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Discussion Starter · #1 ·
Ok.......im new to all this mustang stuff. I picked up an 89 notch with a 306, upper and lower Trick Flow intake, E cam, and a bbk cold air intake. My car is also running air density instead of the mass air. I also have an s-trim vortec i would like to put on and just wondering what else i would ahve to add to make this work or is it just a bolt on? looking to run 6lbs boost jsu to start. I know i will ahve to increase fuel. I have been reading and it seems putting in some bigger injectors is the way to go and not the FMU. I have a set of 42# i can use.
 

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You'll need a tune with those 42lb injectors if not your driveability will be complete **** but there good injectors and can handle a bunch of power. The FMU some skate by with but I wouldn't suggest using it if you have the injectors.. the fmu is more of a bandaid for inadequate injectors

I'd look into upgrading the fuel pump asap with that s trim going on.. and being speed density your going to have to convert over to mass air which isn't that hard but requires a computer from a maf car example a9l or a9p etc. Change a few pins around on the wire harness etc
 

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Discussion Starter · #6 ·
So first off ill have to work on moving over to mass air which i have most the parts for already. And the stock computer can be flashed for the 42lbs? or am i going to have to switch to some aftermarket efi system? I may even have to a9l comp (have a 2nd mustang). Am i able to swap out the mass air meter and swap out the comp or is it a bigger job then it sounds?
 

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So first off ill have to work on moving over to mass air which i have most the parts for already. And the stock computer can be flashed for the 42lbs? or am i going to have to switch to some aftermarket efi system? I may even have to a9l comp (have a 2nd mustang). Am i able to swap out the mass air meter and swap out the comp or is it a bigger job then it sounds?
You'll need to throw that a9l into the car your converting because it's a maf ecm. Do a search in google for converting mustang to mass air and you'll find step by step directions. It's not that hard at all just takes a little time.

With those 42lb injectors you'll have to have a custom tune done on a chip for the a9l ecm.

also if your car is an 89 it's mass air already or should be unless someone swapped an older fox harness into it for some odd reason.
 

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Discussion Starter · #9 ·
So wat you are sayin is the a9l and watever computer i have are swapable with the same harness? And if it is the corrrect harness for mass air there should be the plug floating around somewhere under the hook by my intake for the meter right? And no difference since its a manual.....a9l is the one? IF this is the case ill do the mass air swap first (and i have a vacuume leak somewhere no big deal) and get the car running like that then do the injectors/chip/charger and w/e other little things i run into. Prob after that the pump is going to have to be swapped for a larger one if i run outta fuel at the top end.

btw thanx for all the replies im gettin on this def answered alot of questions and saved alot of time :D
 

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Discussion Starter · #10 ·
Also.....this chip i been looking and asking around i have heard good things bout the sct chip and there are 2 versions, the one with the one custom tune and the one wit 5 custom tunes with dial. Now where exactly does this chip install to? does it go inline somewhere with the main harness or plug into the ecu??? most i have worked with are inline somewhere.
 

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So wat you are sayin is the a9l and watever computer i have are swapable with the same harness?
If your car is in fact an 89 it should have the a9l already in it. It should also have the 89 engine harness which goes through the firewall above the heater box and would have a plug for your mass air meter to attach to.

And if it is the corrrect harness for mass air there should be the plug floating around somewhere under the hook by my intake for the meter right?
Yes

And no difference since its a manual.....a9l is the one?
A9L is the maf 5 speed computer yes but the A9P will work as well which is the auto trans one.

IF this is the case ill do the mass air swap first (and i have a vacuume leak somewhere no big deal) and get the car running like that then do the injectors/chip/charger and w/e other little things i run into. Prob after that the pump is going to have to be swapped for a larger one if i run outta fuel at the top end.
Speed density runs off vacuum so if you have a vac leak right now the car is idling and running like complete ****. Locate and resolve the vacuum leak and look around the pas side fender area for that maf harness. If you find it then you can plug in a maf meter and pull the computer down out of the pas side kick panel and make sure it's a a9l or a9p and your good. If you don't have the harness you need to go to the junkyard and cut the harness out of a fox car, add your own wiring back to the ecm and repin the large harness plug to the ecm. I believe you move four pins but forget it's been years since I had to do it but like I said google it there's tons of step by step with picture write ups it's easy.

So to go maf you need the harness or convert the harness, maf ecm, and meter of choice.

You don't have to go maf until you make a modifcation that'll change the vacuum of the car like a power adder or cam. Bolt ons won't require maf but larger injectors require a retune and burn of a chip for it which is a pita with speed density so the easy short answer people will give you is convert to mass air at that point.
 

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Discussion Starter · #12 ·
Yea my car idle is horrible most of the time jumping from 500rpm up to 1500rpm but every now and then it will idle at a steady 1000 rpm. And your sayin i would have to go to maf if i had a power adder and i already have an e303 cam in it. Could this be a reason my car idles like complete shyt? Tonight when i get home i will check the computer and harness.

This charger seems to be opening a big can of worms lol. But id love for my car to idle right so im not the idiot at the lights all the time reving my engine to keep it running.


Alsoooo by meter of choice im going to have to match that with my injectors right? so if i match it to my 19# rt now im going to have to change it out when i put in the 42#


sry for the long posts but something new seems to up up each time lol
 

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Yea my car idle is horrible most of the time jumping from 500rpm up to 1500rpm but every now and then it will idle at a steady 1000 rpm. And your sayin i would have to go to maf if i had a power adder and i already have an e303 cam in it. Could this be a reason my car idles like complete shyt? Tonight when i get home i will check the computer and harness.
That e303 cam would be your vacuum leak... I don't believe that's a speed density friendly cam. If that is the origin to your idle issue then converting to maf will resolve it. Your speed density works off of vacuum, that black little box on the firewall in the middle or a little to the driver side with wire and vac line to it is your BAP or MAP sensor which is a key part in this. When you go maf you pull that vacuum line off of it but leave the wire harness plugged in fyi.


Alsoooo by meter of choice im going to have to match that with my injectors right? so if i match it to my 19# rt now im going to have to change it out when i put in the 42#
Meters have to be calibrated to your injector size.. most can be recalibrated by your tuner or the manufacture. You generally want to have the largest meter you can get because there's no draw backs to going large with this part.
 

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Discussion Starter · #14 ·
Ok so thats good to know so either way watever happens mass air it is since its def not near a stock motor. But i also have a small oil leak thinking the guy i got it from didnt tighten the valve covers enough. Only leaks when driving or rt after parked when driving so its def an issue comming from the top end. Also havea mass air meter just gotta see wat kind/size it is.....im thinking a 75mm which should be good.
 

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Discussion Starter · #16 ·
DA1 is the computer in my car and there are 4 plugs under the hood not connected to anything rt by the firewall passanger side and also one by the passanger strut tower so im guessing its a harness for the a9l which means the connector for the computer is the same on the DA1 and the a9l? Do i still ahve to switch pins around or its a plug and play?
 

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da1 is the speed density ecm.. the 87 and 88 speed density harnesses are the same as an 89 harness except for the lack of the maf connector. Both could be used with a speed density ecm but why? I'd take some pictures of the plugs that you found unplugged and post them up in another thread asking to id these plugs and where they go etc so that we can all help you sort weather or not you have the 89 harness or a non mass air harness. If it's the 89 harness then you'll just have to pop in a maf ecm and meter I believe.
 

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Discussion Starter · #18 ·
well put my car into a wall tonight so got bigger problems then the speed density now lol........car still runs tho!!! no radiator tho : /
 
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