Idle dip

[TStafford]

This is one of the reasons I got the OFT and run that. The problem you describe is not present after the Stage 1 flash. Also I got a little boost over all in the way the car revs. Best $$$ I spent so far

[Fizz]

Originally Posted by steve99

As per my previous relpy in this thread.

What Calibration ROM are you running in the ECU, their was a series of "fixs" for this from toyota/subaru

ZA1J700C was original then ZA1J900C then A00C , A01C B00C and B01C now we have ZA1JD00C or D for autos. If your not on the latest calibration ID get dealer to update their are TSB out to get updated to at least ZA1JB01C or D.

unless your turbo or substantial mods just take it to dealer and complain is under warantee, it may have other issues like cam actuator, vacuum leak maf sensor issues o2 sensor issues or problems.

If you want to do it yourself buy a Tacrix for $170 and read the Tacrix/Ecuflash thread link below, or take it to dealer and get them to do it.

Steve do you know what was the actual fix in the latter cal ID's? Was it simply raising the idle speed?

My having this issue, and I thought I'd just get my tuner to raise the idle a little, but if it's more than just raising the idle I'd like to know how best to advice my tuner where to look within the tune in order to resolve this.

[steve99]

Originally Posted by Fizz

Steve do you know what was the actual fix in the latter cal ID's? Was it simply raising the idle speed?

My having this issue, and I thought I'd just get my tuner to raise the idle a little, but if it's more than just raising the idle I'd like to know how best to advice my tuner where to look within the tune in order to resolve this.

the idle speed was not changed in the stock rom calid updates, bumping the idle speed is something most tuners do to get arround the problem, but probably costs fuel efficiency and emmisions.
The calid updates have changed idle control logic possibly related to a\c switching and other things either in the rom code or in undefined tables.

Hopefully you tunes is based on latest calid for your car A02G for man A01I for auto unless your late 2014 build.

basing the tune on latest calid is only way to get those updates as no one not even ecutek delves that deep into the rom code.

[Toyota John]

If anyone has idle dip, update to B01C or newer ROM for Manual shift and B01D or newer ROM for Auto(US spec). Also the idle is way to low for my taste. I have heard people complain about rattles at idle. Have your tuner or use your editing software to raise idle to 750rpm on all the lower limits. I have not had a single problem of idle dip since.

[Fizz]

Originally Posted by steve99

the idle speed was not changed in the stock rom calid updates, bumping the idle speed is something most tuners do to get arround the problem, but probably costs fuel efficiency and emmisions.
The calid updates have changed idle control logic possibly related to a\c switching and other things either in the rom code or in undefined tables.

Hopefully you tunes is based on latest calid for your car A02G for man A01I for auto unless your late 2014 build.

basing the tune on latest calid is only way to get those updates as no one not even ecutek delves that deep into the rom code.

My tune is based on the A00G so doesn't look like it had the idle fix. Also not sure if it's got the DI seal fix either.

[ztan]

I never had this problem on stock injectors, have had some idle dip and stumble with higher flow injectors whilst tuning.

<I think> my problem has been that there has been insufficient fuel from the port injectors operating in a non-linear range and the engine going lean.

Before I got my injector scaling and minimum PI IPW right, I would get PI IPW times that were under the linear range with latency added - the revs would dip on switchover to PI and then STFT would shoot up a couple of log lines later, sometimes 20-30%.

Now I've got some minor driveability problems at low load - minor hesitation at low throttle. Logs show this most often happens when I go from DI to split DI:PI operation and my PI IPWs again put the injectors under the linear range - there is a switch in fuelling and by STFT jumps by 15-20% after the hesitation. I'm going to try playing with DI:PI ratios to have full DI operation with lower load and kick in PI later when the IPW will be more linear.

Unfortunately, however, I don't think we have full control of DI:PI ratio stuff in the idle situation yet.

