb injector an hour away to a tuner.
thanks for the reply!

John
 

ttocs

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talk to your tuner and you might be able to get him to run a basic baseline tune for you to get it there and then from there he can tweek it. You might need to offer to put a deposit down or pay in advance to ensure that your not going to take the free tune and run.
 

John1998

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talk to your tuner and you might be able to get him to run a basic baseline tune for you to get it there and then from there he can tweek it. You might need to offer to put a deposit down or pay in advance to ensure that your not going to take the free tune and run.
Cool, so plan now is to get a 2004 MAF and splice the pins from the iat to the connector for the maf get a stock Delphi pump and 24 lb injectors and I should be set! I’m gona see if the SCT tuner can maybe get it running good enough to drive it to a tuner I’ve never used one so it’ll be interesting if worse comes to worse I’ll see if the tuner can give me a baseline one like you said. Thanks for the help.

John
 

Silver95bird

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check your harness to see if the other two pins are present in the connector, or you may need the later pigtail as well.

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Boostr1

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I would just upgrade to a 255 pump if your gonna change the old one out anyway.
 

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