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Thread: 350 Vortec w/ Pro-Flo XT 42lb Inj and 5.3 MAF

  1. #1
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    350 Vortec w/ Pro-Flo XT 42lb Inj and 5.3 MAF

    I built up my 350 vortec got it running with the spider injectors but decided to upgrade to a Edelbrock Pro-Flo Xt intake w/ 42 lb injectors and I will be using a 5.3 MAF sensor with IAT sensor in it so I don't have to make a hole in my intake for the stock IAT sensor for my truck.

    I have to install a LS1 MAP sensor but not sure if I only need a 2 bar or 3 bar sensor.

    Ive read you maybe able to use a LT1 tune as a base tune for this type of intake swap on the 350 vortec but idk.

    I should have everything I need to install it this weekend so I'm looking for any advice you guys might have on what to put in this thing for a base tune to get started.


    350 vortec bored .30
    Flat top pistons
    Summit vortec racing heads
    Mellings Cam w/ 283int./287exh. Duration
    headman short headers.

  2. #2
    Advanced Tuner mbray01's Avatar
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    unless your going with boost, there is absolutely zero need for anything other that a 1 bar map
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    20yr Master Tech.
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    Custom Car Fabrication, Customization, High Performance.
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    Quote Originally Posted by mbray01 View Post
    unless your going with boost, there is absolutely zero need for anything other that a 1 bar map
    Sweet, Thank you for clarifying. No boost but possibly a small nitrous shot in the future.

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    The Express van tune files seem to be most accessible. And work great.
    97 ext cab short bed silverado 5.7 411 swap, edelbrock 29135 intake, lightly ported 906 heads milled .035 thou. factory press in rocker studs & rockers, comp 787 retainers & stock locks, ls6 springs. Comp cams 08-503-8 T56 swap

    86 SWB crate vortec 5.7/th350 The wife's truck

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    Quote Originally Posted by lazydogtuning View Post
    I built up my 350 vortec got it running with the spider injectors but decided to upgrade to a Edelbrock Pro-Flo Xt intake w/ 42 lb injectors and I will be using a 5.3 MAF sensor with IAT sensor in it so I don't have to make a hole in my intake for the stock IAT sensor for my truck.

    I have to install a LS1 MAP sensor but not sure if I only need a 2 bar or 3 bar sensor.

    Ive read you maybe able to use a LT1 tune as a base tune for this type of intake swap on the 350 vortec but idk.

    I should have everything I need to install it this weekend so I'm looking for any advice you guys might have on what to put in this thing for a base tune to get started.


    350 vortec bored .30
    Flat top pistons
    Summit vortec racing heads
    Mellings Cam w/ 283int./287exh. Duration
    headman short headers.
    Why so much injector? I have a 500 hp 383 on E85 with 48 lb/hr injectors. My old 350 was making about 380 hp on E85 with 30 lb/hr injectors

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    Quote Originally Posted by Fast4.7 View Post
    Why so much injector? I have a 500 hp 383 on E85 with 48 lb/hr injectors. My old 350 was making about 380 hp on E85 with 30 lb/hr injectors
    Idk, just what I picked.

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    I have the engine running but it has no power and runs like garbage. Im sure Ive tuned something wrong but maybe you guys can take a look and let me know what you think.
    Attached Files Attached Files

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    Quote Originally Posted by lazydogtuning View Post
    I have the engine running but it has no power and runs like garbage. Im sure Ive tuned something wrong but maybe you guys can take a look and let me know what you think.
    It looks rich by the fuel trims, it has low timing advance IMO for that engine setup. Now that is not to say something else is not wrong, valve adjustment, firing order, etc.

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    Quote Originally Posted by Fast4.7 View Post
    It looks rich by the fuel trims, it has low timing advance IMO for that engine setup. Now that is not to say something else is not wrong, valve adjustment, firing order, etc.
    It was the new maf I put on. Good ole Amazon Special.. lol. I picked one up from autozone tonight and it runs much better. I put a near stock express Van tune back on it.
    Attached Files Attached Files

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    I am not saying this is safe to use in your setup, however this is what ran in my Express van when it still had a mildly cammed L31 in it with headers. This was in a heavy van, towing a 6,000 lbs trailer pretty frequently. In a light vehicle I am sure it would have liked more timing. This combination was knock limited on 91 octane.

    Chris 350 0411.hpt

    PS that engine is practically sizzling, need to see what you can do to get it cooled down. 170*F thermostat for a start.
    Last edited by Fast4.7; 1 Week Ago at 01:21 AM.

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    Quote Originally Posted by Fast4.7 View Post
    I am not saying this is safe to use in your setup, however this is what ran in my Express van when it still had a mildly cammed L31 in it with headers. This was in a heavy van, towing a 6,000 lbs trailer pretty frequently. In a light vehicle I am sure it would have liked more timing. This combination was knock limited on 91 octane.

