Bouncing revs
 

Hi!
mine is suffering the following desease: when i switch to neutral and drop throttle after driving load (it doesnot concern to stationary iding throttle games) from say 4000 rpm level, revs dropping down to idle speed and then bounce up to 1400-1500 rpms and then slowly goes down to idle speed level.
I have HKS snorkel, K&N drop in, sound tube delete and some oil catch can, stage2UEL OTS modifyed tune (it behaves the same on several various OTS ROMs, i didnot try stock ROM yet but the last thing i would think in this case is software issue) and OFH header and catless front pipe.
I was thinking that my intake could be leaking somehow, double checked possible leaks but didnot find any.
If someone faced same problem or may advise where should i put my sting first to check the leaks (i already deleted oil catch can and even breathed into/from PCV, but it didnot cure me bouncing) :bonk:
And my OFT or Techstream health check both don't show any DTCs.

check for intake or exhaust leaks
look at you long term fuel trim it it high at low rpm ie over 10

is the k&n an oiled filter if so try cleaning maf sensor maybe oil on maf sensor.

This is the log
http://datazap.me/u/ondreiko/some-wo...log=0&data=1-5

Thank you for the suggestion, will try cleaning MAF sensor. I've seen it not so long ago and it didnot look dirty, but will do anyway. What liquid could i use safely for sensor - soap water or petrol or wynn's? Or some sprayed carb cleaner?
As for leaks - i tried to avoid em just by manual checking and tightening the connections of possible leaking points but failed to find any (intake, didnot actually check exhaust).

does mine LTFT look in gauge? Then they are not leaks?:iono:

ltft looks good unlikely their is leaks

then where to put my sting into? =))

yes can see prroblem here

http://datazap.me/u/ondreiko/some-wo...-917-4476-4480


Verry strange maybe flash stock tune just to eliminate that, wont harm engine but may throw cel coe p0420 due to catless header..

not sure what problem could be maybe check battery volts weird things can happen if battery is dying. also check earth connections in engine bay.

maybe uplug and replug connector on throttle body wth ca switched off.

thank you mate. thought about the battery, and charged it by some automatic charging unit and it seemed the procedure went the normal way. Also when i went to dealer, asked them about and they just cleaned the throttle body, what didnot help neither.

yep, and i added peak bounce line as i see it
http://datazap.me/u/ondreiko/some-wo...4476-4480-4489

Remember that with a snorkel the MAF will catch hell with air being rammed in the box and the throttle closed. example take a fan and blow it in the box while idling your motor will act all sorts of crazy sometimes it stalls the motor. The MAF voltage is fluctuating with the throttle closed and that seams strange to me.


This is when I call my tuner and say hey check this out and he explains its nothing and I feel stupid just sayin. Thank goodness for DT

High pal!
It sounds very true and prospective taking into consideration the fact that i got this bounce only after i disengage the clutch and drop throttle, i.e. only while moving. On the stationary vehicle i cannot reproduce this bounce. The only thing confuses me a bit: how the air is getting inside the bumper? There shouldn't be a direct flow as the duct is located under the front bumper, or do i miss something?
And the suggection: if i use stock filter with same snorkel/airbox, should the issue leave? And one sad thing about the airbox: its rear part has ben slightly deformed due to the jams crowling underhood heat. Now i solved the hood ventilation problem, but the airbox remained deformed - i beleive it shouldnot leak as i checked, but i may appeаr too optimistic as usually:bonk:

I have a AIRAID cold air intake with a greddy scoop and Bill at Delicious Tuning has created a tune that makes the car drive like stock no issues. Now if I shoot a fan at it it will do what you described. Call Bill or Zac at delicious tuning I feel its your tune good luck.
As far as air flow behind your bumper its there and it's powerful.

Thank you again mate. Will try to find if its tru by adding some restrictive materiak into airbox and stock filter. If something changes, then you are crystally right.:happyanim:

Here is fresh log of mine
http://datazap.me/u/ondreiko/fresh-w...9-10-14&solo=2 starting with wot pulls (and there are some thereafter)
i seem knocking. Or not? Log looks really strange cos MAF is jumping upto 14+ whilst the pull - should this issue be somehow concerned to overflowing do you think? Or is this the direct reason for knocking? And do i knock at all (flkc) taking into consideration advance multiplier 1?

Or is it my throttle died a bit?...

My friend, the log doesn't look right to me but I can't tell you why or what to look for in tuning. Try posting your logs in the tuning section maybe someone else can help. good luck

has that tune has maf scaling changed ?

if so check the values maf values at low flow rates mabye some typing error and the load limits.


load the stock tune and see if problem is still their

Hey Steve!

It is bouncing the same way as on OFT OTS Stg2 tune as will as on slighly tweaked MAF scale - it should not be a reason as far as i understand it.

Just flashed stock and put on the stock air filter - picture is the same, the bounce is clearly there
http://datazap.me/u/ondreiko/stock-f...a=1-2-6&solo=2
i also inspected MAF sensor - it doesnot feel sticky at all - do i have to try clean it anyway or should i better find some other possible reason?:bonk:

Now the same picture shows at stock ROM and Takeda intake - i may now suggest that it suppose NOT to be intake or software issue - then what!? Exhaust leaking? May exhaust produce this revs bounce? Unless my throttle is in order...
http://datazap.me/u/ondreiko/takeda-...2-3-6&mark=179

Did takeda intake use oiled filter ?
if so maf may have some oil on ir, you can buy special maf cleaner spray, but you can also use electronic circuit cleaner.

now you know its not tune or intake and if its not dirty maf then its likely to be difficult issue to track down.

now car is back to stock if still under warantee best take to dealer as may be throttle body issue or maf sensor ect.