[ztan]

Can anyone with the idle dip problem set all 3 PI/DI ratio tables to have full DI up to 0.3 g/rev load (see figure)? My theory is that it may eliminate DI/PI switchover at low IPW where the port injectors get activated in the non-linear range and send the engine transiently lean - especially if the PI scaling is unbalanced to the lean side.

As per last post, I have had a bit of hesitation at low loads (2000-3500 rpm at part throttle, 0.2-0.3 g/rev load) with bigger injectors and doing this has solved the problem for me.

[yomny]

Didn't really read all the replies post my last one but I had two tuners while being NA that we're able to eliminate not sure what they did but it was fixed.. one of the tunes reaised the idle a tad and when the dip occured, nothing was felt. The other tune left the idle alone and the dip still didn't occur. The dealer wont fix crap in my opinion unless they've actually come up with a flash that addresses this.

[Toyota John]

Originally Posted by ztan

Can anyone with the idle dip problem set all 3 PI/DI ratio tables to have full DI up to 0.3 g/rev load (see figure)? My theory is that it may eliminate DI/PI switchover at low IPW where the port injectors get activated in the non-linear range and send the engine transiently lean - especially if the PI scaling is unbalanced to the lean side.

As per last post, I have had a bit of hesitation at low loads (2000-3500 rpm at part throttle, 0.2-0.3 g/rev load) with bigger injectors and doing this has solved the problem for me.

I checked my DI to PI ratio and the PI scaling is off on the stock tune. I haven't had a chance to fix it yet after Snowmageddon hit the north east. My car is stuck behind my house.

[Fizz]

Originally Posted by ztan

Can anyone with the idle dip problem set all 3 PI/DI ratio tables to have full DI up to 0.3 g/rev load (see figure)? My theory is that it may eliminate DI/PI switchover at low IPW where the port injectors get activated in the non-linear range and send the engine transiently lean - especially if the PI scaling is unbalanced to the lean side.

As per last post, I have had a bit of hesitation at low loads (2000-3500 rpm at part throttle, 0.2-0.3 g/rev load) with bigger injectors and doing this has solved the problem for me.

Im getting mild hesitation on light loads around 3k rpm. Do you foresee any issues if this is done with stock injectors?

[ztan]

Originally Posted by Fizz

Im getting mild hesitation on light loads around 3k rpm. Do you foresee any issues if this is done with stock injectors?

No mate, though the non-linear time in the stock injectors is less than my DWs - you may only need to zero PI/DI ratio up to 0.2 or 0.25 g/rev I reckon the running transiently lean with hesitation at PI/DI switchover is probably worse for the engine and drivetrain than having full DI operation running smoothly at low load.

Try it and see, let us know if it helps or not.

[Fizz]

Originally Posted by ztan

No mate, though the non-linear time in the stock injectors is less than my DWs - you may only need to zero PI/DI ratio up to 0.2 or 0.25 g/rev I reckon the running transiently lean with hesitation at PI/DI switchover is probably worse for the engine and drivetrain than having full DI operation running smoothly at low load.

Try it and see, let us know if it helps or not.

So i did what you suggested, zero'd everything in 0.20 and immediately noticed an improvement in the low speed/low revs driving. The hesitation is almost gone! Very slight hint of it still but hardly noticeable now.

[ztan]

Originally Posted by Fizz

So i did what you suggested, zero'd everything in 0.20 and immediately noticed an improvement in the low speed/low revs driving. The hesitation is almost gone! Very slight hint of it still but hardly noticeable now.

Nice. Glad to be of practial help.

I've zeroed up to 0.3 g/rev for larger DW450 injectors with more non-linear time as well as increasing the ratio when they kick in to make a smooth transition.

[frsdiy]

Ok, I had this exact same issue. Idles at 600 rpm and with the AC on it dips when coming to a stop (in neutral gear) to slightly less than 500 rpm. I sprayed some "garage door lubricant" on all the pulleys including the crank, the ac compressor, etc. Now the car idles smoother and the RPM does dip with the AC on but not enough to induce the stuttering before I sprayed the pullyes around the belt. I hope this helps someone. Please let us know.