Can you run 440cc injectors with stock 1g M/T FPR, ECU, ETC?

hamiltonben32 · Aug 8, 2021

Hello, I'm swapping a 4g63 into my mighty max and if I could avoid having to wire in and purchasing the resistor pack that would be awesome (used 450cc injectors are also kinda pricey). That being said is it possible to run 440cc high impedance injectors instead of the stock 450cc injectors? I'm just going to be running the engine and 14b as stock as possible. It is only a 2.2% difference in cc's so I would assume that the maf could make up for that? However I would still like to know for sure before I go about assuming... Thanks for any/all responses

Bud92gsx · Aug 9, 2021

Years ago people would run evo injectors with a 2g maf and have no issues cause the maf would make up for it.
At 38 lbs fuel pressure, you shouldn't run into issues with the manual ecu.
Us auto guys used to run 450s with a manual ecu with no issues either, it was recommended to use a 2g maf tho. I did that myself for a year before a 2g maf with no tune.

pauleyman · Aug 9, 2021

The maf doesn't make up for it, the ecu does. You have a range of fuel trim within the ecu to try and reach stoic. If you use a stock maf, stock ecu and the injectors are only 2% off then yes it should be fine. No different then when injectors get a little worn or clogged over time.

NOSLO2PT0 · Aug 9, 2021

Since when are used stock 450’s expensive? Did they go up in value recently? Last I knew, people could barely give ‘em away for $50 (except to the Honda crowd!)

You don’t have to pay anything for the resistor delete plug to run hi-z injectors if you have a stock 4g63 harness.

Bud92gsx · Aug 10, 2021

pauleyman said:
The maf doesn't make up for it, the ecu does. You have a range of fuel trim within the ecu to try and reach stoic. If you use a stock maf, stock ecu and the injectors are only 2% off then yes it should be fine. No different then when injectors get a little worn or clogged over time.

So why was it a thing? I mean this was back when people used safc's. Id like to know why this was the go to mod back then, if u wouldn't mind please?

pauleyman · Aug 10, 2021

Bud92gsx said:
So why was it a thing? I mean this was back when people used safc's. Id like to know why this was the go to mod back then, if u wouldn't mind please?

Maf is just a sensor. It provides info to ecu. When you used a 2g maf you essentially lied to ecu. Couple that with 550 injectors and it sort of balances out. Ecu never knows what fuel is actually flowing. This is the same reason you can't just slap larger injectors in a car. Ecu adjusts fuel based on o2 sensor feedback. If you ever put 550s on a stock ecu you would quickly see fuel trims being pulled to the max trying to take fuel out and then a check engine light and a lot of black smoke

1990TSIAWDTALON · Aug 10, 2021

I did that exact thing on my 1st DSM for a while. 550s, 2g MAF, Walbro 255

Bud92gsx · Aug 11, 2021

pauleyman said:
Maf is just a sensor. It provides info to ecu. When you used a 2g maf you essentially lied to ecu. Couple that with 550 injectors and it sort of balances out. Ecu never knows what fuel is actually flowing. This is the same reason you can't just slap larger injectors in a car. Ecu adjusts fuel based on o2 sensor feedback. If you ever put 550s on a stock ecu you would quickly see fuel trims being pulled to the max trying to take fuel out and then a check engine light and a lot of black smoke

I appreciate u dumbing it down for me. I may know bolt on stuff fairly well. But it's always nice to learn why, so thank you.
I still think my yes, you'll be fine answer is sufficient, but I do appreciate learning sumthing as well.

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Can you run 440cc injectors with stock 1g M/T FPR, ECU, ETC?

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