I have 2 different MAF sensors - one for Takeda, one for stock tube and both of them behave same way. And there is dry filter on takeda, so should not be sensor issue anyway.

The dealers here... you know, i feel i know much more about my car than the local dealer, so i would better find what is wrong myself then take it to the dealer directly pointing the issue. I told you i was at the dealer and asked about the bounce, so they just cleaned throttle body. But will try it sometime anyway.

@Ondreiko did you go stock everything? Stock ROM, stock filter, and remove the HKS snorkel?






did it still do it?

Try cleaning your throttle body its a long shot but you never know.

i went stock everything except snorkel, but the picture didnot change at all - i was trying to catch some differencies in order to determine the reason of the issue, but didnot find any changes yet. My throttle body is clean - couple weeks ago i was at the dealer's and they did it first after i told them about the issue - but it didnot help either...
Wiil go and buy some silicone spray and will refresh manifold pressie sensor's o-ring now again - to see if this changes something. Have no more ideas to investigate.:bonk:

manifold pressure sensor o-ring refreshing didnot help too.
Let me know if the throttle graph in logs showing command or real throttle position? i am wondering, if it shows 0, does it definitely mean that the throttle is closed or is it just DBW command line?
http://datazap.me/u/ondreiko/3-wots-...-6-11&mark=317

You changed everything except the snorkel! try stock snorkel, reflash to stock rom and see what happens

just was at the dealer's service. they didnot recognise the issue, made a log with the bounce and reflashed me upto A02G (my original cal id was A00G). So they promised to send the file to subaru motorz as soon as the warranty engineer returns from vacation (in one-two weeks).
And i am terribly knocking on this new flash A02G.
http://datazap.me/u/ondreiko/stock-a...=0&data=1-9-14

And another reason i dont think it is snorkel issue - she was working fine for quite a while but then suddenly something happened and this bounce appeared. It was ok with HKS duct before.

What makes you say that? I see no evidence in that log. What I do see is that you're not using the right addresses for the change in ROM.

OK heres the deal on A02G roms and OFT

If your running a real A02G rom flashed by the dealer the OFT will not log it correctly.

The reason is the ram addresses for logging knock parameters changed between the A01G and the A02G roms. That why tour IAM reads zero its not knock its just the oft logging incorrect address in ecu. looks like MAF parameters not logging correctly either.

The OFT A02G rom is not rearly an A02G rom its a hacked A01G rom so its loggs correctly but your not actually getting the A02G updates which were probably only idle related as the OFT A02G is rearly just an A01G calid adjusted

The tune tables timing/fueling ect are same A01G/A02G their appeared to be only changes to undefined tables and must have been some code change to shift the ramm addresses for logging

From memory the only knock parameter that logs correctly is KC Learned you can derive IAM and knock from that if your keen.

the oft will log a couple of "throttle" related parameters i cannot rember them at present but i think one is accelerator pedal position ie the input to ecu and the other is the throttle plate position.

it may be worth logging those and seeing if the throttle pedal position remains constant when you get the rpm bounce.

It going to be difficult to diagnose. lots of stuff happens at idle




your going to have to flash a OFT A01G/A02G rom so your logging works again as it looks like the maf v is also not logging correctly.

Advance multiplier = 0, FLKC = 100. My usual reading should read AM = 1, FLKC = or less than 0. So i was thinking Adv. multiplier less than 1 means knocking anyway.
I just reflashed to OFT OTS based A02G tune and it shows everything as i like =))

Do you mean my OFT was logging A02G using A00G definitions and this is the reason why i saw knocks?

Now i start to undrrstand that features, thank you, mate!

Yesterday i reflashed scared mine to OFT based A02G Rom, now it reads correctly

And seems i forgot to mention another symptom of the same, as i think, issue - my revs are dropping too slow if i drop accel pedal on either stationary or moving vehicle. It probably can't be measured (i mean dropping speed), but my feeling is strong and i am sure it is not normal and it should drop faster.

Maybe throttle body actuator is slow to act or faulty, but this is expensive part too expensive to just try without knowing for sure, maybe have to wait for dealer diagnosis.

maybe just try unplugging and cleaning connector at throttle body.

maybe log throttle/accelerator position and throttle plate position on see they move in sync when throttle released.

I think this will work with car just turned on without starting, you could also watch throttle plate like this by removing intake hose with engine off but ignition on.

This is actually what dealer tried to find yesterday - discrepance between command and actual throttle position, but noone was sure if it was detected yesterday. Anyway, dealer loged all throttle related readings. Will see what kind of answer Subaru motors would receive from Toyota motors, where Subaru definitely will forward my request :party0030:

So i found to change MAP, MAF sensors and throttle body - nothing has changed, the bounce is still there. I removed HKS duct as well with the same result.
Moreover, today they called me from local dealer as they received answer from Subaru motors. It stated that my case is not an issue and my engine is working the way it should. I promised to inform them as soon as i find the reason of the bounce myself.
Still thinking of a possible bounce source.