Engine bogging / stumble / hesitation / jerking during accelaration ard 2.5k - 3k RPM
 

Hi all, firstly just wanted to say what great forum, loads of helpful advice and tons of information, keep up the good work!

I've bought my Toyota 86 (that's what its called here) used, just 6 months ago. It is an Automatic, 2013 model, bought new by PO in Nov 2013 and currently has just over 28,000 kms on the clock.

The story starts like this, I've bought the car with just one key (dont worry I got the car for a very good price), PO said he lost the other key. My car's got the keyless smart key system with push start button. The dealership wanted about BND$1800 (USD$1300) all in just to make another copy of the key which I thought is just plain bonkers daylight robbery. Last time I checked its a Toyota not a Ferarri. Anyway, so last two weeks I drove the car some 60 miles to meet this locksmith who says he might be able to duplicate the key for about a third of the price (which I think is still expensive but what can I do).

Once at the locksmith, the technician plugged some kind of handheld decive (like a typical code reader) into the OBD2 port under the steering wheel panel (RHD car) to begin the programming process. What happened after I cant recall exactly but I remember whilst programming he mentioned something about the ECU got unresponsive because I opened the passenger door (I didnt know I'm not allowed to) and he maybe had to reset the ECU and restart the process again.

Long story short, he didnt get to succesfully duplicate my key bcos the blank key he had did not match the originals after looking at the internals, although appears identical on the outside.

The problem began just moments after I left the locksmith. When accelerating with moderate throttle input, say from stop or when merging onto the highway, the engine stumbles/bogs/hesitatates at around 2.5k RPM to about 3k RPM distinctly. Its not there (or I dont realise its there) when in 1st gear but in 2nd, 3rd, 4th, 5th its quite clear. It feels like fuel being cut or as if there are air bubbles in the fuel line and as a result accelaration is slow - embarrassingly slow when merging onto the highway - increasing throttle input also doesnt help much unless I really punch it until it kickdowns and the revs get out of the 2.5-3k range. Sometimes it can get so noticeable that I can feel the car jerking forwards and backwards. Happens both in normal mode and in sport mode. In some rare occassions it is absent but most of the time it is there, the car hasn't been accelarating smoothly ever since.

The car has been well maintained with frequent oil changes and has never been tracked/raced, just occassional spirited runs and most of the time its just cruising along. Its been about a week now since I started noticing it and I've done about 300kms so far. I've also had about 2 fuel fill ups so far so can safely assume its not fuel related.

When it happens, there is no CEL Light, no traction light. I checked the air filter before, removed a small leaf, but problem still persists. It is most noticeable when engine is warm and ambient conditions are also warm i.e. during daytime when temp can reach around 35 deg celcius, and after idling for quite some time i.e. in traffic. During cold i.e. just after a cold start it is barely noticeable or maybe even non-existent.

So far I havent pulled any codes - dont have access to a code reader at the moment and I am hoping to avoid a visit to the dealership for now (lets say bcos of a bad experience before) although I feel I might not have much choice at the moment.

I am stumped as to what is causing this behavior - I dont know much about engines let alone the FA20 boxer. There are so much possibities - the high pressure fuel pump, the compex DI & Port injection programming, the torque dip, a relearning ECU, possibly plugs (happened to my other car before) etc. I think it is the ECU - due to the incident with the locksmith - he probably reset it and now its relearning, but I've already driven about 300kms now in a weeks time so I'm not sure if it should still be relearning, tried the 'pedal reset' method to no avail. I am hoping the solution would be something simple like loose vacuum hose or sensor plug or at least an ECU flash or something.

So far I've searched BRZ/86/FRS forums to no avail, if anyone had experienced the problem before or if you have suggestions or opinion please feel free to chime in. I know there are quite a few gurus here in this forum and I am keen to see what you guys think the issue is.

Thanks for spending time reading my super long post and also thanks in advance for any responses.

Regards, mo420.

I dont think they would be looking to access the ECM (engine control module) but rather the BCM (body control module) when trying to program a key so that shouldn't have anything to do with your issue. I would disconnect the battery let it sit for 10 or so minutes and hook it back and and then go for a good drive. Other then that I wouldn't waste your time trying to fix it if you still got warranty. Yes I know you had a bad experience but most dealership staff is there to help you. I would say give them another shot because its not worth the headache for you to fix if they can do it for free or at the very least find your issue.

