cam and injector help

[offroadranger]

Hope this helps!

ford injectors
19lb - orange
24lb - light blue
30lb - red
36lb - dark blue
42lb - lime green

immensly! thanks!

 

[offroadranger]

Hey guys, thatnks for all the help so far.

I got some 19lb injectors out of a buddys old engine, had em rebuilt/cleaned/tested, and drilled out the MAF tube to 15/32".

I just want to make sure this is all going to work correctly.

When you drill that out do you remove that rectangle aluminum plate thats riveted to the backside of that tube? Or leave it in? I dont mean just to drill it out, but permently, does it stay or go or get cut down or......?

Also what is the reasoning behind drilling out that sampling tube? I'm just not seeing the connection there?

THANK YOU!

 

[offroadranger]

Bueller? Bueller?

Going back together with new injectors this weekend......some help would be sweet!

 

[Dave R]

The idea behind drilling out the sampling tube is to change the ratio of air that passes through the tube vs the meter to better match your new injectors. Basically your attempting to fool the meter into thinking that less air is passing through the meter so that it reduces the injector pulse that's going to your larger injectors. It sounds complicated but it's not really.

As for the actual modifying of the MAF housing, there are two different types. sounds like you have the older one.

 

[offroadranger]

The idea behind drilling out the sampling tube is to change the ratio of air that passes through the tube vs the meter to better match your new injectors. Basically your attempting to fool the meter into thinking that less air is passing through the meter so that it reduces the injector pulse that's going to your larger injectors. It sounds complicated but it's not really.

As for the actual modifying of the MAF housing, there are two different types. sounds like you have the older one.

Hmm. OK, but if your fooling it to think theres LESS air coming in.....wouldnt the computer then give LESS fuel? So does that mean the 19lb are too much and were going for somewhere inbetween 14 and 19? I have a decent amount of modifications. Gonna be good? Thanks again

 

[offroadranger]

um, can I get a little help here?

I put the new 19lb injectors in last night with the modified maf, and my truck runs like absolute crap. It idles fine, but if you try and give it ANY gas at all, it sputters real bad and then it'll sit at 2k rpm for a few seconds and eventually wind back down. One time after it was warm from idling I tried to rev it (just a bit)and it shot to 4k rpm and stayed there till I could run around and shut it off....what gives?

 

[offroadranger]

Anyone? I have a race to get to in 1 week. I spent $200 on injectors and have a MAF thats modified now.....REALLY need to get this working right........does anyone know what thier talking about with this or is this all hear say?

 

[Zer0PSI]

Man, thats never happened to me, then again I didnt modify my MAF. All that I can think of is to reset the EEC (disconnect the battery for 10 mins) and then drive it around so the computer can readjust.

 

[offroadranger]

Man, thats never happened to me, then again I didnt modify my MAF. All that I can think of is to reset the EEC (disconnect the battery for 10 mins) and then drive it around so the computer can readjust.

Yeah as I was drilling out the MAF sensor I thought, man I should have tried it stock first, but I put all my trust in the guys that said to do it, asked for an explanation of WHY but got nothing back, so I'm hoping they will chime in here.

I reset the computer and got the same results.

 

[offroadranger]

so, zer0 - did you run the bigger injectors with the stock MAF? and it worked fine?

 

[Zer0PSI]

Yes I did, but I run megasquirt, meaning that I can tune the injectors the way I want them, I just ported my MAF. The entire reason behind drilling out the MAF is so that the computer is tricked into thinking that their is less air traveling through the sampling tube than there actually is. With larger injectors their is probably going to be more fuel injected into the cylinders than you actually need, the reason behind drilling the MAF is so the injectors pulse width is shortened (injectors close sooner). Hope that helps

 

[offroadranger]

I got it running. Thanks for the help and sorry for doubting you guys - totally my fault. Its runs perfect now.

 

[Zer0PSI]

What did you do to get it running??

 

[Dave R]

Hmm. OK, but if your fooling it to think theres LESS air coming in.....wouldnt the computer then give LESS fuel? So does that mean the 19lb are too much and were going for somewhere inbetween 14 and 19? I have a decent amount of modifications. Gonna be good? Thanks again

The computer has no idea what size injectors are actually attached to it. If the computer trims the injector pulses by, say, 10% due to the 'decreased' air flowing through the MAF, your still getting more fuel than you would have stock since you have installed 35% larger injectors. It takes the computer a short time to relearn but, it shouldn't be a problem.

What did you do to solve your trucks issues?

How did the modifying the MAF go for you?