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Guest autoxer

Fuel Injectors

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Guest autoxer

Hi all,

 

I'm a new owner of a 1990 toyota corolla dx. I was just wondering what cc the fuel injectors are?

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trap

From what I can remember, stock 4AFE injectors are 170-180cc. The ones in the 4AGE are larger, something like 220cc. Depending on your application, bumping up to larger injectors does NOT equal more power - if anything, the car will run worse because the ECM doesn't know what to do with the larger injectors - your existing air/fuel maps are all off.

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Guest autoxer

thank you.....I was just wondering cuz I am looking at autocrossing with the car (hence the username). So putting bigger injectors will not give more performance?

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Correct, in almost all cases, larger injectors will not see any increase performance. Curious - do you think you are having a fuel/injector issue when running on auto-x? Car seems to be losing power in sharp transitions?

 

If you were planning on adding a piggyback ECM or go with a full stand alone engine management system, then I could see you tuning the engine to use more fuel. or if you were planning on a forced induction project, where you have more air - then it makes sense to add larger injectors to support that.

 

To find out where you stand, fuel wise, be a good idea to see what the duty cycles are like with the current injectors. My suspicion is that the injectors are plenty big enough, but you could be having issues with supply, ie. the fuel pump and pressure regulator could be starving the injectors for fuel. Definitely check on the fuel filter before you start swapping anything else in there.

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There are a few autoXers on the forum, myself included. Is this for SCCA SOLO rules? What class are you looking to build it for?

 

Is this for the stock ECU, or are you changing something with engine management?

 

Typically, you do not need larger injectors unless you're converting to forced induction or changing the internals enough to significantly increase power (cams, head/valving, etc). If the car is running fine-- don't change the injector sizes. It won't add power, and will do nothing more than confuse the ECU.

 

Most stock pumps/injectors have enough 'overhead' to provide a little bit of extra fuel for cars with less restrictive intakes and exhaust. Is it running lean when wide open at high RPM? If so, it could have a weak pump or clogged injectors.

 

If the pump and injectors are OK and you're still *juuust barely* running out of fuel at the top end, you might be able to go to *slightly* larger injectors and let the ECU re-learn the fuel trims.

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