Idle dip
 

Disclaimer- Please keep it civil, yes i did search and please don't interrupt/thread drift, don't try to solve the world with one phrase.. this solely for those with tuning experience that have actively engaged in trying to solve this idle dip condition. If you're going to clutter or cause distress, leave. Sorry if i may seen like an a#$, i'm not but I'm tired of people hijacking threads with useless junk. We're here to learn and discuss what we each think could help the community.

Has anyone(tuner)logged to see why and what happens when the cars rpm stumble causing a near stall situation before bouncing back up. In my situation my car's idle doesn't fluctuate when the AC is off. They settle at 600 or so when fully stopped, or coming to a stop. When the AC is on, at times, coming to a stop the RPMs will drop just under 600 and the car wants to stall for a sec before correcting itself. I thought before it was always like this and by raising the idle speed like most tuners do, this will be fixed. I see now the car could idle that low without issues unless the AC is on. I was wondering if anyone has logged this event and seen anything unusually causing this. I recall a similar situation in my S2000 after installing an AEM standalone, this was fixed by a tuner "Lance" and i recall him mentioning something about adjusting timing when the AC was on at idle.

I don't have access to a logger my self at the moment, just want to bring this up since i will be digging into the matter as soon as i get my ecutek prokit. If someone does have this condition and the ability to log it, please post it. Thanks :burnrubber:

mine does the exact same thing when the AC is on, while running on E85

It's gotta be something in the software. I already went to the dealer for the service bulletin and they were able to replicate it. They said the updated the software but the car runs exactly the same.

You can try tweaking the idle stability tables (3D table RPM delta vs. Idle target error).

Idle dip
 

Aggh lol that's talking Chinese to me, I really haven't had the chance to log anything or even use the ecutek software but I'll be sure to keep this in mind once I do. As of now im just trying to apply a bit of logic and reasoning to pin some ideas for when I could tweak the settings my self. It seems that the idle speed is low and once it reaches the 600rpm idle and the AC compressor kicks in, for a second the rpms drop too low and cause the near-stall scene before the car compensates. Could be harder that I could imagine to sort out but seems at the moment with the right knowledge about ecutek or any other software, this could be fixed. Thanks for your input guys.

What modifications have you done?

I'm guessing your car is stock ?

You are running stock ROM flashed by dealer.

Your in Miami USA so your probably running a C series ROM

so is it 700C , A00C , A01C, B00C or B01C might be worth asking the dealer what version they flashed if you don't know. They had a couple of goes at fixing idle problems latest ROM revision is apparently B01C

Yeah my car is stock. I had such a bad experience with the dealer that I doubt asking them would help me. Which ever they flashed my car with, it didn't work. I didn't even bother taking it back. I'm planning on tuning soon so maybe that'll take care of it. I like tuning and such so usually with a problem like this I like to try and figure it out. Thanks for your input.

I believe they're supposed to write the version of the ECU they update you to on the bottom of the hood. Check there?

Yeah first thing I checked for since I read the TSB and it specified to do so. Since it's not there makes me wonder if they did anything at all. Dealers dealers, this was on a car with 500 miles and no modifications and even so they don't want to perform their duties. I wish I worked at a service dept for a week to have a clue why they give such a hard time to perform work the factory pays them for.

Sorry to bring this one back from the dead, but any resolution? My idle dips have gotten worse recently, to the point where the car is stalling trying to start in 1st

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.

I have the same issue. While in park with the air on it will idle at 650 RPM, then slowly drop to below 500 RPM. It eventually "stumbles", which seems to get somethings attention and it then quickly goes to 950 RPM. It then settles back down to 650 for a minute and the cycle starts over again.

It does not seem to be coordinated with the air conditioning compressor cycling on and off in any way.

It is a 2015 FRS automatic with 1250 miles on it.

Modifications include dealer installed TRD springs, sway bars and brake pads plus an owner installed master cylinder brace. I am assuming none of those have any affect on engines ability to idle :D

I picked the car up on August 18th, 2014. I am assuming ... possibly incorrectly ... that I have the latest and greatest updates in the ECU. Regretfully I do not know how to determine the ECU ROM version, but if someone has a link I'd be glad to follow it.

Is the TSB number or identifier available that I can reference when I talk to my dealer?

Thanks,
Arvid

excellent advice - thank you. I don't have any mods aside from a K&N drop-in, so I'm fairly peeved about this. I am guessing I'm on the latest calibration, as they've re-flashed it twice already trying to fix it. Cheers!

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 :)

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.

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.

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.

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.

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.

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.

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.

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.

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. :thumbup:

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.

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.

@ztan My idle is around 0.28 and up to 0.33 when AC is on. Would I need to zero 0.3 column in addition to 0.2?

@ztan @Wayno I zero'd the 0.3 column as well recently and it seems better than previously when it was only zero'd till 0.2

On a sidenote, do you think there's any inherent danger in zero-ing further up? Say to 0.4 and then push the current 0.4 to 0.6 tables one step higher on the g/rev axis?

http://s1.postimg.org/bx37ojyzj/PI_DI_idle.jpg

Probably not - a lot of engines running 100% DI, and stock tune uses 100% DI higher in the rev range under full load. Only would expect it to be a problem when the DI injectors run out of headroom high in the rev range or under FI loads.

If you're getting dip at 0.33 load with AC, I'd try zeroing up above that (or change the scaling axes so 0.2 reads 0.35 or so). If you're not getting a big dip, don't worry about it.

As an aside, I just put on a 3" overpipe back x-force exhaust and my idle has been smoother again (as well as a bit louder).

I'm still trying to get rid of the minor stutter/hesitation when moving off in 1st and 2nd gear under light throttle and low load. Zeroing up to 0.3 has helped abit, but I noticed the problem happens up to 0.6 as well....so i'm thinking of zeroing up to 0.4 or even 0.5 to see if it makes any more difference. Running sprintex kit, stock injectors.

The current FI tune has some PI from 0.9 onwards from 3200rpm and above.

Have you been logging your PI duty? I suspect hesitation due to PI ratios would only be a problem if you are running a PI value under 0.6ms in the non-linear injector range.

Excluding manifold leaks, I'd wonder if playing with your EL comp table will help - the intake flow changes with a blower and intercooler will likely affect VE quite unpredictably (your MAF sits before both and may not be fully compensating for them).

It's likely to be actual fueling error that's causing it. EL Comp is worth a look. If you run 100% DI and then 100% PI in those regions and see whether you can get a indication of the change in error. It may be that those need some tweaking in the low RPM ranges. You could always increase your PI latency if you think that that is causing you issues.

done this thanks

only did it for 0.2 load (my manual trans NA car idles at 0.2 load)
smoother idle , actually dropped my idle back to 700 from 750 rpm as a result of this change
no dip when a/c cuts in, actually get a slight bump up in rpm now as a/c cuts in at idle
no rattly sound when coasting to a stop in neutral

This is on E85 , NA

Thanks guys for the feedback and help, im sure this will help a lot of people out there because obviously the so called dealer flash isn't helping crap.

Glad to be of help.

Getting Rid Of Idle Dip without a Tune.
 

I have an update on the Idle dip with the AC on. I discovered that even if you spray lubricant on the pulleys if you have the stock Crank Pulley the idle dip will still happen. I lubricated the pulleys AND installed a lightweight crank pulley and the idle dip is much less noticeable and rarely causes the annoying clacking noise when the Idle dips with the AC on.