1ZZ Injectors on NA Setup

[MGargano]

I'm kicking around the idea of upgrading to 1ZZ injectors, but I'm wondering if the hassle of disassembling the top of the engine to do to the swap outweighs any potential benefits I might see.

I have a basic NA setup, with a few bolt-ons: AFE intake, NST pulleys, 1ZZ TB with spacer, Megan header & axle-back with custom mid-pipe.

I have no plans to do a turbo, s/c, or nitrous, so I'm looking for input as to whether I should bother with larger injectors at all.

If I do decide to do the swap, do I need new coils and rail? Or just the injectors?

Is there any way to do the swap without removing the valve cover and exposing the cams, etc? It just seems like I'm opening a door to potential problems by digging that far into the block.

Any advice would be appreciated.

[lilredrocket]

You don't have to remove the valve cover to do the swap.

[MGargano]

You don't have to remove the valve cover to do the swap.

That's good to hear. I was looking at the repair manual .pdf posted in the DIY forum, and that seemed to be the "official" method, but I'd love to avoid doing all that, if possible.

[lilredrocket]

There are 2 bolts holding down the fuel rail take those out and pull up. You wont have as much room to work with but you can still get the job done.

[MGargano]

There are 2 bolts holding down the fuel rail take those out and pull up. You wont have as much room to work with but you can still get the job done.

Excellent- that's definitely good news. Any idea if I'd see any gains by doing the swap?

[lilredrocket]

Not sure. I know Mikenacarato had to use 1zz injectors when he had his 1zz TB and spacer installed he kept throwing lean codes... not sure if he gained anything from them other than fixing his lean problem

[MGargano]

The first time I tried the 1ZZ swap, I got P0505- Idle Malfunction. I never saw any CEL's for lean condition, but it oscillates and jerked like crazy.

I'm planning to swap to the 1ZZ TB again tomorrow, hopefully with better results.

[lilredrocket]

Good luck. He didn't get the lean code with just the TB he got it when he installed the spacer.

[MGargano]

Good luck. He didn't get the lean code with just the TB he got it when he installed the spacer.

Good to know. Maybe I'll need the injectors after all. :laugh:

[cali yaris]

Won't the ECU just change the injector duty cycle to keep the AFR exactly the same as stock? The TB I understand, this mod seems like it wouldn't make power to me.

[MGargano]

Won't the ECU just change the injector duty cycle to keep the AFR exactly the same as stock? The TB I understand, this mod seems like it wouldn't make power to me.

That's what I think, too. I'm hoping to find out for sure from someone who's done it before I waste my money and time.

[lilredrocket]

Well the 1zz TB is a half inch bigger than the 1nz one so it can let more air pass through it when opened the same ammount. If you can get more air comming across your MAF sensor it will tell you ECU to dump more fuel into each cyl. the more air/fuel mix you can get into your cyl the better to a certian point. If you can add more air/fuel mix at the same ratio (stoich) as stock (on a stock motor ie. no FI) the longer the mix will burn pushing your pistons further and with more force on the power stroke. When adding more air/fuel than your motor can burn on the power stroke (running rich) your wasting fuel and ruining your CAT and O2 sensors. When your motor is getting more air as above your ECU will try and richen up the air/fuel mix to try and keep the mix stoich if your injectors cannot put out enough fuel you start running lean making it hotter in your cyl. (and running into the chance of melting things) the ECU overrides your pedal signal and starts closing your butterfly returning the mix back to stoich making you lose potental power.

Did I confuss you yet.

So by putting the larger TB on and getting more air into the motor adding the extra length of the spacer making the intake "hold" a larger volume of air starts letting to much air into the cyl. and the stock 1nz inj. cannot put all the fuel the ECU is telling them to put in the cyl. you start runing lean. So by adding the larger 1zz inj. being able to add the extra fuel bring the mix back to (happy) stoich.

[MGargano]

Did I confuss you yet.

Yes indeed.

Basically you're saying you recommend adding the 1ZZ injectors to eliminate any possible lean conditions and to maximize overall air/fuel mixture with the 1ZZ TB, right?

[lilredrocket]

You can add just the TB and get away with it. I would try the TB and spacer and see if your get lean codes if you do then I would suggest the larger inj. you don't want to be running rich and ruin a CAT they can get expensive people hate when they come to my shop and I tell them the price to replace a cat.

[MGargano]

Ok sounds good. Thanks for the advice, I'll give it a try.