JDM 3.0R bogging down

[jbrizz]

Hi all,

I have a 2004 JDM 3.0R Spec B which I bought a few months ago. It is a pre Si-Drive model.

Initially my car performed like a bag of crap on 95 RON fuel, with loads of detonation in low RPM and lots of hesitation and jerkiness. It was better on 98 RON, but still did the hesitation/bogging thing. I could still hear a bit of detonation, so I put it down to that, figuring I will get it tuned for 95 (98 is hard to get here).

Well I've had it tuned a couple days ago and it runs awesome now, for the most part, except I still fairly often have an issue where I put my foot down and I've got very little power for a second or two, then it all comes at once. It's most noticeable on upshifts, but will usually do it if I just stomp on the throttle too. It won't usually do it if I am taking all the way to the redline and shifting, usually only in the 2000 - 4500 rpm range. It feels like when I stomp on the throttle the butterfly is only opening a crack, waiting a second or two then opening all the way. Or, it feels almost exactly like turbo lag. When I finally get the power, it won't be until 3500 - 4000 rpm, or prior to the tune it sometimes not until around 5500 rpm. I haven't done enough driving since the tune to know of the issue is any better, but I don't think it is.

The car has no CEL codes, the MAF has been cleaned, new air filter, and we couldn't reproduce it on the hub brake dyno. Logging is showing the throttle butterfly is doing what it should, the AVCS is following a smooth curve, oil is Castrol Magnatec 5w30 fully synthetic, there is no detonation. ODO is only 43,700 km too.

The car also has an extremely dead throttle for the first 30 seconds to a minute after I start it. Want to pull out into traffic straight away? Not a chance, won't accelerate faster than a Prius. It's a very similar feeling, so might be related. If the revs get up enough (4500 rpm +) it will finally take off. Is this normal?

Lastly, the ROM image "internal ID" that came off my ECU is D2WD606A, and I'm guessing 606 is the version and if that is correct then I know there are newer ones floating around the Internet. So my next step might be to ask Subaru NZ to ask Subaru Japan if there are any firmware updates for it, all at a cost of course.

Any insight into this extremely frustrating problem, or even some comparisons to what I describe to how your own cars go would be much appreciated!

Edit: for anyone stumbling across this post who happens to have similar problems, it was just the knock retard causing the bogging. NZ's 98 octane petrol wasn't good enough for this car and/or the knock sensors were picking up noise. In theory 98 oct should be fine, so we moved the knock sensors down to the back of the engine (at the end of the intake IIRC) and the problem is solved. I can't hear any knock but the car accelerates smoothly and doesn't bog down anymore. The knock I was complaining about goes away after 500km or so of driving and the ECU learns. Ideally a tune is still a good idea as the factory tune seems to prefer 100+ oct which is hard to get in NZ/Aus and Europe.

[alessandro132]

Sounds like a DBW issue to me.

[Robbks]

you need to do some road logging to recoed it and work it out.
these cars have issues with hard jabs at the throttle making the engine knock and pull timing

[jbrizz]

you need to do some road logging to recoed it and work it out.
these cars have issues with hard jabs at the throttle making the engine knock and pull timing

This is what I thought it was initially, hence first thing I really did was take it to get tuned. It's possible that it's still pulling timing, if it is it must be pulling it back by a huge amount.

$1200 for their dyno tune though, I'd like to know what is wrong before I take it back in case I get charged more!

[dr20t]

Fuel type - pure and simple

Jdm hi octane is like 100ron albeit much higher knock resistance than our shitty fuel

Need to remove timing by 2-2.5 degrees in high load / peak torque regions and smoothen the timing table