Hi thanks for your response. And thanks for pointing out re the BCM and ECM, didnt know there were different 'sections' in an ECU.

So your advice is to unplug the terminals, so that the ECU gets reset? Yeah I think its worth a try.

You are right, I am planning a visit to the stealership if I cant get this sorted myself since the car's still under warranty (however regarding this warranty being honored or otherwise is a different story altogether given the dealership's reputation).

I am just blindly hoping for the vague possibility that someone who had a similar problem shows up here with their solution as I've just came across two threads talking abt the same issue but strangely the OP didnt post how they solved the issue.

Something probably also worth noting is, when I took the car for the 60mi journey, there was a section where the roads were very bad and bumpy, potholes everywhere, road cracks, the lot. After this trip the prpblem started to appear.

Could this have caused my issue? I imagine the severe vibrations could have probably knocked loose a connector, or a vacuum line etc? So far I have briefly inspected the engine and I dont see anything hanging loose, any ideas of potential areas commonly known for stuff to hang loose that I should perhaps check out?

Like mentioned above, I also suggest you disconnect the battery and re-connect to see the ECU will right itself.

You may consider purchasing an inexpensive and check for any stored codes.

Maybe a trip to the dealer is in order.


humfrz

Problem Solved (Hopefully)
 

Hi all, just thought I'd post the updates on my issue.

As suggested, I've tried the ECU reset by unplugging the battery terminal. Drove for about 300kms and problem still persisted. Sigh time to take to the stealership I thought. Because of being busy with work and all so I've left it in the garage for some time.

Eventually I booked for a slot last Thurs at the stealership. Wasnt so convinced by their merits at first (one of the service managers told me the car had no spark plugs since it had direct injectors. Wow) but let them diagnose for the problem for me anyway, they were gona charge $60 per hour.

They did a Techstream scan of the engine and came up to the conclusion that its my direct injectors. By this time my car had now attraced a crowd of mechanics and engineers prolly because its the only exciting car in for repairs today haha so took this opportunity to talk to them abt the injectors. The mechanic in charge of my car told me he's done a lot of DI replacements already so I bit the bullet and let them work on my car. The DIs were replaced under warranty.

Took my car home that afternoon and since then have put about 80kms without any of the earlier bogging issues. The car felt slightly sluggish though but I am assuming this is because the ECU is resetting since they unplugged battery earlier. So I think my issue is solved (hopefully!). Will do some more driving over thr weekend to see if it improves.

The stealership did give me a fews 'gifts' for sending it in - a lot of streak marks from a carwash I specifically told them not to do, a dirty engine bay and best of all - a nasty ding on my left fender :mad0260::( . After complaining they told me they'd putty it and respray for free which I am still considering bc I know their finished quality will never match OEM :(

Anyway, I've uploaded some pics of my dirty DIs for those interested below.

Cheers all,
Mo

Is the yellow the bottom part of the seal? Looks like it was burning away. And seems to be a lot of crud at the tip!

I am not too sure what the yellow part is as I hv yet to see how a new injector looks like. But you are right looks like something was being burnt of other than the fuel and the tip looks sooo dirty for an engine with only 28k kms. I imagine my plugs would also be equally dirty from all the misfiring I've had :(

I wonder if using a top tier gasoline would keep the injectors cleaner? They look like they have 100K miles on them


http://www.toptiergas.com/retailers/

Certainly looks like deposits from crap fuel...

Those injectors look like the non-rechargable batteries i put into a charger.

Hopefully the dealership updated you ECU to the latest revision should be ZA1JB01C (MAN) OR ZA1JB01D (AUTO).

ha ha thought you were in USA

they should update you to latest rom for you region think its ZA1JA01J or A01J

ECU firmware revisions up to A00x had a problem with the Transient ingnition retard settings which contributed to DI seal failure on injectors when accompanied by shifting at redline and poor quality fuel. and ECU firmware A01x or later solved the issue.

Although the injector may have failed for some other reason, there was nothing wrong with the seal. Zero blow-by.

We only have one type of fuel in this country - Shell RON 97 Premium. And yeah the techs are saying fuel quality here is bad. I've heard a lot of R35 GTRs here have suffered bcos of this unfortunately theres no viable alternative :sigh: