DIY - 1.8L 1ZZ-FE TB Connector Chip Swap

[jkuchta]

Have you adjusted the idle screw? If you've turned the screw out too far you could get this code...try turning the screw in one or two turns (with the car off). This should fix the problem.

If you haven't adjusted the idle set screw, turn it counter-clockwise 1.5 turns (with the engine off), and see what happens.

[MGargano]

Originally Posted by jkuchta

Have you adjusted the idle screw? If you've turned the screw out too far you could get this code...try turning the screw in one or two turns (with the car off). This should fix the problem.

If you haven't adjusted the idle set screw, turn it counter-clockwise 1.5 turns (with the engine off), and see what happens.

I haven't touched the idle screw at all. The thing was working perfectly for over a month, right up until I disconnected the battery. I'm not going through this every time I disconnect the battery... plus, even when it's working perfectly, the high idle is now quite loud with the exhaust I have. I'm 99% I'm switching back to the stocker today.

[jkuchta]

Originally Posted by MGargano

I haven't touched the idle screw at all. The thing was working perfectly for over a month, right up until I disconnected the battery. I'm not going through this every time I disconnect the battery... plus, even when it's working perfectly, the high idle is now quite loud with the exhaust I have. I'm 99% I'm switching back to the stocker today.

If you turn the idle set screw out about a turn and a half, all of your problems will go away.

When you leave the screw is the "corolla" position, the yaris ECU adjusts the idle fuel to get a stable idle. This takes time, as the ECU needs to make some pretty big changes. When you adjust the idle set screw to the correct position, the ECU doesn't have to work nearly as hard to get a normal idle, so the ECU doesn't freak out.

The idle rpm fluctuations are a result of the ECU hunting for the right fueling to maintain a steady 600-700 rpm idle in the face of way too much air going through an unadjusted corolla TB.

The P0505 code is the ECU saying..."WTF!!...Why can't I idle at the fuel trims I'm programmed with...something must be wrong!!"

[MGargano]

Originally Posted by jkuchta

If you turn the idle set screw out about a turn and a half, all of your problems will go away.

So I should turn it all the way in, then back out 1.5 turns? If not, what's the 'correct' procedure for adjusting the idle screw?

[tk-421]

Originally Posted by MGargano

So I should turn it all the way in, then back out 1.5 turns? If not, what's the 'correct' procedure for adjusting the idle screw?

1. Turn engine off
2. Adjust the screw to your liking
3. Turn engine on and test for oscillation and high idle
4. If you need to modify the value, go to step 1
5. If you're satisfied with the setting, throw some epoxy in there and let dry (optional, but recommended)

FYI, I've read that it's better not to try adjusting the screw with the engine on, or else the ECU might need to be rebooted one last time to reset the values.

I had no idea which direction to turn to or anything like that... All I did was turn clockwise until I found the best setting after the second try. I guess I got lucky, because the damn screw got stripped at a very decent setting, so I didn't need to do any tweaking afterwards.

I also let the gasket maker do its thing for at least 4 hours IIRC, with the battery disconnected the whole time. I also did the coolant bypass, but didn't need to burp it afterwards.

No big oscillations, no CELs, and a pretty decent 2.5K idle... could've been a bit better, but I'm not complaining.

[Yoda]

I am gonna watch it over the week or so. My cold idle is 1.5k. and i didnt touch the screw. If it comes back the i will look into it but for right now its running great. I had to install the orignal TB back on to get the drill to drill out the rivets and forgot to reset the ecu when i replaced it with the 1zz. Then i drove it a bit not too hard. Then turned it off for 5 min or so. when i started it up again oscillation gone. Drove it again. Turned it off. Started up cel gone
Think my ECU went to college

[Yoda]

Originally Posted by tk-421

1. Turn engine off
2. Adjust the screw to your liking
3. Turn engine on and test for oscillation and high idle
4. If you need to modify the value, go to step 1
5. If you're satisfied with the setting, throw some epoxy in there and let dry (optional, but recommended)

FYI, I've read that it's better not to try adjusting the screw with the engine on, or else the ECU might need to be rebooted one last time to reset the values.

I had no idea which direction to turn to or anything like that... All I did was turn clockwise until I found the best setting after the second try. I guess I got lucky, because the damn screw got stripped at a very decent setting, so I didn't need to do any tweaking afterwards.

I also let the gasket maker do its thing for at least 4 hours IIRC, with the battery disconnected the whole time. I also did the coolant bypass, but didn't need to burp it afterwards.

No big oscillations, no CELs, and a pretty decent 2.5K idle... could've been a bit better, but I'm not complaining.

I thought you were suppose to do it while the engine is on. Look at it like a clock and turn buy 2 each time as you find the sweet spot(form 12 oclock to 2 or from 12 to 10 and so on) At each turn let the engine settle at the new position for 3 min if not the right idle turn it again. Not sure if its the same for our car tho.

[jkuchta]

Originally Posted by MGargano

So I should turn it all the way in, then back out 1.5 turns? If not, what's the 'correct' procedure for adjusting the idle screw?

No...turn it 1.5 turns counter-clockwise from the stock Corolla position (where it is when you first get the epoxy off).

[MGargano]

Originally Posted by jkuchta

No...turn it 1.5 turns counter-clockwise from the stock Corolla position (where it is when you first get the epoxy off).

I got the epoxy off, but stripped the head of the screw trying to turn it. No matter which allen I tried, none seemed to fit correctly and I ended up rounding the edges of the hex off. Ideas for removal/replacement?