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.

unless your going with boost, there is absolutely zero need for anything other that a 1 bar map

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Originally Posted by mbray01

unless your going with boost, there is absolutely zero need for anything other that a 1 bar map

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Sweet, Thank you for clarifying. No boost but possibly a small nitrous shot in the future.

The Express van tune files seem to be most accessible. And work great.

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Originally Posted by lazydogtuning

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.

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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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Originally Posted by Fast4.7

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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Idk, just what I picked.

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.

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Originally Posted by lazydogtuning

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.

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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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Originally Posted by Fast4.7

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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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.

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.

Attachment 124528

PS that engine is practically sizzling, need to see what you can do to get it cooled down. 170*F thermostat for a start.

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Originally Posted by Fast4.7

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.

Attachment 124528

PS that engine is practically sizzling, need to see what you can do to get it cooled down. 170*F thermostat for a start.

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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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Originally Posted by lazydogtuning

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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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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Originally Posted by Fast4.7

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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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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Originally Posted by lazydogtuning

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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If you loaded it straight into your truck, you surely floaded it. That setup only had ~25 lb/hr injectors.

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Originally Posted by Fast4.7

If you loaded it straight into your truck, you surely floaded it. That setup only had ~25 lb/hr injectors.

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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.

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Originally Posted by lazydogtuning

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.

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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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Originally Posted by Fast4.7

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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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.

Ignition control module may have failed. Check for spark.

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Originally Posted by crankz1

Ignition control module may have failed. Check for spark.

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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.

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