    Chris 350 0411.hpt

    PS that engine is practically sizzling, need to see what you can do to get it cooled down. 170*F thermostat for a start.
    That tune has quite a few changes in it. I'm just learning to tune so I appreciate the help.

    Yea, the truck never ran that hot before the rebuild.
    I used the same water pump because it only had 20k on it but I'm, not sure what the issues is with it heating up.
    It didn't run that hot with a stock 350 in it but I don't see any reason for this engine to run hotter so I've got an issue somewhere.

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    Quote Originally Posted by lazydogtuning View Post
    That tune has quite a few changes in it. I'm just learning to tune so I appreciate the help.

    Yea, the truck never ran that hot before the rebuild.
    I used the same water pump because it only had 20k on it but I'm, not sure what the issues is with it heating up.
    It didn't run that hot with a stock 350 in it but I don't see any reason for this engine to run hotter so I've got an issue somewhere.
    Retarded ignition timing will generally cause them to run hot. As you increase airflow on the stock tune the timing aggressively retards.

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    Quote Originally Posted by Fast4.7 View Post
    Retarded ignition timing will generally cause them to run hot. As you increase airflow on the stock tune the timing aggressively retards.
    I checked out your tune and it didn't look like anything that would hurt to try, just to see if it started up and what the perimeters were reading and then decide if I wanted to test drive it.
    The jimmy is 4000LBs and I will be towing with it so I gave it a try.
    I'm unsure if something just decided to go bad when I parked it last night or if I messed something up.. lol, not funny tho.
    Idk, I loaded the tune the truck didn't want to start to I reloaded my tune and now it wont start at all. First V8 build and mostly the first timer tuning, what a pain. lol

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    Quote Originally Posted by lazydogtuning View Post
    I checked out your tune and it didn't look like anything that would hurt to try, just to see if it started up and what the perimeters were reading and then decide if I wanted to test drive it.
    The jimmy is 4000LBs and I will be towing with it so I gave it a try.
    I'm unsure if something just decided to go bad when I parked it last night or if I messed something up.. lol, not funny tho.
    Idk, I loaded the tune the truck didn't want to start to I reloaded my tune and now it wont start at all. First V8 build and mostly the first timer tuning, what a pain. lol
    If you loaded it straight into your truck, you surely floaded it. That setup only had ~25 lb/hr injectors.

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    Quote Originally Posted by Fast4.7 View Post
    If you loaded it straight into your truck, you surely floaded it. That setup only had ~25 lb/hr injectors.
    That all I changed was the flow rate.
    The tune attached here is what I loaded into my ecu.
    I have my lightly modified tune back in that it was running pretty good on before but it still wont start. I waited half a day and tried again, Ill try in the morning I guess. Hopefully it fires up.
    Attached Files Attached Files

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    Quote Originally Posted by lazydogtuning View Post
    That all I changed was the flow rate.
    The tune attached here is what I loaded into my ecu.
    I have my lightly modified tune back in that it was running pretty good on before but it still wont start. I waited half a day and tried again, Ill try in the morning I guess. Hopefully it fires up.
    Floor the pedal to put it in fuel cut before spinning it over, after it has spun over for ~5-10 seconds, release the pedal. If it was flooded, it should start.

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    Quote Originally Posted by Fast4.7 View Post
    Floor the pedal to put it in fuel cut before spinning it over, after it has spun over for ~5-10 seconds, release the pedal. If it was flooded, it should start.
    Already tired. I pulled the fuse for the pump and still no start. I don't have any starter fluid but breaklean should work and still no fired. I'm going to pull the injectors and test them I suppose.
    Last edited by lazydogtuning; 1 Week Ago at 01:45 PM.

  18. #18
    Ignition control module may have failed. Check for spark.

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    Quote Originally Posted by crankz1 View Post
    Ignition control module may have failed. Check for spark.
    Has spark. Shocking, trust me.. lol
    Really tho, it has spark at the coil and at the wire ends I checked.
    I have a pressure gauge on the fuel rail and it shows good fuel pressure.
    Timing was good so I don't see that being the issue.

    I pulled the plugs and they seemed pretty wet even tho I had the fuel pump relay out for a bit trying to start it.
    I'll be running test on all the sensors if needed. I think only the cam or crank sensor would cause this type of no starting issue if I have spark and fuel.
    I did flash the ECU once during this process with the battery charger on it so maybe I screwed up there but that was after it wouldn't start and the battery died.

  20. #20
    I think flashing with the charger is ok and even recommended. Flashing with a low battery is what can get you in trouble.