Fuel injectors

[austinasto]

okay im new to the game when it comes to adding power the right way. I have a 07 scion tc and when i accelerate from first gear to second gear and so on my car doesnt seem to keep its momentum going. like, it slows down in btween gears as if i was shifting from first to third. and thats only when racing. so far i have sri, headers, and exhaust. should i get bigger injectors to fix this problem?

[CadenceScion]

I wouldn't get bigger injectors untill you upgrade to a turbo or supercharger. Have you tried doing a fuel injection cleaner (Lucas, STP, Cheveron w/ Techron)? I would also check and make sure your fuel pump and fuel filter is still good and maintaining the proper fuel pressure. If your looking to pick a few more ponies, I would do the following upgrades:

* Fidanza Light Weight Flywheel
* Agency or NST Lite Weight Crank Pulley
* Exedy, ACT, Cluchmasters
* Energy Suspension Engine/Tranny Bushings

What octane are you using?
Have you had your fluids checked/replaced or flushed?

[navylife59]

Do you have an automatic or manual transmission? The auto has it's own ECU that opens up a few possibilities. How many miles on the odometer? What aftermarket parts do you have, ie intake and exhaust?

My RS3.0 with a 5-speed has a bogging down issue that I believe is similar to yours. It will start out strong but the power curve seems to bog down in the upper RPM band. Could be fuel related (weak fuel pump, dirty injectors, clogged filter), vacuum leak, air filter, dirty MAF sensor, clogged (reduced flow) catalytic converter, VVT-i related (bad VVT-i tables, clogged VVT-i solenoid, or low oil press), poorly designed aftermarket intake, or even the A/C clutch not disengaging on acceleration.

I would do the following trouble shooting steps. Do them in order, one step at a time, to determine the problem.
1. Do a full ECM reset. http://www.club-tc.com/forums/engine...ables-ecm.html
2. Check vacuum leaks. Do you have a higher than normal idle speed w/o anything turned on?
3. Check intake air filter - clean or replace as necessary.
Note: Step 4 can be done with Step 3.
4. Clean MAF Sensor with CRC MAF Sensor Cleaner.
5. Lucas Oil Deep Clean Fuel System Cleaner treatment.
6. Inspect fuel strainer (in-tank filter). Clean or replace as necessary. http://www.club-tc.com/forums/genera...l-install.html
Note: Step 7 and Step 8 can be accomplished during Step 6 if so desired to save labor.
7. If fuel pump is suspect, have it professionally tested.
8. If fuel strainer was clogged or gummed up, fuel injectors may need to be professionally cleaned.

Troubleshooting further would require a competent, full diagnostic repair shop or dealership. Things to look at would be operation of the OCV for VVT-i, fuel trims, ignition timing, DBW throttle, and automatic engagement (if applicable).