Idle issue?

[post_break]

Here's my idle issue. Stock intake.

[ame="https://www.youtube.com/watch?v=XXuxOnrQDrQ"]FRS Idle dip when the gas pedal is pressed - YouTube[/ame]

[BRZnut]

These engines do idle poorly when cold, but have never seen that in my BRZ. But I usually just start and drive, even when below freezing.

What happens if you just drive it? Is the idle steading when moving at constant speed??

[Marrk]

[QUOTE=post_break;735670]Here's my idle issue. Stock intake.


Does this happen when he engine is at normal operating temperature — say, after a five mile drive?

[OrbitalEllipses]

That is weird. I just have a small stumble when I idle at a light occasionally, though it has been happening more often with the cold weather.

Perhaps you have DBW/TPS discontinuity of some kind?

[Fenrir]

One thing I'm noticing is that after it dips, it settles back in at a lower RPM than the initial spike. Haven't really seen that on other cars. How long has it been doing that? Might just be some bad gas the car is having trouble balancing?

[post_break]

Originally Posted by BRZnut

These engines do idle poorly when cold, but have never seen that in my BRZ. But I usually just start and drive, even when below freezing.

What happens if you just drive it? Is the idle steading when moving at constant speed??

[quote=Marrk;735991]

Originally Posted by post_break

Here's my idle issue. Stock intake.


Does this happen when he engine is at normal operating temperature — say, after a five mile drive?

Originally Posted by OrbitalEllipses

That is weird. I just have a small stumble when I idle at a light occasionally, though it has been happening more often with the cold weather.

Perhaps you have DBW/TPS discontinuity of some kind?

Originally Posted by Fenrir

One thing I'm noticing is that after it dips, it settles back in at a lower RPM than the initial spike. Haven't really seen that on other cars. How long has it been doing that? Might just be some bad gas the car is having trouble balancing?

To answer all of your questions at once. My car has always seemed to do this, but I've finally narrowed it down. I always seemed to get very close to stalling when backing up or leaving in the morning and this is why.

The car revs to what it should, then dips by as much as 700rpm and then goes up to a lower rev limit.

It doesn't do this when it's warmed up.

It does this even when the cam angles are at negative values.

It's done this since day one it seems so it can't be the gas.

[Marrk]

Originally Posted by post_break

It doesn't do this when it's warmed up.

Putting aside for the moment the fact that the engine and engine management system on these cars maybe be crap, is it possible that you are dealing with a situation that only happens when the car is in "Choke" mode? In other words, because the car is not yet up to running temperature, the ecu is mixing the air/fuel to accommodate a cold engine. When you step on the gas, you mess with this (because the "Choke" setting works best in neutral at idle) and when the car is fully warmed and out of "Choke" mode, the problem goes away.

Obviously, I'm guessing here, but I have experienced a very mild version of what you have, and I have experienced it on many fuel injected cars with ecu. The FT-86 needs better sensors, a better feedback loop, and better fuel mapping. Not your problem. Toyota's problem.


P.S. Concerning Choke mode, there may be some alternate timing changes going on, too. I'm not am expert. Others here may know.

[strat61caster]

Mine will do it occasionally, bouncing between 500-800 rpms and it is disconcerting.

It ONLY happens when the defroster is on, A/C seems to be consistent, it doesn't hunt unless I've got the defroster on.

Could just turn off the defroster when sitting at lights, turn it back on when on the move
At least that's my current solution given that it only drops below 30 degrees a couple weeks a year where I live.

[Sigh-on-Rice]

Originally Posted by post_break

Here's my idle issue. Stock intake.

I tried this and my car does this too. It does it even when the engined is fully warmed up (after 1/2 hour drive). I've never done this on any other car, so I don't know if this is normal or not, but it doesn't bother or worry me.

[Skurj]

My Yaris has done this since day one.. an 09

It does it with AC on or when the fan is directed at windshield and not set to recirc (that also triggers the AC compressor).

AC compressor kicking in does it.

[quasi86]

I really just think we all have a car with a engine that isn't happy until it's screaming at 5300 rpm and higher. I think any time you have a high revving, high output motor like this it's going to idle a little rough. The high compression prolly plays a role too

Sent from my EVO using Tapatalk 2

[BRZnut]

Originally Posted by quasi86

I really just think we all have a car with a engine that isn't happy until it's screaming at 5300 rpm and higher. I think any time you have a high revving, high output motor like this it's going to idle a little rough. The high compression prolly plays a role too

Sent from my EVO using Tapatalk 2

I wonder if you are on to something....its almost like when you see a race car at idle in NASCAR...its very rough. Seems like the BRZ/FRS is designed to just run and not sit still!

[Marrk]

^^Not sure I agree.

How about EPA and emissions-limiting design as the cause for idle problems? Sports cars today have to perform like sports cars but pollute like sub-compacts. A difficult marriage of outcomes. The only reason we have DI on cars (as far as I can gather) is because of its potential to achieve greater fuel efficiency.

[TPTBOY]

I had the idle fluctuation today....car almost stalled. I don't believe I have had the ECU reflash. Should I do that or call to report the issue?